Meeting Abstract
Predicting the magnitude and nature of changes in a species’ range is becoming ever more important as an increasing number of species are faced with habitat changes, or are introduced to novel areas. An organism’s investment in life history traits is expected to change during range shifts or range expansion because populations encounter new ecological conditions. We studied the reproductive investment of an invasive amphibian, Xenopus laevis, and tested the hypothesis that allocation to reproduction decreases at the range edge relative to the core. We measured reproductive allocation in three populations distributed from the centre to the edge of the colonized range of X. laevis in France. Allocation was estimated as the relative gonad mass of both sexes during the local optimal period of reproduction of the species. We observed that the relative gonad mass significantly decreased at the range edge in both sexes while body condition remained constant. Moreover, females from the range edge were sexually active later than females from the range core. The level of resources allocated to reproduction decreased progressively from the center to the periphery of the colonized range revealing changes in trade-offs between life history traits. Such a pattern could be explained by interspecific competition or enhanced investment in dispersal capacity.
