No abstract

BackgroundFemales have often been shown to exhibit preferences for certain male traits. However, little is known about behavioural rules females use when searching for mates in their natural habitat. We investigated mate sampling tactics and related costs in the territorial strawberry poison frog (Oophaga pumilio) possessing a lek-like mating system, where both sequential and simultaneous sampling might occur. We continuously monitored the sampling pattern and behaviour of females during the complete period between two successive matings.ResultsWe found no evidence that females compared males by visiting them. Instead females mated with the closest calling male irrespective of his acoustic and physical traits, and territory size. Playback experiments in the natural home ranges of receptive females revealed that tested females preferred the nearest speaker and did not discriminate between low and high call rates or dominant frequencies.ConclusionsOur results suggest that females of O. pumilio prefer the closest calling male in the studied population. We hypothesize that the sampling tactic in this population is affected by 1) a strongly female biased sex ratio and 2) a low variance in traits of available males due to strong male-male competition, preventing low quality males from defending a territory and mating.

In many species male reproductive success is limited by access to females. Territoriality is one behavioural strategy which helps to acquire females. In the present study, we investigated the correlation between territory size and (1) female availability and (2) rate of intrusion by conspecific males in strawberry poison frogs, Oophaga pumilio. Males defended smaller territories in areas with a high female density and high rate of intrusion by conspecific males. Only males with high body condition values were able to establish territories in areas of high female density probably due to better fighting abilities. Moreover, dominant calling frequency was lower during agonistic interactions. Because only males with high body condition values were able to produce very low dominant frequencies, the acoustic properties appear to be an honest signal containing information about fighting abilities. Thus, the negative correlation between dominant frequency and mating success of males found in previous studies seems to be in part the result of intrasexual competition between males.

Aim To investigate the intra-specific genetic divergence and phenotypic diversification in Oophaga granulifera, analysing phylogeographical patterns, population structure, coloration and traits potentially involved in reproductive isolation.Location Costa Rica.Methods Our phylogeographical analysis used the mitochondrial genes cytochrome b and 16S. We sequenced the two markers in 28 individuals belonging to 10 populations and 16 individuals from nine populations, respectively. The population structure was analysed based on seven polymorphic microsatellite loci in 7-15 individuals from 11 populations using maximum likelihood and Bayesian analyses. The colour phenotypes of 189 frogs and the reflectance spectra of 15 frogs from five populations were measured. In nine populations, we recorded the advertisement calls of 59 males and measured 10 morphological variables from 147 frogs.Results Our phylogeographical reconstruction supported the divergence into southern and northern lineages in O. granulifera. In a colour transition area between the main red and green morphs, we describe novel gradual intermediate phenotypes occurring in polymorphic populations. The colour distribution was asymmetrical compared to the genetic variation: the southern lineage included only monomorphic red populations while the northern lineage contained red, green and polymorphic populations. The two lineages differed significantly in advertisement calls and morphology. Microsatellites confirmed the clear interlineage divergence. In the northern lineage, the red morph differed from the intermediate and green morphs in the pulse rate of the advertisement call and in body size. In the colour transition area, there was no simple genetic or colour cline.Main conclusions Oophaga granulifera has evolved into two genetic lineages. The reduced gene flow and diversification in advertisement calls and morphology point to reproductive isolation between lineages. Within the northern lineage, the presence of gradual intermediate morphs and the population structure support the presence of gene flow across the colour transition area while the red versus intermediate-green divergence in both calls and morphology reveals the potential for assortative mating. Our data all congruently show that O. granulifera presents deep intra-specific divergence. The lack of genetic diversification among colour morphs and the genetic connectivity among the populations defining the colour transition area suggest that the colour diversification in the species is a recent phenomenon.

No abstract