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Density effects on life‐history traits of an island lizard population
Author(s) -
Hasegawa Masami
Publication year - 1997
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/bf02523776
Subject(s) - avian clutch size , juvenile , biology , reproduction , life history theory , density dependence , population density , lizard , life history , population , ecology , population size , zoology , demography , sociology
Long‐term monitoring of life‐history traits and the effects of density upon them were studied in an island population of the lizard Eumeces okadae . Although life‐history traits such as clutch size, egg size and the proportion of mature reproductive females varied little over 7 years in the intact population, manipulation of density to simulate decreased population density enhanced juvenile growth rate, age at first reproduction, frequency of female reproduction and size‐specific clutch mass. In particular, the proportion of mature females reproducing annually increased almost 10 times from 5.6% to 53.8% after the removal of some lizards. However, body size at first reproduction and egg size were almost identical under both high and low density conditions. This study suggests that there were strong density‐dependent effects on several life‐history traits and that E. okadae attained a density close to the carrying capacity of the environment.