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opencc-zeroDec 2012View details →

Data from: Geographic variation in morphology of Dark-eyed Juncos and implications for population divergence

Geographic variation in morphology that develops among closely related populations can help drive genetic divergence, and eventually speciation, when those morphological traits are the basis for social interactions that influence reproduction. The North American Dark-eyed junco (Junco hyemalis) complex is an interesting case in speciation. The numerous subspecies have distinct breeding ranges and unique plumage coloration, but based on the presence of hybrid populations and recent genetic data, can be considered to belong to a single species. Research within various populations of juncos has shown first, that wing length and the amount of white on the tail feathers ("tail white") influence an individual's dominance status and mating success, and second, that these traits can undergo rapid evolution when social and environmental conditions change. Here, I used museum specimens to examine tail white and body size, as measured by wing and tail length, of males and females within and among 13 geographically distinct Dark-eyed Junco subspecies. I documented geographic variation of mean values for each of these morphological traits, as well as patterns of trait co-variation and the degree of sexual dimorphism. I discuss these results in relation to what they may indicate about the generation and maintenance of divergence among the subspecies.

opencc-zeroDec 2017View details →

Data from: Molecular phylogeny of Terniopsis (Podostemaceae) and contrasting molecular and morphological variations in two species

Podostemaceae show different patterns of morphological variation relative to molecular ones between genera and between species, but additional material was necessary to make the patterns clearer. Using new material collected from Cambodia, we compared the variations of Terniopsis chanthaburiensis and T. heterostaminata in Cambodia, Laos and Thailand, and conducted matK phylogenetic analysis with many samples and most species of the genus. In contrast to the narrow molecular variation, the morphological variation (e.g., in the length of the shoots and pedicels) is large and continuous. The results indicate that variation in the two species is intraspecific. A similar pattern exists in two pairs of other species of Terniopsis, in which the morphological variation is large and discontinuous, while there is little molecular difference. The opposite pattern is present in other cases (e.g., Dalzellia zeylanica and Tristicha trifaria). The variation in T. chanthaburiensis and T. heterostaminata does not appear to be a response to variation in the habitats, that is submerged rock surfaces in fast currents. Distributional and phylogenetic data indicate that Terniopsis diversified primarily in Laos and Thailand, then expanded into neighboring regions. A synopsis of the genus Terniopsis and its 14 species is given.

opencc-zeroOct 2019View details →

The spatial analysis of biological interactions: morphological variation responding to the co-occurrence of competitors and resources

By sharing geographic space, species are forced to interact with one another and the contribution of this process to evolutionary and ecological patterns of individual species is not fully understood. At the same time, species turnover makes that species composition varies from one area to another, so the analysis of biological interaction cannot be uncoupled from the spatial context. This is particularly important for clades that show high degree of specialization such as hummingbirds, where any variation in biotic pressures might lead to changes in morphology. Here, we describe the influence of biological interactions on the morphology of Hylocharis leucotis by simultaneously considering potential competition and diet resources. We characterized the extent of local potential competition and local available floral resources by correlating two measurements of hummingbird diversity, floral resources and the size of morphological space of H. leucotis along its geographic distribution. We found that H. leucotis shows an important morphological variability across its range and two groups can be recognized. Surprisingly, morphological variation is not always linked to local hummingbird richness or the phylogenetic similarity of. Only in the southern part of its distribution, H. leucotis is morphologically more variable in those communities where it coexist with closely related hummingbird species. We also found that morphological variation in H. leucotis is independent from the availability of floral resources. Our results suggest that abiotic factors might be responsible for morphological differences across populations in Hylocharis leucotis being biological interactions of minor importance.

opencc-zeroDec 2017View details →

Data from: Study of morphological variation of northern Neotropical Ariidae reveals conservatism despite macrohabitat transitions

Background: Morphological convergence triggered by trophic adaptations is a common pattern in adaptive radiations. The study of shape variation in an evolutionary context is usually restricted to well-studied fish models. We take advantage of the recently revised systematics of New World Ariidae and investigate skull shape evolution in six genera of northern Neotropical Ariidae. They constitute a lineage that diversified in the marine habitat but repeatedly adapted to freshwater habitats. 3D geometric morphometrics was applied for the first time in catfish skulls and phylogenetically informed statistical analyses were performed to test for the impact of habitat on skull diversification after habitat transition in this lineage. Results: We found that skull shape is conserved throughout phylogeny. A morphospace analysis revealed that freshwater and marine species occupy extreme ends of the first principal component axis and that they exhibit similar Procrustes variances. Yet freshwater species occupy the smallest shape space compared to marine and brackish species (based on partial disparity), and marine and freshwater species have the largest Procrustes distance to each other. We observed a single case of shape convergence as derived from 'C-metrics', which cannot be explained by the occupation of the same habitat. Conclusions: Although Ariidae occupy such a broad spectrum of different habitats from sea to freshwater, the morphospace analysis and analyses of shape and co-variation with habitat in a phylogenetic context shows that conservatism dominates skull shape evolution among ariid genera.

opencc-zeroDec 2015View details →

Data from: Extensive variation in sperm morphology in a frog with no sperm competition

Background: Recent comparative studies of several taxa have found that within-species variation in sperm size decreases with increasing levels of sperm competition, suggesting that male-male gamete competition selects for an optimal sperm phenotype. Previous studies of intraspecific sperm length variation have all involved internal fertilizers where some other factors—e.g., sperm storage and sperm movement along the walls of the female's reproductive tract—probably also influence and reduce sperm size variation. Thus external fertilizers, where those factors are absent, might be expected to exhibit even more variation when there is little or no sperm competition. To test that idea, we studied the sperm morphology of a North American chorus frog, the spring peeper (Pseudacris crucifer), a species in which males encounter little or no sperm competition. Results: As expected, sperm size was highly variable in the spring peeper, largely due to variation in flagellum length within and among individual males, among populations and between mitochondrial lineages in southwestern Ontario. In addition, a large proportion of spermatozoa in all males was abnormal in such a way that the ability of abnormal spermatozoa to fertilize was probably compromised. There were no differences in the frequencies of abnormalities among populations or mitochondrial lineages. Conclusions: In the absence of sperm competition, we suggest that genetic drift has probably played a role in the generation of diversity in sperm morphology in this species, potentially resulting in the observed differences among populations. Such interpopulation difference in sperm morphology might be expected to increase the degree of reproductive isolation between populations even before other isolating mechanisms evolve.

opencc-zeroDec 2015View details →

Data from: Geographic variation in hybridization and ecological differentiation between three syntopic, morphologically similar species of montane lizards

To understand factors shaping species boundaries in closely related taxa, a powerful approach is to compare levels of genetic admixture at multiple points of contact and determine how this relates to intrinsic and extrinsic factors, such as genetic, morphological and ecological differentiation. In the Australian Alps, the threatened alpine bog skink Pseudemoia cryodroma co-occurs with two morphologically and ecologically similar congeners, P. entrecasteauxii and P. pagenstecheri, and all three species are suspected to hybridize. We predicted that the frequency of hybridization should be negatively correlated with genetic divergence, morphological differentiation and microhabitat separation. We tested this hypothesis using a mitochondrial locus, 13 microsatellite loci, morphological and microhabitat data and compared results across three geographically isolated sites. Despite strong genetic structure between species, we detected hybridization between all species pairs, including evidence of backcrossed individuals at the two sites where all three species are syntopic. Hybridization frequencies were not consistently associated with genetic, morphological or ecological differentiation. Furthermore, P. entrecasteauxii and P. pagenstecheri only hybridized at the two sites where they are syntopic with P. cryodroma, but not at the largest site where P. cryodroma was not recorded, suggesting that P. cryodroma may serve as a bridging species. This study reveals the complex dynamics within a three species hybrid zone and provides a baseline for assessing the impact of climate change and anthropogenic habitat modification on future hybridization frequencies.

opencc-zeroApr 2020View details →

Data from: True colors: commercially-acquired morphological genotypes reveal hidden allele variation among dog breeds, informing both trait ancestry and breed potential

Direct-to-consumer canine genetic testing is becoming increasingly popular among dog owners. The data collected therein provides intriguing insight into the current status of morphological variation present within purebred populations. Mars WISDOM PANELTM data from 11,790 anonymized dogs, representing 212 breeds and 4 wild canine species, were evaluated at genes associated with 7 coat color traits and 5 physical characteristics. Frequencies for all tested alleles at these 12 genes were determined by breed and by phylogenetic grouping. A sub-set of the data, consisting of 30 breeds, was divided into separate same-breed populations based on country of collection, body size, coat variation, or lineages selected for working or conformation traits. Significantly different (p ≤ 0.00167) allele frequencies were observed between populations for at least one of the tested genes in 26 of the 30 breeds. Next, standard breed descriptions from major American and international registries were used to determine colors and tail lengths (e.g. genetic bobtail) accepted within each breed. Alleles capable of producing traits incongruous with breed descriptions were observed in 143 breeds, such that random mating within breeds has probabilities of between 4.9e-7 and 0.25 of creating undesirable phenotypes. Finally, the presence of rare alleles within breeds, such as those for the recessive black coloration and natural bobtail, was combined with previously published identity-by-decent haplotype sharing levels to propose pathways by which the alleles may have spread throughout dog breeds. Taken together, this work demonstrates that: 1) the occurrence of low frequency alleles within breeds can reveal the influence of regional or functional selection practices; 2) it is possible to trace the mode by which characteristics have spread across breeds during historical breed formation; and 3) the necessity of addressing conflicting ideals in breed descriptions relative to actual genetic potential is crucial.

opencc-zeroJun 2019View details →

Data from: Evolution of asexual Daphnia pulex in Japan: variations and covariations of the digestive, morphological and life history traits

Background Several genetic lineages of obligate parthenogenetic Daphnia pulex, a common zooplankton species, have invaded Japan from North America. Among these, a lineage named JPN1 is thought to have started colonization from a single genotype several hundred to thousand years ago and subsequently produced many genotypes in Japan. To examine the phenotypic variations due to ecological drivers diverging the genotypes in new habitats, we measured heritability and variation in 17 traits, including life history, morphology and digestive traits, and the genetic distance among the D. pulex JPN1 genotypes in Japan. Results We found that most of the traits measured varied significantly among the genotypes and that heritability was highest in the morphological traits, followed by the digestive and life history traits. In addition, 93% of the variation in these traits was explained by the first three components in the principal component analysis, implying that variations of these heritable traits are not random but rather converged into a few directions. These relations among traits revealed the potential importance of predation pressures and food conditions as factors for diverging and selecting different genotypes. However, the magnitude of the difference in any single trait group did not correlate with the genetic distance. Conclusions Our findings show that the divergent traits evolved within D. pulex JPN1 without genetic recombination since their ancestral clone invaded Japan. Large variations and covariations of the phenotypic traits, irrespective of the genetic distance among the genotypes, support the view that the invasive success of D. pulex JPN1 was promoted by a genetic architecture that allowed for large phenotypic variations with a limited number of functionally important mutations without recombination.

opencc-zeroDec 2012View details →

Data from: The quantitative genetics of physiological and morphological traits in an invasive terrestrial snail: additive versus non-additive genetic variation

1. The distribution of additive versus non-additive genetic variation in natural populations represents a central topic of research in evolutionary/organismal biology. For evolutionary physiologists, functional or whole-animal performance traits ("physiological traits") are frequently studied assuming they are heritable and variable in populations. 2. Physiological traits of evolutionary relevance are those functional capacities measured at the whole-organism level, with a potential impact on fitness. They can be classified as capacities (or performances) or costs, the former being directly correlated with fitness, and the latter being inversely correlated with fitness (usually assumed as constraints). 3. In spite of their obvious adaptive significance, the additive genetic variation of physiological traits, and its relative contribution to phenotypic variance (or narrow-sense heritability) in comparison to maternal, dominance or epistatic variance, is known only for a few groups such as insects and mammals. 4. In this study, we assessed the additive and maternal/non-additive genetic variation in a suite of physiological and morphological traits in populations of the land snail Cornu aspersum. 5.Except for dehydration rate (h2= 0.32 ± 0.15), egg mass (h2= 0.82 ± 0.30) and hatchling mass (h2= 1.01 ± 0.31) (population = fixed effect), we found very low additive genetic variation. Large non-additive/maternal effects were found in all traits. Cage effects did not change the results, indicating low contribution of common environmental variance to our results. No differences were found between the phenotypic or non-additive genetic variance/covariance matrices. 6. Even though we compared populations across 1300 km in a common garden setup, our results suggest an absence of physiological as well as morphological differentiation in these populations. 7. These results contrast with previous analyses in the original distributional range of this species, which found high additive genetic variation in morphological traits. These are intriguing results demanding further quantitative genetic studies in the original distributional range of this species as well as the history of colonization of this invasive species.

FIGURE 5 in Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

FIGURE 5. Representative specimens of Melanopareia torquata, showing the extremes of color variation observed. From left to right, M. t. torquata (MZUSP 86363 from Maranhão), M. t. rufescens (MZUSP 53453 from São Paulo) and M. t. bitorquata (MZUSP 78064 from Mato Grosso). Note that the white interscapular patch is intentionally exposed.

FIGURE 3 in Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

FIGURE 3. Scatterplot for the first versus the second principal component scores of a Principal Component Analysis of mensural variables of specimens of Melanopareia torquata.

FIGURE 4 in Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

FIGURE 4. Examples of color variation in Melanopareia torquata. From left (south) to right (north), specimens from Emas, São Paulo, 23°32'S, 46°37'W (MZUSP 59751), Franca, São Paulo, 20°32'S, 47°24'W (MZUSP 8018), Goiânia, Goiás, 16°40'S, 49°16'W (MZUPS 66058), Xavantina, Mato Grosso, 14°40'S, 52°21'W (MZUSP 32436), Rio das Mortes, Mato Grosso, 13°23'S, 51°22'W (MZUSP 17571), Goiatins, Tocantins, 07°52'S, 47°54'W (MZUSP 86383) and Sambaíba, Maranhão, 07°34'S, 45°46'W (MZUSP 86363).

FIGURE 1 in Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

FIGURE 1. Localities of the examined specimens of Melanopareia torquata. Specimens from southern Pará and northwestern Mato Grosso have not been referred to any subspecies and are indicated by white circles. Gray, black and white stars indicate the type localities of Synallaxis torquata zu Wied-Neuwied, 1831, Melanopareia torquata rufescens Hellmayr, 1924, and Synallaxis bitorquata d'Orbigny & Lafresnaye, 1837, respectively. The dashed line indicates the range of the species according to Ridgely & Tudor (2009).

FIGURE 2 in Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

FIGURE 2. Correlation between latitude and lengths of tail (left) and culmen (right) of specimens of Melanopareia t. torquata and M. t. rufescens examined in this study (black circles). Specimens from northwestern Mato Grosso and southern Pará have not been referred to any subspecies (labelled as "Amazonian" specimens) and were not included in the calculation of the fitting line.

FIGURES 10A–E in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURES 10A–E. Leiobunum hiraiwai, penis, ventral view (left) and tip of penis, lateral view (right), Kinki race. Localities: A. Mt Hoko (14). B. Kisokomakôgen (15). C. Mt Ontake (17). D. Narai (18). E. Mt Kokuzô (19). Numerals in parentheses denote code numbers of localities given in Fig. 7.

FIGURES 1A–L in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURES 1A–L. Leiobunum hiraiwai (Sato & Suzuki). A–B. Eye tubercle of male, lateral view. C–F. Genital operculum (C–D male, E–F female). G–H. Labrum of female, lateral view. IK. Chelicera of male, mesal view. L. Body of female, dorsal view. Localities (numerals in parentheses denote code numbers given in Fig. 7): A. Mt Bunagatake (10 — Kinki race). B, J. Mt Utsukushigahara (42 — Utsukushigahara race). C. Mt Hyônosen (8 — Kinki race). D, K. Mt Amagi (40 — Izu race). E, G, L. Kisokomakôgen (15 — Kinki race). F, H. Togakushi (50 — Western Kantô race). I. Mt Hiko (2 — KyushuHiroshima race).

FIGURE 18 in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURE 18. Diagrams illustrating the possible evolution of the races in Leiobunum hiraiwai. Details in the text.

FIGURES 5A–E in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURES 5A–E. Male karyotypes of Leiobunum hiraiwai. Races: A. KyushuHiroshima race. B–C. Kinki race. D–E. Intermediate populations. Localities: A. Mt Hikosan (2n = 18). B. Mt Bunagatake (2n = 20). C. Tsuetsukitôge Pass (2n = 20). D. Todai (2n = 20). E. Mt Nyûgasa (2n = 20).

FIGURES 6A–E in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURES 6A–E. Male karyotypes of Leiobunum hiraiwai. Races: A. Kamikôchi race. B–C. Utsukushigaraha race. D. Western Kantô race. E. Izu race. Localities: A. Ariake Spa (2n = 20). B. Mt Utsukushigahara (2n = 20). C. Kowashimizu, 1630 m alt., Mt Kirigamine (2n = 20). D. Mt BushûMitake (2n = 22). E. Mt Amagi (2n = 22).

FIGURES 14A–F in Geographic variation of chromosomes and somatic morphology in the Japanese polymorphic species Leiobunum hiraiwai (Arachnida: Opiliones: Sclerosomatidae)

FIGURES 14A–F. Leiobunum hiraiwai, penis, ventral (left) and lateral view (right), Utsukushigahara race. Localities: A. Yashajintôge Pass (46). B–D. Mt Kirigamine, Kowashimizu, 1660 m alt. (45). E. Tobira Pass (43). F. Mt Utsukushigahara (42). Numerals in parentheses denote code numbers of localities given in Fig. 7.