A morphometric assessment of species boundaries in a widespread anole lizard (Squamata: Dactyloidae)

Abstract

Cryptic species – genetically distinct species that are morphologically difficult to distinguish – present challenges to systematists. Operationally, cryptic species are very difficult to identify and sole use of genetic data or morphological data can fail to recognize evolutionarily isolated lineages. We use morphometric data to test species boundaries hypothesized with genetic data in the North Caribbean bark anole (Anolis distichus), a suspected species complex. We use univariate and multivariate analyses to test if candidate species based on genetic data can be accurately diagnosed. We also test alternative species delimitation scenarios with a model fitting approach that evaluates normal mixture models capable of identifying morphological clusters. Our analyses reject the hypothesis that the candidate species are diagnosable. Neither uni- nor multivariate morphometric data distinguish candidate species. The best-supported model included two morphological clusters; however, these clusters were uneven and did not align with a plausible species divergence scenario. After removing two related traits driving this result, only one cluster was supported. Despite substantial differentiation revealed by genetic data, we recover no new evidence to delimit species and refrain from taxonomic revision. This study highlights the importance of considering other types of data along with molecular data when delimiting species.

Improving species delimitation for effective conservation: a case study in the endemic maple‐leaf oak (Quercus acerifolia)

“…Phenotypic data are our primary source of evidence for species delimitation (de Queiroz, 1998; Yeates et al ., 2011; Myers et al ., 2020). However, because phenotypic traits often vary plastically with environmental conditions (Darwin, 1859; Desmond et al ., 2021), morphometric analyses based on field samples risk identifying environmentally induced morphological clusters as distinct species (Mathieson et al ., 1981; Sultan, 2000).…”

Transcriptomic Analysis of Skin Color in Anole Lizards

“…Most dewlap variation in Hispaniolan trunk anoles is found among geographic populations that have been recognized as subspecies. Although some of these subspecies likely warrant status as full species, most appear to experience some degree of intergradation where they come into contact ( Glor and Laport 2012 ; Geneva et al 2015 ; MacGuigan et al 2017 ; Myers et al 2020 ). Moreover, a significant correlation between dewlap color and environmental variation across trunk anole populations suggests that dewlap color may be driven by selection for visibility across different environments rather than reflecting boundaries between reproductively isolated populations ( Leal and Fleishman 2004 ; Ng et al 2013 ).…”