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Reproductive Biology of Insular Reptiles: Marine Subsidies Modulate Expression of the "Island Syndrome"

In English

Författare

Summary, in English

Differences in ecological conditions can result in the evolution of dramatic inter-population shifts in whole suites of traits. We studied variation in reproductive output in three lizard populations of the Skyros Wall Lizard (Podarcis gaigeae, Lacertidae) endemic to the Skyros Archipelago (Greece), which live under similar climatic conditions but differ in predation pressure and food availability. Based on the "Island syndrome" hypothesis, we predicted that females from Island populations would produce larger, but fewer offspring. The study populations differ conspicuously in average body size, with males from the satellite Lakonissi and Diavates islets being respectively 20% and 39% larger than males from the main Skyros Island. Lizards from these predator-free islets produced eggs of larger size than the main Skyros population; however, they also produced significantly larger clutches than the Skyros population (2.31 +/- 0.83 and 2.73 +/- 1.0 vs. 1.97 +/- 0.58 eggs). All inter-population differences in clutch size, clutch volume, and egg size were explained by corresponding differences in average body size of the dams, revealing that across all populations, reproductive effort scaled similarly with maternal body size. There was no evidence of trade-offs between egg size and clutch size as generally encountered in many reptile taxa. The occurrence of this unusual pattern of reproductive investment among islet populations of giants is probably best explained by the occurrence of two underlying drivers: first, the substantial marine subsidies by resident seabird colonies and second, the existence of intense cannibalistic behaviors in the form of attacks to the tail and severe intraspecific predation on juveniles. This suggests that subsidies-driven gigantism in island endemics may free species from such trade-offs and allow a population to maximize reproductive output in multiple, normally conflicting dimensions.

Publiceringsår

2011

Språk

Engelska

Sidor

545-552

Publikation/Tidskrift/Serie

Copeia

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

American Society of Ichthyologists and Herpetologists

Ämne

  • Biological Sciences

Status

Published

Forskningsgrupp

  • Speciation, Adaptation and Coevolution
  • Evolution and Ecology of Phenotypes in Nature

ISBN/ISSN/Övrigt

  • ISSN: 0045-8511