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The Ecological Relationship of the Salamander Ambystoma laterale to its All-Female, Gynogenetic Associate
Henry M. Wilbur
Vol. 25, No. 1 (Mar., 1971), pp. 168-179
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2406509
Page Count: 12
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In southeastern Michigan the all-female, gynogenetic salamander Ambystoma tremblayi is associated with a bisexual, diploid form, A. laterale. A. laterale has contributed two sets of chromosomes to the triploid genome of A. tremblayi. The present gynogenetic relationship between the two forms is probably a transitory stage in an evolutionary sequence that could result in the reproductive independence of the triploid line by the evolution of a parthenogenetic or of a bisexual, tetraploid form. Extinction of either form by competitive exclusion by the other form is also a possibility. Experimental larval populations in field enclosures tested the alternative hypotheses that the two forms do not overlap at all in their ecological requirements or that they interact as ecological equals. The outcomes of the experiments were measured by the survivorship of the population, the body sizes at metamorphosis and the lengths of the larval period. The results indicated that the two forms have different ecological requirements but still interact significantly. This interaction is affected by the microhabitat and the density of the population. Diploid larvae are less adversely affected by the presence of triploid larvae than triploid larvae are to the presence of diploid larvae. The shorter larval period of the diploid larvae is advantageous in the uncertain vernal pond habitat.
Evolution © 1971 Society for the Study of Evolution