Form, function, foam: evolutionary ecology of anuran nests and nesting behaviour

Surviving in the urban jungle: The role of foam nests as thermal insulator in Pleurodema borellii (anura: Leptodactylidae)

Urbanisation stands as a primary driver of biodiversity loss globally, reshaping natural landscapes and imposing novel environmental conditions upon organisms. This ecological novelty poses challenges, and species capable of thriving in urban environments are considered tolerant. Among vertebrates, anurans are the most susceptible to land-use changes, mainly due to their life history and morphological traits. They exhibit a great diversity of reproductive strategies and modes, among which the foam nest plays several important roles, such as moderating or buffering adverse conditions. In this study, we assessed the foam nest of Pleurodema borellii, an urban tolerant species, as a potential thermal insulator in the city of San Salvador de Jujuy, Argentina. We carried out our surveys within San Salvador and surrounding areas, focusing on urban and peri-urban environments. We measured the height, length, and internal temperature of 48 foam nests, as well as the temperature of their immediate environment (water and air at one cm above the nest), over consecutive days from the first day until the nest disappeared. Finally, we collected four to five embryos from each foam nest once a day to identify their developmental stage. Our results suggest that foam nests not only mitigate low temperatures but also buffer against the heat of urban environments. These findings suggest that the foam nest could be one of the traits that facilitates the occurrence of this anuran species in the city and therefore may explain its tolerance to urbanisation.

Contrasting nidification behaviors facilitate diversification and colonization of the Music frogs under a changing paleoclimate

In order to cope with the complexity and variability of the terrestrial environment, amphibians have developed a wide range of reproductive and parental behaviors. Nest building occurs in some anuran species as parental care. Species of the Music frog genus Nidirana are known for their unique courtship behavior and mud nesting in several congeners. However, the evolution of these frogs and their nidification behavior has yet to be studied. With phylogenomic and phylogeographic analyses based on a wide sampling of the genus, we find that Nidirana originated from central-southwestern China and the nidification behavior initially evolved at ca 19.3 Ma but subsequently lost in several descendants. Further population genomic analyses suggest that the nidification species have an older diversification and colonization history, while N. adenopleura complex congeners that do not exhibit nidification behavior have experienced a recent rapid radiation. The presence and loss of the nidification behavior in the Music frogs may be associated with paleoclimatic factors such as temperature and precipitation. This study highlights the nidification behavior as a key evolutionary innovation that has contributed to the diversification of an amphibian group under past climate changes.

A perspective on neuroethology: what the past teaches us about the future of neuroethology

For 100 years, the Journal of Comparative Physiology-A has significantly supported research in the field of neuroethology. The celebration of the journal's centennial is a great time point to appreciate the recent progress in neuroethology and to discuss possible avenues of the field. Animal behavior is the main source of inspiration for neuroethologists. This is illustrated by the huge diversity of investigated behaviors and species. To explain behavior at a mechanistic level, neuroethologists combine neuroscientific approaches with sophisticated behavioral analysis. The rapid technological progress in neuroscience makes neuroethology a highly dynamic and exciting field of research. To summarize the recent scientific progress in neuroethology, I went through all abstracts of the last six International Congresses for Neuroethology (ICNs 2010-2022) and categorized them based on the sensory modalities, experimental model species, and research topics. This highlights the diversity of neuroethology and gives us a perspective on the field's scientific future. At the end, I highlight three research topics that may, among others, influence the future of neuroethology. I hope that sharing my roots may inspire other scientists to follow neuroethological approaches.

Adhesive properties of Aphrophoridae spittlebug foam

Aphrophora alni spittlebug nymphs produce a wet foam from anal excrement fluid, covering and protecting themselves against numerous impacts. Foam fluid contact angles on normal (26°) and silanized glass (37°) suggest that the foam wets various substrates, including plant and arthropod surfaces. The pull-off force depends on the hydration state and is higher the more dry the fluid. Because the foam desiccates as fast as water, predators once captured struggle to free from drying foam, becoming stickier. The present study confirms that adhesion is one of the numerous foam characteristics resulting in multifunctional effects, which promote spittlebugs' survival and render the foam a smart, biocompatible material of biological, biomimetic and biomedical interest. The sustainable 'reuse' of large amounts of excrement for foam production and protection of the thin nymph integument suggests energetic and evolutionary advantages. Probably, that is why foam nests have evolved in different groups of organisms, such as spittlebugs, frogs and fish.