New paper!

Dong X. et al.: "Comparative phylogeography of three Cletus species pairs reveals shared responses to quaternary environmental change".

Understanding how co-distributed species respond to shared environmental histories is a central question in evolutionary biology. Although comparative phylogeography has advanced rapidly in vertebrates, insects—despite comprising most terrestrial biodiversity—remain underrepresented. Here, we conducted a comparative phylogeographic study of three closely related phytophagous insect species pairs in the genus Cletus (Heteroptera: Coreidae) distributed across eastern Asia. Using genome-wide SNPs generated by ddRAD-seq, we integrated coalescent-based demographic modeling, ecological niche modeling, and full-likelihood Bayesian tests to explore patterns of divergence and demographic history. Our results revealed strong phylogeographic structure in all three species pairs, with genetic clusters largely partitioned along a north–south axis. Demographic modeling supported initial divergence during the Early Pleistocene followed by recent secondary contact during Late Pleistocene climatic oscillations. Bayesian model choice identified a single synchronous divergence event among all three lineages, indicating a shared response to Quaternary climatic changes. Species distribution modeling and Stairway Plot analyses further revealed asymmetrical demographic histories between northern and southern species, with northern taxa showing glacial contractions followed by recent expansion. Additionally, isolation-by-distance (IBD) was consistently detected across all lineages, whereas isolation-by-environment (IBE) was significant only in lineage I. Together, these findings suggest that historical climatic change was associated with parallel diversification and lineage-specific traits also contributed to differences in demographic responses. This study advances our understanding of insect diversification in eastern Asia and highlights the value of comparative genomic approaches for resolving complex evolutionary histories.

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New paper!

Evans-Blake C., Rubin J. J. & Somjee U.: "Flag-waving behavior in matador bugs is an antipredatory strategy".

To dissuade predator attack, animals may advertise their chemical defense with bright coloration and specialized behaviors. However, these antipredator adaptations can be costly, if they unnecessarily draw attention to the prey animal. Thus, animals with elaborate antipredator traits may be under pressure to selectively increase advertisement of their defenses in particular contexts. The matador bug, Bitta alipes (Hemiptera: Coreidae), possesses large, colorful flags on its hind tibia that it uses in a stereotypic “waving” behavior. Previous research found no evidence that this waving behavior is employed in social or sexual interactions. Here, we experimentally tested for a potential antipredator function of flag waving by exposing a matador bug to either an arthropod predator (praying mantid) or a similarly sized nonpredatory arthropod (nonpredatory katydid). In total, we recorded 2,938 leg waves among 25 individuals. We found that matador bugs’ waving behavior increased in duration, frequency (number of wave bouts), and intensity (number of waves per bout) in the presence of praying mantids. Notably, we found on average a 7-fold increase in the number of waves in the presence of a mantid relative to a similarly sized nonpredatory arthropod. Praying mantids consumed very few matador bugs (3/25) and never attacked bugs that were waving, lending support to the hypothesis that flags serve an antipredator function in matador bugs. We find similar flag-waving behavior in at least 5 closely-related flag-legged bug species, all of which have expanded tibial flags with contrasting coloration and are Passiflora specialists, providing opportunities for future studies to examine the evolution of elaborate flag-waving behavior as an antipredator behavior in this group.