TY - JOUR

T1 - Developmental dynamics of ecomorphological convergence in a transcontinental lizard radiation

AU - Hipsley, Christy A.

AU - Müller, Johannes

PY - 2017

Y1 - 2017

N2 - Phenotypic convergence has confounded evolutionary biologists for centuries, explained as adaptations to shared selective pressures, or alternatively, the result of limited developmental pathways. We tested the relative roles of adaptation and constraint in generating convergent cranial morphologies across a large lizard radiation, the Lacertidae, whose members inhabit diverse environments throughout the Old World and display high amounts of homoplasy associated with ecological niche. Using 3D X-ray computed tomography, we quantified cranial shape variation associated with ontogeny, allometry, and ecology, covering all lacertid genera and one-third of species diversity. Landmark-based geometric morphometrics showed that cranial shape varied significantly among biomes, with substantial convergence among arid-dwelling lineages. Comparisons of species cranial growth trajectories between biomes revealed that allometric postdisplacement, as evidenced by decreased elevation of a constant ontogenetic slope, drives the convergent paedomorphic appearance of independent arid-dwelling forms. We hypothesize that observed heterochronic changes reflect temporal compression of ancestral life history in response to extreme environments, with associated phenotypes occurring as by-products of adaptive shifts in reproductive investment. Although allometry has long been considered a developmental constraint, our results demonstrate that allometric flexibility during early ontogeny produces convergent ecomorphologies over vast temporal and spatial scales, thus dramatically obscuring underlying phylogenetic signals.

AB - Phenotypic convergence has confounded evolutionary biologists for centuries, explained as adaptations to shared selective pressures, or alternatively, the result of limited developmental pathways. We tested the relative roles of adaptation and constraint in generating convergent cranial morphologies across a large lizard radiation, the Lacertidae, whose members inhabit diverse environments throughout the Old World and display high amounts of homoplasy associated with ecological niche. Using 3D X-ray computed tomography, we quantified cranial shape variation associated with ontogeny, allometry, and ecology, covering all lacertid genera and one-third of species diversity. Landmark-based geometric morphometrics showed that cranial shape varied significantly among biomes, with substantial convergence among arid-dwelling lineages. Comparisons of species cranial growth trajectories between biomes revealed that allometric postdisplacement, as evidenced by decreased elevation of a constant ontogenetic slope, drives the convergent paedomorphic appearance of independent arid-dwelling forms. We hypothesize that observed heterochronic changes reflect temporal compression of ancestral life history in response to extreme environments, with associated phenotypes occurring as by-products of adaptive shifts in reproductive investment. Although allometry has long been considered a developmental constraint, our results demonstrate that allometric flexibility during early ontogeny produces convergent ecomorphologies over vast temporal and spatial scales, thus dramatically obscuring underlying phylogenetic signals.

KW - Allometry

KW - constraint

KW - convergence

KW - Lacertidae

KW - ontogeny

U2 - 10.1111/evo.13186

DO - 10.1111/evo.13186

M3 - Journal article

C2 - 28085191

AN - SCOPUS:85012050914

VL - 71

SP - 936

EP - 948

JO - Evolution; international journal of organic evolution

JF - Evolution; international journal of organic evolution

SN - 0014-3820

IS - 4

ER -