Female mating preferences and offspring survival: testing hypotheses on the genetic basis of mate choice in a wild lekking bird

Indirect benefits of mate choice result from increased offspring genetic quality and may be important drivers of female behaviour. ‘Good‐genes‐for‐viability’ models predict that females prefer mates of high additive genetic value, such that offspring survival should correlate with male attractiveness. Mate choice may also vary with genetic diversity (e.g. heterozygosity) or compatibility (e.g. relatedness), where the female's genotype influences choice. The relative importance of these nonexclusive hypotheses remains unclear. Leks offer an excellent opportunity to test their predictions, because lekking males provide no material benefits and choice is relatively unconstrained by social limitations. Using 12 years of data on lekking lance‐tailed manakins, Chiroxiphia lanceolata, we tested whether offspring survival correlated with patterns of mate choice. Offspring recruitment weakly increased with father attractiveness (measured as reproductive success, RS), suggesting attractive males provide, if anything, only minor benefits via offspring viability. Both male RS and offspring survival until fledging increased with male heterozygosity. However, despite parent–offspring correlation in heterozygosity, offspring survival was unrelated to its own or maternal heterozygosity or to parental relatedness, suggesting survival was not enhanced by heterozygosity per se. Instead, offspring survival benefits may reflect inheritance of specific alleles or nongenetic effects. Although inbreeding depression in male RS should select for inbreeding avoidance, mates were not less related than expected under random mating. Although mate heterozygosity and relatedness were correlated, selection on mate choice for heterozygosity appeared stronger than that for relatedness and may be the primary mechanism maintaining genetic variation in this system despite directional sexual selection.     

Reproductive allocation in Aidablennius sphynx (Teleostei, Blenniidae): females lay more eggs faster when paired with larger males

Individuals are expected to invest more in current reproductive effort when paired with a partner of higher than average quality. Aidablennius sphynx is an external fertilizing fish with paternal care in which females gain direct benefits from spawning with large males, but often 'make do' with small males. In this study, female reproductive responses to large and small males were investigated. When paired with large males, females spawned more eggs per unit time (i.e., at a faster rate). There was no difference in the size of the eggs spawned by females in relation to partner size. By ovipositing at a faster rate, females may have allocated more reproductive effort to large males. In addition, since small males are known to release far fewer sperm than large males, females may have reduced their spawn rate with small males as a tactic to ensure fertilization.