Aposematism increases acoustic diversification and speciation in poison frogs

Abstract

Multimodal signals facilitate communication with conspecifics during courtship, but they can also alert eavesdropper predators. Hence, signallers face two pressures: enticing partners to mate and avoiding detection by enemies. Undefended organisms with limited escape abilities are expected to minimize predator recognition over mate attraction by limiting or modifying their signalling. Alternatively, organisms with anti-predator mechanisms such as aposematism (i.e. unprofitability signalled by warning cues) might elaborate mating signals as a consequence of reduced predation. We hypothesize that calls diversified in association with aposematism. To test this, we assembled a large acoustic signal database for a diurnal lineage of aposematic and cryptic/non-defended taxa, the poison frogs. First, we showed that aposematic and non-aposematic species share similar extinction rates, and aposematic lineages diversify more and rarely revert to the nonaposematic phenotype. We then characterized mating calls based on morphological (spectral), behavioural/physiological (temporal) and environmental traits. Of these, only spectral and temporal features were associated with aposematism. We propose that with the evolution of antipredator defences, reduced predation facilitated the diversification of vocal signals, which then became elaborated or showy via sexual selection.

Interacting amino acid replacements allow poison frogs to evolve epibatidine resistance

“…The Epipedobates, Ameerega , and Dendrobates ( Oophaga ) clades, which are evolutionarily young (6, 36), are an example of rapid and ongoing diversification possibly driven by the evolution of resistance to anti-predator toxins (15). We demonstrate that resistance to epibatidine involves finely tuning a highly conserved binding site without disrupting receptor function, providing insights into evolutionary pathways culminating in chemical defenses.…”

Antipredator defenses predict diversification rates

“…However, visual classification by human observers is a commonly used method to study animal color patterns in the literature (10,19,28). Perhaps most notably, coding of coloration based on the human visual system cannot account for UV colors (32), although we acknowledge that UV could also contribute to diversification dynamics.…”

“…The escape-and-radiate hypothesis is influential in the adaptive radiation literature (2,5,6) but has been tested surprisingly rarely (6)(7)(8). The very few macroevolutionary studies on animal defenses focus only on coloration, are small-scale, and often only consider net diversification or comparisons of species richness in relation to the defensive trait of interest (5,9,10). For instance, one recent study on poison dart frogs included defense-based diversification analyses as part of an examination of acoustic divergence (10).…”

“…The very few macroevolutionary studies on animal defenses focus only on coloration, are small-scale, and often only consider net diversification or comparisons of species richness in relation to the defensive trait of interest (5,9,10). For instance, one recent study on poison dart frogs included defense-based diversification analyses as part of an examination of acoustic divergence (10). However, that study was relatively small scale, as it focused on only one group of frogs with insufficient sample sizes for some aspects of those analyses (particularly extinction estimates).…”

On the distinctive call of a threatened phenotype of Allobates femoralis (Anura: Aromobatidae) and its recognition by allopatric conspecific males

“…The characterization of A. femoralis advertisement calls recorded near Altamira adds to previous work that sampled the species' repertoire. It might influence future reappraisals of the species' biogeography (Amézquita et al, 2009) and sound signal evolution and its correlates (Santos et al, 2014), for which comprehensive data on intraspecific variation are desirable. Importantly, the recognition of the new, six-note call arrangement in the field led to concomitant DNA barcoding that associated this call morphotype to unique and distinct mitochondrial DNA haplotypes (Simões et al, 2014).The description presented in this study can therefore be used in the forthcoming years in monitoring programs to confirm whether the distribution of this lineage is restricted to forest remnants in or near sites impacted by the Belo Monte dam, on the Xingu River (Simões et al, 2014).…”