revisiting niche divergence hypothesis in dimorphic birds: is diet overlap correlated with sexual size dimorphism?

The evolution of sexual size dimorphism (SSD) is a long-standing topic in evolutionary biology, but there is little agreement on the extent to which SSD is driven by the different selective forces. While sexual selection and fecundity selection have traditionally been proposed as the two leading hypotheses, SSD may also result from natural selection through mechanisms such as sexual niche divergence, which might have reduced resource competition between sexes. Here, we revisited the niche divergence hypothesis by testing the relationship between the sexual overlap in diet and SSD of 56 bird species using phylogenetic comparative analyses. We then assessed how SSD variation relates to the three main hypotheses: sexual selection, fecundity selection, and sexual niche divergence using phylogenetic generalized least squares (PGLS). Then, we compared sexual selection, fecundity selection, and niche divergence selection as SSD drivers through phylogenetic confirmatory path analyses to disenta..., The database of diet overlap was compiled through a literature survey of all major ornithological journals. The ISI Web of Knowledge was systematically searched for original case studies in which data on the diet composition of males and females were provided. A total of 289 references were examined, 62 of which provided data on the diet of both sexes for 58 species belonging to 32 families. We discarded studies based on prey types brought to the nest by adults (n=8) because food provisioning to chicks does not represent the actual nutritional requirements of males and females, or those based on isotope analyses (n=10), since both sexes might show overlapping isotopic niches, while having a different trophic niche, for instance, if both sexes feed on different prey with similar δ15N values (Bearhop et al., 2004). Diet composition was described using stomachs, esophageal contents, and regurgitations (80.3% of the studies), feces (13.1%), and direct observation (6.6%).
The description of ..., , # Revisiting niche divergence hypothesis in sexually dimorphic birds: is diet overlap correlated with sexual size dimorphism?

This study explores the relationship between Sexual Size Dimorphism (SSD) and ecological dynamics in bird species. The dataset includes information on the diet of 58 bird species, aiming to investigate the correlation between SSD and diet overlap, mating systems, sexual display behaviors, and clutch size.

\**Dataset contents: ** We compiled data from a thorough literature survey, sifting through 289 references to focus on 58 bird species. The dataset includes details on diet overlapping between both males and females. Mating systems were categorized, incorporating polyandry, monogamy, and polygyny. Male sexual display behaviors were classified based on a five-point scale, ranging from ground displays to acrobatic aerial displays. Clutch size, representing fecundity, was also documented. Morphometric traits, such as body mass, wing length, bill length, and tar...