Genetic diversity and sex ratio of naked mole rat, Heterocephalus glaber, zoo populations.

The naked mole rat, Heterocephalus glaber, is a highly unusual mammal that displays a complex social system similar to that found in eusocial insects. Colonies of H. glaber are commonly maintained in zoo collections because they represent fascinating educational exhibits for the public. However, little is known about the genetic structure or sex ratio of captive populations of H. glaber. In this study, we developed a set of microsatellite markers to examine genetic variation in three captive zoo populations of H. glaber. We also studied sex ratio of these captive populations. Our goal was to determine levels of genetic variation within, and genetic differences between, captive populations of H. glaber. Overall, we found modest levels of genetic variation in zoo populations. We also uncovered little evidence for inbreeding within the captive populations. However, zoo populations did differ genetically, which may reflect the isolation of captive naked mole rat colonies. Finally, we found no evidence of biased sex ratios within colonies. Overall, our study documents levels of genetic variation and sex ratios in a captive eusocial mammalian population. Our results may provide insight into how to manage captive populations of H. glaber.

Gene duplication and the evolution of phenotypic diversity in insect societies.

Gene duplication is an important evolutionary process thought to facilitate the evolution of phenotypic diversity. We investigated if gene duplication was associated with the evolution of phenotypic differences in a highly social insect, the honeybee Apis mellifera. We hypothesized that the genetic redundancy provided by gene duplication could promote the evolution of social and sexual phenotypes associated with advanced societies. We found a positive correlation between sociality and rate of gene duplications across the Apoidea, indicating that gene duplication may be associated with sociality. We also discovered that genes showing biased expression between A. mellifera alternative phenotypes tended to be found more frequently than expected among duplicated genes than singletons. Moreover, duplicated genes had higher levels of caste-, sex-, behavior-, and tissue-biased expression compared to singletons, as expected if gene duplication facilitated phenotypic differentiation. We also found that duplicated genes were maintained in the A. mellifera genome through the processes of conservation, neofunctionalization, and specialization, but not subfunctionalization. Overall, we conclude that gene duplication may have facilitated the evolution of social and sexual phenotypes, as well as tissue differentiation. Thus this study further supports the idea that gene duplication allows species to evolve an increased range of phenotypic diversity.

Population genetic structure of the predatory, social wasp Vespula pensylvanica in its native and invasive range.

Invasive species cause extensive damage to their introduced ranges. Ocean archipelagos are particularly vulnerable to invasive taxa. In this study, we used polymorphic microsatellite markers to investigate the genetic structure of the social wasp Vespula pensylvanica in its native range of North America and its introduced range in the archipelago of Hawaii. Our goal was to gain a better understanding of the invasion dynamics of social species and the processes affecting biological invasions. We found that V. pensylvanica showed no significant genetic isolation by distance and little genetic structure over a span of 2000 km in its native range. This result suggests that V. pensylvanica can successfully disperse across large distances either through natural- or human-mediated mechanisms. In contrast to the genetic patterns observed in the native range, we found substantial genetic structure in the invasive V. pensylvanica range in Hawaii. The strong patterns of genetic differentiation within and between the Hawaiian Islands may reflect the effects of geographic barriers and invasion history on gene flow. We also found some evidence for gene flow between the different islands of Hawaii which was likely mediated through human activity. Overall, this study provides insight on how geographic barriers, invasion history, and human activity can shape population genetic structure of invasive species.