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opencc-zeroDec 2013View details →

Data from: Body size and allometric shape variation in the molly Poecilia vivipara along a gradient of salinity and predation

Background: Phenotypic diversity among populations may result from divergent natural selection acting directly on traits or via correlated responses to changes in other traits. One of the most frequent patterns of correlated response is the proportional change in the dimensions of anatomical traits associated with changes in growth or absolute size, known as allometry. Livebearing fishes subject to predation gradients have been shown to repeatedly evolve larger caudal peduncles and smaller cranial regions under high predation regimes. Poecilia vivipara is a livebearing fish commonly found in coastal lagoons in the north of the state of Rio de Janeiro, Brazil. Similar to what is observed in other predation gradients, lagoons inhabited by P. vivipara vary in the presence of piscivorous fishes; contrary to other poeciliid systems, populations of P. vivipara vary greatly in body size, which opens the possibility of strong allometric effects on shape variation. Here we investigated body shape diversification among six populations of P. vivipara along a predation gradient and its relationship with allometric trajectories within and among populations.ResultsWe found substantial body size variation and correlated shape changes among populations. Multivariate regression analysis showed that size variation among populations accounted for 66% of shape variation in females and 38% in males, suggesting that size is the most important dimension underlying shape variation among populations of P. vivipara in this system. Changes in the relative sizes of the caudal peduncle and cranial regions were only partly in line with predictions from divergent natural selection associated with predation regime.ConclusionsOur results suggest the possibility that adaptive shape variation among populations has been partly constrained by allometry in P. vivipara. Processes governing body size changes are therefore important in the diversification of this species. We conclude that in species characterized by substantial among-population differences in body size, ignoring allometric effects when investigating divergent natural selection?s role in phenotypic diversification might not be warranted.

opencc-zeroDec 2012View details →

Data from: Heterozygosity and orange colouration are strongly associated in the guppy (Poecilia reticulata)

The good-genes-as-heterozygosity hypothesis predicts that more elaborate male sexual ornaments are associated with higher levels of heterozygosity. Recent theoretical work suggests that such associations are likely to arise in finite, structured populations. We investigated the correlation between multilocus heterozygosity (MLH), which was estimated using 13 microsatellite loci, and male coloration in a wild population of guppies (Poecilia reticulata), a model species in sexual selection research. We found that MLH was a significant predictor of the relative area of orange spots, a trait that is subject to strong female preference in this species. Neither the relative area of black spots nor the number of black or orange spots was significantly correlated with MLH. We found no statistical support for local effects (i.e. strong effects of heterozygosity at specific markers), which suggests that relative orange spots area reflects genome-wide heterozygosity.

opencc-zeroDec 2015View details →

Data from: Effects of light environment during growth on the expression of cone opsin genes and behavioral spectral sensitivities in guppies (Poecilia reticulata)

Background: The visual system is important for animals for mate choice, food acquisition, and predator avoidance. Animals possessing a visual system can sense particular wavelengths of light emanating from objects and their surroundings and perceive their environments by processing information contained in these visual perceptions of light. Visual perception in individuals varies with the absorption spectra of visual pigments and the expression levels of opsin genes, which may be altered according to the light environments. However, which light environments and the mechanism by which they change opsin expression profiles and whether these changes in opsin gene expression can affect light sensitivities are largely unknown. This study determined whether the light environment during growth induced plastic changes in opsin gene expression and behavioral sensitivity to particular wavelengths of light in guppies (Poecilia reticulata). Results: Individuals grown under orange light exhibited a higher expression of long wavelength-sensitive (LWS) opsin genes and a higher sensitivity to 600-nm light than those grown under green light. In addition, we confirmed that variations in the expression levels of LWS opsin genes were related to the behavioral sensitivities to long wavelengths of light. Conclusions: The light environment during the growth stage alters the expression levels of LWS opsin genes and behavioral sensitivities to long wavelengths of light in guppies. The plastically enhanced sensitivity to background light due to changes in opsin gene expression can enhance the detection and visibility of predators and foods, thereby affecting survival. Moreover, changes in sensitivities to orange light may lead to changes in the discrimination of orange/red colors of male guppies and might alter female preferences for male color patterns.

opencc-zeroDec 2013View details →

Data from: Do freshwater ecoregions and continental shelf width predict patterns of historical gene flow in the freshwater fish Poecilia butleri?

We examined historical patterns of gene flow in the freshwater fish Poecilia butleri in western Mexico. We tested the hypothesis that the boundaries between four freshwater ecological communities (ecoregions) might have limited the movement of P. butleri because changes in species compositions might restrict establishment between adjacent ecoregions, even in situations where a physical barrier is absent. Hence, we predicted that boundaries between ecoregions should correspond to phylogeographical breaks in P. butleri. We also tested the hypothesis that the width of the continental shelf affected historical gene flow in P. butleri because a broad continental shelf provides a greater opportunity for rivers to coalesce during historical episodes of low sea levels as opposed to a narrow continental shelf that should restrict the potential for gene flow among adjacent rivers. Hence, we predicted greater amounts of historical gene flow among neighbouring river basins in the region of western Mexico where the continental shelf is wider, whereas, in the region where the continental shelf is narrower, we expected to detect limited levels of historical gene flow. We analyzed mitochondrial DNA sequence data (cytochrome b) taken from 264 individuals of P. butleri collected from 34 locations distributed across four different ecoregions in western Mexico. To examine patterns of phylogenetic diversification and historical gene flow in P. butleri, we employed several analytical approaches, including traditional tree-based phylogenetic analyses (likelihood and parsimony), haplotype network reconstruction, analyses of molecular variance, and spatial analysis of molecular variance. We found genetic breaks coinciding with two out of three different ecoregion boundaries, suggesting limited historical gene flow. In addition to different species compositions between these adjacent ecoregions, geological features such as the Trans-Mexican Volcanic Belt and the mountainous topography in south-western Mexico, likely contributed to these observed genetic breaks. By contrast, no genetic break was evident between two other ecoregions, a result that partially rejects our first hypothesis. Several results were consistent with our second hypothesis. Changes in the width of the continental shelf in western Mexico are associated with the observed patterns of historical gene flow. Our results indicate that the interactions among multiple geological and biological factors affect the spatial patterns of genetic diversity of widespread freshwater species.

opencc-zeroDec 2014View details →

Data from: Unique evolutionary trajectories in repeated adaptation to hydrogen sulphide-toxic habitats of a neotropical fish (Poecilia mexicana)

Replicated ecological gradients are prime systems to study processes of molecular evolution underlying ecological divergence. Here, we investigated the repeated adaptation of the neotropical fish Poecilia mexicana to habitats containing toxic hydrogen sulphide (H2S) and compared two population pairs of sulphide-adapted and ancestral fish by sequencing population pools of >200 individuals (Pool-Seq). We inferred the evolutionary processes shaping divergence and tested the hypothesis of increase of parallelism from SNPs to molecular pathways. Coalescence analyses showed that the divergence occurred in the face of substantial bidirectional gene flow. Population divergence involved many short, widely dispersed regions across the genome. Analyses of allele frequency spectra suggest that differentiation at most loci was driven by divergent selection, followed by a selection-mediated reduction of gene flow. Reconstructing allelic state changes suggested that selection acted mainly upon de novo mutations in the sulphide-adapted populations. Using a corrected Jaccard index to quantify parallel evolution, we found a negligible proportion of statistically significant parallel evolution of Jcorr = 0.0032 at the level of SNPs, divergent genome regions (Jcorr = 0.0061) and genes therein (Jcorr = 0.0091). At the level of metabolic pathways, the overlap was Jcorr = 0.2545, indicating increasing parallelism with increasing level of biological integration. The majority of pathways contained positively selected genes in both sulphide populations. Hence, adaptation to sulphidic habitats necessitated adjustments throughout the genome. The largely unique evolutionary trajectories may be explained by a high proportion of de novo mutations driving the divergence. Our findings favour Gould's view that evolution is often the unrepeatable result of stochastic events with highly contingent effects.

FIGURE 6 in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 6. Scanning electron microscopy images of female genital pores of (a) P. w i n g e i (Laguna de los Patos), (b) P. reticulata (Caroni Swamp), (c) P. obscura, (Upper Oropuche). Bar represents 200 mm.

FIGURE 1 in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 1. Origins of guppies used in this study from Trinidad and Tobago (a), and mainland South America (b). Stars indicate exactly known collection sites, all other designations are for rivers or areas from which the fish were collected.

FIGURE 7 in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 7. Phylogramm of P. obscura, and P. reticulata from different localities and P. w i n g e i based on approx. 2200bp of mitochondrial DNA sequences. 50% majority rule consensus tree rooted on M. picta as outgroup. Average bootstrap values obtained using different types of analysis (see Materials and Methods) are indicated above the branches. For abbreviations of origins see table 1. Numbers in brackets indicate different individuals from the same locality.

FIGURE 4 in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 4. CPD/SL/CPD ratios of P. obscura (symbols, population Rio Seco (RS), population Oropuche (OR)) and P. reticulata females (symbols, population Claxton Bay (CB) population Caroni Swamp (CS)).

FIGURE 8 in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 8. Phylogramm of P. o b s c u r a and P. reticulata and P. w i n g e i from different localities based on approximately 800 bp of cytochrome b DNA sequences. 50% majority rule consensus tree rooted on M. picta as outgroup. Average bootstrap values obtained using different types of analysis (see Materials and Methods) are indicated above the branches. For abbreviations of origins see table 1. Numbers in brackets indicate different individuals from the same locality.

FIGURE 2. P in Description of Poecilia (Acanthophacelus) obscura n. sp., (Teleostei: Poeciliidae), a new guppy species from western Trinidad, with remarks on P. w i n g e i and the status of the " Endler's guppy "

FIGURE 2. P. obscura male (a) and female (b) from locus typicus, Oropuche River (OR). (c) P. obscura, population Rio Seco (RS); (d) P, reticulata, population Caroni Swamp (CS); (e) P. reticulata, population Rio Yaguaracual (RY); (f) P. c f "wingei" from El Cordon waterfall (EC); (g) P. w i n g e i from locus typicus, population Campoma (Ca); (h) P. w i n g e i, population Laguna de los Patos (LP).

opennotspecifiedAug 2018View details →

FIGURE 2. A in Poecilia (Pamphorichthys) akroa, a new poeciliid species (Cyprinodontiformes: Poeciliidae) from the Rio Tocantins basin, Brazil

FIGURE 2. A. Osteology of the gonopodium of Poecilia (Pamphorichthys) akroa sp. n., scale bar: 1 mm; B. detail of gonopodium tip. Gonopodium palp represented by long, contiguous lines over osteological structures, scale bar: 0.25 mm.

opennotspecifiedAug 2018View details →

FIGURE 3 in Poecilia (Pamphorichthys) akroa, a new poeciliid species (Cyprinodontiformes: Poeciliidae) from the Rio Tocantins basin, Brazil

FIGURE 3. Ventral view of pelvic fins, urogenital region and anterior portion of anal fin of Poecilia (Pamphorichthys) akroa, MZUSP 83547, 23.9 mm SL, female. Anterior to left. Scale bar: 1 mm.

opennotspecifiedAug 2018View details →

FIGURE 1 in Poecilia (Pamphorichthys) akroa, a new poeciliid species (Cyprinodontiformes: Poeciliidae) from the Rio Tocantins basin, Brazil

FIGURE 1. Poecilia (Pamphorichthys) akroa sp. n.: top, holotype, MZUSP 121698, 16.9 mm SL, male, Brazil, Tocantins, Dianópolis, rio Palmeiras; bottom, MZUSP 83547, 23.9 mm SL, female, same locality as holotype.

opennotspecifiedJan 2011View details →

FIGURE 1 in Designation of the lectotype of Poecilia amazonica Garman, 1895 (Cyprinodontiformes, Poeciliidae) and discussion of its nomenclatural status

FIGURE 1. Poecilia amazonica, lectotype, MCZ 168870, 16.19 mm SL, Pará, Belém and environs, C. Cooke, 25 Oct 1859.