Inbreeding and inbreeding avoidance in wild giant pandas

Abstract

Inbreeding can have negative consequences on population and individual fitness, which could be counteracted by inbreeding avoidance mechanisms. However, the inbreeding risk and inbreeding avoidance mechanisms in endangered species are less studied. The giant panda, a solitary and threatened species, lives in many small populations and suffers from habitat fragmentation, which may aggravate the risk of inbreeding. Here, we performed long-term observations of reproductive behaviour, sampling of mother-cub pairs and large-scale genetic analyses on wild giant pandas. Moderate levels of inbreeding were found in 21.1% of mating pairs, 9.1% of parent pairs and 7.7% of panda cubs, but no high-level inbreeding occurred. More significant levels of inbreeding may be avoided passively by female-biased natal dispersal rather than by breeding dispersal or active relatedness-based mate choice mechanisms. The level of inbreeding in giant pandas is greater than expected for a solitary mammal and thus warrants concern for potential inbreeding depression, particularly in small populations isolated by continuing habitat fragmentation, which will reduce female dispersal and increase the risk of inbreeding.

Walking in a heterogeneous landscape: Dispersal, gene flow and conservation implications for the giant panda in the Qinling Mountains

“…In our analysis, male giant pandas represented closer genetic relationships than females in proximal distance. This finding is in accordance with a recent study in giant pandas (Hu et al., ). Some long‐distance dispersal events have been recorded in Qinling (Pan et al., ; Zhang et al., ), and this kind of behaviour is expected to disrupt the IBD pattern.…”

No evidence forMHC‐based mate choice in wild giant pandas

“…Paternity analysis identified the fathers of 11 panda cubs. Furthermore, for mother‐father‐cub trios, the genotyped MHC alleles at locus DRB1 were consistent with Mendel's law of inheritance, reflecting the reliability of our paternity analysis (see details in Hu et al., ).…”

“…Sex identification results confirmed the inference of male and female identity based on reproductive behavior and spatial position clues. Each mating site comprised one estrous female and between 1 and 6 males (see details in Hu et al., ).…”

“…Two methods, tracking GPS‐collared pandas (Wei et al., ) and following the unique vocalizations of courting or mating pandas, were used to search for mating sites from 2008 to 2016 in Foping and from 2008 to 2010 in Changqing (see details in Hu et al., ). We identified the estrous female, dominant male (i.e., the male who won the combat), and the subordinate males (i.e., other males who participated in combat) by observing behavioral and spatial position cues (Pan et al., ; Schaller et al., ).…”

“…PCR volumes and conditions as well as microsatellite genotyping are detailed in Hu et al. (). After obtaining multi‐locus combined genotypes, we identified individuals following Zhan et al.…”