Bank Voles in Southern Eurasia: Vicariance and Adaptation

Microevolutionary variation in molar morphology of Onychomys leucogaster decoupled from genetic structure

In neutral models of quantitative trait evolution, both genetic and phenotypic divergence scale as random walks, producing a correlation between the two measures. However, complexity in the genotype-phenotype map may alter the correlation between genotypic and phenotypic divergence, even when both are evolving neutrally or nearly so. Understanding this correlation between phenotypic and genetic variation is critical for accurately interpreting the fossil record. This study compares the geographic structure and scaling of morphological variation of the shape of the first lower molar of 77 individuals of the northern grasshopper mouse Onychomys leucogaster to genome-wide SNP variation in the same sample. We found strong genetic structure but weak or absent morphological structure indicating that the scaling of each type of variation is decoupled from one another. Low P_ST values relative to F_ST values are consistent with a lack of morphological divergence in contrast to genetic divergence between groups. This lack of phenotypic structure and the presence of notable within-sample phenotypic variance are consistent with uniform selection or constraints on molar shape across a wide geographic and environmental range. Over time, this kind of decoupling may result in patterns of phenotypic stasis masking underlying genetic patterns.

Differentiation of the Chestnut Tiger Butterfly Parantica sita (Lepidoptera: Nymphalidae: Danainae) in China

The chestnut tiger butterfly, Parantica sita (Kollar) (Lepidoptera: Nymphalidae: Danainae), occurs in Asia, along the Himalayas, and into the Malayan region. Previous studies found three types of mitogenomes with substantial genetic divergence in samples from China. To clarify the level of differentiation within P. sita, we investigated both molecular data and morphological features in 429 individuals from China. Upon examination, mitochondrial cytochrome oxidase subunit I (COI) sequences showed three substantially diverged haplotype groups. Based on microsatellite genotypes, the samples divided into three clusters that were consistent with the COI haplotype groups. With that genetic data, we named three distinguishable P. sita lineages: PS-A, PS-B, and PS-C. We also found obvious morphological differences in wing color, male sex brand, and genitalia structures among the three lineages. According to the published structure of male genitalia, that of PS-A is identical to that of P. s. sita, and that of PS-B is identical to that of P. pedonga. Based on all the results, we tentatively propose dividing P. sita into three species: PS-A (the former P. s. sita) is the typical Parantica sita [Kollar, (1844)], mainly distributed in southwestern China; PS-C (the former P. s. niphonica) is elevated to full species as Parantica niphonica (Moore, 1883), distributed in Taiwan Island and Japan; and PS-B will be Parantica pedongaFujioka, 1970, mainly distributed in Tibet and western Sichuan. Divergence time estimates showed that PS-A separated from the PS-B + PS-C clade about 8.79 million years ago (Ma), when the Hengduan Mountains underwent an appreciable elevation increase, isolating the Tibet population from the others. PS-B and PS-C diverged about 4.87 Ma, in accord with the formation of Taiwan Island mountains. The founder effect may explain why PS-C’s genetic diversity is lower than that of the other clades.

Testing the occurrence of convergence in the craniomandibular shape evolution of living carnivorans

Convergence consists in the independent evolution of similar traits in distantly related species. The mammalian craniomandibular complex constitutes an ideal biological structure to investigate ecomorphological dynamics and the carnivorans, due to their phenotypic variability and ecological flexibility, offer an interesting case study to explore the occurrence of convergent evolution. Here, we applied multiple pattern‐based metrics to test the occurrence of convergence in the craniomandibular shape of extant carnivorans. To this aim, we tested for convergence in many dietary groups and analyzed several cases of carnivoran convergence concerning either ecologically equivalent species or ecologically similar species of different body sizes described in the literature. Our results validate the occurrence of convergence in ecologically equivalent species in a few cases (as well as in the case of giant and red pandas), but almost never support the occurrence of convergent evolution in dietary categories of living carnivorans. Therefore, convergent evolution in this clade appears to be a rare phenomenon. This is probably the consequence of a complex interplay of one‐to‐many, many‐to‐one, and many‐to‐many relationships taking place between ecology, biomechanics, and morphology.