Generation gland morphology in cordylid lizards: An evolutionary perspective

Abstract

To elucidate the functional significance of the three distinct types of generation glands that have been identified among cordylid lizards, we mapped gland type to the terminal taxa in the most recent phylogenetic tree for the Cordylidae. We used the phylogenetic programme Mesquite and applied the principle of parsimony to infer character states for the ancestral nodes in the tree. For those species where information on gland type was not available from the literature, we conducted a histological investigation of generation gland morphology, using standard histological techniques. We included two species of the sister family Gerrhosauridae in the analysis to serve as outgroups. In both Gerrhosaurus typicus and G. flavigularis, scales immediately anterior to the femoral pores displayed glandular activity, but differed from generation glands of cordylids in the absence of mature glandular generations. Among the cordylids investigated, we identified a fourth type of generation gland in Pseudocordylus subviridis, P. spinosus, and in the two Hemicordylus species, one where the glands consistently comprise of two mature glandular generations. In H. capensis, both single- and two-layer type glands are present. Our reconstruction of ancestral character states suggests a minimum of six transformations from one gland type to another during the evolutionary history of the family. The reconstruction furthermore suggests that the single-layer type gland reappeared at least once (in Hemicordylus) in the Cordylinae after having been lost. The reconstruction also unequivocally shows that the pit-like multiple-layer type gland evolved directly from the single-layer type and not from the protruding multiple-layer type. The two-layer type gland appears to be an intermediary condition between the multiple-layer and single-layer types. The evolutionary transformation of generation gland type appears to be linked to changes in lifestyle and associated changes in degree of territoriality and the need for chemical communication.

Australian lizards are outstanding models for reproductive biology research

“…They are secreted from the skin (e.g. van Wyk and Mouton 1992;Mouton et al 2010Mouton et al , 2014, including from specialised epidermal glands, such as generation glands and follicular pores (Cole 1966;Maderson 1972;Mayerl et al 2015), or from specialised glands within the cloaca (Cooper and Grastka 1987;Cooper and Trauth 1992;Siegel et al 2014). Pheromones identified from the scats of several Australian Egerniinae (Bull et al 1999a(Bull et al , 1999b(Bull et al , 2000 are likely produced from glands in the cloaca and deposited onto the surface of the faeces, although this hypothesis remains untested.…”

The tongue of Leopard Gecko (Eublepharis macularius): LM, SEM and confocal laser study

“…Nevertheless, the role of the tongue was widely demonstrated in reptiles as chameleons, agamids and iguanids, as in numerous fish and birds too (Abbate et al, , , , ; Abbate, Guerrera, Montalbano, Ciriaco, & Germanà, ; Abbate, Guerrera, Montalbano, De Carlos, et al, ; Abramjan, Bauerová, Somerová, & Frynta, ; Bels & Baltus, ; Bels & Delheusy, ; Bels & Goose, ; Erdoğan & Iwasaki, ; Guerrera et al, ; Herrel, Cleuren, & Vree, ; Herrel, Deban, Schaerlaeken, Timmermans, & Adriaens, ; Herrel, Redding, Meyers, & Nishikawa, ; Jackowiak, Skieresz‐Szewczyk, Godynicki, Iwasaki, & Meyer, ; Jackowiak, Skieresz‐Szewczyk, Kwieciński, Trzcielińska‐Lorych, & Godynicki, ; Kraklau, ; Montalbano et al, ; Schwenk, ; Schwenk & Bell, ; Schwenk & Throckmorton, ; Skieresz‐Szewczyk & Jackowiak, ; Wainwright & Bennett, ; Wainwright, Kraklau, & Bennett, ; Yang & Wang, ). In reptiles, the tongue morphology was studied in several species (Baeckens et al, ; Beisser, Lemell, & Weisgram, ; Heiss et al, ; Jamniczky, Russell, Johnson, Montuelle, & Bels, ; Koca, Oğuz, & Osanç, ; Lemell, Beisser, & Weisgram, ; Mouton, Flemming, & Broeckhoven, ; Putterill & Soley, ; Rehorek et al, ), and in some cases, as happens in snakes, its role is important only for the olfaction (Filoramo & Schwenk, ; Nishida, Yoshie, & Fujita, ). Several and peculiar different characteristics were observed in several vertebrates, including mammals (see for a review Iwasaki, ).…”

Sexual Dimorphism in Namibian Endemic Herero Nama Lizards ( Namazonurus pustulatus)

“…In general, communication via femoral pore secretions is widespread among squamates (Mason 1992;Garcı a-Roa et al 2017) and is important for intraspecific interactions (Mason and Parker 2010). As with femoral pores, generation glands may play an important role in communication and social structure in cordylids (Mouton et al 2005;Louw et al 2011;Mouton et al 2014).…”