A new species of Ischnocnema (Anura: Brachycephalidae) from the mountainous region of Atlantic Forest, southeastern Brazil, with a new phylogeny and diagnose for Ischnocnema parva series

We describe a new species of Rain Frog from Brazil’s Atlantic Forest, which harbors high richness, endemism and threatened species of anurans. Ischnocnema crassa sp. nov. is a leaf litter breeder from the montane rainforest of Santa Teresa, state of Espírito Santo, southeastern Brazil. Remarkably, the new species is so far unique amongst Ischnocnema for having moderate hand webbing between fingers. Ischnocnema crassa sp. nov. is the third species belonging to I. parva series and we present a new phylogeny based on molecular data and propose a new diagnosis for the series. We provide field and laboratory observations regarding amplexus, antipredator mechanisms, microhabitat preferences and conservation remarks. Although Santa Teresa is one of the most sampled areas in Brazil, new species are often discovered. Santa Teresa is a priority for amphibian conservation because it harbors 109 species of anurans (9% of Brazil’s species).

Coevolution of group-living and aposematism in caterpillars: warning colouration may facilitate the evolution from group-living to solitary habits

Background Animals use diverse antipredator mechanisms, including visual signalling of aversive chemical defence (aposematism). However, the initial evolution of aposematism poses the problem that the first aposematic individuals are conspicuous to predators who have not learned the significance of the warning colouration. In one scenario, aposematism evolves in group-living species and originally persisted due to kin selection or positive frequency-dependent selection in groups. Alternatively, group-living might evolve after aposematism because grouping can amplify the warning signal. However, our current understanding of the evolutionary dynamics of these traits is limited, leaving the relative merit of these scenarios unresolved. Results We used a phylogenetic comparative approach to estimate phenotypic evolutionary models to enable inferences regarding ancestral states and trait dynamics of grouping and aposematic colouration in a classic model system (caterpillars). We find strong support for aposematism at the root of the clade, and some (but weaker) support for ancestral solitary habits. Transition rates between aposematism and crypsis are generally higher than those between group-living and solitary-living, suggesting that colouration is more evolutionarily labile than aggregation. We also find that the transition from group-living to solitary-living states can only happen in aposematic lineage, suggesting that aposematism facilitates the evolution of solitary caterpillars, perhaps due to the additional protection offered when the benefits of grouping are lost. We also find that the high frequency of solitary, cryptic caterpillars is because this state is particularly stable, in that the transition rates moving towards this state are substantially higher than those moving away from it, favouring its accumulation in the clade over evolutionary time. Conclusions Our results provide new insights into the coevolution of colour and aggregation in caterpillars. We find support for an aposematic caterpillar at the root of this major clade, and for the signal augmentation hypothesis as an explanation of the evolution of aposematic, group-living caterpillars. We find that colouration is more labile than aggregation behaviour, but that the combination of solitary and cryptic habits is particularly stable. Finally, our results reveal that the transitions from group-living to solitary-living could be facilitated by aposematism, providing a new link between these well-studied traits.

Behavioral and chemical antipredator mechanisms in ground beetles: an attempt to reconcile within a phylogenetic frame

Like other coleopterans, Carabids are recognized for the use of passive and active strategies against their enemies. They are known to produce dangerous and distasteful chemicals and to use anti-predator behaviors such crypsis/mimicry, gregariousness, intra- and interspecific helpful interactions, sound production and aposematism. While defensive chemicals have been an important element in the successful diversification of ground beetles, in many tribes of this wide adephagan family many other systems have evolved and discovered. Here we present a review on the current knowledge of the avoidance mechanisms in carabids, with a discussion of data on chemical products, morphological adaptations and behaviors used against vertebrate and invertebrate predators. The most widespread strategy is discouragement of the predators using pygidial gland secretions, but passive anti-predator strategies are also displayed as group-protecting behavior through intraspecific aggregations or communal roosting. Most adult carabids tend to be dark in color and thus less detectable, but chemically well-protected taxa use the opposite strategy, displaying bright colors related to mimicry or aposematism. In aposematic species, group-protecting behavior has probably evolved from intraspecific gregariousness into multispecies aggregations. Larval behavioral strategies are related more closely to the epigean or underground lifestyle. In surface-living larvae, cannibalism avoidance and the usage of defensive substances have been reported for Chlaeniini. In this tribe we found an interesting coincidence between a high level of toxicity/distastefulness and a complex larval behavior. Based mainly on the genus-level supertree of Beutel et al. (2008) and the phylogenetic analyses of Ober & Maddison (2008) we reconstructed the evolutionary relationships among the chemical classes isolated inside the tribes. The scenario shows that several semiochemical classes (quinone/benzoquinones, formic acid, m-cresol, methacrylic acid, isovaleric acid, ß-necrodol, benzaldehyde, etc.) found in carabids are at least in part related to their life style and habitat selection. The proposed relationship still lacks other chemical data of the missing genera/species and even if the knowledge of carabid anti-predator strategies still seems to be in the pioneer stage, future studies on carabid anti-predator behavior look very promising.

Too much of a good thing? A landscape-of-fear analysis for collared peccaries (Pecari tajacu) reveals hikers act as a greater deterrent than thorny or bitter food

To study how wildlife perceive recreating humans, we studied the habitat selection of a human commensalist, the collared peccary (Pecari tajacu (Linnaeus, 1758)). We measured peccary activity patterns in an area of high human activity (Tumamoc Hill Desert Laboratory in Tucson, Arizona, USA) using a landscape-of-fear analysis. We examined whether the perception of risk from human activity interacted with the chemical (tannin) and mechanical (thorns) antipredator mechanisms of local plant species. The peccaries avoided food stations near a hiking trail. The population foraged less near houses, i.e., moderate human activity, than in the perceived safety of a small wadi. Plant defence treatments impacted the harvesting of food only in the safe zone, suggesting that risk trumps food selectivity. The strong effect of the hiking trail on habitat selection in this disturbance-loving species is an indicator of a much larger impact on sensitive species in conservation areas.

Antipredator Behaviour ofLimnonectes blythii(Boulenger, 1920) (Anura: Dicroglossidae) from Kedah, Peninsular Malaysia

The frogLimnonectes blythiiwas collected at different locations in Kedah, Peninsular Malaysia, three from Sungai Sedim Recreational Forest, two from Bukit Hijau Recreational Forest, and two from Ulu Paip Recreational Forest. Nine antipredator mechanisms were displayed by this species, including fleeing, hiding among leaf litter, diving into water, bladder discharge, defensive call, feigning death, crouching, inflating the body, and body-raising. The two latter actions were accompanied by a defensive call. These observations document for the first time antipredator behaviour inL. blythii.