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Family: Leiuperidae
Foam Toad, more...Guayaquil Dwarf Frog, Mud-puddle Frog, Tungara Frog, Tungara Frog (es: Rana Túngara, Rana Tungara, Sapito Tungara)
[Physalaemus pustulosus (Cope, 1864), morePhysalaemus stentor (Jiménez de la Espada, 1872)] |
Adult: Species description based on Ibanez et al (1999) and Savage (2002). Small, toady frog with a squat body and short limbs. Males to 33 mm; females to 36 mm. Dorsal: The grayish-brown dorsal surface is covered with wartlike bumps. Darker mottling often present. Ventral: Ventral surface smooth and white with little to lots of dark mottling. Male vocal sac dark grey to black with median white line. Eye: Iris tan or light brown. Pupil horizontal. Extremities: Hands not webbed. Feet with some basal webbing. Breeding season: Tungara frogs breed year-round and in nearly every body of water they come across, from permanent ponds to puddles. Males call while floating in the water. Two cues females are known to use to select oviposition site choices are shallow water and a vertical surface perpendicular to the surface of the water--frogs construct their nests against this vertical structure (Sexton and Ortleb 1966). Females prefer to oviposit in bodies of water than lack nests of conspecifics, presumably to avoid intraspecific competition (Dillon and Fiano 2000). Breeding activity varies in response to annual and nightly patterns of rainfall. In dry years, tungara frogs tend to breed on rainy nights, but in average years, they are more active on dry nights (Marsh 2000). Tungara frogs also concentrate breeding activity in areas of high pond density (Marsh 2001). Frogs also behave differently on moonlit versus moonless nights. Females are less likely to go to males in dim light than when in total darkness (Rand et al 1997). Tungaras are more likely to construct nests in covered areas when there is some light than in total darkness (Tarano 1998). Egg: Many, small cream-colored eggs are laid in a foam nest constructed by the parents. Heyer and Rand (1977) and Dalgetty et al. (2010) provide detailed descriptions of foam nest construction as well as the function of the foam nest. Tadpole: Tadpole bodies are mostly brown with some mottling. Tail is similiar in color, although the tail fins may be transparent. The ventral surface is white. Tadpoles develop in numerous environments, from permanent ponds to puddles. However, contrary to expectations, tadpole survival was not increased by conditions associated with new pond environments (Fegraus and Marsh 2000). Tadpoles are consumed by fish (Hews 1995), dragonfly larvae and turtles (Heyer and Muedeking 1976) and tadpoles of Leptodactylus pentadactylus (Heyer et al 1975). Dytiscid beetles are also closely associated with tungara frogs. Adult beetles lay their eggs on tungara foam nests, and when the larvae hatch they consume tungara tadpoles (Villa et al 1982). Habitat: Tungaras are one of the commonest frogs encountered in the lowlands of Panama (up to 1500 m). Tungaras are primarily an inhabitant of leaf litter, but can be found all kinds of habitats, from forest to more disturbed areas, and in both wet and dry forest. Ecology: Tungaras are active at night (Park et al 1940) but also during the day, when they feed (Jaeger and Hailman 1981). Adult tungara frogs are eaten by bats (Trachops cirrosus), other species of frogs (Rhinella marina, Leptodactylus savagei), opposums (Philander opossum), snapping turtles (Pseudemis scripta), snakes (Leptodeira annulata) and crabs (Potamocarcinus richmondi)(Tarano 1998). The complex calls (whine plus one or more chucks) produced by tungara frogs increase chances of detection by predators and parasites, including bats (Tuttle et al 1981), opposums (Tuttle et al 1982), and blood-sucking flies (Bernal et al 2007). Bernal et al (2007) demonstrated that eavesdroppers such as blood-sucking flies prefer complex calls because they indicate high densities of frog hosts. Call: A "whine" followed by zero to several "chucks". The release call consists of a series of clucks (Savage 2002). Type locality: New Grenada, on the River Truando (Colombia) Behavior and communication: Males call in choruses, often establishing a calling heirarchy, with one male starting a round of calling and others following in sequence (Brattstrom and Yarnell 1968). When more males are present in a chorus (i.e. their is greater competition for females), males are more likely to produce chucks in addition to whines. In individual male-male interactions, males respond dynamically to calls from conspecifics, only adding more chucks when the competitor's reaction is to escalate (Goutte et al 2010). Female preference has been studied extensively in tungara frogs. In general, females prefer larger males (Rand 1980, Ryan 1980b, and Ryan 1983), but also males that produce whines followed by one or more chucks over males that produce only whines (Ryan 1980b). Females do not discriminate between calls of heterospecific males and calls of a most common ancestor (Ryan and Rand 1995), and this finding was robust to different models used to estimate the ancestral call (Ryan and Rand 1999). Females vary in their committedness to mate choice; females in better condition are more committed to their choice for a particular male than females in lesser condition (Baugh and Ryan 2009). The male vocal sac has been hypothesized to be important in visual communication between males and females. The vocal sac is the most reflective part of the male's body and females in reproductive condition have the highest visual sensitivity (Cummings et al 2008). Rosenthal et al (2004) and Taylor et al (2008) demonstrated that the vocal sac is indeed an important component of male advertising that females attend to. Evolotion: Female preference for chucks likely evolved via sensory exploitation of pre-existing biases (Cannatella et al 1998). Moreover, Phelps and Ryan (1998, 2000) showed that artificial neural networks evolving through calls mimicking the calls of ancestors of tungara frogs accurately predicted the response biases of females. Much genetic variation exists among this widespread species. Northern (above Panama) and southern (below Panama) populations are genetically distinct (Weigt et al 2005, Prohl et al 2006). Colonization of Central American likely occurred prior to the formation of the Panama land bridge (Weigt et al 2005). In general, genetic differentation among populations is correlated with geographic distance, and rivers can be successful barriers to gene flow among populations (Lampert et al 2003). Moreover, some island populations are genetically distinct from mainland populations (Lampert et al 2007). These island populations are often larger than their mainland counterparts (Lampter et al 2007). Physiology: The chuck call is produced by a separate vocal apparatus--a fibrous mass--from that which produces the whine (Ryan and Drewes 1990, Gridi-Papp et al 2006). Producing chucks is no more energetically costly than producing whines (Bucher et al 1982, Ryan et al 1983, Ryan 1985). Females exposed to male choruses produce elevated levels of estradiol, suggesting that male chorus behavior may help maintain females in reproductive state (Lynch and Wilczynski 2006). Further, estradiol alone injected into females induces reproductive behavior (Chakraborty and Burmeister 2009). The hormonal state of females also affects female choice (Lynch et al 2006). Neurobiology/Neuroethology: The hypothalamic region of the tungara brain is stimulated by acoustic cues, as measured by egr-1 mRNA levels (Hoke et al. 2005). However, the response of the hypothalamic region depends on the social relevance and attractiveness of the acoustic cue (Hoke et al. 2005, Hoke et al. 2007). The midbrain region of male and female tungaras respond differently to con- and hetero-specific calls. As predicted by theory that females should be more selective in their likelihood to respond to mating signals, females do not respond to calls of heterospecifics, whereas males do (Hoke et al. 2008). |
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