The model organism
The Neotropical frog A. femoralis has a pan-Amazonian distribution and is forming disjunct local populations (Amézquita et al. 2009). During the reproductive season, males call from elevated structures on the forest floor to announce territory possession to male competitors and to attract females (Hödl et al. 2004). Pair formation, courtship, and mating take place in the male’s territory (Roithmair 1994, Montanarin et al. 2011), where externally fertilized terrestrial clutches of approximately 20 eggs are laid in the leaf litter. Females can produce one clutch every eight days on average (Weygold 1980), and males were observed to attend up to five clutches at the same time (Ursprung et al. 2011). Both sexes are highly iteroparous and polygamous within prolonged but rather discrete reproductive periods that coincide with the local rainy seasons. This results in a high percentage of females as well as males that produce progeny which survive until adulthood. Despite significant differences in the reproductive behaviour of males and females, successful individuals of both sexes have similar numbers of mating partners and produce similar numbers of adult progeny. Reproductive success is significantly higher in territorial males, but not related to territory size in males or body size in both sexes (Ursprung et al. 2011). In a recent study on the effect of parental relatedness on reproductive success we found no evidence for inbreeding avoidance in A. femoralis females but indications for an optimal genetic divergence between successful mating partners (Ringler et al., submitted). Tadpole transport takes place after 15–20 days of larval development and is mainly performed by males. However, occasional cases of transporting females have been documented (Weygold 1987, Caldwell & Araújo 2005) and were also observed by us (unpubl. data). For tadpole deposition, A. femoralis usually uses rather large water bodies ranging from floodplains to medium sized temporal pools (Gascon 1993, Ringler et al. 2009), but also peccary wallows and footprints (Beck et al. 2010). Small terrestrial phytotelmata like palm fronds and holes in fallen trees are also used when available (pers. obs.). Tadpoles require 40-50 days until metamorphosis (Weygold 1980).
Figure 1: The complex life cycle of Allobates femoralis. Egg production is determined by the sex ratio (ρ) multiplied by the number of clutches per female (N) and the average clutch size (φ), while initial reproductive output is further influenced by fertilisation rate (α). Eggs survive to become aquatic larvae with the probability of σe, which is composed of the probability to survive until tadpole transport (σe1) and the probability to get transported to water successfully (σe2). Larvae survive to metamorphosis with the probability of σt, and metamorphs reach sexual maturity until the next reproductive season with the probability of σm. Adults (A) survive to the next year with the probability of σa.
Amézquita A, Lima AP, Jehle R, Castellanos L, Ramos Ó et al. (2009) Calls, colours, shape, and genes:a multi-trait approach to the study of geographic variation in the Amazonian frog Allobates femoralis. Biol J Linn Soc 98:826–838.
Beck H, Thebpanya P, Filiaggi M (2010) Do neotropical peccary species (Tayassuidae) function as ecosystem engineers for anurans. J Trop Ecol 26:407–414.
Caldwell JP, Araújo MC de (2005) Amphibian faunas of two eastern Amazonian rainforest sites in Pará, Brazil. Occasional Papers Sam Noble Oklahoma Museum of Natural History 16:1–41.
Gascon C (1993) Breeding-habitat use by five Amazonian frogs at forest edge. Biodiv Cons 2:438–444.
Hödl W, Amézquita A, Narins PM (2004) The role of call frequency and the auditory papillae in phonotactic behavior in male dart-poison frogs Epipedobates femoralis (Dendrobatidae). J Comp Physiol A 190:823–829.
Montanarin A, Kaefer IL, Lima AP (2011) Courtship and mating behaviour of the brilliant-thighed frog Allobates femoralis from Central Amazonia: implications for the study of a species complex. Ethol Ecol Evol 23:141–150.
Ringler M, Ursprung E, Hödl W (2009) Site fidelity and patterns of short- and long-term movement in the brilliantthighed poison frog Allobates femoralis (Aromobatidae). Behav Ecol Sociobiol 63:1281–1293.
Roithmair ME (1992) Territoriality and male mating success in the dart-poison frog, Epipedobates femoralis (Dendrobatidae, Anura). Ethology 92:331–343.
Ursprung E, Ringler M, Jehle R, Hödl W (2011) Strong male/male competition allows for nonchoosy females: high levels of polygynandry in a territorial frog with paternal care. Mol Ecol 20:1759–1771.
Weygold P (1980) Zur Fortpflanzungsbiologie von Phyllobates femoralis (Boulenger) im Terrarium. Salamandra 16:215–226.
Weygold P (1987) Evolution of parental care in dart poison frogs (Amphibia:Anura:Dendrobatidae). Z Zool Syst Evolutionsforsch 25:51–67.