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AN INTRASPECIFIC COMPARATIVE ANALYSIS OF CHARACTER DIVERGENCE BETWEEN SYMPATRIC SPECIES.

AN INTRASPECIFIC COMPARATIVE ANALYSIS OF CHARACTER DIVERGENCE BETWEEN SYMPATRIC SPECIES.

Authors :
Marko, Peter B.
Harrison, R.
Source :
Evolution. Mar2005, Vol. 59 Issue 3, p554-564. 11p. 1 Diagram, 1 Chart, 4 Graphs.
Publication Year :
2005

Abstract

Although sympatric character divergence between closely related species has been described in a wide variety of taxa, the evolutionary processes responsible for generating these patterns are difficult to identify. One hypothesis that can explain sympatric differences is ecological character displacement: the sympatric origin of morphologically divergent phenotypes in response to selection caused by interspecific competition. Alternatively, populations may adapt to different conditions in allopatry, with sympatric distributions evolving through selective colonization and proliferation of ecologically compatible phenotypes. In this study, I characterize geographic variation within two sibling species of rocky-shore gastropods that have partially overlapping distributions in central California. In sympatry, both Nucella emarginata and N. ostrina show significant differences in shell shape and shell ornamentation that together suggest that where the two species co-exist, divergent phenotypes arose as an evolutionary consequence of competition. To examine the evolutionary origins of divergent characters in sympatry, I used a comparative method based on spatial autocorrelation to remove the portion of the phenotypic variance among populations that is explained by genetic distance (using mitochondrial DNA sequences and allozyme frequency data). Because the remaining portion of the phenotypic variance represents the independent divergence of individual populations, a significant sympatric difference in the corrected dataset provides evidence of true character displacement: significant sympatric character evolution that is independent of population history. After removal of genetic distance effects in Nucella, shell shape differences remain statistically significant in N. emarginata, providing evidence of significant sympatric character divergence. However, for external shell ornamentation in both species and shell shape in N. ostrina, the significance of sympatric... [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00143820
Volume :
59
Issue :
3
Database :
Academic Search Index
Journal :
Evolution
Publication Type :
Academic Journal
Accession number :
16789513
Full Text :
https://doi.org/10.1554/04-205