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Iberian populations of large-bodied newts, with Triturus marmoratus in the north and T. pygmaeus in the south of the peninsula, were studied for external morphology, mitochondrial dna and for a panel of single nucleotide polymorphisms. This confirmed the species' low level of interspecific hybridization and their parapatric, mosaic-like mutual range border across the peninsula. The genetic data also revealed substantial variation within T. pygmaeus, with narrow (0.43-35.2 km) clinal transitions in the very centre of Portugal. Similar clines were observed for body size and colouration pattern. Pygmy newts in the west of Portugal are larger, with a more striped (less reticulated) green dorso-lateral colouration pattern than those in the east and south of the country. The western group of populations is described as a new species, Triturus rudolfi sp. nov., on account of a long, ca. 2.5 Ma, independent evolutionary history and limited hybridization with its sister-species T. pygmaeus, suggesting selection against hybrid offspring. The range of the newly described species may be restricted to the wider Lisbon Peninsula, stretching northwards along the Atlantic coast to the river Vouga estuary. Inland, the range border may be set by the lower Tejo River, or by the currently wide area of agricultural land at either side of that river, that may accommodate a residual hybrid zone. The close contact between both pygmy newt species is effectively limited to a ca. 20 × 40 km area directly north of the town Entroncamento, where T. rudolfi sp. nov. is sandwiched in between T. marmoratus and the river Tejo. [ABSTRACT FROM AUTHOR]

Morphological and genetic variation of organisms is generally lower in northern than in southern regions of the Palearctic. This ubiquitous geographical pattern has been associated with extinction and recolonization processes in the north versus persistence in the Mediterranean area, as governed by climate change in the Pleistocene. One area of differentiation and complexity is the Iberian Peninsula where two distinct sister-species of marbled newts possess adjoining and geographically sharply delimited ranges over the north (Triturus marmoratus) and the south of the peninsula (T. pygmaeus). Within the latter species two forms are here documented, with different colouration patterns and non-overlapping ranges. The southern form is striped, much as in T. marmoratus, and occurs to the south of the Guadalquivir River. The northern form, here described as a new subspecies, has a reticulated dorsal colouration. It occurs only north of the Guadalquivir and is thus sandwiched in between two striped marbled newt taxa. Both T. pygmaeus subspecies engage inside the Doñana National Park in a ca. 2,500 m narrow contact zone. Although an inferred substantial selection against hybrids goes a long way to support species status, a reanalysis of published genetic data is required to solve this issue, along with the wider investigation of the same type of (microsatelite) data for the southern, nominotypical subspecies. [ABSTRACT FROM AUTHOR]

The evolution and maintenance of color clines is a classic topic of research in evolutionary ecology. However, studies analyzing the temporal dynamics of such clines are much less frequent, due to the difficulty of obtaining reliable data about past color distributions along environmental gradients. In this article, we describe a case of decades-long temporal stability and directional change in a color cline of the marine snail Littorina saxatilis along the coastal inlet of the Ría de Vigo (NW Spain). L. saxatilis from this area shows a clear color cline with 3 distinct areas from the innermost to the more wave-exposed localities of the Ría: the inner, protected localities show an abundance of fawn-like individuals; the intermediate localities show a high diversity of colors; and the outer, wave-exposed localities show populations with a high frequency of a black and lineated morph. We compare data from the 1970s and 2022 in the same localities, showing that the cline has kept relatively stable for at least over half a century, except for some directional change and local variability in the frequency of certain morphs. Multiple regression analyses and biodiversity measures are presented to provide clues into the selective pressures that might be involved in the maintenance of this color cline. Future research avenues to properly test the explanatory power of these selective agents as well as the possible origins of the cline are discussed. [ABSTRACT FROM AUTHOR]

Simple Summary: Two species of Sympetrum, namely S. depressiusculum and S. frequens, have been documented in South Korea. However, the distinction between these two species and their identity within South Korean populations has been a longstanding point of contention. To solve this issue, morphology, two mitochondrial genes, and one nuclear region were analyzed for S. depressiusculum samples from The Netherlands and Russia and S. frequens samples from Japan, as well as samples of Sympetrum from South Korea. Further, available public sequence data for the two species were included. Morphology, sequence divergence, and phylogenetic results all consistently suggest that South Korean populations form a single species. Analyses of haplotype network and gene pool distribution patterns in a nuclear region conducted to better explain the current taxonomic implications indicated changes in the dominant gene pool from The Netherlands and Russia to South Korea and Japan. However, such divergence and subdivision could be explained within the context of within-species diversification patterns, suggesting that South Korean populations constitute one species, S. depressiusculum, by applying the senior name. In South Korea, both Sympetrum depressiusculum Sélys, 1841 (Odonata: Libellulidae), which is distributed throughout Europe and from Russia to the Korean Peninsula, and Sympetrum frequens Sélys, 1883, which is endemic to Japan, are recorded. However, the identity of South Korean populations and the validity of listing the two species have not yet been settled. In this study, we collected seventy-four individuals of Sympetrum species from South Korea (five localities), Russia, The Netherlands, and Japan. These samples were examined for morphology and sequenced for partial COI, 16S rRNA, and a nuclear internal spacer (ITS) region, after which these molecular data were combined with available public data from Russia, Japan, and The Netherlands. Major morphological characters that have been used to distinguish the two species and phylogenetic, network, and structure analyses all consistently suggest that South Korean populations form a single species. Consequently, it could be valid to treat South Korean populations as one species, S. depressiusculum, by applying the senior name. Nevertheless, the validity of maintaining each as an independent species in other countries may need additional study considering that our samples were focused more on South Korea and limited for Europe, Russia, and Japan. [ABSTRACT FROM AUTHOR]

Clinal variation in some morphological traits is described in the Italian locust Calliptamus italicus italicus. The trait values increasing from west to east and from north to south can be accounted for by the effect of climatic factors, mostly the temperature, the number of warm days, and the amount of precipitation during the warm period. Records of the species in East Transbaikalia outside its known distribution range are presented. [ABSTRACT FROM AUTHOR]

In insects, male mating success and female fecundity usually increase with body size. However, natural selection favors faster maturation, reducing the risk of pre‐reproductive death, when the reproductive season is short in habitats located at high altitudes or far from the equator. Also, if males that mature earlier than females under these conditions increase their mating opportunities, protandry may evolve in their populations. Nonetheless, as body size is strongly correlated with maturation time in insects, faster sexual maturation is reached at the expense of having a small body size. We analyzed the differences in adult body size of males and females of the grasshopper Sphenarium histrio Gerstaecker (Orthoptera: Pyrgomorphidae) in three sites across an altitudinal gradient in southern Mexico. We also evaluated the possibility of protandry in these sampling sites using a common garden experiment. Male and female grasshoppers collected from low altitude sites in the field and reared in the laboratory were larger than those from a high altitude, suggesting genetic differentiation. Grasshoppers from a high altitude hatched earlier, had a shorter development time, presented fewer instars, and were smaller than grasshoppers from the other sampling sites. Moreover, development time in the three sampling sites was shorter in males than in females, suggesting protandry. Interestingly, the males from the three sites showed similar growth rates, but the females from low and high altitudes, respectively, had the fastest and slowest growth rates. In general, the adaptive value of the evolution of protandry has been focused on males. However, it may be that the growth rates of females in these sites could modify the degree of protandry as a response to their risk of pre‐reproductive death and the potential benefits associated with multiple matings. [ABSTRACT FROM AUTHOR]

A central question in invasion biology is whether adaptive trait evolution following species introduction promotes invasiveness. A growing number of common‐garden experiments document phenotypic differences between native‐ and introduced‐range plants, suggesting that adaptive evolution in the new range may indeed contribute to the success of invasive plants. However, these studies are often subject to methodological pitfalls, resulting in weak evidence for post‐introduction adaptive trait evolution and leaving its role in the invasion process uncertain. In a common‐garden glasshouse study, we compared the growth, life‐history, and reproductive traits of 35 native‐ and introduced‐range Polygonum cespitosum populations. We used complementary approaches including climate‐matching, standardizing parental conditions, selection analysis, and testing for trait–environment relationships to determine whether traits that increase invasiveness adaptively evolved in the species' new range. We found that the majority of introduced‐range populations exhibited a novel trait syndrome consisting of a fast‐paced life history and concomitant sparse, reduced growth form. Selection analysis confirmed that this trait syndrome led to markedly higher fitness (propagule production) over a limited growing season that was characteristic of regions within the introduced range. Additionally, several growth and reproductive traits showed temperature‐based clines consistent with adaptive evolution in the new range. Combined, these results indicate that, subsequent to its introduction to North America over 100 generations ago, P. cespitosum has evolved key traits that maximize propagule production. These changes may in part explain the species' recent transition to invasiveness, illustrating how post‐introduction evolution may contribute to the invasion process. [ABSTRACT FROM AUTHOR]

Abstract Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common garden study to quantify variation in growth and drought resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high integrated water use efficiency (δ13C). Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and low δ13C. Irrespective of climate, we also observed trade‐offs between biomass production and drought resistance traits. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. In addition, ecotypes that grow rapidly may be less able to persist under dry conditions. Land managers may be able to use this variation to improve restoration success by seeding ecotypes with multiple drought resistance traits in areas with lower precipitation. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions.

Genetic variation is often lower at high latitudes, which may compromise the adaptability and hence survival of organisms. Here we show that genetic variability is negatively correlated with northern latitude in European green toads (Bufotes viridis). The result holds true for both putatively neutral microsatellite variation and supposedly adaptive MHC Class IIB variation. In particular, our findings have bearing on the conservation status of this species in Sweden, on the northern limit of its distribution where local populations are small and fragmented. These genetically impoverished populations are closely related to other populations found around the Baltic Sea basin. The low neutral and adaptive variation in these fringe populations compared to population at central ranges confirms a pattern shared across all other amphibians so far studied. In Sweden, the situation of green toads is of concern as the remaining populations may not have the evolutionary potential to cope with present and future environmental challenges. [ABSTRACT FROM AUTHOR]

The commonly observed negative relationship between stomatal density (SD) and atmospheric CO2 has led to SD being proposed as an indicator of atmospheric CO2 concentration. The use of SD as a proxy for CO2, however, has been hampered by an insufficient understanding of the intraspecific variation of this trait. We hypothesized that SD in Pinus sylvestris, a widely distributed conifer, varies geographically and that this variation is determined by major climatic variables. By sampling needles from naturally growing trees along a latitudinal range of 32.25°, equivalent to 13.7°C gradient of mean annual temperature (MAT) across Europe, we found that SD decreased from the warmest southern sites to the coldest sites in the north at a rate of 4 stomata per mm2 for each 1°C, with MAT explaining 44% of the variation. Additionally, samples from a provenance trial exhibited a positive relationship between SD and the MAT of the original localities, suggesting that high SD is an adaptation to warm temperature. Our study revealed one of the strongest intraspecific relationships between SD and climate in any woody species, supporting the utility of SD as a temperature, rather than direct CO2, proxy. In addition, our results predict the response of SD to climate warming. We showed that mean annual temperature is a major positive driver of stomatal density (SD) in Pinus sylvestris needles, both in samples collected across its European range and in a common‐garden trial. This finding suggests that SD may be used as a temperature indicator in climatic research and allows to predict the response of SD to climate warming. [ABSTRACT FROM AUTHOR]

The name Rhodanthidium caturigense (s.l.) combines several similar taxa which have been described on the level of form, subspecies or species and which occur in an area which extends from Iran in the south-east, across the Alps in the north and to the Iberian Peninsula in the west. A detailed quantitative assessment of 17 parameters describing the colour pattern reveals that it follows a smooth geographical cline, with rich yellow coloration in the south being gradually replaced by more melanic colorations in the north. The correlation between geographic latitude and colour scores follows a linear pattern and is highly significant in both sexes (p < 0.0001). In addition, the body size also increases with the geographic latitude, also following a linear trend (p < 0.001). Females in the northernmost population are on average 7.0% and males 19.1% larger than those in the southernmost populations. Some morphological features such as the shape of the male clypeus and the form of the axillae are also subject to variation along a south-north cline. Finally, while there is no sexual size dimorphism in the southernmost populations (size difference, p > 0.05), the males are on average 9.7% larger than the females in the northernmost populations (p < 0.0001). These multiple clinal variations result in geographic forms which are often easily distinguishable from each other but need to be regarded as conspecific because of the gradual character change. Additional evidence that all these forms belong to the same species was obtained from sequencing the mitochondrial CO1 gene. The pairwise genetic distance between specimens from various populations is 1.42% with a maximum of 2.7%, and all specimens are allocated to the same Barcode Index Number (BIN) as established by the Barcode of Life Data System based on algorithms that do not use prior taxonomic knowledge. Rhodanthidium caturigense herewith turns out to be a species with high phenotypic plasticity and apparently a high epigenetic capacity to adapt to certain environmental conditions, not based on genotypic selection mechanisms. [ABSTRACT FROM AUTHOR]

Increased aridity, associated with climate change, is predicted worldwide in the coming decades. Species persistence in the face of climate change is thought to be influenced by plasticity, potential for adaptation, and dependence on non-climatic factors, but their relative importance has rarely been quantified. We investigated 13 populations of Eschscholzia californica (California poppy) distributed across a fourfold gradient in annual precipitation. In a greenhouse, plants received precipitation treatments approximating the wettest and driest sites, crossed with the presence and absence of soil inoculum from their collection location. We documented clinal variation across populations; plants from southern populations (arid sites) emerged later, flowered earlier, had shorter growing seasons, higher mean fitness, higher reproductive effort, and were more drought tolerant than plants from northern populations (mesic sites). A second experiment demonstrated clinal variation in biomass allocation, with higher root allocation in northern populations. We found no evidence of adaptive phenological plasticity to drought; instead, the drought treatment decreased fitness and growing season length (maladaptive phenological plasticity) more for plants from mesic than arid sites. Individuals grown with home soil inoculation produced 10% more biomass than when grown in common garden soil; however, the influence of soil was small relative to the 13-fold variation across populations in fitness responses to drought. Our results suggest that restoration efforts involving California poppy may benefit from assisted gene flow; sourcing seeds from arid parts of the species range may improve individual fitness and population persistence of this iconic species in the face of future climate change.

Seasonal timing traits are commonly under recurrent, spatially variable selection, and are therefore predicted to exhibit clinal variation. Temperate perennial plants often require vernalization to prompt growth and reproduction; however, little is known about whether vernalization requirements change across the range of a broadly distributed species. We performed a critical vernalization duration study in Mimulus ringens, coupled with population genomic analysis. Plants from eight populations spanning the latitudinal range were exposed to varying durations of 4°C vernalization between 0 and 56 days, and flowering response was assessed. RADSeq was also performed to generate 1179 polymorphic SNPs, which were used to examine population structure. We found unexpected life history variation, with some populations lacking vernalization requirement. Population genomic analyses show that these life history variants are highly divergent from perennials, potentially revealing a cryptic species. For perennial populations, minimum vernalization time was surprisingly consistent. However, once vernalized, northern populations flowered almost 3 weeks faster than southern. Furthermore, southern populations exhibited sensitivity to vernalization times beyond flowering competency, suggesting an ability to respond adaptively to different lengths of winter. Mimulus ringens, therefore, reveals evidence of clinal variation, and provides opportunities for future studies addressing mechanistic and ecological hypotheses both within and between incipient species. [ABSTRACT FROM AUTHOR]

Spatial and seasonal variations in the environment are ubiquitous. Environmental heterogeneity can affect natural populations and lead to covariation between environment and allele frequencies. Drosophila melanogaster is known to harbor polymorphisms that change both with latitude and seasons. Identifying the role of selection in driving these changes is not trivial, because nonadaptive processes can cause similar patterns. Given the environment changes in similar ways across seasons and along the latitudinal gradient, one promising approach may be to look for parallelism between clinal and seasonal changes. Here, we test whether there is a genome‐wide correlation between clinal and seasonal changes, and whether the pattern is consistent with selection. Allele frequency estimates were obtained from pooled samples from seven different locations along the east coast of the United States, and across seasons within Pennsylvania. We show that there is a genome‐wide correlation between clinal and seasonal variations, which cannot be explained by linked selection alone. This pattern is stronger in genomic regions with higher functional content, consistent with natural selection. We derive a way to biologically interpret these correlations and show that around 3.7% of the common, autosomal variants could be under parallel seasonal and spatial selection. Our results highlight the contribution of natural selection in driving fluctuations in allele frequencies in natural fly populations and point to a shared genomic basis to climate adaptation that happens over space and time in D. melanogaster. [ABSTRACT FROM AUTHOR]

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Intersexual morphological differences within a species occur in many traits, including body size and shape. Many processes that cause geographic variability in morphology have been proposed: population structure, phenotypic plasticity (environmental effects on development), and natural and/or sexual selection. Several hypotheses can explain patterns of sexual dimorphism in anurans, including natural or intra/inter-sexual selection, and differences in life history strategies between sexes. Limnomedusa macroglossa is considered a habitat specialist restricted to rocky outcrops in Brazil, Argentina, Paraguay, and Uruguay. We evaluated the extent of sexual (size and shape) dimorphism in L. macroglossa from Uruguay based on morphometrics and secondary sexual characteristics, while taking into account geographic variation. Sexual dimorphism in body size of adults was found, but multivariate analyses did not demonstrate the existence of significant differences in shape. There were also significant differences in body size and hind leg measurements among six hydrographic basins as a result from the phenotypic plasticity correlated with local temperature, representing a clinal variation along the latitudinal gradient of Uruguay. The sexual dimorphism found in body size is probably the consequence of higher growth rates and/or late sexual maturity in females, which favors larger body size for accommodating larger ovaries, and thus, higher reproductive output. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eoanthidium insulare was found to have larger and darker bodies in northern latitudes. • The validity of Bergmann's Rule is herein confirmed for a poikilotherm animal. • Despite the size and colouration variation, genetic diversity is very low, and recognition of subspecies is not justified. To analyse geographic variation patterns and assess the applicability of biogeographical rules in insects, the West Palaearctic anthidiine bee Eoanthidium insulare serves as an excellent model. This species showcases a highly variable black-and-yellow colour pattern, with a distribution spanning over 4400 km from the Adriatic Sea to the Pamir Mountains and extending over 1660 km in a south-north direction. We examined 214 specimens from all geographic regions of its distribution and identified a significant increase in both body size and the proportion of black in the integument from south to north. This phenomenon may be attributed to a more efficient exploitation of solar energy through a larger integument surface area (Bergmann's Rule) and enhanced heat retention due to lower skin reflectance (Thermal Melanism Hypothesis). These two processes, therefore, complement each other. However, despite the cooler climates at higher altitudes, we found no correlations between body size and altitude. Furthermore, while we observed an increase in the proportion of black in the integument from east to west, there was no significant increase in body size. Notably, no correlation between body size and body colouration was identified, suggesting that size and colour adaptation are independent processes. Given that the various colour and size patterns were identified as clinal rather than discontinuous, and the intraspecific genetic distance across the distribution area was remarkably low (0.00138), featuring only four distinct haplotypes of the mitochondrial COI region DNA sequence, we suggest that the subspecies E. i. persicolum and E. i. lemesium be regarded as synonymous with the nominate subspecies (syn. nov.). These findings suggest that, although Bergmann's Rule and the Thermal Melanism Hypothesis can account for certain aspects of geographic variation in the body size and colouration of E. insulare , their effects may be influenced or superimposed by factors such as genetic constitution. [ABSTRACT FROM AUTHOR]

Drosophila melanogaster, an ancestrally African species, has recently spread throughout the world, associated with human activity. The species has served as the focus of many studies investigating local adaptation relating to latitudinal variation in non-African populations, especially those from the United States and Australia. These studies have documented the existence of shared, genetically determined phenotypic clines for several life history and morphological traits. However, there are no studies designed to formally address the degree of shared latitudinal differentiation at the genomic level. Here we present our comparative analysis of such differentiation. Not surprisingly, we find evidence of substantial, shared selection responses on the two continents, probably resulting from selection on standing ancestral variation. The polymorphic inversion In(3R)P has an important effect on this pattern, but considerable parallelism is also observed across the genome in regions not associated with inversion polymorphism. Interestingly, parallel latitudinal differentiation is observed even for variants that are not particularly strongly differentiated, which suggests that very large numbers of polymorphisms are targets of spatially varying selection in this species.

Intersexual morphological differences within a species occur in many traits, including body size and shape. Many processes that cause geographic variability in morphology have been proposed: population structure, phenotypic plasticity (environmental effects on development), and natural and/or sexual selection. Several hypotheses can explain patterns of sexual dimorphism in anurans, including natural or intra/inter-sexual selection, and differences in life history strategies between sexes. Limnomedusa macroglossa is considered a habitat specialist restricted to rocky outcrops in Brazil, Argentina, Paraguay, and Uruguay. We evaluated the extent of sexual (size and shape) dimorphism in L. macroglossa from Uruguay based on morphometrics and secondary sexual characteristics, while taking into account geographic variation. Sexual dimorphism in body size of adults was found, but multivariate analyses did not demonstrate the existence of significant differences in shape. There were also significant differences in body size and hind leg measurements among six hydrographic basins as a result from the phenotypic plasticity correlated with local temperature, representing a clinal variation along the latitudinal gradient of Uruguay. The sexual dimorphism found in body size is probably the consequence of higher growth rates and/or late sexual maturity in females, which favors larger body size for accommodating larger ovaries, and thus, higher reproductive output.

Populations along steep environmental gradients are subject to differentiating selection that can result in local adaptation, despite countervailing gene flow, and genetic drift. In montane systems, where species are often restricted to narrow ranges of elevation, it is unclear whether the selection is strong enough to influence functional differentiation of subpopulations differing by a few hundred meters in elevation. We used targeted capture of 12 501 exons from across the genome, including 271 genes previously implicated in altitude adaptation, to test for adaptation to local elevations for 2 highland hummingbird species, Coeligena violifer (n = 62) and Colibri coruscans (n = 101). For each species, we described population genetic structure across the complex geography of the Peruvian Andes and, while accounting for this structure, we tested whether elevational allele frequency clines in single nucleotide polymorphisms (SNPs) showed evidence for local adaptation to elevation. Although the 2 species exhibited contrasting population genetic structures, we found signatures of clinal genetic variation with shifts in elevation in both. The genes with SNP-elevation associations included candidate genes previously discovered for high-elevation adaptation as well as others not previously identified, with cellular functions related to hypoxia response, energy metabolism, and immune function, among others. Despite the homogenizing effects of gene flow and genetic drift, natural selection on parts of the genome evidently optimizes elevation-specific cellular function even within elevation range-restricted montane populations. Consequently, our results suggest local adaptation occurring in narrow elevation bands in tropical mountains, such as the Andes, may effectively make them "taller" biogeographic barriers. [ABSTRACT FROM AUTHOR]

Geographic variation in acoustic signals may arise in vocal learning species due to processes of cultural evolution and population dynamics, but few studies have evaluated geographic vocal variation for large-bodied non-oscine species such as parrots. We evaluated similarity in a contact call of the Military Macaw (Ara militaris) among three populations along the coast of Jalisco, Mexico. We compared contact calls among sites using two approaches i) analysis of specific acoustic parameter measures using GLMM on Principal Components; and ii) evaluation of spectrogram similarity using cross-correlation with a Mantel test to evaluate site and distance effects. Acoustic parameter analysis found that incorporating the site where recordings were obtained significantly explained variation in call features, for both the complete and reduced, balanced dataset. The spectrogram cross-correlations similarity analysis indicated an association with site in spectral similarity of calls, and that call similarity decreased with distance. Our results demonstrated the accumulation of small, fine-scale changes in Military Macaw calls with distance, suggesting that large-bodied non-oscines such as macaws may be able to maintain connectivity among sites by dispersal, facilitating call diffusion, while limited movements among some populations may account for the differentiation among sites in call features. [ABSTRACT FROM AUTHOR]

In boreal forests, autumn frost tolerance in seedlings is a critical fitness component because it determines survival rates during regeneration. To understand the forces that drive local adaptation in this trait, we conducted freezing tests in a common garden setting for 54 Pinus sylvestris (Scots pine) populations (>5000 seedlings) collected across Scandinavia into western Russia, and genotyped 24 of these populations (>900 seedlings) at >10 000 SNPs. Variation in cold hardiness among populations, as measured by QST, was above 80% and followed a distinct cline along latitude and longitude, demonstrating significant adaptation to climate at origin. In contrast, the genetic differentiation was very weak (mean FST 0.37%). Despite even allele frequency distribution in the vast majority of SNPs among all populations, a few rare alleles appeared at very high or at fixation in marginal populations restricted to northwestern Fennoscandia. Genotype–environment associations showed that climate variables explained 2.9% of the genetic differentiation, while genotype–phenotype associations revealed a high marker-estimated heritability of frost hardiness of 0.56, but identified no major loci. Very extensive gene flow, strong local adaptation, and signals of complex demographic history across markers are interesting topics of forthcoming studies on this species to better clarify signatures of selection and demography.

Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common garden study to quantify variation in growth and drought resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high integrated water use efficiency (δ13C). Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and low δ13C. Irrespective of climate, we also observed trade‐offs between biomass production and drought resistance traits. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. In addition, ecotypes that grow rapidly may be less able to persist under dry conditions. Land managers may be able to use this variation to improve restoration success by seeding ecotypes with multiple drought resistance traits in areas with lower precipitation. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions. [ABSTRACT FROM AUTHOR]

Abstract Background Species delineation is particularly challenging in taxa with substantial intra-specific variation. In systematic studies of fishes, meristics and linear measurements that describe shape are often used to delineate species. Yet, little is known about the taxonomic value of these two types of morphological characteristics. Here, we used Tropheus (Teleostei, Cichlidae) from the southern subbasin of Lake Tanganyika to test which of these types of characters best matched genetic lineages that could represent species in this group of stenotypic rock-dwelling cichlids. We further investigated intra-population variation in morphology. By linking this to a proxy of a population’s age, we could assess the evolutionary stability of different kinds of morphological markers. Results Morphological data was collected from 570 specimens originating from 86 localities. An AFLP approach revealed the presence of five lineages in the southern subbasin: T. moorii, T. brichardi, T. sp. ‘maculatus’, T. sp. ‘Mpimbwe’ and T. sp. ‘red’, which we consider to represent distinct species. Although both types of morphological data supported this classification, a comparison of PST-values that describe inter-population morphological differentiation, revealed a better correspondence between the taxon delineation based on AFLP data and the patterns revealed by an analysis of meristics than between the AFLP-based taxon delineation and the patterns revealed by an analysis of shape. However, classifying southern populations of Tropheus was inherently difficult as they contained a large amount of clinal variation, both in genetic and in morphological data, and both within and among species. A scenario is put forward to explain the current-day distribution of the species and colour varieties and the observed clinal variation across the subbasin’s shoreline. Additionally, we observed that variation in shape was larger in populations from shallow shores whereas populations from steep shores were more variable in meristics. This difference is explained in terms of the different timescales at which small and large scale lake level fluctuations affected populations of littoral cichlids at steep and shallow shores. Conclusions Our results showed meristics to be more evolutionary stable, and of higher taxonomic value for species delimitation in Tropheus, than linear measurements that describe shape. These results should be taken into account when interpreting morphological differences between populations of highly stenotypic species, such as littoral cichlids from the Great East African Lakes.

Knowledge about geographic variation within the native range of forest tree species is the logical first step in genetic studies. Wild almond (Amygdalus scoparia Spach.) is a multi-purpose species with a widespread geographic distribution in most of the vegetation regions of Iran. In order to study the geographic variation of wild almond, nineteen biometric features of seed, leaf and seedling from seven natural population of this species in Fras province were measured. Significant differences were observed among the populations for all of the studied characteristics. Hundred seed weight, leaf area and number of stems showed maximum variation among the studied traits. Seed traits presented a significant positive correlation in terms of mean annual rainfall. Correlation analyses between biometric traits and geoclimatic factors indicated the existence of clinal variation in some seed, leaf and seedling traits. Seedling leaf morphometric (dimension) traits decreased gradually from north to south populations; while seedling height declines from east to west populations. That means the geographic variation of the plant at the seedling stages reveals a two- way variation with the latitude and longitude. Principal component analysis (PCA) and cluster analysis of data revealed four distinct groups of populations, and separated populations of high rainfall area form that of lower rainfall area. Results also revealed that A. scoparia uses adaptive strategies in response to water deficit.

In this study, we examined the evolutionary outcome of and interplay between historic isolation and current selection pressures on traits more or less closely connected to fitness in the Pearly Heath butterfly (Coenonympha arcania) across its range in Europe. We hypothesized that a trait mean is more related to historic events if it has low connection to fitness, while a trait more closely connected with fitness is expected to have a mean that relates more to current selection pressures. In order to test this, we collected 322 butterflies from across the species range in Europe and measured five wing traits relating to size and color patterns. To infer a phylogeographic history for each individual, we sequenced a 594 bp fragment of the COI gene. The morphological data were then analyzed in relation to selected climatic variables and the history of individuals to disentangle which factors best correlated with morphological variation. The results supported our hypothesis in that wing sizes correlated with summer precipitation but not with its inferred location during the last glaciation. Eyespot position, on the other hand, correlated with the history of individuals but not with the analyzed climatic indicators. The sizes of the black spot and the white band, two traits that were expected to have intermediate selection pressure, were associated with both history and current conditions. Thus, this study illustrates the fascinating interplay between events and processes that lead to a specific evolutionary outcome. [ABSTRACT FROM AUTHOR]

Key message: Black spruce ecotypes exhibit temperature-adapted bud burst, while bud set is independent of temperature. Warmer conditions could advance bud burst, but no direct effect is expected for bud set Phenological adjustment is a key adaptive trait closely associated with the environment. Species spreading over a wide geographical range can evolve ecotypes that are able to grow and reproduce under particular local conditions. We compared the thermal conditions during bud phenology in black spruce [Picea mariana (Mill.) BSP] populations to assess the differences among ecotypes. The phases of bud burst and bud set were monitored weekly during 2015, 2017 and 2018 in saplings growing in a common garden, and originating from a latitudinal range across the whole closed boreal forest of Quebec, Canada. Provenances from the northern sites exhibited both earlier bud burst and bud set, with differences of 8 and 11 days, respectively, between the northern and southern provenances. Bud burst occurred under colder temperatures in provenances from the northern sites. The phase of open bud occurred at 4 °C in the northernmost provenance, compared to 8 °C in the southernmost one. Bud set occurred in summer, when temperatures still exceeded 20 °C, and no difference was observed between provenances. Black spruce populations exhibit a clear clinal differentiation in ecotypes showing temperature-adapted bud burst of the apical meristem. The need to complete formation of the winter bud and hardening before autumn leads bud set to being independent of the air temperature. Warmer conditions can affect the timings of spring phenology by anticipating bud burst in black spruce, although no direct effect may be expected for bud set. [ABSTRACT FROM AUTHOR]

Reproductive diapause is a primary mechanism used by arthropods to synchronize their life cycle with seasonal changes in temperate regions. Our study species, Drosophila montana, represents the northern insect species where flies enter reproductive diapause under short day conditions and where the precise timing of diapause is crucial for both survival and offspring production. We have studied clinal variation in the critical day length for female diapause induction (CDL) and their overall susceptibility to enter diapause (diapause incidence), as well as the temperature sensitivity of these traits. The study was performed using multiple strains from four latitudinal clines of the species – short clines in Finland and Alaska and long clines in the Rocky Mountains and the western coast of North America – and from one population in Kamchatka, Russia. CDL showed strong latitudinal clines on both continents, decreasing by one hour per five degrees decline in latitude, on average. CDL also decreased in all populations along with an increase in fly rearing temperature postponing the diapause to later calendar time, the effects of temperature being stronger in southern than in northern population. Female diapause incidence was close to 100% under short day/low temperature conditions in all populations, but decreased below 50% even under short days in 19°C in the southern North American western coast populations and in 22°C in most populations. Comparing a diversity of climatic data for the studied populations showed that while CDL is under a tight photoperiodic regulation linked with latitude, its length depends also on climatic factors determining the growing season length. Overall, the study deepens our understanding of how spatial and environmental parameters affect the seasonal timing of an important biological event, reproductive diapause and helps to estimate the evolutionary potential of insect populations to survive in changing climatic conditions. [ABSTRACT FROM AUTHOR]

Picumnus limae Snethlage, 1924 and Picumnus fulvescens Stager, 1961 are two similar species of piculets distinguished by their plumage colouration and distribution. We present here a taxonomic reassessment of these two species based on a large sample of museum specimens and photographic material. We show that the two species are highly variable in colouration, showing a clinal colour gradient. Picumnus fulvescens is not diagnosable from P. limae by any morphological features or vocalization. We thus suggest that P. fulvescens should be considered a synonym of P. limae, which presents a large variation in plumage colour. [ABSTRACT FROM AUTHOR]

The force of sexual selection acts upon the mating process of all beings, this great force is influenced by different factors as phenotypic characteristics. Related to mate choice, in humans, recent studies have shown that, along with eye color, hair color is considered a relevant physical trait (Frost, 2006). Thereby, the purpose of this study is to reveal how these two factors influence mate choice by analyzing the hair color preference of a small population from Romania. Additionally, we explore how different types of selection influence each other and assume that both contribute in choosing a partner. In order to obtain basic data, a socio-demographic survey was addressed to adult male and female individuals. Based on their answers, disregarding the gender, a considerable number of individuals are brown-haired, as we expected from this area of the globe. Among the results obtained, the following considerations are worth mentioning: the most common hair color in Romania is brown, individuals with this trait are considered the most attractive for the opposite sex and parents' hair color represents a predictor for future partners. These preferences are both in concordance and in contrast with natural selection. However, much more research is needed, approaching other areas such as genetics and forensics to determine how all these mechanisms, as well as others, affect the process of mating. [ABSTRACT FROM AUTHOR]

Progenies from open pollinated cones collected in natural populations of Norway spruce (Picea abies (L.) Karst.) distributed along two altitudinal transects in Mid-Norway were tested in the nursery, in short term tests and in long-term field trials. The populations showed clinal variation related to the mean annual temperatures of the populations, with the earliest bud flush and cessation of shoot elongation and lowest height at age nine years for the high altitude populations. Within population variation was considerable as the narrow sense heritability for these traits was 0.67, 0.31 and 0.09 in one transect and 0.55, 0.18 and 0.14 in the other transect, respectively. Lammas shoots occurred in the short term trials with large variation in frequency between years. There was significant family variation for this trait, but also interactions between populations and year. The variance within populations was considerably larger in the populations from low altitude compared to the high-altitude populations. Significant genetic correlations between height and phenology traits and damage scores indicate that families flushing early and ceasing growth late were taller. Taller families also had higher frequencies of damages. Selection of the top 20% families for height growth in short term tests at age nine years gave a simulated gain of 11% increased height growth at age 18 years in long term trials at altitudes similar to those of origin of the populations. The gain was negative when high altitude populations were selected based on testing in the lowland.

• The wild-ginger, series Sakawanum shows clinal floral variation. • Evolutionary history of four taxa was inferred by molecular markers. • Two admixture events may have occurred between morphologically distinct taxa. • Geographic range shift to glacial refugia could have allowed secondary contact. • A complicated demographic history may have shaped intertaxonomic clinal variation. Clinal variation is a major pattern of observed phenotypic diversity and identifying underlying demographic processes is a necessary step to understand the establishment of clinal variation. The wild ginger series Sakawanum (genus Asarum) comprises four taxa, which exhibit intertaxonomic clinal variation in calyx lobe length across two continental islands isolated by a sea strait. To test alternative hypotheses of the evolutionary history and to determine the implications for the formation of clinal variation, we conducted approximate Bayesian computation (ABC) analysis and ecological niche modeling (ENM). ABC analysis indicated that the scenario assuming multiple admixture events was strongly supported. This scenario assumed two admixture events occurred between morphologically distinct taxa, likely leading to the generation of intermediate taxa. One of the admixture events was estimated to have occurred during the last glacial maximum (LGM), during which the taxa were estimated to have formed a common refugia in southern areas by ENM analysis. Although four taxa are currently distributed allopatrically on different islands and trans-oceanic dispersal appears unlikely, the formation of a land bridge and the geographic range shift to refugia would have allowed secondary contact between previously isolated taxa. This study suggests that clinal variation can be shaped by demographic history including multiple admixtures due to climatic oscillations. [ABSTRACT FROM AUTHOR]

The reality of spatial clinal variation in morphological traits of freshwater pulmonate snails (Gastropoda: Pulmonata) has repeatedly been questioned or totally discounted. There is a lack of sound statistical evidence in the articles hitherto published on this subject supporting these claims. Here, by means of different analytical methods (analysis of spatial autocorrelation, linear regression analysis, canonical correlation analysis and others), we demonstrate that shell variation in the dwarf pond snail, Galba truncatula, is patterned in space throughout the northern and central Palearctic, with latitudinally-oriented clines in body size and in some shell proportions. Shell size in G. truncatula decreases with latitude and temperature, representing a special case of converse Bergmann cline. However, the temperature itself is hardly the main driver of shell size variation. It is argued that the shorter growing seasons at high latitudes may represent a better explanation for the observed trend. Shell proportions in the dwarf pond snails vary weakly at the macrogeographic scale, being spatially patterned at lower (mesogeographic) scales around 1200–1500 km. In general, spatial variation in G. truncatula shell size is decoupled from variation in shell shape, demonstrating clear scale-dependence similar to that found in different species of terrestrial (non-aquatic) pulmonate snails. [ABSTRACT FROM AUTHOR]

Plasticity, local adaptation and evolutionary trade‐offs drive clinal variation in traits associated with lifetime growth. Disentangling the processes and determinants that cause these traits to vary helps to understand species' responses to changing environments. This is particularly urgent for exploited populations, where size‐selective harvest can induce life‐history evolution.Lake trout (Salvelinus namaycush) are an exploited fish with a life history adapted to low‐productivity freshwaters of northern North America, which makes them highly vulnerable to ecosystem changes and overfishing. We characterized life‐history variation across a broad and diverse landscape for this iconic northern freshwater fish and evaluated whether clinal variation was consistent with hypotheses for local adaptation or growth plasticity.We estimated growth‐associated traits for 90 populations exposed to a diversity of environments using a Bayesian multivariate hierarchical model. We tested for clinal variation in their somatic growth, size at maturity and reproductive allocation along environmental gradients of lake productivity, climate, prey and exploitation clines under competing hypotheses of plasticity and local adaptation.Clinal life‐history variation was consistent with growth plasticity and local adaptations but not harvest‐induced evolution. Variation in somatic growth was explained by exploitation, climate and prey fish occurrence. Increased exploitation, from pristine to fully exploited conditions, led to increased somatic growth (from 32 to 45 mm/year) and adult life spans, and reduced age at maturity (from 11 to 8 years). Variation in size at maturity was explained by climate and, less certainly, prey fish occurrence, while reproductive allocation was explained by evolutionary trade‐offs with mortality and other traits, but not environment. Lake trout life‐history variation within this range was as wide as that observed across dozens of other freshwater species.Lake trout life histories resulted from evolutionary trade‐offs, growth plasticity and local adaptations along several environmental clines. Presuming a plastic response, we documented ~1.4‐fold growth compensation to exploitation—lower growth compensation than observed in many freshwater fishes. These results suggest that harvested species exposed to spatially structured and diverse environments may have substantial clinal variation on different traits, but due to different processes, and this has implications for their resilience and successful management. [ABSTRACT FROM AUTHOR]

Taxa harboring high levels of standing variation may be more likely to adapt to rapid environmental shifts and experience ecological speciation. Here, we characterize geographic and host‐related differentiation for 10,241 single nucleotide polymorphisms in Rhagoletis pomonella fruit flies to infer whether standing genetic variation in adult eclosion time in the ancestral hawthorn (Crataegus spp.)‐infesting host race, as opposed to new mutations, contributed substantially to its recent shift to earlier fruiting apple (Malus domestica). Allele frequency differences associated with early vs. late eclosion time within each host race were significantly related to geographic genetic variation and host race differentiation across four sites, arrayed from north to south along a 430‐km transect, where the host races co‐occur in sympatry in the Midwest United States. Host fruiting phenology is clinal, with both apple and hawthorn trees fruiting earlier in the North and later in the South. Thus, we expected alleles associated with earlier eclosion to be at higher frequencies in northern populations. This pattern was observed in the hawthorn race across all four populations; however, allele frequency patterns in the apple race were more complex. Despite the generally earlier eclosion timing of apple flies and corresponding apple fruiting phenology, alleles on chromosomes 2 and 3 associated with earlier emergence were paradoxically at lower frequency in the apple than hawthorn host race across all four sympatric sites. However, loci on chromosome 1 did show higher frequencies of early eclosion‐associated alleles in the apple than hawthorn host race at the two southern sites, potentially accounting for their earlier eclosion phenotype. Thus, although extensive clinal genetic variation in the ancestral hawthorn race exists and contributed to the host shift to apple, further study is needed to resolve details of how this standing variation was selected to generate earlier eclosing apple fly populations in the North. We advance understanding of the genomic basis for adaptation and the origins of biodiversity by demonstrating that selection on standing geographic variation for diapause timing in the ancestral race of Rhagoletis pomonella, a model for ecological speciation in action, can account for substantial genomic differentiation between recently diverged host races. Photo credit: Hannes Schuler. [ABSTRACT FROM AUTHOR]

Genetic resources have to be managed appropriately to mitigate the impact of climate change. For many wildland plants, conservation will require knowledge of the climatic factors affecting intraspecific genetic variation to minimize maladaptation. Knowledge of the interaction between traits and climate can focus management resources on vulnerable populations, provide guidance for seed transfer, and enhance fitness and resilience under changing climates. In this study, traits of big sagebrush (Artemisia tridentata) were examined among common gardens located in different climates. We focus on two subspecies, wyomingensis and tridentata, that occupy the most imperiled warm‐dry spectrum of the sagebrush biome. Populations collected across the sagebrush biome were recorded for flower phenology and survival. Mixed‐effects models examined each trait to evaluate genetic variation, environmental effects, and adaptive breadth of populations. Climate variables derived from population‐source locations were significantly associated with these traits (P < 0.0001), explaining 31% and 11% of the flower phenology and survival variation, respectively. To illustrate our model and assess variability in prediction, we examine fixed and focal point seed transfer approaches to map contemporary and climate model ensemble projections in two different regions of the sagebrush biome. A comparison of seed transfer areas predicts that populations from warmer climates become more prevalent, replacing colder‐adapted populations by mid‐century. However, these warm‐adapted populations are often located along the trailing edge, margins of the species range predicted to be lost due to a contraction of the climatic niche. Management efforts should focus on the collection and conservation of vulnerable populations and prudent seed transfer to colder regions where these populations are projected to occur by mid‐century. Our models provide the foundation to develop an empirical, climate‐based seed transfer system for current and future restoration of big sagebrush. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photoperiodic regulation of diapause is disturbed at high temperatures. • Critical temperature, where diapause is prevented, increases towards high latitudes. • Effects of temperature are stronger in continuous darkness than in short daylength. • Critical temperature shows correlation with the daylength inducing diapause. • Diapause is less sensitive to climate warming at high than at low latitudes. Insect adaptation to climatic conditions at different latitudes has required changes in life-history traits linked with survival and reproduction. Several species, including Drosophila montana , show robust latitudinal variation in the critical day length (CDL), below which more than half of the emerging females enter reproductive diapause at a given temperature. Here we used a novel approach to find out whether D. montana also shows latitudinal variation in the critical temperature (CTemp), above which the photoperiodic regulation of diapause is disturbed so that the females develop ovaries in daylengths that are far below their CDL. We estimated CTemp for 53 strains from different latitudes on 3 continents after measuring their diapause proportions at a range of temperatures in 12 h daylength (for 29 of the strains also in continuous darkness). In 12 h daylength, CTemp increased towards high latitudes alongside an increase in CDL, and in 3 high-latitude strains diapause proportion exceeded 50% in all temperatures. In continuous darkness, the diapause proportion was above 50% in the lowest temperature(s) in only 9 strains, all of which came from high latitudes. In the second part of the study, we measured changes in CTemp and CDL in a selection experiment favouring reproduction in short daylength (photoperiodic selection) and by exercising selection for females that reproduce in LD12:12 at low temperature (photoperiodic and temperature selection). In both experiments selection induced parallel changes in CDL and CTemp, confirming correlations seen between these traits along latitudinal clines. Overall, our findings suggest that selection towards strong photoperiodic diapause and long CDL at high latitudes has decreased the dependency of D. montana diapause on environmental temperature. Accordingly, the prevalence and timing of the diapause of D. montana is likely to be less vulnerable to climate warming in high- than low-latitude populations. [ABSTRACT FROM AUTHOR]

Individuals within a geographically widespreadspecies may face considerably different environmental and ecological conditions depending on which part of the range they inhabit. This is especially true for species with long latitudinal distributions. Natural selection pressure may lead to genetic divergence and eventual speciation if the homogenizing effects of broad based gene flow are insufficient to prevent it. Therefore, clinal variation may be due either to local environmental influence on gene expression or to natural selection and reduced gene flow at the edges of the distribution.Mitochondrial DNA sequence data and morphological characters for three species of edible goose barnacles are compared in the examination of three situations which exhibit varying degrees of potential gene flow. The first of these is possible genetic clinal variation within an apparently continuous population of Pollicipes polymerus, having a 3,300 km latitudinal distribution. The second is genetic divergence between seemingly geographically separate sub-populations of a congener, Pollicipes elegans, with a 4,400 km latitudinal distribution. The last question concerns the genetic relationships between these two eastern Pacific Ocean species, and a third, geographically isolated congener from the eastern Atlantic Ocean, Pollicipes pollicipes.Surprisingly, the present data do not reveal a genetic discontinuity or latitudinal gradient in Pollicipes polymerus, despite the fact that the distribution of this species crosses a major marine biogeographic boundary between the Oregonian and Californian faunal provinces. This finding contradicts the hypothesis that differing reproductive types north and south of Pt. Conception are due to reduced gene flow and genetic divergence.The disjunct (paramphitropical) sub-populations of Pollicipes elegans have a net nucleotide sequence divergence of about 1.2%. Calculated estimates for the timing of this genetic divergence range from 292,500 to 1,260,000 years before present. A divergence of this magnitude coincides with Pleistocene Epoch cooling periods and the narrowing or disappearance of the warmer sea surface temperatures forming the northequatorial barrier between present day sub-populations. This "ice age" timing for genetic interchange is not unexpected. However, the present data offer evidence for multiple transgressions of the equatorial barrier in both directions, rather than a single limited exchange.Pollicipes, represented by three extant species, has a Tethyan distribution. Curiously, Pollicipes elegans, from the eastern Pacific, is more similar to Pollicipes pollicipes, the eastern Atlantic species, than it is to P. polymerus from the northeastern Pacific. Estimated time of genetic divergence for these two species is about 37 million years before present, near the Eocene/Oligocene boundary, when the Tethys Sea was uninterrupted and the Atlantic was significantly narrower that it is today.

Support for macroecological rules in insects is mixed, with potential confounding interrelations between patterns rarely studied. We here investigate global patterns in body and wing size, sexual size dimorphism and range size in common fruit flies (Diptera: Drosophilidae) and explore potential interrelations and the predictive power of Allen's, Bergmann's, Rensch's and Rapoport's rules. We found that thorax length (r2 = 0.05) and wing size (r2 = 0.09) increased with latitude, supporting Bergmann's rule. Contrary to patterns often found in endothermic vertebrates, relative wing size increased towards the poles (r2 = 0.12), a pattern against Allen's rule, which we attribute to selection for increased flight capacity in the cold. Sexual size dimorphism decreased with size, evincing Rensch's rule across the family (r2 = 0.14). Yet, this pattern was largely driven by the virilis–repleta radiation. Finally, range size did not correlate with latitude, although a positive relationship was present in a subset of the species investigated, providing no convincing evidence for Rapoport's rule. We further found little support for confounding interrelations between body size, wing loading and range size in this taxon. Nevertheless, we demonstrate that studying several traits simultaneously at minimum permits better interpretation in case of multiple, potentially conflicting trends or hypotheses concerning the macroecology of insects. [ABSTRACT FROM AUTHOR]

Pleistocene glacial periods have had a major influence on the geographical patterns of genetic structure of species in tropical montane regions. However, their effect on morphological differentiation among populations of cloud forest plants remains virtually unexplored. Here, we address this question by testing whether geographical patterns of morphological variation in Ocotea psychotrioides can be explained by the intensity of climate change occurring during 130,000 years. For this, we measured vegetative and reproductive traits for 96 individuals from 36 localities registered across the species’ distribution range. Species distribution models and multivariate statistics were used to investigate geographical patterns of morphological variation and test their association with current and past climatic conditions. Leaf size and pubescence in O. psychotrioides showed a latitudinal pattern of clinal variation that does not fit the geographical gradient of increasing leaf size towards lower latitudes observed globally among plants. Instead, the observed clinal variation conforms to a pattern of increasing leaf size towards higher latitudes. However, our analyses showed weak to non-significant association between morphology and current climate. Interestingly, our analyses showed that predicted shifts in the distribution range of O. psychotrioides during the last 130,000 years were accompanied by significant changes in climatic conditions, particularly temperature seasonality and precipitation. Accordingly, climatic instability showed a better fit to the observed patterns of leaf size and pubescence variation than current climate conditions. These results suggest that climatic instability during the Pleistocene glacial periods might play a key role in promoting morphological differentiation among populations of cloud forest plants. [ABSTRACT FROM AUTHOR]

Abstract: Speciation is a process proceeding from weak to complete reproductive isolation. In this continuum, naturally hybridizing taxa provide a promising avenue for revealing the genetic changes associated with the incipient stages of speciation. To identify such changes between two subspecies of rabbits that display partial reproductive isolation, we studied patterns of allele frequency change across their hybrid zone using whole‐genome sequencing. To connect levels and patterns of genetic differentiation with phenotypic manifestations of subfertility in hybrid rabbits, we further investigated patterns of gene expression in testis. Geographic cline analysis revealed 253 regions characterized by steep changes in allele frequency across their natural region of contact. This catalog of regions is likely to be enriched for loci implicated in reproductive barriers and yielded several insights into the evolution of hybrid dysfunction in rabbits: (i) incomplete reproductive isolation is likely governed by the effects of many loci, (ii) protein–protein interaction analysis suggest that genes within these loci interact more than expected by chance, (iii) regulatory variation is likely the primary driver of incompatibilities, and (iv) large chromosomal rearrangements appear not to be a major mechanism underlying incompatibilities or promoting isolation in the face of gene flow. We detected extensive misregulation of gene expression in testis of hybrid males, but not a statistical overrepresentation of differentially expressed genes in candidate regions. Our results also did not support an X chromosome‐wide disruption of expression as observed in mice and cats, suggesting variation in the mechanistic basis of hybrid male reduced fertility among mammals. [ABSTRACT FROM AUTHOR]

The Rusty-breasted Antpitta ( Grallaricula ferrugineipectus) is widely distributed within the tropical Andes of South America. We analyzed 73 study specimens, 25 vouchered tissue samples, and 123 audio recordings to assess geographic variation in genetics, vocalizations, and morphology and evaluate species limits. We found that Grallaricula ferrugineipectus as currently defined is polyphyletic because populations from Colombia and Venezuela form a clade closely related to Andean populations of G. nana, whereas populations from Peru and Bolivia are recovered as sister to G. lineifrons. Birds in Colombia and Venezuela (the northern group) last shared a common ancestor with birds from Peru and Bolivia (the southern group) more than 10 million years ago. Northern and southern groups additionally differ in song, suggesting they may have evolved substantial premating reproductive isolation. Discriminant function analysis reliably distinguished songs from northern and southern groups in multivariate acoustic space, but univariate analyses found non-overlapping acoustic variation between northern and southern groups in only one trait: mean note maximum frequency (and other correlated measures of song pitch). This finding suggests that the 'three-trait' threshold for using vocalizations to inform species limits, which was developed for another suboscine group, the antbirds (Thamnophilidae), may be conservative when applied to antpittas (Grallariidae). In addition, we document apparent clinal variation in song pace within the southern group, a rare example of a suboscine with geographic clinal variation in a vocal trait. Finally, we show that northern and southern groups differ markedly in morphology. In summary, northern and southern groups of Rusty-breasted Antpittas are divergent in genetics, vocalizations, and morphology, demonstrating that these taxa are best classified as 2 monophyletic, biological species with allopatric distributions. [ABSTRACT FROM AUTHOR]