Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource

Abstract

Although rapid adaptive changes in morphology on ecological time scales are now well documented in natural populations, the effects of such changes on whole-organism performance capacity and the consequences on ecological dynamics at the population level are often unclear. Here we show how lizards have rapidly evolved differences in head morphology, bite strength, and digestive tract structure after experimental introduction into a novel environment. Despite the short time scale (Ϸ36 years) since this introduction, these changes in morphology and performance parallel those typically documented among species and even families of lizards in both the type and extent of their specialization. Moreover, these changes have occurred side-by-side with dramatic changes in population density and social structure, providing a compelling example of how the invasion of a novel habitat can evolutionarily drive multiple aspects of the phenotype.bite force ͉ diet ͉ evolution ͉ gut structure

Niche expansion leads to small-scale adaptive divergence along an elevation gradient in a medium-sized passerine bird

“…For these reasons, it is desirable to study contemporary niche expansions to gain insight into what ecological and geographical settings promote differentiation. Well-described examples come from fishes in postglacial lakes (Schluter & Rambaut 1996;Knudsen et al 2006;Roy et al 2007), lizards on islands (Herrel et al 2008) and host shifts in insect systems ( Feder et al 1988;Carroll & Boyd 1992), but little is known about the initial stages of niche expansion outside these settings.…”

“…Niche expansion, where a species augments its realized niche when presented with ecological opportunity, is thought to play an important role in species formation (Simpson 1953;Schluter 2000), and its link to adaptive divergence has been the focus of study during colonization of islands (Losos et al 1994;Grant 1998;Herrel et al 2008) and postglacial lakes (Schluter & Rambaut 1996;Knudsen et al 2006), and after host shifts in insect systems (Feder et al 1988;Carroll & Boyd 1992). However, the ecological triggers of divergence during niche expansion are little studied compared with the ecological consequences of niche expansion (e.g.…”

Divergence across diet, time and populations rules out parallel evolution in the gut microbiomes of Trinidadian guppies

“…The change in LP guppy gut length, however, is not a drastic structural shift in comparison, for example, to an introduced lizard population's rapid cecal valve evolution with increased plant consumption (Herrel et al, 2008). Therefore, despite dietary differences in HP and LP guppies, both ecotypes still rely on high intake and fast dietary passage that may hinder the pressure for whole-sale changes in gut communities.…”

The Relationship Between Cephalic Scales and Bones in Lizards: A Preliminary Microtomographic Survey on Three Lacertid Species

“…It is widely accepted that morphological differences between species reflect differences in diet, ecology and patterns of bone growth (Moreno and Carrascal, 1993;Niehoff et al, 2004;Herrel et al, 2008; but see Schwenk, 2000Schwenk, , 2002. The way such morphological differences have evolved may provide useful information on morphogenetic patterns and selective pressures acting on them.…”

“…Under this scenario, applications of geometric modeling to study the morphology and the biomechanical dynamics of skull proved useful to quantify differences between species, providing helpful information on the structural organization of the skull (Hallgrimsson et al, 2007). Lacertids are one of the most diverse groups of lizards in terms of dietary specialization, and although they have been well described in the literature (e.g., Arnold, 1989;Barahona and Barbadillo, 1998;Herrel et al, 2004Herrel et al, , 2008Evans, 2008), the degree to which the mechanics of their skulls differs among species remains unexamined.…”