Abstract
Some 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 (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, 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.
Footnotes
Data accessibility: Supporting data, model structures and R scripts can be found in the Open Science Framework at https://osf.io/tgsz8/.
Authors’ contributions: W.F. and B.K. designed and planned the study. W.F., D.W. and K.M. collected reproductive performance data. Y.P. and W.F. analyzed the data with inputs from J.R. Y.P., W.F. and B.K. interpreted the results and wrote the manuscript with inputs from J.R. All authors contributed to the final manuscript.
Competing interests: We have no competing interests.
Funding: This research was supported by the Max Planck Society (to B.K.). Y.P. was part of the International Max Planck Research School for Organismal Biology.