A new species of leaf-toed gecko (Phyllodactylidae, Phyllodactylus) from María Cleofas Island, Nayarit, Mexico

We describe a new species of leaf-toed gecko of the genus Phyllodactylus from María Cleofas Island, the smallest island of Tres Marías Archipelago, Nayarit, México. Genomic, phylogenomic, and morphological evidence support that the new species presents a unique combination of diagnostic characters. Morphologically, the new species has a high number of tubercles, head to tail (mean 47), longitudinal ventral scales (mean 61), and third labial-snout scales (mean 26). Gene flow tests revealed the genetic isolation of insular populations from mainland counterparts. In addition, we confirmed the non-monophyly of P. homolepidurus and P. nolascoensis, and we show that the taxon P. t. saxatilis is a complex; therefore, we propose taxonomic changes within the saxatilis clade. The discovery of this new insular endemic species highlights the urgency of continued exploration of the biological diversity of island faunas of Mexico.

Eye size in North American watersnakes (genus Nerodia) correlates with variation in feeding ecology

Visual acuity and sensitivity positively correlate to eye size in vertebrates, and eye size relates to the ecology of colubrid snakes. We investigated whether eye morphology of North American colubrids of the genus Nerodia correlates with ecology as well. Although all members of the genus utilize aquatic habits, they differ widely in the proportion of anurans they eat. We specifically tested whether eye size and placement is associated with the proportion of frogs in the diet to determine whether these two aspects of eye morphology relate to feeding ecology. Using phylogenetic comparative methods, we found a significantly positive association between eye size and the proportion of anurans eaten by Nerodia species. Although the evidence is equivocal, the anterior placement of relatively small eyes in one species may also enhance anurophagy. Although eye size may improve a snake’s ability to feed on frogs, eye size must compete with other selective forces on head shape in trade-offs that may also influence eye size.

Captivity Affects Head Morphology and Allometry in Headstarted Garter Snakes, Thamnophis sirtalis

In response to the growing number of amphibian and reptiles species in decline, many conservation managers have implemented captive breeding and headstarting programs in an effort to restore these populations. However, many of these programs suffer from low survival success, and it is often unclear as to why some individuals do not survive after reintroduction. Here I document changes to head morphology in the eastern garter snake, Thamnophis sirtalis, in response to time spent in captivity. Thamnophis raised on three diet treatments all differed in head size from wild individuals, and head size differed between the three treatments. Overall, head size was smaller in all three diet treatments than in wild snakes, potentially limiting the available prey for the captive garter snakes. Allometric patterns of growth in head size were also different for each diet treatment. Several potential implications of these changes in morphology are discussed, and what these changes may mean for other species that are part of headstarting and reintroduction programs.