Phylogenetic signal in amphibian sensitivity to copper sulfate relative to experimental temperature

The release of large quantities of chemicals into the environment represents a major source of environmental disturbance. In recent years, the focus of ecotoxicology has shifted from describing the effects of chemical contaminants on individual species to developing more integrated approaches for predicting and evaluating long term effects of chemicals across species and ecosystems. Traditional ecotoxicology is typically based on data of sensitivity of a few surrogate species to a contaminant and often considers little variability in chemical sensitivity within and among taxonomic groups. This approach assumes that evolutionary history and phylogenetic relatedness among species have little or no impact on species’ sensitivity to chemical compounds. Few studies have tested this assumption. Using phylogenetic comparative methods and published data for amphibians, we show that sensitivity to copper sulfate, a commonly used pesticide, exhibits a strong phylogenetic signal when controlling for experimental temperature. Our results indicate that evolutionary history needs to be accounted for to make accurate predictions of amphibian sensitivity to this contaminant under different temperature scenarios. Since physiological and metabolic traits showing high phylogenetic signal likely underlie variation in species sensitivity to chemical stressors, future studies should evaluate and predict species vulnerability to pollutants using evolutionarily informed approaches

Unravelling the macro-evolutionary ecology of fish–jellyfish associations: life in the ‘gingerbread house’

Fish–jellyfish interactions are important factors contributing to fish stock success. Jellyfish can compete with fish for food resources, or feed on fish eggs and larvae, which works to reduce survivorship and recruitment of fish species. However, jellyfish also provide habitat and space for developing larval and juvenile fish which use their hosts as means of protection from predators and feeding opportunities, helping to reduce fish mortality and increase recruitment. Yet, relatively little is known about the evolutionary dynamics and drivers of such associations which would allow for their more effective incorporation into ecosystem models. Here, we found that jellyfish association is a probable adaptive anti-predator strategy for juvenile fish, more likely to evolve in benthic (fish living on the sea floor), benthopelagic (fish living just above the bottom of the seafloor), and reef-associating species than those adapted to other marine habitats. We also found that jellyfish association likely preceded the evolution of a benthic, benthopelagic, and reef-associating lifestyle rather than its evolutionary consequence, as we originally hypothesized. Considering over two-thirds of the associating fish identified here are of economic importance, and the wide-scale occurrence and diversity of species involved, it is clear the formation of fish–jellyfish associations is an important but complex process in relation to the success of fish stocks globally

Terrestrial reproduction and parental care drive rapid evolution in the trade-off between offspring size and number across amphibians.

The trade-off between offspring size and number is central to life history strategies. Both the evolutionary gain of parental care or more favorable habitats for offspring development are predicted to result in fewer, larger offspring. However, despite much research, it remains unclear whether and how different forms of care and habitats drive the evolution of the trade-off. Using data for over 800 amphibian species, we demonstrate that, after controlling for allometry, amphibians with direct development and those that lay eggs in terrestrial environments have larger eggs and smaller clutches, while different care behaviors and adaptations vary in their effects on the trade-off. Specifically, among the 11 care forms we considered at the egg, tadpole and juvenile stage, egg brooding, male egg attendance, and female egg attendance increase egg size; female tadpole attendance and tadpole feeding decrease egg size, while egg brooding, tadpole feeding, male tadpole attendance, and male tadpole transport decrease clutch size. Unlike egg size that shows exceptionally high rates of phenotypic change in just 19 branches of the amphibian phylogeny, clutch size has evolved at exceptionally high rates in 135 branches, indicating episodes of strong selection; egg and tadpole environment, direct development, egg brooding, tadpole feeding, male tadpole attendance, and tadpole transport explain 80% of these events. By explicitly considering diversity in parental care and offspring habitat by stage of offspring development, this study demonstrates that more favorable conditions for offspring development promote the evolution of larger offspring in smaller broods and reveals that the diversity of parental care forms influences the trade-off in more nuanced ways than previously appreciated

Citizen science data reveal altitudinal movement and seasonal ecosystem use by hummingbirds in the Andes Mountains

Acknowledgements We thank all the people who love birds and contribute their observations to public citizen science databases such as eBird, providing researchers with powerful datasets to study nature. We are grateful to colleagues who gave useful suggestions to improve this work, including Stephen C. F. Palmer, Julián Pérez-Correa, David Burslem and Thomas Bodey. We also thank NERC for funding C.R.-U. Funding This work was supported by the UKRI Natural Environment Research Council (grant no. NE/S007377/1).Peer reviewe

The evolution of fighting structures in hartebeest

Question: Is sexual selection for the evolution of larger horns and related fighting structures opposed by food constraints in bovids? Data studied: Horn circumference and length, pedicel height, skull weight, and body size (skull length) were measured on 382 skulls belonging to all eight hartebeest subspecies (Aleelaphus ssp.). We used mean group size and length of the breeding season for each subspecies as surrogates for the intensity of sexual selection through the potential for polygyny; mean annual rainfall and index of seasonality of each subspecies range quantified habitat primary production. The phylogeny of the hartebeest tree and the branch lengths were based on Flagstad et al. (2001). Search methods: Within- and across-taxa variation infighting structures: One-way analysis of variance and independent sample t-tests. Phylogenetically uncorrected. Dimorphism, as Log (M/F), regressed against independent variables (surrogates of sexual selection and habitat productivity, plus Log female size to check for allometry) with stepwise regressions weighted by the sample size of specimens measured for each ssp. Phylogenetically corrected: Independent contrasts using the program CAIC (Purvis and Rambaut, 1995). Conclusions: The length of the breeding season was the only predictor for dimorphism in pedicel height and skull weight and the best, albeit non-significant, predictor for horn circumference. Only mean annual rainfall predicted horn length dimorphism. Thus, taller pedicels and heavier skulls appear to be under sexual selection, while natural selection seems to affect the evolution of fighting structures by limiting investment in longer horns. We argue that the pedicel, by increasing the defence to the head during clashes, might reduce the selective pressures on horns as protective structures

The reproductive ecology drivers of egg attendance in amphibians

Parental care is extremely diverse but, despite much research, why parental care evolves is poorly understood. Here we address this outstanding question using egg attendance, the simplest and most common care form in many taxa. We demonstrate that, in amphibians, terrestrial egg deposition, laying eggs in hidden locations and direct development promote the evolution of female egg attendance. Male egg attendance follows the evolution of hidden eggs and is associated with terrestrial egg deposition but not with direct development. We conclude that egg attendance, particularly by females, evolves following changes in reproductive ecology that are likely to increase egg survival, select for small clutches of large eggs and/or expose eggs to new environmental challenges. While our results resolve a long-standing question on whether reproductive ecology traits are drivers, consequences or alternative solutions to caring, they also unravel important, yet previously unappreciated, differences between the sexes