A novel epidermal gland type in lizards (α-gland): structural organization, histochemistry, protein profile and phylogenetic origins

Abstract

Chemical signalling is an essential component of the communication system of lizards, and epidermal glands are responsible for producing semiochemicals that regulate many behavioural interactions. Two types of epidermal glands have been previously described for lizards: follicular and generation glands. Generation glands are characterized by the aggregation of novel glandular cell types in the epithelium and the lack of a lumen or external pore. Despite the fact that several subtypes of generation glands have been recognized over the years, the morphology, taxonomic distribution, function and evolutionary origins of generation glands remain nearly unexplored in Neotropical clades. Here, we describe a novel escutcheon-type generation gland (‘α-gland’) for lizards of the South American family Tropiduridae, characterize its structural and ultrastructural organization, and study the homology of the constituent parts in a phylogenetic framework. The α-glands emerged in the ancestor of Eurolophosaurus, Plica, Strobilurus, Tropidurus and Uracentron, and are found in at least 39 species with diverse ecological habits. We preliminarily analysed the protein profile of α-glands and discovered differential expression of protein components between sexes. Our investigations change the general view about epidermal gland homology, leading us to argue that generation and follicular glands are possibly more closely related functionally and evolutionarily than previously thought.

Environmental temperature predicts resting metabolic rates in tropidurinae lizards

“…We actively searched for lizards during their activity period (0800–1700 h) and collected them by lassoing. We sexed individuals based on the presence of femural and precloacal glandular patches (α‐glands) that are only present in adult males (Carvalho et al, 2020). Our sampling was restricted to adult males to minimize the potential effects of age and sex over metabolic rates.…”

“…Fourth, we tested how non‐phylogenetic residual VO 2rest responded to both micro‐ and macrohabitat variables in a linear model fit through PGLS. For all tests, we used a subset of the Tropidurinae phylogeny proposed by Carvalho et al (2020). We followed the protocol described in Carvalho et al (2018) to add a GenBank sequence of Tropidurus aff.…”

“…We collected Tropidurinae lizards of the genera Eurolophosaurus (Frost et al, 2001) and Tropidurus (Wied-Neuwied, 1825) during four field trips to localities within the Cerrado (savanna), Caatinga (semiarid), and Atlantic rainforest domains in Brazil (Figure 1; Supporting Information: Table S1). Despite the wide geographic distribution of the subfamily across South America, their high degree of endemism, and the cryptic habits of some species, we were able to collect 14 out of the 30 species of Tropidurus (~50% of the total diversity) and all three species of Eurolophosaurus described so far (Carvalho et al, 2020). Fieldwork took place in open areas (urban and natural) during the reproductive season (austral spring and summer).…”

A guide to incubate eggs of Tropidurus lizards under laboratory conditions

“…Feiner, 2016;Sanger et al, 2012) due to the following features: (1) large clutch sizes (3-10 eggs; Arruda et al, 2019;Delssin et al, 2019); (2) widespread distribution in South America (Carvalho, 2013;Frost et al, 2001;Rodrigues, 1987); (3) strong territoriality that enables tracking the same individuals for several weeks (Kohlsdorf et al, 2006;Rodrigues & Kohlsdorf, 2019); (4) social structure in harems, with several (gravid) females associated to the same territory (Melo et al, 2017); (5) easy capture by lasso and relatively simple maintenance in the lab (Delssin et al, 2019;Py-Daniel et al, 2017;Van Sluys, 1993). Finally, phylogenetic relationships have been addressed intensely in this family (Carvalho et al, 2016;Carvalho et al, 2018;Carvalho et al, 2020;Carvalho, 2016;Domingos et al, 2017;Matos et al, 2016;Teixeira et al, 2016;Werneck et al, 2015), which allow evolutionary inferences from comparative studies.…”