Building a home from foam—túngara frog foam nest architecture and three-phase construction process

Abstract

Frogs that build foam nests floating on water face the problems of over-dispersion of the secretions used and eggs being dangerously exposed at the foam : air interface. Nest construction behaviour of túngara frogs, Engystomops pustulosus , has features that may circumvent these problems. Pairs build nests in periodic bursts of foam production and egg deposition, three discrete phases being discernible. The first is characterized by a bubble raft without egg deposition and an approximately linear increase in duration of mixing events with time. This phase may reduce initial over-dispersion of foam precursor materials until a critical concentration is achieved. The main building phase is marked by mixing events and start-to-start intervals being nearly constant in duration. During the final phase, mixing events do not change in duration but intervals between them increase in an exponential-like fashion. Pairs joining a colonial nesting abbreviate their initial phase, presumably by exploiting a pioneer pair's bubble raft, thereby reducing energy and material expenditure, and time exposed to predators. Finally, eggs are deposited only in the centre of nests with a continuously produced, approximately 1 cm deep egg-free cortex that protectively encloses hatched larvae in stranded nests.

Biología reproductiva de Pleurodema guayapae (Anura: Leptodactylidae: Leiuperinae)

“…Therefore, communal nesting in species that deposits eggs in foam may be an important adaptation enhancing survival of these species inhabiting environments of unpredictable rainfall patterns (Downie, 1988;Hödl, 1990;Zina, 2006). In this regard, it has already been confirmed the presence of communal nests in some species of Leiuperinae (Barreto & Andrade, 1995;Tára-no, 1998;Giaretta & Menin, 2003;Dalgetty & Kennedy, 2010) and also within the genus Pleurodema in P. diplolister (Höld, 1992;Cardoso & Arzabe, 1993) and P. cinereum (Agostini, Cajade & Roesler, 1997). Faivovich et al (2012) suggested that eggs laid in a foam nest built by the mating pair during the amplexus is a synapomorphy for the clade composed by Edalorhina, Engystomops, Physalaemus and Pleurodema, but their results also showed that Pleurodema has experienced subsequent evolutive transformations from foam nest clutches to eggs laid in gelatinous structures, being subspherical masses, ovoid and plate-like, or egg strings.…”

“…Several authors suggested that foam nest construction is an adaptation to avoid desiccation of eggs and early larval stages (Dobkin & Gettinger, 1985;Downie, 1988;Cardoso & Arzabe, 1993;Prado, Uetanabaro & Haddad, 2002). Eggs and larvae that develop within foam nests are more protected from predators and against desiccation (Crump, 1974;Haddad, Pombal & Gordo, 1990;Silva, Giaretta & Facure, 2005;Dalgetty & Kennedy, 2010) and they are exposed to adequate supplies of oxygen and to temperatures that favour their development (Petranka, Hopey, Jennings, Baird & Boone, 1994;Haddad & Hödl, 1997). Moreover, Hödl (1992) suggested that the foam nest of Pleurodema diplolister reduced egg predation by conspecific larvae.…”

A phylogenetic analysis of Pleurodema (Anura: Leptodactylidae: Leiuperinae) based on mitochondrial and nuclear gene sequences, with comments on the evolution of anuran foam nests

“…Foam nests in anurans are produced by the whipping of oviductal secretions by one or both parents. Although some progress in the biochemical characterization of these secretions (Cooper et al., 2005; McMahon et al., 2006; Hissa et al., 2008; Fleming et al., 2009; Mackenzie et al., 2009) and in the anatomy and histochemistry of the secreting section of the oviduct (Coe, 1974; Kabisch et al., 1998; Alcaide et al., 2009; Furness et al., 2010) is slowly starting to take place, most studies have focused on the mechanics of foam production by the amplectic couple (Tyler and Davies, 1979; Hödl, 1986, 1990, 1992; Schlüter, 1990; Williams and Tyler, 1994; Altig and McDiarmid, 2007; Bastos et al., 2010; Dalgetty and Kennedy, 2010).…”

Neural control of maternal and paternal behaviors

“…Many species of anurans and salamanders display care for offspring beyond egg laying, with roughly 50 independent evolutionary transitions to parental care (18). These behaviors include preparation of foam nests (19), egg guarding, transport of offspring piggyback style (20), and egg incubation in dorsal pouches, vocal sacs, or the stomach. South American poison frogs ( Dendrobatidae ) show particularly striking diversity in which sex cares for offspring within closely related species (21).…”