The role of post-natal ontogeny in the evolution of phenotypic diversity in Podarcis lizards

Abstract

""Understanding the role of the developmental pathways in shaping phenotypic diversity allows appreciating in full the processes influencing and constraining morphological change. Podarcis lizards demonstrate extraordinary morphological variability that likely originated in short evolutionary time. Using geometric morphometrics and a broad suite of statistical tests, we explored the role of developmental mechanisms such as growth rate change, ontogenetic divergence ⁄ convergence ⁄ parallelism as well as morphological expression of heterochronic processes in mediating the formation of their phenotypic diversity during the post-natal ontogeny. We identified hypermorphosis – the prolongation of growth along the same trajectory – as the process responsible for both intersexual and interspecific morphological differentiation. Albeit the common allometric pattern observed in both sexes of any species constrains and canalizes their cephalic scales variation in a fixed portion of the phenotypic space, the extended growth experienced by males and some species allows them to achieve peramorphic morphologies. Conversely, the intrasexual phenotypic diversity is accounted for by nonallometric processes that drive the extensive morphological dispersion throughout their ontogenetic trajectories. This study suggests a model of how simple heterochronic perturbations can produce phenotypic variation, and thus potential for further evolutionary change, even within a strictly constrained developmental pathway."

Allometric trajectories of body and head morphology in three sympatric Arctic charr (Salvelinus alpinus (L.)) morphs

“…This points to a close origin for this morph pair, with the morphology of the PB‐morph arising from a cessation in the increase in body size (paedomorphism) compared with the PP‐morph. Similar common ontogenetic trajectories have been found for Podarcis lizards (Piras et al., 2011). For these lizards, there is a prolongation of growth along the same trajectories that is producing both intersexual and interspecific morphological differences through the process of hypermorphosis.…”

Rapid action in the Palaeogene, the relationship between phenotypic and taxonomic diversification in Coenozoic mammals

“…Equally robust evolutionary theory rejects the idea that rates need to be coupled. First, if morphological evolution tends towards an adaptive peak, rates of phenotypic change can be high but just vary randomly around the peak [9,10], or else they can slow down irrespective of the net diversification rate [11]. Secondly, no relationship is expected to occur during non-adaptive radiations [12].…”

Talpa fossilis or Talpa europaea? Using geometric morphometrics and allometric trajectories of humeral moles remains from Hungary to answer a taxonomic debate

“…Then, for each species, the residuals were added to species specific shapes predicted at maximum and minimum, species-specific size values. This procedure ensures elimination of intraspecific allometry while maintaining the interspecific size-shape differences due to evolutionary allometry (Piras et al, 2011(Piras et al, , 2014. The differences between the predicted shape variables have been evaluated performing a perMANOVA using the function adonis().…”