Scientists and conservationists may be looking in the wrong place for corals best equipped to ride out the global climate-change crisis, according to research published in a recent issue of the journal Science.
Ann Budd and John Pandolfi concluded thus after analyzing the relationship between geography and evolutionary innovation in the boulder star coral (Montastraea annularis) species complex, a group of Caribbean reef corals for which morphological and molecular data concur on species differences.
The authors carried out a shape analysis of the various growth forms of both fossil (dating back to more than 850,000 years ago) and living coral to assess morphological disparity within the group.
They found that the greatest and most rapid changes to the morphology of the fossil coral growth forms, implying lineage splitting and fusion, were concentrated at the edge zones (i.e. towards the limit of the corals’ distribution) and that the least and slowest changes, implying lineage stasis, characterized the interior locations towards the central part of their distribution.
The results of their study suggested that species edge zones played an important part in evolutionary innovation, which may be caused by factors ranging from hybridisation to parapatric or peripatric speciation.
This has important implications for coral reef conservation, because conventional wisdom is to preserve the centres of high species richness (typically in the interior portions of the corals’ distribution).
However, by doing so, the authors argue that important sources of evolutionary novelty during periods of global change might be overlooked.
According to lead author Ann Budd, "…areas ranked highly for may not represent regions of maximum evolutionary potential." The paper concludes that future design of marine reserves should also take into account evolutionary processes and the connectivity among populations by focusing on the peripheral areas.
For more information, see the paper: Budd, AF and JM Pandolfi (2010) Evolutionary novelty is concentrated at the edge of coral species distributions. Science 328, pp. 1558–1561.