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The reproductive and phylogenetic relationships of lenoks of the genus Brachymystax are considered based on analysis of 30 allozyme loci and two fragments (411 and 987 base pairs) of the mitochondrial DNA control region. The presence of three phylogenetic lenok groups, the blunt-snouted and sharp-snouted groups from Russia and neighboring countries and the Qinling group from China and South Korea, has been confirmed. It is assumed that the center of origin of the genus Brachymystax was Primorye and the blunt-snouted lenok from this region is closest to the ancestral form. Modern assumptions on the taxonomic status of different forms of lenok are contradictory both in the number of species (from one to five) and in their composition. The identification of two or three species in the genus Brachymystax is most reasonable. The main problems that should be solved to clarify the phylogeny and taxonomy of representatives of this genus are indicated. [ABSTRACT FROM AUTHOR]

Summary: Between 1959 and 1988, three populations of purple-flowered terrestrial orchids attributable to Dactylorhiza subgenus Dactylorhiza were discovered in Canada. The populations at Timmins, Ontario, and St John's, Newfoundland were strongly marked on both flowers and leaves, in contrast with the anthocyanin-deficient population at Tilt Cove, Newfoundland. All three populations have since experienced a wide range of taxonomic assignments; debates are also ongoing regarding their origin and most appropriate conservation status. Here, we address these questions by combining detailed in situ morphometric analyses based on 52 characters with allozyme profiles and data from nrITS, 15 plastid microsatellites and seven nuclear microsatellites. The allozyme data alone are sufficient to both confirm allopolyploidy and categorically refute past assignments of these populations to D. incarnata, D. maculata, D. fuchsii, D. majalis or D. purpurella. Several morphometric characters, nuclear microsatellites and nrITS all reliably distinguish each of the three study populations, whereas the two sampled subpopulations from St John's proved near-identical morphologically. In contrast, morphological variation within each of the three populations is strikingly low, particularly in characters other than those influenced by plant vigour. Similarly, compared with 14 European populations, the three Canadian populations proved genetically impoverished (two were near-invariant) and likely experienced recent, extreme genetic bottlenecks during establishment. The three populations differ substantially, both morphologically and molecularly, therefore probably representing independent immigration events. Although clearly attributable to D. praetermissa, all three populations deviate significantly in morphology and DNA data from comparable populations sampled across Europe, preventing identification of their precise geographic origins. Any attempt to determine their mode or origin — through natural long-distance transport, or accidental or deliberate introduction by humans – is challenged to explain why three lineages of a single European Marsh-orchid species, each in different ways atypical of that species, arrived independently in North America whereas no other European dactylorchid species has become established there. [ABSTRACT FROM AUTHOR]

Botrychium farrarii is described as a new species from the Bighorn Mountains of Wyoming, U.S.A. Based on allozyme patterns and chloroplast and nuclear sequence data, it is inferred to be a diploid and the maternal (i.e., chloroplast donor) parent of three allotetraploids, B. furculatum, B. minganense, and B. paradoxum, with which it shares similar morphological traits. Botrychium farrarii is closely related to B. campestre sensu lato, from which it differs primarily by having longer trophophore and sporophore stalks. A key to B. farrarii and morphologically-similar species is presented. At this time, B. farrarii is documented by few individuals from four small, montane forest openings and roadsides in close proximity within a single watershed. Its full geographic range and habitat preferences remain unknown, and we hope this paper will spur discovery of additional populations. Until the species is known to be more abundant, it would be prudent to manage each site to maintain population viability, including avoidance of actions that could adversely impact plant persistence or habitat suitability. [ABSTRACT FROM AUTHOR]

In the case of Aegilops tauschii the comparison of intraspecies molecular phylogeny based on DNA sequences of nuclear gene Got2 with electrophoretic polymorphism of allozymes and hystone H1 proteins is actually a comparison of the one detailed phylogenetic tree with a set of low resolution trees. It could help to understand peculiarities of the species evolutionary history and role of cross-pollination in it. Proteins polymorphism patterns rather satisfactory corresponded to Got2 DNA tree. Electrophoretic polymorphism of essentially polymorphic in Ae. tauschii subsp. strangulata protein encoding loci considered (Ak, Est2, Got1, Got3, Hst2, Hst3) and essentially polymorphic in Ae. tauschii subsp. tauschii locus Fdp displayed correspondence with the molecular phylogenetic tree: each allele was common or predominant on some branches of the tree and rare or absent on the other. In contrast, alleles of Cat2 locus, Cat235 and Cat2140, were “scattered” sporadically through Ae. tauschii subsp. tauschii branches on phylogenetic tree. Also in Ae. tauschii subsp. tauschii a set of different extremely rare allozyme alleles, Acph4113, Aco2110, Mdh1113, Nadhd188, was found among three out of four accessions belonging to one of the relict clades of this subspecies on the molecular phylogenetic tree. The data obtained displayed that subsp. tauschii, now being relatively less polymorphic than subsp. strangulata, in ancient times had good opportunities for genetic exchange between its different phylogenetic lineages, all but one of which are relicts in present time. And the patterns of Hst3977 allele occurrences indicated cross-pollination between subsp. tauschii and subsp. strangulata.

Fred Utter died in his sleep during the night of 5 March 2023 at the age of 91. In this paper, 3 friends and colleagues of Fred describe the important role that his genetics research has played in the management and conservation of fish populations. [ABSTRACT FROM AUTHOR]

Context: Galaxiids are a widespread, southern hemisphere, radiation of mostly obligate freshwater fishes. Tasmania houses a diversity of endemic species of Galaxias and Paragalaxias. Of these, many are at risk of extinction, being landlocked, range-restricted and subject to anthropogenic threats, placing a high-conservation priority on the region. Aim: Our aim was to synthesise historic and published molecular datasets to provide the sound systematic framework needed to underpin future conservation and taxonomic efforts for Tasmanian galaxiids. Methods: Novel and published nuclear (allozyme) and matrilineal (cytb) datasets were generated and integrated for every putative Tasmanian galaxiid species lacking a comparable multi-gene assessment. Key results: The Tasmanian galaxiids are phylogenetically diverse, with molecular data generally supporting the accepted taxonomy, but with potential species-level diversity noted within an alpine radiation of the Galaxias truttaceus complex and further support for synonymy of G. niger within G. brevipinnis. Conclusions: This study highlights the value of multi-locus studies in both validating species-level taxonomy and resolving taxonomic ambiguities and conservation priorities within Tasmania's galaxiids. Implications: Our integrated genetic analyses provide a framework to underpin more in-depth genomic approaches to assess additional cryptic diversity and conservation planning, such as genetic rescue and ex situ population security. Tasmania represents less than 1% of Australia's landmass, yet houses a quarter of Australia's threatened freshwater fishes, all of them being galaxiids. However, comprehensive genetic assessments of the taxonomic integrity of Tasmania's galaxiid fishes are available only for 2 of its 17 described species. This study had plugged this gap for the remaining 15 species. Although confirming most species as valid, it identified instances of taxonomic uncertainty and highlighted priority areas for future conservation genomic investigation. [ABSTRACT FROM AUTHOR]

We use Helianthemum oelandicum subsp. oelandicum as a model for studies of mechanisms shaping the diversity in a rapidly radiating lineage of the H. oelandicum aggregate. Locally, correlations between drainage conditions (using GIS to measure variation in the micro-topography on the more or less horizontal bedrock) and frequency of alleles of Mendelian genes for pubescence indicated that hairs are markers of adaptation to the unique environmental conditions (drought and periodic flooding) on the alvar habitats of Öland. An allozyme study showed that 1 and 4% of the genetic diversity is partitioned among two varieties and natural populations, respectively. F ST for hair alleles was up to ten time greater than F ST for allozymes. Öland rose above sea level after the LGM, which makes it possible to date the onset of the post-glacial diversification on the island. Only two, mainly allopatric, plastid DNA haplotypes were detected, H1 and H2. The southern Helianthemum oelandicum subsp. oelandicum var. canescens has only H1, whereas the more widespread var. oelandicum possesses both haplotypes. A restricted occurrence of haplotype H1 in the core area of var. oelandicum in the central Öland, coincided with the highest elevation on the island, probably representing the post-glacial arrival of the species on the island. [ABSTRACT FROM AUTHOR]

Summary: The intensively studied Eurasian orchid genus Dactylorhiza has become a model system for exploring allopolyploid evolution, yet determining the optimal circumscriptions of, and most appropriate ranks for, its constituent taxa remain highly controversial topics. Here, novel allozyme data and detailed morphometric data for 16 Scottish marsh-orchid populations are interpreted in the context of recent DNA sequencing studies. Despite being derived from the same pair of parental species, the two allopolyploid species that currently occur in Scotland can reliably be distinguished using allozymes, haplotypes, ribotypes or sequences of nuclear genes. A modest range of diverse morphological characters are shown to distinguish the two molecularly-circumscribed species, but they have in the past been obscured by equivalent levels of infraspecific variation in characters rooted in anthocyanin pigments; these characters are better employed for distinguishing infraspecific taxa. Dactylorhiza francis-drucei (formerly D. traunsteinerioides) is confirmed as being distinct from the continental D. traunsteineri/lapponica, probably originating through allopatric isolation once the continental lineage reached Britain. All Scottish populations are attributed to the comparatively small-flowered, anthocyanin-rich subsp. francis-drucei, which includes as a variety the former D. 'ebudensis'; the less anthocyanin-rich subsp. traunsteinerioides is confined to Ireland, North Wales and northern England. In contrast with D. francis-drucei, only a minority of Scottish populations of D. purpurella are attributed to the anthocyanin-rich race, var. cambrensis. This species most likely originated through an allopolyploidy event that occurred comparatively recently within the British Isles, as it contains allozyme alleles distinctive of British rather than continental D. incarnata (its diploid pollen-parent). In contrast, the rare Scottish population of D. incarnata subsp. cruenta shares with its Irish counterparts a continental genotype, and is most likely a recent arrival in Scotland through long-distance dispersal. Among all European allotetraploid dactylorchids, D. purpurella is the species that most closely resembles D. incarnata, both molecularly and morphologically. [ABSTRACT FROM AUTHOR]

The Eurasian perch Perca fluviatilis (Linnaeus, 1758) is a common species of fish in northern ecosystems. The species demonstrates high phenotypic diversity when it inhabits various types of water bodies. Here, we investigate whether there is a relationship between the genetic variability and phenotypic diversity in natural perch populations. Perca fluviatilis samples (n = 218) were collected from seven localities in the Ob-Irtysh river basin in western Siberia, Russia. We used color morphs and standard morphometric approach to study phenotypic diversity, allozyme and ISSR-PCR markers to study the genetic variability of the perch. In total, 19 types of perch colouration were found. The number of color morphs varied from 4 to 16 in different reservoirs. The sets of colour morphs and prevailing coloration types, as well as some morphometric characteristics, were significantly different in all studied populations. Low allozyme variability was identified in the perch. The average observed and expected allozyme heterozygosity was 0.003 and 0.056, respectively; 13% of the loci were polymorphic. The genetic diversity (h) of the markers (ISSR) was 0.31; from 53% to 96% of the bands were polymorphic. Genetic differentiation in the perch was high, especially in allozyme loci. The FST and GST values were 0.39 and 0.085 for allozyme and ISSR markers, respectively. The genetic variability indices of the perch did not correlate with phenotypic diversity. Our results suggest that the use of different phenotypic or genetic markers can provide extremely different information on the level of variability in the population.

Iphigenia brasiliensis is a bivalve mollusk exploited as a shellfish and subsistence resource on the Brazilian coast, mainly in the north and northeast regions. Genetic (allozyme electrophoresis revealed eight gene loci) and morphological variations (multivariate morphometry of valves used 13 linear measurements of traditional and 19 Fourier coefficients of geometric morphometry) were studied, considering the geographic (445 km of the southwest tropical Atlantic), environmental (mangroves and channels of communication with the sea of three estuaries in the state of Rio de Janeiro), and temporal dimensions (over two years). I. brasiliensis showed high levels of genetic variation (the average number of alleles per locus ranged from 2.8 to 3.4, and the average heterozygosity ranged from 0.441 to 0.675). Bayesian analysis of population partitioning showed that the highest LnP(D) value was achieved for K = 3. These results indicated mixed ancestry, possibly oscillations in the dispersion dynamics among the different sampling groups, and temporal oscillations in the population sizes due to the anthropogenic influence on the studied estuaries. The results of morphological variation, inferred by the PERMANOVA from the Fourier analysis, indicated that a similar influence might occur in valves (also, the discriminant analysis showed that different groups could be consistently identified). In this sense, the studied populations may be organized in a dynamic of metapopulations. Finally, these are the first data on morphological and genetic variation of the species in the latitudinal, environmental, and temporal dimensions studied simultaneously, thus providing relevant information for the exploration, management, and conservation of this commercially important species. [ABSTRACT FROM AUTHOR]

The genetic diversity and differentiation of natural populations of Pinus nigra Arn. in Bulgaria was studied by isozyme gene markers. Sixteen populations were included in the study, representing the whole area of species' distribution in the country. Polymorphism and diversity parameters were relatively high and corresponded to the values reported in other studies on the species. Mean allele number ranged from 2 to 2.62 (average 2.24), effective number of alleles ranged from 1.12 to 1.45 (average 1.32) and percent of polymorphic loci - from 50 to 100. Observed heterozygosity ranged from 0.11 to 0.28. The differentiation among populations was low (7 %), which is typical for the species with similar life-history characteristics. The results could be useful in designing of management and conservation of Pinus nigra genetic resources in Bulgaria. [ABSTRACT FROM AUTHOR]

The genetic structure and differentiation of 12 Siberian dwarf pine populations from Chukotka, the Kamchatka Peninsula, Sakhalin Island and Kunashir Island were studied using 28 allozyme loci (Adh-1, Adh-2, Fdh, Fest-2, Gdh, Got-1, Got-2, Got-3, Idh-1, Lap-2, Lap-3, Mdh-1, Mdh-2, Mdh-3, Mdh-4, Mnr-1, Pepca, 6Pgd-2, 6Pgd-3, Pgi-1, Pgi-2, Pgm-1, Pgm-2, Skdh-1, Skdh-2, Sod-2, Sod-3, Sod-4). In total, 26 of the studied loci (92.9%) turned out to be variable, the mean number of alleles per locus was 2.3, and the mean heterozygosity (HE) was 0.248. The levels of intrapopulation variability were close to the mean values in the majority of populations. Interpopulation differentiation within the population group of Kamchatka turned out to be quite high (FST = 0.028). Weak differentiation was observed between two northern Chukotka populations (FST = 0.013), as well as two Sakhalin Island populations (FST = 0.013). The maximum level of genetic differentiation was found between the populations of Kunashir Island, growing in contrasting environmental conditions in a geographically small area (FST = 0.041). The genetic differences between the Kunashir populations of Siberian dwarf pine are comparable to the differences between the populations of the Baikal zone, where this species grows in contrasting ecological conditions. On the whole, the differentiation of populations in the Pacific region was 0.07. Nei's genetic distances (DN) range from 0.005 between two populations of Kunashir Island to 0.043 between the populations of Kamchatka and Kunashir. Factor analysis revealed clusters of populations by geographical origin, and also showed a high degree of differentiation between localities within Kunashir Island and the Kamchatka Peninsula, which may indicate a high degree of adaptation of individual populations to their habitat. Thus, we can conclude that the high rates of interpopulation differentiation of Siberian dwarf pine depend not only on geographical origin, but also on growing conditions. [ABSTRACT FROM AUTHOR]

The study is focused on the differentiation morphoecological and genetic analysis of the morphs of the whitefish Coregonus lavaretus L. sensu lato (Teleostei: Salmoniformes: Coregoninae) from Lake Kuetsjärvi, located in the lower reaches of one of the largest lake-river systems in the north of Europe, Pasvik-Inari (Barents Sea basin). Four morphs of whitefish have been identified: slow and fast growing medium rakered and slow and fast growing sparsely rakered. It was shown that there is practically no differentiation in the frequencies of allozyme loci at pronounced and stable differences in the number of gill rakers, head shape, growth rate and trophic features. The results confirm the analysis of multilocus allozyme genotypes using Bayesian clustering in the Structure program, which did not reveal any differences in the proportion of initial clusters between the morphs. We consider the recent and incomplete isolation of the described morphs, the phenotypic differences of which can be determined by epigenetic features, as an explanation for the observed picture. [ABSTRACT FROM AUTHOR]

The hybridization zone on the northern border of the overlapping ranges at the junction of the Prilensky Plateau with the Stanovoy and Aldan highlands is studied using the analysis of the genotypes of adult plants of dwarf Siberian pine, Pinus pumila (Pall.) Regel, and Siberian stone pine, Pinus sibirica Du Tour, based on allozyme (nuclear codominant markers with biparental inheritance) and mtDNA data. We obtain evidence of modern hybridization of these species, as well as past hybridization events. Our study reveals that, in the conditions of Southern Yakutia, hybridization takes place mainly unidirectionally with an asymmetric flow of genes between species. The replacement of the mitochondrial genomes of Pinus sibirica with the genomes of Pinus pumila is noted in most of the studied samples from the sympatry zone. This phenomenon can be adaptive and contribute to the expansion of the distribution range of Siberian stone pine. [ABSTRACT FROM AUTHOR]

Identification of discrete stocks of Greenland halibut is an important aspect of proper fisheries exploitation. Available literature data indicated a lack of significant inter‑area differences between Greenland halibut populations from the Northeast Atlantic. To define the population diversity, two aspects were taken into account: enzyme‑genetic diversity and the concentration of heavy metals in tissues. Seven allozyme loci variations were used to characterize the genetic structure of four populations of Greenland halibut from the Western Barents Sea region. The samples were collected from the spawning area in the period when this species took migration to spawn. The sample RH4 was significantly different from the other samples collected from the same location (RH2 and RH3) and depth for over two days. Another sample (RH8), collected from the nearby area 6 days later was similar to the samples RH2, RH3. We noticed a significant divergence between the sample RH4 and the three remaining samples, where the value of the index FST fluctuated about 0.40 and approximately 0.01 between three similar populations. This genetic fluctuation negates the thesis of a panmictic character of the Western Atlantic population. Feeding groups of Greenland halibut are moving along the Barents Sea shelf and they are exposed to different heavy metals concentrations according to the food preferences or the exact place of feeding. We identified similar concentrations of heavy metals, i.e., Zn, Cu, Cd, and Pb in all samples. Trace metal analysis of aquatic organisms from the Barents Sea can provide important information on the degree of environmental contamination, and the potential impact of seafood consumption.

A recent study argued that coalescent-based models of species delimitation mostly delineate population structure, not species, and called for the validation of candidate species using biological information additional to the genetic information, such as phenotypic or ecological data. Here, we introduce a framework to interrogate genomic datasets and coalescent-based species trees for the presence of candidate species in situations where additional biological data are unavailable, unobtainable or uninformative. For de novo genomic studies of species boundaries, we propose six steps: (1) visualize genetic affinities among individuals to identify both discrete and admixed genetic groups from first principles and to hold aside individuals involved in contemporary admixture for independent consideration; (2) apply phylogenetic techniques to identify lineages; (3) assess diagnosability of those lineages as potential candidate species; (4) interpret the diagnosable lineages in a geographical context (sympatry, parapatry, allopatry); (5) assess significance of difference or trends in the context of sampling intensity; and (6) adopt a holistic approach to available evidence to inform decisions on species status in the difficult cases of allopatry. We adopt this approach to distinguish candidate species from within-species lineages for a widespread species complex of Australian freshwater fishes (Retropinna spp.). Our framework addresses two cornerstone issues in systematics that are often not discussed explicitly in genomic species discovery: diagnosability and how to determine it, and what criteria should be used to decide whether diagnosable lineages are conspecific or represent different species. [ABSTRACT FROM AUTHOR]

Levels of genetic variation can steer the future adaptability and correlate to reduced inbreeding of species. Therefore, for any conservation measure, determining the levels of genetic variations and its implications in endangered species is a priority. Here, we investigate allozyme genetic variation of a critically endangered killifish species, Anatolichthys transgrediens, one of the most threatened species in the world with extremely small distribution range. Our results clearly point out perilously low levels of genetic variation, with only three out of 15 loci examined were polymorphic, likely reflecting their small population size and genetically deteriorated population structure. Fixation indices estimated also indicate high levels of inbreeding within A. transgrediens which may result in inbreeding depression and further population declines. We discuss the possible drivers for this situation and call the urgency of an integrated action for conservation of this endangered killifish species. [ABSTRACT FROM AUTHOR]

Aphanius fasciatus (Valenciennes, 1821) is a small cyprinodontid fish with external sexual dimorphism. Endemic to the Mediterranean. It is strongly eurythermic and euryhaline. This study concerns morphological differences and genetic structure of this species in North Africa, the most westerly area of its distribution range. A total of 141 individuals were collected using a beach seine from three locations in Algeria: Mellah lagoon (N = 41) and its neighbour Marsh (N = 30), Ayata Lake (N = 29) and one in Tunisia: Bizerte lagoon (N = 41). For morphometric analysis, 13 landmarks were positioned on lateral photographs taken of the fish. Shape information was extracted from the data with a procrustes superimposition and grouped by gender and location. Proteins extracts were obtained from liver and muscle and used for allozymic analysis to determine genetic variations across locations. Seven isoenzymatic systems: MDH (malate dehydrogenase), GOT (Glutamate oxaloacetate transaminase), PGI (phosphoglucose isomerase), PGM (phosphoglucomutase), EST (esterase), IDH (isocitrate dehydrogenase), LDH (lactate dehydrogenase) were revealed using enzyme-specific stains. Canonical variate analysis and discriminant function among procruste covariation matrix shows that the shape of the specimen of Ayata Lake is different from those of the three other localities. Ayata Lake fishes have heads shorter than the other populations; their anal fin is smaller and its distance from pelvic fin is more important than observed in other populations. Genetically, Ayata Lake population is distinguished from other localities by the highest values of Fst (fixation index), Ap (private alleles), Ar (Allelic richness). The Jackknife test shows that the PGM system is responsible of this variation. Evolution and adaptation mechanisms of this species according to different habitats are discussed. [ABSTRACT FROM AUTHOR]

In human-altered landscapes, species with specific habitat requirements tend to persist as metapopulations, forming colonies restricted to patches of suitable habitats, displaying mutually independent within-patch dynamics and interconnected by inter-colony movements of individuals. Despite intuitive appeal and both empirical and analytical evidence, metapopulations of only relatively few butterfly systems had been both monitored for multiple years to quantify metapopulation dynamics, and assayed from the point of view of population genetics. We used allozyme analysis to study the genetic make-up of a metapopulation of a declining and EU-protected butterfly, Euphydryas aurinia, inhabiting humid grasslands in western Czech Republic, and reanalysed previously published demography and dispersal data to interpret the patterns. For 497 colony x year visits to the 97 colonies known at that time, we found annual extinction and colonisation probabilities roughly equal to 4%. The genetic diversity within colonies was intermediate or high for all assessed parameters of population genetic diversity and hence higher than expected for such a habitat specialist species. All the standard genetic diversity measures were positively correlated to adult counts and colony areas, but the correlations were weak and rarely significant, probably due to the rapid within-colony population dynamics. Only very weak correlations applied to larval nests numbers. We conclude that the entirety of colonies forms a well-connected system for their majority. Especially in its core parts, we assume a metapopulation structure with a dynamic equilibrium between local extinction and recolonization. It is vital to conserve in particular these structures of large and interconnected colonies. Implications for insect conservation: Conservation measures should focus on considering more in depth the habitat requirements of E. aurinia for management plans and on stabilisation strategies for colonies, especially of peripheral ones, e.g. by habitat restoration. [ABSTRACT FROM AUTHOR]

This review summarizes the development of population genetics and population genomics studies of forest trees in Slovakia during the past 40 years. Various protein and DNA markers have been applied during this period to address several topics in evolutionary genetics and biogeography of trees: allozymes, uniparentally inherited chloroplast and mitochondrial markers, simple sequence repeats and single nucleotide polymorphisms. The main object of studies of phylogeny and postglacial migration were Fagus sylvatica s.l. and eastern-Mediterranean firs (Abies Mill. section Abies), where the divergence of genetic lineages (species and subspecific taxa) in time, as well as colonization of the current ranges during the Holocene were reconstructed. The studies on intraspecific gene flow and homoploid hybridization focused on hybrid swarms Pinus sylvestris/P. mugo and firs. Unusual maternal inheritance of chloroplast DNA was revealed in P. mugo × P. sylvestris crosses. Contrasting geographical structures of hybrid zones were revealed in wind-dispersed vs. animal-dispersed trees. Within the studies of adaptation, signals of selection were identified both in field observations and common-garden experiments on Picea abies, F. sylvatica and A. alba. Perspectives of ongoing research employing next-generation sequencing were shortly outlined. [ABSTRACT FROM AUTHOR]

The large-scale hybridization of fishes of the subfamily Leuciscinae in the subordinate systems of the Dnipro River basin is presented by the data on two pairs of species, roach Rutilus rutilus × bream Abramis brama, and bleak Alburnus alburnus × rudd Scardinius erythrophthalmus. The hybridization and occurrence of F1 hybrids are confirmed with allozyme spectra and morphological characters on series of samples. A complete morphometric analysis of the characteristics of bleak and rudd hybrids was performed. The paper discusses the intergeneric hybridization in nature, which is a unique phenomenon characteristic only of some groups of cyprinids. The most likely reason is the overestimation of the taxonomic status of European cyprinids, which is confirmed by the insignificant level of intergeneric genetic divergence. [ABSTRACT FROM AUTHOR]

The large-scale hybridization of fishes of the subfamily Leuciscinae in the subordinate systems of the Dnieper river basin is presented by data on two pair of species, Rutilus rutilus and Abramis brama, Alburnus alburnus and Scardinius erythrophthalmus. The hybridization and occurrence of F1 hybrids are confirmed with allozyme spectra and morphological characters on series of samples. The presence of single individuals sharply deviating in morphological characters among the bleak and common rudd hybrids suggests limited backcrossing with rudd. A complete morphometric analysis of the characteristics of bleak and rudd hybrids has been carried out. The paper discusses the issue of intergeneric hybridization in nature, which is a unique phenomenon characteristic only of some groups of cyprinids. The most likely reason is the overestimation of the taxonomic status of European cyprinids, which is confirmed by the insignificant level of intergeneric genetic divergence.

Identification of discrete stocks of Greenland halibut is an important aspect of proper fisheries exploitation. Available literature data indicated a lack of significant inter-area differences between Greenland halibut populations from the Northeast Atlantic. To define the population diversity, two aspects were taken into account: enzyme-genetic diversity and the concentration of heavy metals in tissues. Seven allozyme loci variations were used to characterize the genetic structure of four populations of Greenland halibut from the Western Barents Sea region. The samples were collected from the spawning area in the period when this species took migration to spawn. The sample RH4 was significantly different from the other samples collected from the same location (RH2 and RH3) and depth for over two days. Another sample (RH8), collected from the nearby area 6 days later was similar to the samples RH2, RH3. We noticed a significant divergence between the sample RH4 and the three remaining samples, where the value of the index FST fluctuated about 0.40 and approximately 0.01 between three similar populations. This genetic fluctuation negates the thesis of a panmictic character of the Western Atlantic population. Feeding groups of Greenland halibut are moving along the Barents Sea shelf and they are exposed to different heavy metals concentrations according to the food preferences or the exact place of feeding. We identified similar concentrations of heavy metals, i.e., Zn, Cu, Cd, and Pb in all samples. Trace metal analysis of aquatic organisms from the Barents Sea can provide important information on the degree of environmental contamination, and the potential impact of seafood consumption. [ABSTRACT FROM AUTHOR]

Molecular markers prove to be an invaluable tool in assessing the introduction dynamics, pattern of range expansion, and population genetics of an invasive species. Ventenata dubia (Leers) Coss. (Aveneae; ventenata) is a diploid, primarily self-pollinating, annual grass native to Eurasia and Northern Africa. The grass has a detailed herbarium collection history in the western United States since its discovery in eastern Washington in 1952. Genetic analysis of 51 invasive populations (1636 individuals) of V. dubia, coupled with historical records, suggests moderate propagule pressure from multiple introductions, followed by local or regional range expansion. Allozyme analysis detected nine multilocus genotypes (MLGs) across eight western US states. A single MLG, referred to as the most common genotype, was detected in 37 of 51 (72.5%) invasive populations across all states. The other eight MLGs were generally found in fewer populations, with limited geographic distributions. Despite multiple introductions, invasive populations exhibit low levels of genetic admixture, low levels of genetic diversity within populations (A = 1.03, %P = 2.94, Hexp = 0.007) and high genetic differentiation among populations (GST= 0.864). The apparent reduced evolutionary potential of most V. dubia populations did not preclude the initial establishment and rapid spread of this species across its new range in the western US. [ABSTRACT FROM AUTHOR]

Botrychium furculatum S. J. Popovich & Farrar is a new species widespread in the central and southern Rocky Mountains from Alberta and Montana south to New Mexico, with additional populations in the Cypress Hills of Saskatchewan and the Black Hills of Wyoming and South Dakota. Based on allozyme banding patterns, it is inferred to be an allotetraploid with B. pallidum W. H. Wagner as one parent and another, as yet undescribed, diploid species (B. "farrarii") as the other parent. Genetically, B. furculatum is distinguished from B. pallidum by exhibiting fixed heterozygous loci in which expressed alleles of one of the genomic contributions matches those of B. pallidum, whereas many alleles of the other genomic contribution have not been detected in B. pallidum, but are displayed by B. "farrarii." Morphologically, a suite of leaf characters differentiates B. furculatum from B. pallidum, particularly a more pronounced bowed or wishbone-like junction of sporophore and trophophore. Gradations in morphology and color between the two species have led to erroneous reports of B. pallidum in the Rocky Mountains. A key to differentiate B. furculatum from similar species is presented. [ABSTRACT FROM AUTHOR]

In order to clarify the genetic differentiation and reproductive traits of mixed polyploid populations in Parasenecio kamtschaticus complex, geographical distribution, genetic diversity, and reproductive performance were compared among three intraspecific types composed of two cytotypes and two varieties in Japan. Diploid P. kamtschaticus var. kamtschaticus (2×-kamtschaticus) was distributed at the center of the distribution range, tetraploid P. kamtschaticus var. kamtschaticus (4×-kamtschaticus) existed widely throughout the entire range, and tetraploid P. kamtschaticus var. bulbifera (4×-bulbifera), producing bulbils, was restricted to higher elevations. Genetic structure was analyzed using allozyme markers. The genetic diversity of 4×-kamtschaticus was higher than that of 2×-kamtschaticus, with that of 4×-bulbifera being intermediate. Populations of 4×-bulbifera and 2×-kamtschaticus were genetically discriminable from each other in principle coordinate analysis, and the genetic structure of 4×-kamtschaticus populations largely overlapped with those of the other types. Flower and achene production levels were highest in the 4×-kamtschaticus populations and lowest in the 4×-bulbifera populations. Germination activity of achenes was highest in the 2×-kamtschaticus populations and lowest in the 4×-bulbifera populations. Fruit-set success of 4×-bulbifera decreased with elevation because of a shorter growing season, indicating the importance of vegetative reproduction by bulbils at higher elevations. Unexpectedly, the inbreeding coefficients of the 4×-bulbifera populations were the lowest among the three types. Occasional achene production by outcrossing might maintain the high genetic diversity of the 4×-bulbifera populations. The evolution of polyploidy and subsequent bulbil production might enable P. kamtschaticus to disperse a wider range of environmental conditions. [ABSTRACT FROM AUTHOR]

Pollinator taxa may vary in their contribution to plant outcrossing rates and hence differ in their influence on plant fitness. In plants that have ornithophilous floral traits (large, deep-tubed orange-red flowers with dilute nectar), it is expected that birds should be the most effective agents of outcrossing. However, bees often pollinate plants with ornithophilous floral traits and may contribute to their outcrossing. To assess the contribution of bees to outcrossing rates and inbreeding in the rare self-compatible treelet Aloe thraskii, we compared outcrossing rates (t) and adult inbreeding coefficients (F), in bird-excluded and open-pollinated plants. We then tested whether outcrossing rates, and inbreeding depression (δ) estimated using Ritland’s genetic marker-based approach, varied according to bee and bird visitation rates, plant height, flowering population size, population density, and isolation distance across eight populations. Outcrossing rates did not differ between progeny from open-pollinated and bird-excluded inflorescences. Outcrossing rates increased with bee visitation, but not bird visitation. Adult inbreeding coefficients were low (F = 0–0.1), and inbreeding depression estimates were high (δ = 0.59–1). Estimates of inbreeding depression did not vary according to population aggregation. These results highlight the contribution to outcrossing that insect pollinators can make to outcrossing rates of rare plant species that are seemingly adapted for bird pollination. [ABSTRACT FROM AUTHOR]

An allozyme analysis of five sets of polymorphic loci of the gynogenetic Prussian carp C. gibelio from Northern Ukraine made it possible to identify within this species 29 genetic forms of clonal and recombinant nature, which can be divided into two categories. The first one is represented by the clonal C. gibelio-1 biotype with the modal number of 156 chromosomes and several unique alleles, which distinctly differentiate this biotype from the diploid goldfish C. auratus. The second category is represented by the group of 28 biotypes designated as C. gibelio-2 of a clonal and recombinant nature. Specimens of this group have no allozymes that distinguish them from C. auratus. Within this group, 158 and 160 modal chromosome groups were discovered; each one has special genotypic combination for locus Aat-1. Apparently, the series of biotypes, which are differentiated by the modal chromosome number, emerged independently as a result of hybridization of different pairs of parental species way back in Eastern Asia. At the same time, the emergence of recombinant individuals with unique combinations of genotypes of five protein loci and their own chromosome number within the C. gibelio-2 clone is a secondary event related to the implementation of the inheritance mechanism, which combines cloning and Mendelian inheritance. There are reasons to believe that this mechanism is implemented in pseudogamous crosses of genetically close C. gibelio-2 females with C. auratus males, while the cloning takes place in crosses of C. gibelio-2 females with more distant C. carassius males. [ABSTRACT FROM AUTHOR]

Habitat fragmentation is a serious threat to species survival. In Vietnam, Cycas balansae has been considered as threatened species because of the reduction and fragmentation of its habitats and over-exploitation. We assessed genetic variability and the pattern of population structure among six populations sampled in four provinces: Hoa Binh, Ha Nam, Ninh Binh and Quang Ninh. Polyacrylamide gel electrophoresis was performed on leaf tissues from 152 individuals representing 6 populations of C. balansae. Six of twelve enzyme systems were used to estimate genetic diversity at population and species levels. Eleven loci were examined. The allozyme data showed high levels of genetic diversity within all populations, ranging from 0.538 in Ba Sao to 0.628 in Tan Dan (average 0.576). The maintenance of high levels of expected heterozygosity (average 0.571) and low in observed heterozygosity (average 0.347) might be related to great heterozygote deficiency and increased frequencies of rare alleles. Genetic differentiation among populations was low (Dst = 0.036 and Gst = 0.064), indicating high level of gene flow (Nm = 3.22). Isolation by geographical distance was observed, however, no significant relationship between genetic distances and geographical distances was recorded. Our studies suggest small population sizes of cycads brought about by fragmentation of its habitats, over-exploitation, and increasing number of inbred individuals within populations.

Allozymes and mitochondrial DNA sequences were used to examine the phylogeographical history of the rough-skinned newt, Taricha granulosa, in western North America. Nineteen populations were analysed for allozyme variation at 45 loci, and 23 populations were analysed for cytochrome b sequence variation. Both data sets agree that populations in the southern part of the range are characterized by isolation by distance, whereas northern populations fit the expectations of a recent range expansion. However, the northern limit of isolation by distance (and the southern limit of range expansion) is located in Oregon State by the mtDNA data, and in Washington State by the allozyme data. Nevertheless, both data sets are consistent with the known Pleistocene history of western North America, with phylogenetically basal populations in central and northern California, and a recent range expansion in the north following the retreat of the Cordilleran ice sheet 10 000 years ago. Additionally, a population in Idaho, previously considered introduced from central California based on morphometric analyses, possesses a distinct mtDNA haplotype, suggesting it could be native. The relevance of these results for Pacific Northwest biogeography is discussed.

This study assessed intrinsic differences in tissue quality and growth rate among populations of Metrosideros polymorpha native to sites with a range of soil fertilities. We collected seedlings from three Hawaiian mesic forests that were either phosphorus-limited, nitrogen-limited, or relatively fertile. These individuals were grown in a common garden under a factorial high/low, N/P fertilization regime for 1.5 years and then harvested to determine genetic divergence; aboveground growth rate; and lignin, N, and P concentrations in leaves and roots. Allozyme analyses indicated that the three groups had genetically diverged to some degree (genetic distance = 0.036-0.053 among populations). Relative growth rate did not differ significantly among the populations. Senescent leaves from the fertile-site population had the highest N concentrations (due to low N resorption) and had lower lignin concentrations than plants from the N-limited site. Across treatments, P concentrations in senescent leaves were highest in plants from the fertile and P-limited site. Root tissue quality did not generally differ significantly among populations. Since decomposition rate of senescent leaves in this system is related positively to N concentration and negatively to lignin concentration, senescent leaves from the fertile-site population may have a genetic tendency toward faster decay than the others. The intrinsic qualities of the three populations may provide positive feedbacks on nutrient cycling at each site-nutrient availability may be raised to some degree at the fertile site, and reduced at the N- or P-limited sites. Our results suggest that even a small degree of genetic differentiation among groups can influence traits related to nutrient cycling.

Main results of allozyme-geographical study of the polymorphism, differentiation and origin of natural Pinus sylvestris L. populations in 6phylogeographical regions – Middle Siberian Tableland, Lena-Angara Tableland, South Siberia Mountains, Near-Baikalia, Western Trans-Baikalia and Northern Mongolia – have been briefly analyzed and generalized. A relative homogeneity of the population polymorphism in these regions has been revealed, with the exception of marginal ones (Tura, Ulan-Bator). Genetic distances of M. Nei (1978, DN78) between the extremely remote populations in the investigated regions reach the level of the geographical race, but they are several time lesser in the regions’ limits – not more of the genosystmatic level of the middle differentiated local populations (DN78 = 0.010–0.012). The geographical group of the South Siberia Mountains stand apart distinctly (DN78 = 0.018±0.004) in the genogeographical structure of P. sylvestris on the basis of Nei`s genetic distances analysis and of the genosystematic scale (Sannikov, Petrova, 2012). Besides the Selenga population group (in the rank of local population, DN78 = 0.013), also as well the Angara-Yenisei and North-Baikal population group (in the rank of subpopulation, DN78 = 0.004–0.008) stand apart on the rest of the territory. Gradient-analysis of the genetic distances revealed the borders between the phylogeographical groups of pine populations on the Lena-Angara and Central-Siberian plateaus, on the one hand, in the South Siberia Mountains, Near-Baikal and Trans-Baikalia, on the other hand, and an important role of l. Baikal as a barrier of the migration and differentiation of the populations. As an analysis result of minimal genetic distances between 25 P. sylvestris populations in the south «non-glacial» zone and the group of 8 populations in the «glacial» zone 4 main refugiums (South-Near-Baikal, South-Ural, Upper-Vitim and Upper-Olekma) and several secondary refugiums have been revealed.

Amphibians are the most vulnerable vertebrates to biodiversity loss mediated by habitat destruction, climate change and diseases. Informed conservation management requires improving the taxonomy of anurans to assess reliably the species’ geographic range. The genus Odontophrynus that is geographically refined to Argentina, Bolivia, Brazil, Uruguay and Paraguay includes currently 12 nominal species with many populations of uncertain taxonomic assignment and subsequently unclear geographic ranges. In this study, we applied integrative taxonomic methods combining molecular (mitochondrial 16S gene), allozyme, morphological and bioacoustic data to delimit species of the genus Odontophrynus sampled from throughout Argentina where most species occur. The combined evidence demonstrates one case of cryptic diversity and another of overestimation of species richness. The populations referred to as O. americanus comprise at least three species. In contrast, O. achalensis and O. barrioi represent junior synonyms of the phenotypically plastic species O. occidentalis. We conclude that each of the four species occurring in Argentina inhabits medium to large areas. The Red List classification is currently “Least Concern”. We also propose a phylogenetic hypothesis for the genus and associated genera Macrogenioglottus and Proceratophrys (Odontophrynidae).

Within the genus Centaurea L., polyploidy is very common, and it is believed that, as to all angiosperms, it was key in the history of its diversification and evolution. Centaurea tentudaica is a hexaploid from subsect. Chamaecyanus of unknown origin. In this study, we examined the possible autopolyploid or allopolyploid origin using allozymes and sequences of three molecular markers: nuclear-ribosomic region ETS, and low-copy genes AGT1 and PgiC. We also included three species geographically and morphologically close to C. tentudaica: C. amblensis, C. galianoi, and C. ornata. Neighbor-Net and Bayesian analyses show a close relationship between C. amblensis and C. tentudaica and no relationship to any of the other species, which suggest that C. tentudaica is an autopolyploid of C. amblensis. Allozyme banding pattern also supports the autopolyploidy hypothesis and shows high levels of genetic diversity in the polyploid, which could suggest multiple origins by recurrent crosses of tetraploid and diploid cytotypes of C. amblensis. Environmental niche modeling was used to analyze the distribution of the possible parental species during the present, Last Glacial Maximum (LGM), Last Interglacial Period (LIG), and Penultimate Glacial Maximum (PGM) environmental conditions. Supporting the molecular suggestions that C. tentudaica originated from C. amblensis, environmental niche modeling confirms that past distribution of C. amblensis overlapped with the distribution of C. tentudaica.

Summary: There is disagreement as to the number of genera comprising the mannikins (Lonchurinae). Some authors recognize two to five of the following genera:Lonchura, Euodice, Padda, Spermestes andOdontospiza. Other authors have merged the last four taxa into the enlarged genusLonchura. We bring together data from downy plumes (neossoptiles), nestling palate markings, begging vocalizations, agonistic behaviour, courtship postures and starch gel electrophoresis of allozymes to solve these taxonomic problems. PAUP analysis of the combined data set indicates thatSpermestes andOdontospiza belong to a monophyletic clade separate fromEuodice, Padda andLonchura. We propose mergingOdontospiza withSpermestes, which suggests an African radiation of the group, and placing the generaPadda andEuodice in withLonchura, which represents a mostly Australasian radiation. The genusAmadina has been treated by some as a mannikin (Lonchurinae) and by others as a waxbill (Estrildinae). Our data indicate thatAmadina should be assigned to the estrildines rather than the lonchurines.Amadina's relatively large, mannikin-like conical bill is a result of convergence, probably reflecting selection pressure on bill shape associated with diet specializations. [ABSTRACT FROM AUTHOR]

Amphibians are the most vulnerable vertebrates to biodiversity loss mediated by habitat destruction, climate change and diseases. Informed conservation management requires improving the taxonomy of anurans to assess reliably the species' geographic range. The genus Odontophrynus that is geographically refined to Argentina, Bolivia, Brazil, Uruguay and Paraguay includes currently 12 nominal species with many populations of uncertain taxonomic assignment and subsequently unclear geographic ranges. In this study, we applied integrative taxonomic methods combining molecular (mitochondrial 16S gene), allozyme, morphological and bioacoustic data to delimit species of the genus Odontophrynus sampled from throughout Argentina where most species occur. The combined evidence demonstrates one case of cryptic diversity and another of overestimation of species richness. The populations referred to as O. americanus comprise at least three species. In contrast, O. achalensis and O. barrioi represent junior synonyms of the phenotypically plastic species O. occidentalis. We conclude that each of the four species occurring in Argentina inhabits medium to large areas. The Red List classification is currently "Least Concern". We also propose a phylogenetic hypothesis for the genus and associated genera Macrogenioglottus and Proceratophrys (Odontophrynidae). [ABSTRACT FROM AUTHOR]

Iphigenia brasiliensis (Lamarck, 1818) is a species of bivalve of the family Donacidae Fleming, 1828 which inhabits unconsolidated substrata and occurs in Brazil between 0°07ʹ04ʺS, 49°23ʹ17ʺW and 29º19ʹ46ʺS, 49º42ʹ39ʺW, and is also found in Florida (USA), Suriname and parts of the Caribbean sea. As an estuarine species it is subject to a wide range of environmental variables usually presenting considerable variation in morphological traits and genetic composition. In this paper, the presence and type of asymmetry in the species was inferred based on measures from left and right valves and genetic variation was assessed by means of allozymes electrophoresis. The assessment of levels of asymmetry and genetic variation was done in three different localities and two environments (Channel and Mangrove). The results indicate the generalized presence of asymmetry, which varied between directional (DA) and fluctuating (FA) depending on the environment. Associations between FA and genetic variation were statistically significant on the dependence of the measure assessed. Thus, we present information on the levels of asymmetry and genetic variation of natural populations of I. brasiliensis which may be useful to research and management of this species. [ABSTRACT FROM AUTHOR]

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Abstract: Study deals with peculiarities of four genetic loci alleles' distribution in different populations of common kilka from some parts of its range. Geographical differentiation in muscular lactate dehydrogenase-A (LDH-A*) allele frequencies between populations was found. Allele LDH-A*100 frequency is higher in native range. Allele LDH-A*120 prevails in Volga populations of kilka probably due to presence of landlocked freshwater form in historical perspective. [ABSTRACT FROM AUTHOR]

The genetic variability in selectively controlled in Bulgaria local honey bee populations, representing Apis mellifera macedonica subspecies (type “rodopica”), has been studied by usage of alloenzymic analysis of six enzymic systems (MDH-1, ME, EST-3, ALP, PGM and HK) corresponding to 6 loci. Totally 324 worker bee individuals from 9 different local populations belonging to breeding stock of National Bee Breeding Association were included in this investigation. All of the studied loci were found to be polymorphic in most of the populations with the exception of EST-3 locus which was established to be fixed in two of investigated populations. Polymorphism with three alleles was ascertained for MDH, ME, ALP and PGM loci and with four alleles – for EST-3 and HK loci. The most common alleles in all of the investigated populations were ME 100, EST-3 100, PGM 100 and HK 100. Two private alleles (frequency < 0.05) were found for two of the studied populations. The calculated level of polymorphism was between 88.33% and 100%. The observed and expected heterozygosities were found to range from 0.186 to 0.301, and from 0.205 to 0.305, respectively. The calculated mean Fst level was 0.028. Allele frequencies of all studied loci were used to estimate Nei’s (1972) genetic distance, which was established to range between 0.001 and 0.028 among the selectively controlled populations studied. The assignment test showed a high level of consolidation for the all studied populations.

The genetic polymorphism in selectively reared in Bulgaria, local honey bee populations of Apis mellifera macedonica subspecies (type rodopica), has been studied, using analysis of six enzyme systems (MDH-1, ME, EST-3, ALP, PGM and HK) corresponding to 6 loci. Totally 458 worker bees from 12 bee breeding bases for artificially inseminated queens were used for this study. All these stations are part of the National Bee Breeding Association which officially implements a National Program for sustainable beekeeping in Bulgaria. All of the six loci were found to be polymorphic. Only EST-3 locus was established as fixed in one of the investigated populations. Polymorphism with three alleles was ascertained for MDH, ME, ALP, PGM and HK loci and with five alleles for EST-3 locus. The most common alleles in almost all of the populations were MDH-1 100, ME 100, EST-3 100, PGM 100 and HK 100. Two private alleles (frequency < 0.05) were found for two of the populations. The calculated level of polymorphism was 88.33% in only one of the populations and 100% - in all others. The observed and expected heterozygosities (Ho and He) ranged from 0.157 to 0.250 and from 0.206 to 0.272, respectively. The estimated mean FST value from allozyme data was 0.035. On the bases of the allele frequencies of the studied allozyme loci the Nei's (1972) genetic distance was estimated. It ranged between 0.002 and 0.060 among the populations studied.

The Ross Sea, Eastern Antarctica, is considered a “pristine ecosystem” and a biodiversity “hotspot” scarcely impacted by humans. The sibling species Contracaecum osculatum sp. D and C. osculatum sp. E are anisakid parasites embedded in the natural Antarctic marine ecosystem. Aims of this study were to: identify the larvae of C. osculatum (s.l.) recovered in fish hosts during the XXVII Italian Expedition to Antarctica (2011–2012); perform a comparative analysis of the contemporary parasitic load and genetic variability estimates of C. osculatum sp. D and C. osculatum sp. E with respect to samples collected during the expedition of 1993–1994; to provide ecological data on these parasites. 200 fish specimens (Chionodraco hamatus, Trematomus bernacchii, Trematomus hansoni, Trematomus newnesi) were analysed for Contracaecum sp. larvae, identified at species level by allozyme diagnostic markers and sequences analysis of the mtDNA cox2 gene. Statistically significant differences were found between the occurrence of C. osculatum sp. D and C. osculatum sp. E in different fish species. C. osculatum sp. E was more prevalent in T. bernacchii; while, a higher percentage of C. osculatum sp. D occurred in Ch. hamatus and T. hansoni. The two species also showed differences in the host infection site: C. osculatum sp. D showed higher percentage of infection in the fish liver. High genetic variability values at both nuclear and mitochondrial level were found in the two species in both sampling periods. The parasitic infection levels by C. osculatum sp. D and sp. E and their estimates of genetic variability showed no statistically significant variation over a temporal scale (2012 versus 1994). This suggests that the low habitat disturbance of the Antarctic region permits the maintenance of stable ecosystem trophic webs, which contributes to the maintenance of a large populations of anisakid nematodes with high genetic variability.

Two species of mosquitofish (family Poeciliidae) known to hybridize in nature were introduced into freshwater habitats inside Biosphere 2, and their population genetics were monitored after 2 years. Within four to six generations, nuclear and cytoplasmic markers characteristic of Gambusia holbrooki had risen greatly in frequency, although some Gambusia affinis alleles and haplotypes were retained primarily in recombinant genotypes, indicative of introgressive hybridization. The temporal cytonuclear dynamics proved similar to population genetic changes observed in replicated experimental hybrid populations outside of Biosphere 2, thus indicating strong directional selection favoring G. holbrooki genotypes across the range of environments monitored. When interpreted in the context of species-specific population demographies observed previously, results suggest that the extremely rapid evolution in these zones of secondary contact is attributable primarily to species differences in life-history traits.

The dynamics of mitochondrial and multilocus nuclear genotypic frequencies were monitored for 2 yr in experimental populations established with equal numbers of two poeciliid fishes (Gambusia affinis and Gambusia holbrooki) that hybridize naturally in the southeastern United States. In replicated "small-pool" populations (experiment I), 1018 sampled individuals at six time periods revealed an initial flush of hybridization, followed by a rapid decline in frequencies of G. affinis nuclear and mitochondrial alleles over 64 wk. Decay of gametic and cytonuclear disequilibria differed from expectations under random mating as well as under a model of assortative mating involving empirically estimated mating propensities. In two replicate "large-pond" populations (experiment II), 841 sampled individuals across four reproductive cohorts revealed lower initial frequencies of F1 hybrids than in experiment I, but again G. holbrooki alleles achieved high frequencies over four generations (72 wk). Thus, evolution within experimental Gambusia hybrid populations can be extremely rapid, resulting in consistent loss of G. affinis nuclear and cytoplasmic alleles. Concordance in results between experiments and across genetic markers suggests strong directional selection favoring G. holbrooki genotypes. Results are interpreted in light of previous reports of genotype-specific differences in life-history traits, reproductive ecology, patterns of recruitment, and size-specific mortality, and in the context of patterns of introgression previously studied indirectly from spatial observations on cytonuclear genotypes in natural Gambusia populations.

Spatial genetic structure in populations of mosquitofish (Gambusia) sampled throughout the south‐eastern United States was characterized using mitochondrial (mt) DNA and allozyme markers. Both sets of data revealed a pronounced genetic discontinuity (along a broad path extending from south‐eastern Mississippi to north‐eastern Georgia) that corresponds to a recently recognized distinction between the nominal forms G. affinis to the west and G. holbrooki to the east. However, several populations from the general contact region exhibited unusual allelic associations in high frequency, suggestive of evolutionary processes within a zone of introgressive hybridization. These involve: (i) cytonuclear profiles representing combinations of nuclear and mitochondrial genotypes that tended to be more nearly species‐specific and concordant elsewhere; and (ii) significant nuclear gametic disequilibria, perhaps attributable to positive assortative mating and/or differential fitnesses of homospecific vs. recombinant genotypes. However, outside this suspected hybrid region, ‘heterospecific’ genetic markers also appeared in low frequency, thus complicating interpretations. These discordant alleles on a broader geographic scale may reflect: (a) the retention of polymorphisms from an ancestral gene pool; (b) occasional evolutionary convergence (especially with respect to electrophoretic mobility of allozyme alleles); (c) the ‘footprints’ of a moving hybrid zone; or (d) differential introgressive penetrance across the current hybrid region. Copyright © 1993, Wiley Blackwell. All rights reserved

The Fagus sylvatica L. species complex in Europe and Western Asia comprises two commonly recognized subspecies, F. sylvatica subsp. sylvatica [= F. sylvatica sensu stricto (s. str.)] and F. sylvatica subsp. orientalis (= F. orientalis), and two putatively hybridogenous or intermediate taxa, “F. moesiaca” and “F. taurica”. The present study aimed to examine the demographic history of this species complex using 12 allelic loci of nine allozymes scored in 279 beech populations in western Eurasia. Three sets of phylogenetic scenarios were tested by approximate Bayesian computation: one dealing with the divergence of subspecies and/or regional populations within the whole taxonomical complex, and two others focusing on the potential hybrid origin of “F. moesiaca” and “F. taurica”. The best-supported scenario within the first set placed the time of divergence of regional populations of F. orientalis in the Early Pleistocene (1.18–1.87 My BP). According to this scenario, the Iranian population was the ancestral lineage, whereas F. sylvatica s. str. was the lineage that diverged most recently. “Fagus taurica” was found to have originated from hybridization between the Caucasian population of F. orientalis and F. sylvatica s. str. at 144 ky BP. In contrast, there was no evidence of a hybrid origin of “F. moesiaca”. The best-supported scenario suggested that the Balkan lineage is a part of F. sylvatica s. str., which diverged early from F. orientalis in Asia Minor (817 ky BP), while both the Italian and Central-European lineages diverged from the Balkan one later, at the beginning of the last (Weichselian) glacial period.

Data for electrophoretic pattern of 26 loci, resolved for the 8 protein systems (7- enzyme and 1-non-enzyme) assayed were used to investigate population structure of turbot along the Bulgarian and Romanian Black Sea coasts using genetic diversity measures. Seventeen loci were polymorphic in all populations and a total of 34 alleles were identified. Four types of tissue: muscle, retina, plasma and haemoglobin were analyzed. The percentage of polymorphic loci was high (65.38%) within populations. A low level of genetic differentiation among populations was detected, based on the Shannon’s information index (0.446-0.448) and the coefficient of genetic differentiation between populations (FST =0.014). The overall mean of within-population inbreeding estimate (FIS) was (-0.209) and demonstrated low level of inbreeding. The genetic distance (DNei) between the populations was low and vary between 0.003 and 0.014. Genetic distances among turbot populations were positively correlated with geographic distances (r = 0.474), but the association was not significant according to the Mantel test (p=0.651) and showed a lack of correlation between genetic distance and the geographic location of populations. Results identified one genetic stock with sufficient gene flow between all the three sites to prevent genetic differentiation from occurring. Only 1.4% of the genetic variation was observed among populations. Results revealed that adopting a single stock model and regional shared management could probably be appropriate for sustainable long-term use of turbot along western Black Sea coast. Determination of the contemporary state of the population distribution will be the prerequisite for determination of adequate measures for exploitation and protection of the existing turbot populations along western Black Sea coast.