Experimental Crossing of Two Distinct Species of Leopard Geckos, Eublepharis angramainyu and E. macularius: Viability, Fertility and Phenotypic Variation of the Hybrids

The identity of Tokays (Squamata: Gekkonidae: Gekko) from Hong Kong

The Tokay gecko (Gekko gecko), found throughout Southeast Asia and India, is a heavily harvested species of high commercial value. Recent studies have supported the elevation of the black morph of Tokay gecko, found only in southern China and northern Vietnam, to the species Gekko reevesii. Previous genetic studies focused on specimens of G. reevesii from southwestern populations. Hong Kong, in southeastern China, has native populations of G. reevesii. To verify the identity of G. reevesii in Hong Kong, we employed three mitochondrial genes (COI, Cytb & ND2) and constructed a matrilineal genealogy using other specimens from Guangxi (southwestern China) and northern Vietnam, as well as G. gecko from a wide range of Southeast Asian countries. Our study confirmed that G. reevesii occurs naturally in Hong Kong, but one exotic population of G. gecko, likely a translocation from international trade, was also revealed. Our study did not reject the species ranking of G. reevesii. Moreover, like previous studies, we recovered a paraphyletic G. gecko, which may reflect a species complex, hybridization or incomplete lineage sorting. More extensive sampling of the two species over a broader range of their asserted distribution together with the use of both mitochondrial and nuclear DNA are required to better investigate their biogeography.

The evolutionary history of an accidental model organism, the leopard gecko Eublepharis macularius (Squamata: Eublepharidae)

The leopard gecko, Eublepharis macularius, is a widely used model organism in laboratory and experimental studies. The high phenotypic diversity in the pet trade, the fact that the provenance of different breeding lines is unknown, and that distinct Eublepharis species are known to hybridize, implies that the continued use of E. macularius as a model requires clarity on the origin of the lineages in the pet trade. We combine multi-locus sequence data and the first range-wide sampling of the genus Eublepharis to reconstruct the evolutionary history of the Eublepharidae and Eublepharis, with an updated time-tree for the Eublepharidae. Our sampling includes five of the six recognized species and additional nominal taxa of uncertain status comprising 43 samples from 34 localities plus 48 pet-trade samples. The Eublepharidae began diversifying in the Cretaceous. Eublepharis split from its sister genera in Africa in the Palaeocene-Eocene, and began diversifying in the Oligocene-Miocene, with late Miocene-Pliocene cladogenesis giving rise to extant species. The current species diversity within this group is moderately underestimated. Our species delimitation suggests 10 species with four potentially unnamed divergent lineages in Iran, India and Pakistan. All 30 individuals of E. macularius that we sampled from the pet trade, which include diverse morphotypes, come from a few shallow E. macularius clades, confirming that lab and pet trade strains are part of a single taxon. One of the wild-caught haplotypes of E. macularius, from near Karachi, Pakistan, is identical to (10) pet-trade samples and all other captive populations are closely related to wild-caught animals from central/southern Pakistan (0.1-0.5 % minimum pairwise uncorrected ND2 sequence divergence).

Patterns, Predictors, and Consequences of Dominance in Hybrids

AbstractCompared to those of their parents, are the traits of first-generation (F₁) hybrids typically intermediate, biased toward one parent, or mismatched for alternative parental phenotypes? To address this empirical gap, we compiled data from 233 crosses in which traits were measured in a common environment for two parent taxa and their F₁ hybrids. We find that individual traits in F₁s are halfway between the parental midpoint and one parental value. Considering pairs of traits together, a hybrid's bivariate phenotype tends to resemble one parent (parent bias) about 50% more than the other, while also exhibiting a similar magnitude of mismatch due to different traits having dominance in conflicting directions. Using data from an experimental field planting of recombinant hybrid sunflowers, we illustrate that parent bias improves fitness, whereas mismatch reduces fitness. Our study has three major conclusions. First, hybrids are not phenotypically intermediate but rather exhibit substantial mismatch. Second, dominance is likely determined by the idiosyncratic evolutionary trajectories of individual traits and populations. Finally, selection against hybrids likely results from selection against both intermediate and mismatched phenotypes.

Ultraviolet reflectance and pattern properties in leopard geckos (Eublepharis macularius)

Complex visual signaling through various combinations of colors and patterns has been well documented in a number of diurnal reptiles. However, there are many nocturnal species with highly sensitive vision, being able to discriminate colors in night conditions, as was shown in geckos. Because of their sensitivity to chromatic signals, including UV (ultraviolet), they may have potential hidden features in their coloration, which may play role in intraspecific communication (e.g. mate choice) or interspecific signals (e.g. antipredatory function). We explored this hypothesis in nocturnal Leopard geckos (Eublepharis macularius), a species using visual signals in both antipredation defense and courtship, having ontogenetic color change accompanied by a shift in behavior. We used UV photography and visual modeling in order to compare various aspects of their coloration (luminance, contrast, color proportions) between sexes, age groups and populations. We found that Leopard geckos have considerable UV reflectance in white patches on their tails (and on the head in juveniles). Though, no prominent differences were detected in their coloration between various groups. We hypothesize that the limitation of UV reflectance to the head and tail, which are both actively displayed during defense, especially in juveniles, might potentially boost the effect of antipredation signaling.

Multiple interspecific hybridization and microsatellite mutations provide clonal diversity in the parthenogenetic rock lizard Darevskia armeniaca

Background

The parthenogenetic Caucasian rock lizard Darevskia armeniaca, like most other parthenogenetic vertebrate species, originated through interspecific hybridization between the closely related sexual Darevskia mixta and Darevskia valentini. Darevskia armeniaca was shown to consist of one widespread allozyme clone and a few rare ones, but notwithstanding the origin of clonal diversity remains unclear. We conduct genomic analysis of D. armeniaca and its parental sexual species using microsatellite and SNP markers to identify the origin of parthenogenetic clonal lineages.

Results

Four microsatellite-containing loci were genotyped for 111 specimens of D. armeniaca, 17 D. valentini, and four D. mixta. For these species, a total of 47 alleles were isolated and sequenced. Analysis of the data revealed 13 genotypes or presumptive clones in parthenogenetic D. armeniaca, including one widespread clone, two apparently geographically restricted clones, and ten rare clones. Comparisons of genotype-specific markers in D. armeniaca with those of its parental species revealed three founder-events including a common and two rare clones. All other clones appeared to have originated via post-formation microsatellite mutations in the course of evolutionary history of D. armeniaca.

Conclusion

Our new approach to microsatellite genotyping reveals allele-specific microsatellite and SNP markers for each locus studied. Interspecies comparison of these markers identifies alleles inherited by parthenospecies from parental species, and provides new information on origin and evolution of clonal diversity in D. armeniaca. SNP analyses reveal at least three interspecific origins of D. armeniaca, and microsatellite mutations in these initial clones give rise to new clones. Thus, we first establish multiple origins of D. armeniaca. Our study identifies the most effective molecular markers for elucidating the origins of clonal diversity in other unisexual species that arose via interspecific hybridization.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5359-5) contains supplementary material, which is available to authorized users.

A comparative study of growth: different body weight trajectories in three species of the genus Eublepharis and their hybrids

An extensive research effort is devoted to the evolution of life-histories and processes underlying the variation in adult body weight; however, in this regard, some animal taxa remain neglected. Here we report rates and timing of growth recorded in two wild-derived populations of a model lizard species, Eublepharis macularius (M, W), other two related species, i.e., E. angramainyu (A) and E. sp. (D), and their between-species hybrids. We detected clear differences among the examined species/populations, which can be interpreted in the terms of "fast - slow" continuum of life-history strategies. The mean asymptotic body size was the highest in A and further decreased in the following order: M, W, and D. In contrast, the growth rate showed an opposite pattern. Counter-intuitively, the largest species exhibited the slowest growth rates. The final body size was determined mainly by the inflexion point. This parameter reflecting the duration of exponential growth increased with mean asymptotic body size and easily overcompensated the effect of decreasing growth rates in larger species. Compared to the parental species, the F1 and backcross hybrids exhibited intermediate values of growth parameters. Thus, except for the case of the F2 hybrid of MxA, we failed to detect deleterious effects of hybridization in these animals with temperature sex determination.