The causes and implications of sex role diversity in shorebird breeding systems

Abstract

Males and females often exhibit different behaviours during mate acquisition, pair‐bonding and parenting, and a convenient label to characterize these behaviours is sex role. The diverse roles that male and female shorebirds (plovers, sandpipers and allies) exhibit in mating and parenting have played a key role in advancing mainstream theories in avian ecology and behavioural biology including sexual selection, sexual conflict and parental cooperation. Recent advances in shorebird research have also highlighted the significance of the social environment in driving sex role behaviours by linking the adult sex ratio with breeding behaviour and population demography. Here we review the key advances in sex role research using shorebirds as an ecological model system. We identify knowledge gaps and argue that shorebirds have untapped potential to accelerate diverse research fields including evolutionary genomics, movement ecology, social networks and environmental changes. Future studies of sex roles will benefit from individual‐based monitoring using advanced tracking technologies, and from multi‐team collaborations that are facilitated by standardized data collection methodologies across different species in the field. These advances will not only contribute to our understanding of reproductive strategies, but they will also have knock‐on effects on predicting population resilience to environmental changes and on prioritizing species for conservation.

Sex ratios and gender norms: why both are needed to understand sexual conflict in humans

“…Shorebirds (Scolopaci and Charadrii spp., sandpipers, plovers and allies) have provided an informative model for investigating the relationship between sex ratios and mating and parenting behaviour (Székely et al, 2023). Shorebirds exhibit broad inter-specific variation in mating systems and in the ability of both sexes to provide full parental care on their own, but are generally similar in ecology and variation in sex ratios as result of sex-biases in juvenile survival (Bennett & Owens, 2002;Székely et al, 2006;Liker et al, 2013;Carmona-Isunza et al, 2015;Eberhart-Phillips et al, 2018).…”

“…In species with male-biased adult sex ratios, males are more likely to provide the bulk of parental care, female multiple mating is more common and females have more showy plumage, a trait that is generally associated with investment in mating competition (Liker et al, 2013). A competitive mating market can thus motivate individuals of the abundant sex to provide more parental care to existing offspring (Székely et al, 2023). Similar evidence for parenting behaviour as a flexible response to ASR has been observed in other taxa, such as rails (Maynard Smith & Ridpath, 1972), cichlids (Grüter & Taborsky, 2005) and dung beetles (Rosa et al, 2017).…”

Role-reversed polyandry is associated with faster fast-Z in shorebirds

“…Here, we address this gap in the literature by investigating how fast-Z evolution is impacted by role-reversed polyandry in shorebirds, a paraphyletic group of wading birds within the Charadriiformes order, which are notable for exhibiting a tremendous variety of mating systems [ 33 , 34 ]. To achieve these aims, we first test whether shorebird clades have been evolving under role-reversed polyandry for sufficiently long to expect a genomic signature of this mating system.…”