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AbstractPhenotypic differentiation within polytypic species is often attributed to selection, particularly when selection might be acting on a trait that serves as a signal for predator avoidance and mate choice. We evaluated this hypothesis by examining phenotypic and genotypic clines between populations of the strawberry poison frog Oophaga pumilio, a polytypic species that exhibits aposematic color pattern variation that is thought to be subject to both natural and sexual selection. Our aim was to assess the extent of admixture and to estimate the strength of selection acting on coloration across a region of Panama where monomorphic populations of distinctly colored frogs are separated by polymorphic populations containing both color variants alongside intermediately colored individuals. We detected sharp clinal transitions across the study region, which is an expected outcome of strong selection, but we also detected evidence of widespread admixture, even at sites far from the phenotypic transition zone. Additionally, genotypic and phenotypic clines were neither concordant nor coincident, and with one exception, selection coefficients estimated from cline attributes were small. These results suggest that strong selection is not required for the maintenance of phenotypic divergence within polytypic species, challenging the long-standing notion that strong selection is implicit in the evolution of warning signals.

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Understanding how geographic and environmental heterogeneity drive local patterns of genetic variation is a major goal of ecological genomics and a key question in evolutionary biology. The tropical Andes and inter-Andean valleys are shaped by markedly heterogeneous landscapes, where species experience strong selective processes. We examined genome-wide SNP data together with behavioural and ecological traits (mating calls and body size) known to contribute to genetic isolation in anurans in the banana tree-dwelling frog, Boana platanera, distributed across an environmental gradient in Central Colombia (northern South America). Here, we analysed the relationships between environmentally (temperature and precipitation) associated genetic and phenotypic differentiation and the potential drivers of isolation by environment along an elevation gradient. We identified candidate SNPs associated with temperature and body size, which follow a clinal pattern of genome-wide differentiation tightly coupled with phenotypic variation: as elevation increases, B. platanera exhibits larger body size and longer call duration with more pulses but lower pulse rate and frequency. Thus, the environmental landscape has rendered a scenario where isolation by environment and candidate loci show concordance with phenotypic divergence in this tropical frog along an elevation gradient in the Colombian Andes. Our study sets the basis for evaluating the role of temperature in the genetic structure and local adaptation in tropical treefrogs and its putative effect on life cycle (embryos, tadpoles, adults) along elevation gradients.

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Avian diversity in the Neotropics has been traditionally attributed to the effect of vicariant forces promoting speciation in allopatry. Recent studies have shown that phylogeographical patterns shared among codistributed species cannot be explained by a single vicariant event, as species responses to a common barrier depend on the biological attributes of each taxon. The open vegetation corridor (OVC) isolates Amazonia and the Andean forests from the Atlantic Forest, creating a notorious pattern of avian taxa that are disjunctly codistributed in these forests. Here, we studied and compared the evolutionary histories of Ramphotrigon megacephalum and Pipraeidea melanonota, two passerines with allopatric populations east and west of the OVC that represent different subspecies. These species differ in their biological attributes: R. megacephalum is a sedentary, forest specialist mostly confined to bamboo understorey, whereas P. melanonota is a seasonal migrant and generalist species that ranges in a variety of closed and semi-open environments. We performed genetic and genomic analyses, complemented with the study of coloration and behavioural differentiation, to assess population divergence across the OVC. We found that the evolutionary histories of both R. megacephalum and P. melanonota have been shaped by this environmental barrier. However, these species responded in different and asynchronous manners to the establishment of the OVC and to past connections between the currently isolated South American forests, which can be mostly explained by their distinct ecologies and dispersal abilities. Our results support the fact that the biological attributes of species can make their evolutionary histories idiosyncratic.

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Despite the enormous advances in genetics, links between phenotypes and genotypes have been made for only a few nonmodel organisms. However, such links can be essential to understand mechanisms of ecological speciation. The Costa Rican endemic Mangrove Warbler subspecies provides an excellent subject to study differentiation with gene flow, as it is distributed along a strong precipitation gradient on the Pacific coast with no strong geographic barriers to isolate populations. Mangrove Warbler populations could be subject to divergent selection driven by precipitation, which influences soil salinity levels, which in turn influences forest structure and food resources. We used single nucleotide polymorphisms (SNPs) and morphological traits to examine the balance between neutral genetic and phenotypic divergence to determine whether selection has acted on traits and genes with functions related to specific environmental variables. We present evidence showing: (a) associations between environmental variables and SNPs, identifying candidate genes related to bill morphology (BMP) and osmoregulation, (b) absence of population genetic structure in neutrally evolving markers, (c) divergence in bill size across the precipitation gradient, and (d) strong phenotypic differentiation (P ST) which largely exceeds neutral genetic differentiation (F ST) in bill size. Our results indicate an important role for salinity, forest structure, and resource availability in maintaining phenotypic divergence of Mangrove Warblers through natural selection. Our findings add to the growing body of literature identifying the processes involved in phenotypic differentiation along environmental gradients in the face of gene flow.

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The peppers of the genus Capsicum have economic potential and elevated genetic variability. The objective of the study was to characterize morpho-agronomically and estimate the genetic divergence among pepper accessions of the active germplasm bank of Capsicum of the Instituto Federal do Espírito Santo, Campus Alegre. Thirty accessions were characterized based on ten morphological descriptors being the experimental design completely randomized, with six repetitions. Genetic diversity among the accessions was estimated by the Tocher grouping method as a measurement of dissimilarity and formed eight groups. The Singh method, used to estimate the relative contribution of each character in the expression of genetic divergence, indicated that the diameter of the produce (20.19%) and the height of the plant (19.46%) were the ones to contribute most to the total divergence (39.65%) among the accessions of pepper being studied. The study evidenced the existence of high genetic variability among the accessions of C. annuum collected in the south region of the state of Espírito Santo. No correlation was detected between the genetic distance and location of collections.(AU)

As pimentas do gênero Capsicum possuem potencial econômico e elevada variabilidade genética. Objetivou-se realizar a caracterização morfoagronômica e estimar a divergência genética entre acessos de pimenta do banco ativo de germoplasma de Capsicum do Instituto Federal do Espírito Santo, Campus de Alegre. Foram caracterizados trinta acessos com base em dez descritores morfológicos, sendo o delineamento experimental inteiramente casualizado, com seis repetições. A divergência genética entre os acessos foi estimada pelo método de agrupamento de Tocher, como medida de dissimilaridade, formando-se oito grupos. O método de Singh, utilizado para estimar a contribuição relativa de cada caráter na expressão da divergência genética, indicou que o diâmetro do fruto (20,19%) e a altura da planta (19,46%) foram os que mais contribuíram para a divergência total (39,65%) entre os acessos de pimenta avaliados. O estudo realizado evidencia a existência de alta variabilidade genética entre os acessos de C. annuum coletados no Sul do Estado do Espírito Santo. Não foi detectada correlação entre a distância genética e os locais de coleta.(AU)

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ABSTRACT: The peppers of the genus Capsicumhave economic potential and elevated genetic variability. The objective of the study was to characterize morpho-agronomically and estimate the genetic divergence among pepper accessions of the active germplasm bank of Capsicumof the Instituto Federal do Espírito Santo, Campus Alegre. Thirty accessions were characterized based on ten morphological descriptors being the experimental design completely randomized, with six repetitions. Genetic diversity among the accessions was estimated by the Tocher grouping method as a measurement of dissimilarity and formed eight groups. The Singh method, used to estimate the relative contribution of each character in the expression of genetic divergence, indicated that the diameter of the produce (20.19%) and the height of the plant (19.46%) were the ones to contribute most to the total divergence (39.65%) among the accessions of pepper being studied. The study evidenced the existence of high genetic variability among the accessions of C. annuumcollected in the south region of the state of Espírito Santo. No correlation was detected between the genetic distance and location of collections.

RESUMO: As pimentas do gênero Capsicumpossuem potencial econômico e elevada variabilidade genética. Objetivou-se realizar a caracterização morfoagronômica e estimar a divergência genética entre acessos de pimenta do banco ativo de germoplasma de Capsicumdo Instituto Federal do Espírito Santo, Campus de Alegre. Foram caracterizados trinta acessos com base em dez descritores morfológicos, sendo o delineamento experimental inteiramente casualizado, com seis repetições. A divergência genética entre os acessos foi estimada pelo método de agrupamento de Tocher, como medida de dissimilaridade, formando-se oito grupos. O método de Singh, utilizado para estimar a contribuição relativa de cada caráter na expressão da divergência genética, indicou que o diâmetro do fruto (20,19%) e a altura da planta (19,46%) foram os que mais contribuíram para a divergência total (39,65%) entre os acessos de pimenta avaliados. O estudo realizado evidencia a existência de alta variabilidade genética entre os acessos de C. annuumcoletados no Sul do Estado do Espírito Santo. Não foi detectada correlação entre a distância genética e os locais de coleta.

RESUMO

This study investigated whether the body morphology of the tetra fish Astyanax lacustris (previously Astyanax asuncionensis) varied between populations inhabiting one lagoon (a lentic, shallow environment, with great habitat complexity created by aquatic macrophytes) and an adjacent river (a deeper, lotic environment where aquatic macrophytes are scarce) in a seasonally flooded wetland, despite population mixing during the wet season. Morphological differences matched a priori predictions of the theory relating functional body morphology and swimming performance in fishes between lagoon and river habitats. Observed morphological variation could have resulted from adaptive habitat choice by tetras, predation by piscivores and adaptive phenotypic plasticity during development.

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