Shared and Unique Features of Diversification in Greater Antillean Anolis Ecomorphs

Abstract

Abstract. Examples of convergent evolution suggest that natural selection can often produce predictable evolutionary outcomes. However, unique histories among species can lead to divergent evolution regardless of their shared selective pressures-and some contend that such historical contingencies produce the dominant features of evolution. A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles. On each of four islands, anole species partition the structural habitat into at least four categories, exhibiting similar morphologies within each category. We assessed the relative importance of shared selection due to habitat similarity, unique island histories, and unique effects of similar habitats on different islands in the generation of morphological variation in anole ecomorphs. We found that shared features of diversification across habitats were of greatest importance, but island effects on morphology (reflecting either island effects per se or phylogenetic relationships) and unique aspects of habitat diversification on different islands were also important. There were three distinct cases of island-specific habitat diversification, and only one was confounded by phylogenetic relatedness. The other two unique aspects were not related to shared ancestry but might reflect as-yet-unmeasured environmental differences between islands in habitat characteristics. Quantifying the relative importance of shared and unique responses to similar selective regimes provides a more complete understanding of phenotypic diversification, even in this much-studied system.

Evidence for Concerted and Mosaic Brain Evolution in Dragon Lizards

“…The classical adaptive radiation studies on ecomorph divergence in Anolis lizards reveal strong, repeated, convergent evolution across island systems [Losos et al, 1998;Langerhans et al, 2006]. Interestingly, while Anolis ecomorphs have evolved many times independently, there is no parallel evolution between ecomorph and brain structure [Powell and Leal, 2012].…”

Repeatability of locomotor performance and of morphology – locomotor performance relationships

“…Common patterns of repeated ( parallel or convergent) evolution of the same performance-environment relationships emphasise the role that selection plays in generating among-taxa variation in locomotor performance, and in the physiological, morphological and behavioural traits that determine performance (Taylor and McPhail, 1985;McGuigan et al, 2003;Langerhans and DeWitt, 2004;Langerhans et al, 2006;Dalziel et al, 2012;Franssen et al, 2013;Fu et al, 2013;da Silva et al, 2014;Haas et al, 2015;Nelson et al, 2015). Despite the adaptive significance of locomotion, how the variation in locomotion is generated among individuals within a population, which is what natural selection acts upon, is relatively poorly understood.…”

Is convergence surprising? An examination of the frequency of convergence in simulated datasets

“…The ''evolution of similar features independently in different evolutionary lineages'' (Futuyma, 1998) has been found in many organismal phenotypes, from ecology, behavior, and morphology (Blackledge and Gillespie, 2004;Grenier and Greenberg, 2005;Langerhans et al, 2006;Melville et al, 2006;Moore and Willmer, 1997;Nevo, 1979;Wiens et al, 2006;Wittkopp et al, 2003) to genes, proteins, enzymes or enzyme active sites (Charnock et al, 2002;Chen et al, 1997;Govindarajan and Goldstein, 1996;Kornegay et al, 1994;Lawn et al, 1997;Mattevi et al, 1996). Virtually all current biology texts address this phenomenon (e.g., Campbell et al, 2003, p. 307;Freeman, 2005, p. 501;Starr and Taggart, 2004, p. 313).…”