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The central‐peripheral hypothesis states that the demographic performance of a species decreases from the centre to the edge of its range. Peripheral populations are often smaller and tend to occur under different and suboptimal conditions from those of core populations. Peripheral populations can also coexist during part of their annual cycle with populations from the core of the species' range. Studies on peripheral populations are thus valuable for broadly understanding ecological and evolutionary processes. The Two‐banded Plover (TWBP, Charadrius falklandicus, Charadriidae) is an endemic South American shorebird that breeds in Argentine and Chilean Patagonia and migrates northward during the Austral winter. There are breeding records, however, from Lagoa do Peixe National Park in southern Brazil. In this study, we (i) mapped TWBP nests, (ii) characterised their reproductive biology and nesting habitats, (iii) colour‐marked birds and evaluated their seasonal occurrence patterns and (iv) estimated the size of the Brazilian population by combining supervised habitat classification analyses and generalised additive models. We estimated that the Brazilian population has 55 (95% CI: 44.1–66.6) breeding pairs and found that the length of their breeding season was roughly 5 months, spanning the Austral spring and summer. The population's nesting habitat differed, and their apparent reproductive success was lower than that of core populations. Unlike more southerly populations, the results of our mark‐resighting efforts demonstrate that the Brazilian population is sedentary. Taken together, these results indicate that the Brazilian TWBP population seems geographically isolated from the species' southernmost core populations, resulting in a heteropatric distribution. Furthermore, differences in nesting habitat and year‐round residency indicate that this peripheral population is ecologically distinct. The marked behavioural and ecological differences combined with the small population at the northern edge of the TWBP distribution support the central‐peripheral hypothesis in a Neotropical system. [ABSTRACT FROM AUTHOR]

Aim: How historical and contemporary eco‐evolutionary processes shape the patterns of genetic diversity and differentiation across species' distribution range remains an open question with strong conservation implications. Focusing on the orange stony coral, Astroides calycularis, we (a) characterized the pattern of neutral genetic diversity across the distribution range; (b) gave insights into the underlying processes; and (c) discussed conservation implications with emphasis on a national park located on a hotspot of genetic diversity. Location: South Mediterranean Sea and Zembra National Park. Methods: We combined new data from 12 microsatellites in 13 populations located in the Centre and in the Western Periphery of the distribution range with a published dataset including 16 populations from the Western and Eastern Peripheries. We analysed the relationship among parameters of genetic diversity (He, Ar(g)) and structure (population‐specific FST) and two measures of geographic peripherality. We compared two estimators of pairwise genetic structure (GST, DEST) across the distribution range. The evolutionary and demographic history of the populations following the Last Glacial Maximum was reconstructed using approximate Bayesian computations and maximum‐likelihood analyses. We inferred the contemporary connectivity among populations from Zembra National Park and with the neighbouring area of Cap Bon. Results: We demonstrate a decrease in genetic diversity and an increase in genetic differentiation from the Centre to the Eastern and Western Peripheries of the distribution range. Populations from Zembra show the highest genetic diversity reported in the species. We identified a spillover effect towards Cap Bon. Main conclusions: The patterns of genetic diversity and differentiation are most likely explained by "the postglacial range expansion hypothesis" rather than the "central–peripheral hypothesis." Enforcement of conservation measures should be considered to protect this genetic diversity pattern, in particular when considering the low effective population size inferred at many sites. [ABSTRACT FROM AUTHOR]

Premise of research. Comparative studies of variation in the ecology and genetics of natural plant populations located at the limits and in the center of a species range provide fundamental insights into the historical formation of species distribution patterns. Methodology. In this study, we quantify variation in the ecological niche and the expression of a floral polymorphism across the range of the Mediterranean geophyte Narcissus dubius Gouan. An exhaustive data set of known locations was compiled to distinguish groups of geographically central and peripheral populations in both Spain and France. These occur across a double climatic gradient. First, there is a gradient from a hot and dry Mediterranean climatic regime in eastern Spain to a milder Mediterranean climatic regime in southern France (lower maximum temperature and shorter summer drought). Second, there is a shift to a more continental climate in peripheral populations in inland Spain. We also modeled the current climatic niche and produced historical projections of potential glacial refugia for this species. Pivotal results. Peripheral populations showed consistent patterns of ecological niche differences with a less rupicolous ecology, more bare soil, and a higher cover of annual species. The ecological niche was more variable among peripheral populations than among central populations. Peripheral populations showed a repeated pattern of loss of stigma-height polymorphism and floral traits indicative of a reproductive strategy based on within-morph mating (probably selfing to assure seed set). Climate models indicate that contemporary peripheral populations (particularly in Spain) occur in areas that were least likely to have served as glacial refugia. Conclusions. Historical isolation and recolonization may have shaped contemporary patterns of ecological niche and reproductive trait variation among central and peripheral populations. [ABSTRACT FROM AUTHOR]

The distribution of genetic diversity within and among populations in relation to species' geographic ranges is important to understanding processes of evolution, speciation, and biogeography. One hypothesis predicts that natural populations at geographic range margins will have lower genetic diversity relative to those located centrally in species' distributions owing to a link between geographic and environmental marginality; alternatively, genetic variation may be unrelated with geographic marginality via decoupling of geographic and environmental marginality. We investigate the predictivity of geographic patterns of genetic variation based on geographic and environmental marginality using published genetic diversity data for 40 species (insects, plants, birds, mammals, worms). Only about half of species showed positive relationships between geographic and environmental marginality. Three analyses (sign test, multiple linear regression, and meta-analysis of correlation effect sizes) showed a negative relationship between genetic diversity and distance to environmental niche centroid, but no consistent relationship of genetic diversity with distance to geographic range center. [ABSTRACT FROM AUTHOR]