Biological and extrinsic correlates of extinction risk in Chinese lizards.

China is a country with one of the most species-rich reptile faunas in the world. However, nearly a quarter of Chinese lizard species assessed by the China Biodiversity Red List are threatened. Nevertheless, to date, no study has explicitly examined the pattern and processes of extinction and threat in Chinese lizards. In this study, we conducted the first comparative phylogenetic analysis of extinction risk in Chinese lizards. We addressed the following 3 questions: (1) What is the pattern of extinction and threat in Chinese lizards? (2) Which species traits and extrinsic factors are related to their extinction risk? (3) How can we protect Chinese lizards based on our results? We collected data on 10 species traits (body size [BS], clutch size, geographic range size, activity time, reproductive mode, habitat specialization [HS], habitat use, leg development, maximum elevation, and elevation range) and 7 extrinsic factors (mean annual precipitation (MAP), mean annual temperature, mean annual solar insolation, normalized difference vegetation index (NDVI), human footprint, human population density, and human exploitation). After phylogenetic correction, these variables were used separately and in combination to assess their associations with extinction risk. We found that Chinese lizards with a small geographic range, large BS, high HS, and living in high MAP areas were vulnerable to extinction. Conservation priority should thus be given to species with the above extinction-prone traits so as to effectively protect Chinese lizards. Preventing future habitat destruction should also be a primary focus of management efforts because species with small range size and high HS are particularly vulnerable to habitat loss.

Proximate Causes of Infertility and Embryo Mortality in Captive Zebra Finches.

AbstractSome species show high rates of reproductive failure, which is puzzling because natural selection works against such failure in every generation. Hatching failure is common in both captive and wild zebra finches (Taeniopygia guttata), yet little is known about its proximate causes. Here we analyze data on reproductive performance (the fate of >23,000 eggs) based on up to 14 years of breeding of four captive zebra finch populations. We find that virtually all aspects of reproductive performance are negatively affected by inbreeding (mean r=-0.117); by an early-starting, age-related decline (mean r=-0.132); and by poor early-life nutrition (mean r=-0.058). However, these effects together explain only about 3% of the variance in infertility, offspring mortality, fecundity, and fitness. In contrast, individual repeatability of different fitness components varied between 15% and 50%. As expected, we found relatively low heritability in fitness components (median: 7% of phenotypic variation and 29% of individually repeatable variation). Yet some of the heritable variation in fitness appears to be maintained by antagonistic pleiotropy (negative genetic correlations) between male fitness traits and female and offspring fitness traits. The large amount of unexplained variation suggests a potentially important role of local dominance and epistasis, including the possibility of segregating genetic incompatibilities.