Maternal body-volume as a constraint on reproductive output in lizards: evidence from the evolution of viviparity.

摘要: A few species of squamate reptiles contain both oviparous (egg-laying) and viviparous (live-bearing) populations, thus offer exceptional opportunities to test adaptationist hypotheses on the determinants reproductive output. We focus hypothesis that maternal body-volume constrains output in reptiles. If females are “full” eggs, what happens when viviparity evolves within a lineage? Eggs increase volume mass during development, primarily due uptake water, so how can they be accommodated mother's abdomen? predict resultant relative clutch (RCM) will lessened by (1) decrease (by reducing number or size offspring), and/or (2) an (via modifications shape adult females). Our comparisons conspecific lizards (Lerista bougainvillii) confirm live-bearers carry heavier clutches (in absolute terms) show predicted shifts body females. However, offspring were unaffected evolution viviparity, morphology too small fully offset mass. Thus, RCMs increased 50%, indicating produced which more completely filled space available abdominal cavity. conclude does play role determining output, but observed masses may optimized, rather than maximized, with respect available.