Population Genetic Structure and Historical Demography of the Ground BeetlePheropsophus jessoensisfrom the Tsinling-Dabashan Mountains, Central China Based on Mitochondrial DNA Analysis

Beetle bombing always deters praying mantises

Some animals have evolved chemical weapons to deter predators. Bombardier beetles (Coleoptera: Carabidae: Brachininae: Brachinini) can eject toxic chemicals at temperatures of 100 °C from the tips of their abdomens, ‘bombing’ the attackers. Although some bombardier beetles can reportedly deter predators, few studies have tested whether bombing is essential for successful defence. Praying mantises (Mantodea) are ambush predators that attack various arthropods. However, it is unclear whether bombardier beetles deter mantises. To test the defensive function of bombing against praying mantises, I observed three mantis species, Tenodera sinensis, Tenodera angustipennis, and Hierodula patellifera (Mantidae), attacking the bombardier beetle Pheropsophus jessoensis (Carabidae: Brachininae: Brachinini) under laboratory conditions. All mantises easily caught the beetles using their raptorial forelegs, but released them immediately after being bombed. All of the counterattacked mantises were observed to groom the body parts sprayed with hot chemicals after releasing the beetles. When treated P. jessoensis that were unable to eject hot chemicals were provided, all mantises successfully caught and devoured the treated beetles. Therefore, bombing is essential for the successful defence of P. jessoensis against praying mantises. Consequently, P. jessoensis can always deter mantises.

Relationship of genetic diversity and niche centrality: a survey and analysis

The distribution of genetic diversity within and among populations in relation to species' geographic ranges is important to understanding processes of evolution, speciation, and biogeography. One hypothesis predicts that natural populations at geographic range margins will have lower genetic diversity relative to those located centrally in species' distributions owing to a link between geographic and environmental marginality; alternatively, genetic variation may be unrelated with geographic marginality via decoupling of geographic and environmental marginality. We investigate the predictivity of geographic patterns of genetic variation based on geographic and environmental marginality using published genetic diversity data for 40 species (insects, plants, birds, mammals, worms). Only about half of species showed positive relationships between geographic and environmental marginality. Three analyses (sign test, multiple linear regression, and meta-analysis of correlation effect sizes) showed a negative relationship between genetic diversity and distance to environmental niche centroid, but no consistent relationship of genetic diversity with distance to geographic range center.