Body wiping behaviors associated with cutaneous lipids in hylid tree frogs of Florida

Abstract

Body wiping behavior, integumentary secretions and rates of evaporative water loss (EWL) were examined in six species of Florida tree frogs (Anura: Hylidae). Additionally, morphology of the integument and dermal glands were compared among these and one other Florida tree frog (Hyla andersonii), an arid-adapted tree frog (Phyllomedusa hypochondrialis), and a highly aquatic frog (Rana utricularia). An extra-epidermal layer of lipid and mucus, presumably secreted from dermal granular glands, was detected on the skin of all Florida hylid frogs examined. Distinct body wiping behaviors were observed in the hylid frogs, but these were less complex than those described previously in phyllomedusine frogs, which occupy arid habitats, secrete lipids onto their skin, and are regarded as relatively 'waterproof'. Florida hylids occupy seasonally arid habitats and appear to have reduced rates of EWL. The suite of traits we observed in these frogs have been previously documented in a rhacophorid tree frog from seasonally arid regions of India and likely represent an evolutionary convergent response to periodic dehydration stress. The presence of lipids that are spread by simple wiping behaviors to form an extra-epidermal water barrier may represent an early stage of the more advanced adaptations described in more waterproof arboreal frogs.

Comparative analysis of the integument of different tree frog species from Ololygon and Scinax genera (Anura: Hylidae)

“…Although some studies of the anuran integument are available, such as those of bufonids (de Brito-Gitirana and Azevedo 2005, Almeida et al 2007, Felsemburgh et al 2009), ranids (Azevedo et al 2006, Pelli et al 2010, and leptodactylids (Goniakowska-Witalinska and Kubiczek 1998, Warburg et al 2000, Nosiet al 2002, Barbeau and Lillywhite 2005, Felsemburgh et al 2007, Gonçalves and de Brito-Gitirana 2008, Rigolo et al 2008), information about the integument structure of hylids is still insufficient.…”

“…Cutaneous lipids in tree frogs -Phyl- lomedusa sauvagei Boulenger, 1882, P. iherengii Boulenger, 1885, P. boliviana Boulenger, 1902, Ranoid gracilenta (Peters, 1869, R. caerulea (White, 1790), Polypedates maculatus (Gray, 1830) -are a specialized adaptation to reduce dehydration in arid environments (Amey and Grigg 1995, Lillywhite 2004, Barbeau and Lillywhite 2005, Gomez et al 2006. These lipids are spread over the body by complex self-wiping behavior to form an effective barrier that reduces evaporative water loss (Barbeau and Lillywhite 2005).…”

“…Some anurans, like arboreal frogs, exhibit diverse morphology in their typical integument outline, showing cutaneous adaptations to avoid evaporative water loss (Blaylock et al 1976, Warburg et al 2000, Barbeau and Lillywhite 2005. Such adaptations include exocrine glands secreting lipids, which are spread over the body surface, aided by an elaborate series of behavioral movements to form a useful barrier against water loss.…”

Amphibian Biology and Husbandry

“…Phyllomedusa sauvagii uses its limbs to spread a waxy secretion from glands over its body. Lipids in the skin are probably the basis of the high levels of cutaneous resistance of Chiromantis, Hyperolius, Litoria, and Hyla (Barbeau and Lillywhite 2005;Christian et al 1988;Shoemaker et al 1992).…”

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

“…These anurans often do not actively seek escape from hot, dry conditions but rather have evolved mechanisms to avoid desiccation and overheating (Amey & Grigg 1995). The waterproofing mechanism in the majority of these species is a cutaneous layer of lipids that can either occur in the skin or be excreted from skin glands and wiped over the body (Amey & Grigg 1995;Barbeau & Lillywhite 2005).…”