Environment predicts repeated body size shifts in a recent radiation of Australian mammals*

Closely related species that occur across steep environmental gradients often display clear body size differences, and examining this pattern is crucial to understanding how environmental variation shapes diversity. Australian endemic rodents in the Pseudomys Division (Muridae: Murinae) have repeatedly colonized the arid, monsoon, and mesic biomes over the last 5 million years. Using occurrence records, body mass data, and Bayesian phylogenetic models, we test whether body mass of 31 species in the Pseudomys Division can be predicted by their biome association. We also model the effect of eight environmental variables on body mass. Despite high phylogenetic signal in body mass evolution across the phylogeny, we find that mass predictably increases in the mesic biome and decreases in arid and monsoon biomes. As per Bergmann's rule, temperature is strongly correlated with body mass, as well as several other variables. Our results highlight two important findings. First, body size in Australian rodents has tracked with climate through the Pleistocene, likely due to several environmental variables rather than a single factor. Second, support for both Brownian motion and predictable change at different taxonomic levels in the Pseudomys Division phylogeny demonstrates how the level at which we test hypotheses can alter interpretation of evolutionary processes.     

Species-specific patterns in corallivory and spongivory among Caribbean parrotfishes

Coral Reefs - Parrotfishes are key herbivores on Caribbean reefs but also feed on other benthic taxa such as corals and sponges. Here, we used in situ behavioral observations to show that Caribbean...     

Digest: Colonizing rodents overcome ecological incumbency in an island system*

Do primary radiations inhibit the persistence and diversification of secondary colonizers? Rowsey et al. test predictions of this “incumbency effect” by contrasting patterns of morphological variation in two murine rodent clades on the Philippine island of Luzon. They find that in this system, primary colonizers may impose constraints via biotic filtering, and may also restrict size evolution in secondary colonists.     

Pleistocene climatic changes drive diversification across a tropical savanna

Spatial responses of species to past climate change depend on both intrinsic traits (climatic niche breadth, dispersal rates) and the scale of climatic fluctuations across the landscape. New capabilities in generating and analysing population genomic data, along with spatial modelling, have unleashed our capacity to infer how past climate changes have shaped populations, and by extension, complex communities. Combining these approaches, we uncover lineage diversity across four codistributed lizards from the Australian Monsoonal Tropics and explore how varying climatic tolerances interact with regional climate history to generate common vs. disparate responses to late Pleistocene change. We find more divergent spatial structuring and temporal demographic responses in the drier Kimberley region compared to the more mesic and consistently suitable Top End. We hypothesize that, in general, the effects of species’ traits on sensitivity to climate fluctuation will be more evident in climatically marginal regions. If true, this points to the need in climatically marginal areas to craft more species‐(or trait)‐specific strategies for persistence under future climate change.     

Enrichment and fragmentation approaches for enhanced detection and characterization of endogenous glycosylated neuropeptides

Glycosylated neuropeptides were recently discovered in crustaceans, a model organism with a well-characterized neuroendocrine system. Several workflows exist to characterize enzymatically digested peptides; however, the unique properties of endogenous neuropeptides require methods to be re-evaluated. We investigate the use of hydrophilic interaction liquid chromatography (HILIC) enrichment and different fragmentation methods to further probe the expression of glycosylated neuropeptides in Callinectes sapidus. During the evaluation of HILIC, we observed the necessity of a less aqueous solvent for endogenous peptide samples. This modification enabled the number of detected neuropeptide glycoforms to increase almost two-fold, from 18 to 36. Product ion-triggered electron-transfer/higher-energy collision dissociation enabled the site-specific detection of 55 intact N- and O-linked glycoforms, while the faster stepped collision energy higher-energy collisional dissociation resulted in detection of 25. Additionally, applying this workflow to five neuronal tissues enabled the characterization of 36 more glycoforms of known neuropeptides and 11 more glycoforms of nine putative novel neuropeptides. Overall, the database of glycosylated neuropeptides in crustaceans was largely expanded from 18 to 136 glycoforms of 40 neuropeptides from 10 neuropeptide families. Both macro- and micro-heterogeneity were observed, demonstrating the chemical diversity of this simple invertebrate, establishing a framework to use crustacean to probe modulatory effects of glycosylation on neuropeptides.