The Evolution of Normal and Reverse Sexual Size Dimorphism in Shorebirds and other Birds

Adaptive divergence in the Superb Fairy-wren (Malurus cyaneus): a mainland versus island comparison of morphology and foraging behaviour

“…There is ample evidence that males may increase their body-size to increase their success in intrasexual competitions and thereby increase mating opportunities (Darwin 1896;Downhower 1976;Jehl and Murray 1986;Shine 1989;Andersson 1994;see review in Fairbairn 1997), which may be true as the Superb Fairy-wren is territorial (Rowley 1965) and highly promiscuous (Mulder et al 1994). There may be selective pressure for smaller body-size in female Superb Fairy-wrens to enable them to fit inside the nest (e.g.…”

“…Sexual differences in body-size may be shaped by fitness benefits derived from male-male competition, such as for access to territories or mates, particularly in polygamous or promiscuous species (Darwin 1896;Amadon 1959;Selander 1966Selander , 1972Jehl and Murray 1986;Shine 1989). Sexual differences in size of bill may be allometric (i.e.…”

The evolution of sexual dimorphism in New Zealand giant moa (Dinornis) and other ratites

“…females are more than twice the size of males), whereas the maximum SDI value for jacanas is ca 0.8. This level of sexual dimorphism is almost as great as the highest ratio of male-biased size dimorphism, shown by great bustard Otis tarda (SDI ¼ 1.48 or higher; [1,4,6,12,13]). …”

“…food competition between sexes); reproductive role differentiation or 'dimorphic niche' hypotheses; and behavioural/sexual selection hypotheses [5][6][7][8]. Following Darwin [2] and Wallace [9], these competing hypotheses can also be categorized according to whether they try to explain the evolution of male size, female size or both [10,11].…”

“…The New Zealand moa radiation is phylogenetically nested within modern ratites, although its exact phylogenetic position remains debated [21][22][23][24], and the prevailing view of ratite relationships has been challenged by recent studies suggesting that tinamous are also nested within a paraphyletic ratite clade [24,25]. However, irrespective of which phylogeny is adopted, most living palaeognaths (ratites and tinamous) also exhibit varying levels of RSD, associated with prominent or exclusive paternal care of eggs and offspring, and a diverse array of mating systems ranging from monogamy to mixed polygyny/polyandry [6,[26][27][28].…”