Local habitat distribution determines the relative frequency and interbreeding potential for two Caribbean coral morphospecies

摘要

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 morphospe-cies, thereby influencing the genetic organization of the Madracis coral complex at the ～1-10 km spatial scale.