LOW ANNUAL REPRODUCTIVE OUTPUT IN FEMALE REPTILES FROM NEW-ZEALAND

This paper summarises evidence for low rates of annual reproductive output (no. of offspring or eggs/female/yr) in New Zealand reptiles. Tuatara (Sphenodon spp.) and the geckos Hoplodactylus maculatus and H. duvaucelii are cold-adapted, nocturnal, and long-lived, with evidence in at least some populations of less-than-annual reproduction. Annual reproductive output estimated for three tuatara populations ranges from 1.27 to 2.28 eggs/female/yr. New Zealand geckos produce less than or equal to 2 offspring/female/yr. Hoplodactylus maculatus in the Macraes-Middlemarch region of Central Otago produces only about 0.85 offspring/female/yr, as a consequence of biennial reproduction and clutch sizes that are often less than two. The diurnal skinks Leiolopisma grande and L. otagense from the same region breed annually and have larger clutch sizes, so their annual reproductive output is higher (2.17 and 2.34 offspring/female/yr, respectively). Other wild populations of New Zealand skinks typically produce 1-5 offspring/female/yr. Unlike many species of oviparous geckos overseas, the viviparous New Zealand geckos do not produce multiple clutches per year, and this contributes to relatively low annual reproductive output in some species. Viviparous New Zealand skinks have similar annual reproductive output to viviparous skinks of similar body size from other parts of the world, Low annual reproductive output in New Zealand lizards thus appears to reflect, in part, responses to cool summer temperatures in association with a viviparous reproductive mode (geckos), as well as phylogenetic effects (colonisation by lineages of small clutch and body size, in geckos and skinks).