Biology subjects

Chik, H. Y. J.

Publications and source records attributed to Chik, H. Y. J..

3 recordsLinked to original sources

bioRxiv2022

Indirect genetic effects improve female extra-pair heritability estimates.

The question of why females engage in extra-pair behaviours is long-standing in evolutionary biology. One suggestion is that these behaviors are maintained through pleiotropic effects on male extra-pair behaviors and lifetime reproductive success (genes controlling extra-pair behaviours are shared between sexes, but only beneficial to one, in this case, males). However, for this to occur extra-pair behaviour must be heritable and positively genetically correlated between sexes. Although previous studies have suggested low heritability with no evidence for between-sex genetic correlations in extra-pair behaviours, indirect genetic effects (those derived from the behaviour of others, IGEs) from the social partner, the influence of the social partners genotype on the phenotype of an individual, have not been considered, despite the potential to uncover hidden heritability. Using data from a closed house sparrow population with a genetic pedigree spanning two decades, we tested the influence of IGEs on heritability and genetic correlation estimates of extra-pair behaviour. We found that the inclusion of IGEs improved model fit for both male and female extra-pair heritability. While IGEs did not change between-sex genetic correlations, we found a reduction in uncertainty in our estimates. Future studies should consider the effect of IGEs on the mechanisms of sex specific extra-pair behaviour.

evolutionary biology↗

bioRxiv2022

Increased opposite sex association is linked with fitness benefits, otherwise sociality is subject to stabilising selection in a wild passerine

Animal sociality, an individuals propensity to associate with others, has fitness consequences through mate choice, for example, directly, by increasing the pool of prospective partners, and indirectly through increased survival, and individuals benefit from both. Annually, fitness consequences are realised through increased mating success and subsequent fecundity. However, it remains unknown whether these consequences translate to life-time fitness. Here, we quantified social associations and their link to fitness annually and over lifetime, using a multi-generational, genetic pedigree. We used social network analysis to calculate variables representing different aspects of an individuals sociality. Sociality showed high within-individual repeatability. We found that birds with more opposite-sex associates had higher annual fitness than those with fewer, but this did not translate to lifetime fitness. Instead, for lifetime fitness, we found evidence for stabilizing selection on opposite-sex sociality, and sociality in general, suggesting that reported benefits are only short-lived in a wild population, and that selection favours an average sociality.

evolutionary biology↗

bioRxiv2021

What is the best fitness measure in wild populations? A case study on the power of short-term fitness proxies to predict reproductive value

Fitness is at the core of evolutionary theory, but it is difficult to measure accurately. One way to measure long-term fitness is by calculating the individuals reproductive value, which represents the expected number of allele copies an individual passes on to distant future generations. However, this metric of fitness is scarcely used because the estimation of individuals reproductive value requires long-term pedigree data, which is rarely available in wild populations where following individuals from birth to death is often impossible. Wild study systems therefore use short-term fitness metrics as proxies, such as the number of offspring produced. This study obtained three frequently used short-term proxies for fitness obtained at different offspring life stages (eggs, hatchlings, fledglings and recruits), and compared their ability to predict reproductive values derived from the genetic pedigree of a wild passerine bird population. We used twenty years of precise field observations and a near-complete genetic pedigree to calculate reproductive success, individual growth rate and de-lifed fitness as lifetime fitness measures, and as annual de-lifed fitness. We compared the power of these metrics to predict reproductive values and lineage survival to the end of the study period. The three short-term fitness proxies predict the reproductive values and lineage survival only when measured at the recruit stage. There were no significant differences between the different fitness proxies at the same offspring stages in predicting the reproductive values and lineage survival. Annual fitness at one year old predicted reproductive values equally well as lifetime de-lifed fitness. However, none of the short-term fitness proxies was strongly associated with the reproductive values. In summary, the commonly short-term fitness proxies capture long-term fitness with intermediate accuracy at best, if measured at recruitment stage. As lifetime fitness measured at recruit stage and annual fitness in the first year of life were the best proxies of long-term fitness, we encourage their future use.

evolutionary biology↗