New paper!

Jin Z. et al.: "Mosaic phenotypic evolution underlies the adaptive success of water-surface colonization in Gerromorpha".

Understanding how the remarkable phenotypic diversity observed in organisms arises through shifts in macroevolutionary patterns and tempos is a fundamental challenge in evolutionary biology. Phenotypes often evolve in a mosaic pattern during adaptive transitions. For organisms that have invaded highly specialized habitats, such as the unique two-phase interface habitats (water surfaces), the macroevolutionary history of their phenotypic diversification remains only superficially understood. Semiaquatic bugs (Insecta: Heteroptera: Gerromorpha), which exhibit extensive habitat diversification and unparalleled phenotypic innovation, represent one of the most successful extant adaptive groups at this interface and provide an excellent system for study. By analyzing their adaptive transitions and phenotypic macroevolutionary history, we demonstrate that Gerromorpha experienced a single major adaptive transition from land to the water surface. Subsequently, semiaquatic bugs successfully colonized a wide range of distinct water-surface habitats. During this process, phenotypic space was explored under strong constraints and along pronounced mosaic trajectories; i.e., different body regions exhibited markedly distinct patterns of phenotypic space occupation and partitioning, as well as markedly different evolutionary rates. Furthermore, we showed that this mosaic pattern of phenotypic space occupation and rates of exploration had complex and critical effects on the invasion and colonization of water-surface habitats. Our study provides a typical case of macroevolutionary dynamics in species adapted to specialized air–water interface habitats, emphasizing the complex and significant roles of environmental context and functional demands in shaping patterns of phenotypic evolution.

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New paper!

Dai R. et al.: "Early evolution of Rhopalidae (Hemiptera): the first amber-preserved “scentless bug” from Myanmar with phylogenetic implications".

As an important group within the superfamily Coreoidea, extant Rhopalidae are commonly dubbed “scentless bugs” due to the degeneration of their scent glands, yet their early evolutionary history and phylogenetic relationships have long remained enigmatic. This study integrates fossil evidence with morphological analyses of Rhopalidae Odorocoris longirostris sp. nov., the first rhopalid species discovered in mid-Cretaceous Kachin amber, clarifying the intrafamilial phylogeny. Results demonstrate that: (i) Originicorizus (Yao et al. 2006a, 2006b) and Quatlocellus (Yao et al. 2006a, 2006b) (165 million years ago) represent the oldest-known stem-group rhopalids, retaining plesiomorphic traits including the presence of vein C and a lanceolate ovipositor. (ii) The new Kachin amber genus Odorocoris gen. nov. has a mosaic of character states typical of Serinethinae and Rhopalinae, providing empirical evidence for the paraphyly of the latter and supporting the reclassification of Serinethinae as a tribal-level taxon (Serinethini stat. nov.). (iii) The character states of fossil groups reveal that evolutionary transitions—degeneration of vein C (Jurassic to mid-Cretaceous), transformation of the ovipositor from lanceolate to plate-like (post mid-Cretaceous), and degeneration of scent glands—were synchronous with niche differentiation during the gymnosperm-to-angiosperm transition. In summary, this study reconstructs the evolutionary framework of Rhopalidae using Kachin amber fossils while illuminating the ecological coevolutionary mechanisms between key morphological transitions and the angiosperm radiation.

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New paper!

Frankenberg S. & Weirauch C: "Correlated evolution of exaggerated genitalic structures in the minute litter bug Nannocoris Reuter (Hemiptera: Schizopteridae)".

Studies on animal genitalia have long shaped our understanding of patterns and processes of morphological evolution. Coevolution between male and female genitalic structures is predicted to be ubiquitous, regardless of the evolutionary mechanism involved. However, studies that simultaneously evaluate male and female genitalic variation in a comparative phylogenetic framework have remained relatively scarce. We here investigate correlated male and female genital evolution in Nannocoris Reuter (Hemiptera: Schizopteridae), a minute litter bug genus that may be unique among arthropods in the degree and variation of its exaggerated genitalic traits: we here report that the length of the male intromittent organ differs dramatically between species, ranging from 1/8th to 20 times their respective body length, and that this variation is mirrored in the female spermathecal duct. Using a phylogenetic hypothesis for species of Nannocoris, measurements of male and female genitalic features, and phylogenetically independent contrasts, we find that the length of the male intromittent organ and female spermathecal duct are correlated. The mode of evolution that has led to these striking phenotypes is unknown, but we stress that this system has potential for future research in the evolution of male and female genitalic features in general.

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