Sexual dimorphism in steppe tortoises (Testudo horsfieldii): influence of the environment and sexual selection on body shape and mobility

摘要: Abstract Selective forces shape sexes differently, with male body proportions facing strong selection to enhance mate searching and male-to-male combat traits, female fitness being influenced by the ability assimilate large amounts of nutrients necessary for vitellogenesis (and/or gestation), their carry eggs or embryos. We evaluated sexual dimorphism proportion more than 800 wild steppe tortoises ( Testudo horsfieldii ) in Uzbekistan. The thick, well-developed shell offers protection from predators but pronounced digging habits probably also constrain (e.g. a that is dorso-ventrally flattened, although round dorsal view helps penetrate into, move within soil). Thus, this species, natural might favour heavy flat «closed» small openings appendages. In males, these environmental influences appear be countered selection. Compared females, they weigh less (absolutely relative dimensions), have longer legs, structure allowing wider movements walk faster. Males were able right themselves quickly females did experimental tests. This quick righting critical because intra-sexual combats frequently result males flipped onto backs becoming prone hyperthermia predation. Females are heavily built, wide shells (relative shells), which may provide space carrying eggs. From our results, number simple hypotheses can tested on range chelonian species.