Responses of clonal reef taxa to environmental change

Abstract

SYNOPSIS. Many reef taxa are predominantly clonal, and their clones can spread over tens of meters and live for hundreds of years. Colony growth, which produces large colonies, and vegetative propagation, which can generate many clonal replicates of colonies, affect the response of clonal taxa to climate change through a variety of mechanisms, some of which mitigate and some which amplify effects on individuals. The large numbers of replicate individuals generated among clonal taxa may enable some individuals to survive catastrophic mortality events such as storms and then expand following the perturbation. In those circumstances clonality buffers the effects of environmental change. Conversely, the genetic uniformity of populations dominated by few genotypes may leave clonal taxa more susceptible to physiologic stress than aclonal taxa. Consequently, clonal species may be more sensitive to climate change that has chronic and/or acute effects on survival. Chronic stresses that reduce recruitment will have less obvious effects on clonal taxa than aclonal taxa. Under conditions of reduced recruitment, clonality will allow some species to persist as relict populations due to the longevity of genets. The presence of relict populations has the appearance of resistance to climate change. In fact, these taxa are responding, but at a slower rate. The long generation time of genets will slow the pace of evolution among clonal species, making adaptation at projected rates of climate change unlikely. The differential response of species to environmental change will lead to transitions in community structure as climate changes.