MEPS 226:125-133 (2002)  -  doi:10.3354/meps226125

Reproductive seasonality and sexual dimorphism in green turtles

B. J. Godley*, A. C. Broderick, R. Frauenstein, F. Glen, G. C. Hays

Marine Turtle Research Group, School of Biological Sciences, University of Wales, Singleton Park, Swansea SA2 8PP, Wales, UK

ABSTRACT: The temporal distribution of nesting and mating in green turtles Chelonia mydas at Ascension Island (7°57¹S, 14°22¹W) in the South Atlantic is described. Mathematical description of the seasonal pattern of nesting showed extreme similarity between seasons, and evidence is presented to support the hypothesis that observed patterns are driven by prevailing environmental temperature. Mating was observed to begin before nesting and follow a pattern consistent with a modelled seasonal influx of suitable females into the annual breeding population. When available data on male size are compared with that of females from the same population (n = 12 populations), a pronounced and consistent sexual dimorphism, with males being smaller than females, is highlighted in all populations. The possible mechanisms behind the evolution of such a pattern are discussed.

KEY WORDS: Chelonia mydas · Mating · Breeding · Ascension Island · Sea turtles · Atlantic

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