Contrasting models of parity‐mode evolution in squamate reptiles

Abstract

Recent analyses using large-scale phylogenies suggest a radically different history for the evolution of live birth and egg laying in squamate reptiles (lizards and snakes) than traditionally understood. What is the ancestral condition for lizards and snakes? How frequently does live bearing evolve in egg-laying lineages? Can the eggshell ever re-evolve in live-bearing lineages? Answering these fundamental questions about the evolution of key physiological processes will require additional data from genomic, developmental, and fossil data.

Evolution of viviparity in squamate reptiles: Reversibility reconsidered

“…This is particularly the case, given recent challenges to the use of BiSSE analysis (King and Lee, ; Rabosky and Goldberg, ). For example, one beneficial feature of the gene suppression hypothesis is that it is testable by genetic analyses on extant species (Pyron and Burbrink, ), particularly those that allegedly have resulted from successive transformations back and forth between oviparity and viviparity. Likewise, careful examination of oviparity in some of the better supported inferences of reversal (Lynch and Wagner, ; Fenwick et al, ; King and Lee, ) may well yield evidence relevant to the reversibility hypothesis.…”

“…Likewise, careful examination of oviparity in some of the better supported inferences of reversal (Lynch and Wagner, ; Fenwick et al, ; King and Lee, ) may well yield evidence relevant to the reversibility hypothesis. As noted by Pyron and Burbrink (): “It is unlikely that phylogenetic analyses alone will suffice to understand the evolution of parity mode in squamates, particularly with respect to the likelihood, mechanism, and frequency of transitions to and from oviparity.” Indeed, evolutionary transformations in general are best reconstructed through analysis of phenotypic and genetic features (Cristin et al, 2010; Galis et al, ; also see Kohlsdorf et al, ). Consequently, notwithstanding the utility of theoretical models in generating evolutionary hypotheses and the attractions of their usage, empirical data warrant being fully incorporated into evolutionary reconstructions.…”

Advancing perspectives on parity‐mode evolution

“…Articles in this issue (Blackburn, ,b; Duchêne and Lanfear, ; Griffith et al, ; King and Lee, ; Shine, ; Stewart, ; Wright et al, ) and in other journals (King and Lee, ) have re‐examined our data, analyses, and conclusions, drawing a wide range of inferences. Our summary (Pyron and Burbrink, ) was written before any of the responses appeared, and merely gives an overview of our original conclusions, with some suggestions for future research. Here, I take a final opportunity to digest the recent responses to Pyron and Burbrink (), and offer a complementary perspective.…”

“…This fact should not be overlooked or glossed over by studies attempting to reconstruct these transitions (Lynch and Wagner, ; Fenwick et al, ; Pyron and Burbrink, ; Griffith et al, ). Along these lines, we suggested three sources of evidence (genetic, developmental, and physiological) to supplement phylogenetic analyses (Pyron and Burbrink, ). I agree that “ancestral state reconstructions require biological evidence to test evolutionary hypotheses“ (Griffith et al, ), and suggest that: Gathering new data along these lines will be important going forward.…”

The evolution of oviparity in squamate reptiles: An adaptationist perspective

“…Pyron and Burbrink () identify four lines of evidence that may help to resolve the issue. One of these is improved phylogenetic analysis, based on better‐calibrated and more comprehensive phylogenies.…”