Search results for "lisääntymispanostus"
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Island selection on mammalian life-histories: genetic differentiation in offspring size
2008
BACKGROUND: Since Darwin's pioneering work, evolutionary changes in isolated island populations of vertebrates have continued to provide the strongest evidence for the theory of natural selection. Besides macro-evolutionary changes, micro-evolutionary changes and the relative importance of natural selection vs. genetic drift are under intense investigation. Our study focuses on the genetic differentiation in morphological and life-history traits in insular populations of a small mammal the bank vole Myodes glareolus. RESULTS: Our results do not support the earlier findings for larger adult size or lower reproductive effort in insular populations of small mammals. However, the individuals li…
Frequency and Density-Dependent Selection on Life-History Strategies - A Field Experiment
2008
Negative frequency-dependence, which favors rare genotypes, promotes the maintenance of genetic variability and is of interest as a potential explanation for genetic differentiation. Density-dependent selection may also promote cyclic changes in frequencies of genotypes. Here we show evidence for both density-dependent and negative frequency-dependent selection on opposite life-history tactics (low or high reproductive effort, RE) in the bank vole (Myodes glareolus). Densitydependent selection was evident among the females with low RE, which were especially favored in low densities. Instead, both negative frequency-dependent and density-dependent selection were shown in females with high RE…