Genotypes selected for early and late avian lay date differ in their phenotype, but not fitness, in the wild

Abstract

Global warming has shifted phenological traits in many species, but whether species are able to track further increasing temperatures depends on the fitness consequences of additional shifts in phenological traits. To test this, we measured phenology and fitness of great tits ( Parus major ) with genotypes for extremely early and late egg lay dates, obtained from a genomic selection experiment. Females with early genotypes advanced lay dates relative to females with late genotypes, but not relative to nonselected females. Females with early and late genotypes did not differ in the number of fledglings produced, in line with the weak effect of lay date on the number of fledglings produced by nonselected females in the years of the experiment. Our study is the first application of genomic selection in the wild and led to an asymmetric phenotypic response that indicates the presence of constraints toward early, but not late, lay dates.

Genetic and epigenetic differentiation in response to genomic selection for avian lay date

“…Firstly, our experimental design did not include any replicate lines (Verhagen, Gienapp, et al., 2019 ), limiting our ability to differentiate selection as the underlying cause of the reported epigenetic and genetic differentiation from genetic drift. We, however observe increased differentiation over generations between selection lines in GEBVs (genetic level) and lay dates (phenotypic level) (Lindner et al., 2023 ; Verhagen, Gienapp, et al., 2019 ), indicating that the genomic selection lines offer a suitable contrast between early and late avian lay date for the study of genetic variants and genomic pathways that might be involved in mediating avian lay date.…”

“…Overall, average GEBVs for third‐generation individuals (−0.50 and 0.61 for the early and late selection line, respectively) corresponded reasonably well to the cumulative predictive response to genomic selection of −0.72 days for the early selection line and 0.84 days for the late selection line (Verhagen, Gienapp, et al., 2019 ). The response to genomic selection at the level of GEBVs translated to a response at the phenotypic level when birds were breeding in aviaries (Verhagen, Gienapp, et al., 2019 ) as well as in the wild (Lindner et al., 2023 ). The experiment was performed under the approval by the Animal Experimentation Committee of the Royal Academy of Sciences (DEC‐KNAW), Amsterdam, The Netherlands, protocol NIOO 14.10.…”

“…Genomic selection for lay dates has led to a clear differentiation in GEBVs accompanied by phenotypic differentiation when lay dates were recorded in aviaries (Verhagen, Gienapp, et al., 2019 ) and in the wild (Lindner et al., 2023 ). However, genomic selection based on GEBVs is a ‘blind process’ that does not provide any information on the genetic variants that responded to genomic selection or the epigenetic marks that accompanied the genetic response.…”

Relative breeding timing and reproductive success of a resident montane bird species

“…food availability), and/or late breeders could simply be of lower quality [22]. Results from the selection experiment by Lindner et al [39] may suggest that in wild populations, individual quality and not environmental differences is the main driver leading to decreased reproductive success observed later in the season. Lindner et al [39] artificially selected birds for early or late breeding timing in captivity and found no difference in breeding success between the early and late breeding genetic lines.…”

“…However, this relationship is not consistent across bird species [26], likely owing to other factors influencing breeding timing and success. For example, a recent captive experimental study on great tits (Parus major) created early and late laying selection lines to test the fitness consequences of genetically controlled early versus late breeding timing [39]. Even though birds in the early laying selection line better matched invertebrate phenology, there were no differences in fitness (including survival and lifetime reproductive success) between early and late breeders [39].…”