J P Wares and T M Bell, University of Georgia, Athens, GA, USA © 2008 Elsevier B.V. All rights reserved.
Measuring Isolation Further Reading
An important consideration in the design of ecological reserves and the potential for local adaptation within a species is the occurrence and degree of isolation between populations. Isolation can occur by many mechanisms. Individuals can be isolated 'physically' due to geographic or environmental barriers that limit effective dispersal between regions; 'numerically' (i.e., Allee effects in areas of low population size or reproductive success); 'repro-ductively' (depending on both recognition factors and genetic factors); or 'ecologically'. Isolation should primarily be considered in terms of demography - that is, individuals from different populations may come into contact with one another, but if that contact does not result in successful reproduction then it may indicate a form of isolation.
Isolation is a quantitative and potentially dynamic trait of populations. While the two extremes of this trait might be complete isolation (no interpopulation mating, gene flow, or interaction) or complete mixing of individuals and/or genomes from each population (panmixia), the greater challenge is to understand the mechanisms underlying intermediate patterns of isolation. Situations where isolation has not been completely achieved are a topic of great interest and in some cases are studied as examples of incipient speciation events.
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