GrainGenes Reference Report: OEC-146-549
Reference
OEC-146-549
Title
Females make tough neighbors: sex-specific competitive effects in seedlings of a dioecious grass
Journal
Oecologia
Year
2006
Volume
146
Pages
549-554
Author
Eppley SM
Abstract
If males and females of a species differ in their effect on intraspecific competition then this can have significant ecological and evolutionary consequences because it can lead to size and mortality disparities between the sexes, and thus cause biased population sex ratios. If the degree of sexual dimorphism of competitive effect varies across environments then this variation can generate sex ratio variation within and between populations. In a California population of Distichlis spicata, a dioecious grass species exhibiting extreme within-population sex ratio variation (spatial segregation of the sexes), I evaluated the intraspecific competitive effects of male and female D. spicata seedlings in three soil types. The sex of seedlings was determined using a RAPD-PCR marker co-segregating with female phenotype. Distichlis spicata seedlings, regardless of sex, were six times larger when grown with male versus female conspecific seedlings in soil from microsites where the majority of D. spicata plants are female, and this sexual dimorphism of competitive effect was weaker or did not occur in other soil types. This study suggests that it is not just the higher costs of female versus male reproduction itself that cause spatial segregation of the sexes in D. spicata, but that differences in competitive abilities between the sexes-which occur as early as the seedling stage-can generate sex ratio variation.
GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture.
GrainGenes Reference Report: OEC-146-549
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GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture. | |||