Abstract
Many lizard and amphisbaenian lineages possess follicular glands in the dermis of the inner thighs and/or the area anterior to the cloaca. These tubular glands produce a holocrine secretion that finds its way to the external world through pore-bearing scales (femoral and/or preanal pores). Secretions are composed of proteins and many lipophilic compounds that may function as chemosignals in lizard and amphisbaenian communication. In recent years, we have begun to develop an understanding of the adaptive significance of these secretions, and they are currently thought to play an important role in a variety of processes in these animals. While it appears that epidermal gland secretions function in intra- and interspecific recognition and territoriality, research has focused largely on their role in mate assessment. Despite these recent studies, our knowledge on the true role of the chemicals found in epidermal secretions remains poorly studied, and there are many possible avenues for future research on this topic. Here, we review the literature on the follicular epidermal glands of non-ophidian squamates and provide a first taxon-wide overview of their distribution.
Highlights
Spectroscopic analyses of the gland secretions revealed strong absorption in 279 the ultraviolet light spectra (Alberts, 1989a). These findings argue that secretion deposits of the desert iguana act as an ultraviolet visual marker, providing a possible mechanism for locating these low volatility chemosignals at far range (Alberts, 1989a)
We find that pores were most likely absent in the common ancestor of non-ophidian squamates, we do not make any assumption on the presence or absence of secretory glands in general in the common ancestor
Based on only the chemicals found within femoral secretions, female Iberian rock lizards have been shown to prefer to associate with the scents of males with low Fluctuating asymmetry (FA), and with individuals with more femoral pores on each leg (López, Munoz and Martín, 2002)
Summary
There are at least two possible explanations for this disparity: (1) the number of character state shifts could be higher in a clade inhabiting a wide variety of habitats due to adaptations to their local environment, as chemical signalling efficiency through epidermal glands is affected by environmental conditions (Pincheira-Donoso, Hodgson and Tregenza, 2008; Escobar, Labra and Niemeyer, 2011; Baeckens et al, 2015) or (2) morphological constraints could inhibit (or allow) for the gain or loss of epidermal glands. Female lizards have been found to be able to determine the health status of males based only on the secretion of epidermal glands
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