Phylogenetic Comparative Analysis of Life-History Variation Among Populations of the Lizard Sceloporus Undulatus:an Example and Prognosis

Abstract

Abstract. Over the past 15 years, phylogenetic comparative methods (PCMs) have become standard in the study of life-history evolution. To date, most studies have focused on variation among species or higher taxonomic levels, generally revealing the presence of significant phylogenetic effects as well as residual variation potentially attributable to adaptive evolution. Recently, population-level phylogenetic hypotheses have become available for many species, making it possible to apply PCMs directly to the level at which experiments are typically used to test adaptive hypotheses. In this study, we present the results of PCMs applied to life-history variation among populations of the widespread and well-studied lizard Sceloporus undulatus. Using S. undulatus (which may represent four closely related species) as an example, we explore the benefits of using PCMs at the population level, as well as consider the importance of several thorny methodological problems including but not limited to nonindependence of populations, lack of sufficient variation in traits, and the typically small sample sizes dictated by the difficulty of collecting detailed demographic data. We show that phylogenetic effects on life-history variation among populations of S. undulatus appear to be unimportant, and that several classic trade-offs expected by theory and revealed by many interspecific comparisons are absent. Our results suggest that PCMs applied to variation in life-history traits below the species level may be of limited value, but more studies like ours are needed to draw a general conclusion. Finally, we discuss several outstanding problems that face studies seeking to apply PCMs below the species level.

Variation of Reproductive Traits and Female Body Size in the Most Widely-Ranging Terrestrial Reptile: Testing the Effects of Reproductive Mode, Lineage, and Climate

“…In another lacertid lizard, Psammodromus algirus , two mt-DNA lineages differed in mean incubation time but not in offspring size, fecundity and maternal size (Díaz et al 2012). A weak effect of phylogeny on geographic variation of life-history traits was also reported for a widespread iguanian lizard, Sceloporus undulates (Niewiarowski et al 2004). In contrast, the variation in reproductive and other life-history traits among species of lacertid lizards included a substantial phylogenetic component (Bauwens and Díaz-Uriarte 1997).…”

Peer Review #1 of "The effect of landscape on functional connectivity and shell shape in the land snail Humboldtiana durangoensis (v0.1)"

“…However, whereas these variables were not significant to explain the genetic relationships among the groups, they suggested that both the phenotype and genotype were the results of independent processes (Haase and Misof 2009); that is, the microhabitat conditions had a great effect on the shell despite the existence of gene flow (Chiba and Davison 2007;Fiorentino et al 2013;Stankowski 2013;Proćków et al 2017). Thus, whereas it has been suggested that the use of comparative phylogenetic methods at intrapopulation levels may generate poor informative results (Niewiarowski et al 2004), the power of resolution of these methods may depend on the taxon and the assessed trait (Martins and Housworth 2002), as has been found in this study. In addition, our results suggested that populations with larger shells and apertures are distributed to the north, while populations with smaller shells and apertures were distributed to the south.…”

The effect of landscape on functional connectivity and shell shape in the land snailHumboldtiana durangoensis

“…However, whereas these variables were not significant to explain the genetic relationships among the groups, they suggested that both the phenotype and genotype were the results of independent processes (Haase & Misof, 2009); that is, the microhabitat conditions had a great effect on the shell despite the existence of gene flow (Chiba & Davison, 2007;Fiorentino et al, 2013;Stankowski, 2013;Proćków, Kuźnik-Kowalska & Mackiewicz, 2017). Thus, whereas it has been suggested that the use of comparative phylogenetic methods at intrapopulation levels may generate poor informative results (Niewiarowski, Angilletta & Leaché, 2004), the power of resolution of these methods may depend on the taxon and the assessed trait (Martins & Housworth, 2002), as has been found in this study.…”