Local habitat distribution determines the relative frequency and interbreeding potential for two Caribbean coral morphospecies
2007
Vermeij, Mark J. A | Sandin, Stuart A | Samhouri, Jameal F
We investigate the relationship between habitat heterogeneity and morphological variation in the Caribbean coral species-complex, Madracis pharensis/decactis. This complex showed strong but incomplete morphospecies habitat-matching on a small spatial scale. We find that only one Madracis morphospecies dominates in environments consisting of either few vertical or few horizontal habitats, whereas in environments consisting of a mixture of horizontal and vertical habitats both morphospecies are common. We demonstrate that the observed patterns of morphospecies habitat-matching cannot be explained by a pure polyphenic model, where morphological variants are induced by a genotype-by-environment interaction at their settling site. Instead, we suggest that habitat-matching results in whole or in part from genetically predetermined factors. We present support for the hypothesis that this pattern of habitat-matching is due to habitat- and morphospecies-specific selective factors. Our study describes how a variable environmental factor, i.e. habitat distribution, has a non-linear effect on the spatial distribution of these morphospecies, thereby influencing the genetic organization of the Madracis coral complex at the ~+1-10 km spatial scale.
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