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If an ancestral stem group repeatedly colonizes similar environments, developmental plasticity specific to that group should consistently give rise to similar phenotypes. Parallel selection on those similar phenotypes could lead to the repeated evolution of characteristic ecotypes, a property common to many adaptive radiations. A key prediction of this(More)
Natural populations often experience the weakening or removal of a source of selection that had been important in the maintenance of one or more traits. Here we refer to these situations as 'relaxed selection,' and review recent studies that explore the effects of such changes on traits in their ecological contexts. In a few systems, such as the loss of(More)
REVIEWS I n ethology, there exists a rich tradition of comparative research designed to explore patterns of adaptation and evolutionary change. Almost exclusively , these research programmes have employed inter-specific comparisons in which the behavioural characterization of the species was based on single populations and the behavioural patterns were(More)
Neo-darwinists have long argued that parallel evolution, the repeated evolution of similar phenotypes in closely related lineages, is caused by the action of similar environments on alleles at many loci of small effect. A more controversial possibility is that the genetic architecture of traits initiates parallelism, sometimes through fixation of alleles of(More)
Experimental evidence supporting convergent character displacement is rare; only one example exists and it is in the form of orientation and territory competition experiments performed in the laboratory. However, outcomes of laboratory experiments involving behaviour or competition can be artefacts of unnatural conditions and, therefore, the results of the(More)
The postglacial adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus) has been widely used to investigate the roles of both adaptive evolution and plasticity in behavioral and morphological divergence from the ancestral condition represented by present-day oceanic stickleback. These phenotypes tend to exhibit high levels of ecotypic(More)
At the end of the 19th century, the suggestion was made by several scientists, including J. M. Baldwin, that behavioral responses to environmental change could both rescue populations from extinction (Baldwin Effect) and influence the course of subsequent evolution. Here we provide the historical and theoretical background for this argument and offer(More)
Phenotypic plasticity can influence evolutionary change in a lineage, ranging from facilitation of population persistence in a novel environment to directing the patterns of evolutionary change. As the specific nature of plasticity can impact evolutionary consequences, it is essential to consider how plasticity is manifested if we are to understand the(More)
Changing environments, whether through natural or anthropogenic causes, can lead to the loss of some selective pressures ('relaxed selection') and possibly even the reinstatement of selective agents not encountered for many generations ('reversed selection'). We examined the outcome of relaxed and reversed selection in the adaptive radiation of the(More)