Responses of Clonal Reef Taxa to Environmental Change

SYNOPSIS. Many reef taxa are predominantly clonal, and theirclones can spread over tens of meters and live for hundredsof years. Colony growth, which produces large colonies, andvegetative propagation, which can generate many clonal replicatesof colonies, affect the response of clonal taxa to climate changethrough a variety of mechanisms, some of which mitigate andsome which amplify effects on individuals. The large numbersof replicate individuals generated among clonal taxa may enablesome individuals to survive catastrophic mortality events suchas storms and then expand following the perturbation. In thosecircumstances clonality buffers the effects of environmentalchange. Conversely, the genetic uniformity of populations dominatedby few genotypes may leave clonal taxa more susceptible to physiologicstress than aclonal taxa. Consequently, clonal species may bemore sensitive to climate change that has chronic and/or acuteeffects on survival. Chronic stresses that reduce recruitmentwill have less obvious effects on clonal taxa than aclonal taxa.Under conditions of reduced recruitment, clonality will allowsome species to persist as relict populations due to the longevityof genets. The presence of relict populations has the appearanceof resistance to climate change. In fact, these taxa are responding,but at a slower rate. The long generation time of genets willslow the pace of evolution among clonal species, making adaptationat projected rates of climate change unlikely. The differentialresponse of species to environmental change will lead to transitionsin community structure as climate changes.