Biology subjects

Crumiere, A. J. J.

Publications and source records attributed to Crumiere, A. J. J..

3 recordsLinked to original sources

bioRxiv2018

Hox genes mediate the escalation of sexually antagonistic traits in water striders

Sexual conflict occurs when traits favoured in one sex impose fitness costs on the other sex. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance females resistance to mating and traits that increase males persistence. How this escalation in sexually antagonistic traits is established during ontogeny remains unclear. In the water strider Rhagovelia antilleana, male persistence traits consist of sex combs in the forelegs and multiple rows of spines and a thick femur in the rearlegs. Female resistance trait consists of a prominent spike-like projection of the pronotum. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction of both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rearlegs. These results demonstrate that Hox genes can mediate sex-specific escalation of antagonistic traits along the body axis of both sexes.

evolutionary biology↗

bioRxiv2018

Escalation and constraints of antagonistic armaments in water striders

Sexual conflict may result in the escalating coevolution of sexually antagonistic traits. However, our understanding of the evolutionary dynamics of antagonistic traits and their role in association with sex-specific escalation remains limited. Here we study sexually antagonistic coevolution in a genus of water striders called Rhagovelia. We identified a set of male grasping traits and female anti-grasping traits used during pre-mating struggles and show that natural variation of these traits is associated with variation in mating performance in the direction expected for antagonistic co-evolution. Phylogenetic mapping detected signals of escalation of these sexually antagonistic traits suggesting an ongoing arms race. Moreover, their escalation appears to be constrained by a trade-off with dispersal through flight in both sexes. Altogether our results highlight how sexual interactions may have shaped sex-specific antagonistic traits and how constraints imposed by natural selection may have influenced their evolution.

evolutionary biology↗

bioRxiv2017

Molecular evolutionary trends and feeding ecology diversification in the Hemiptera, anchored by the milkweed bug genome

BackgroundThe Hemiptera (aphids, cicadas, and true bugs) are a key insect order, with high diversity for feeding ecology and excellent experimental tractability for molecular genetics. Building upon recent sequencing of hemipteran pests such as phloem-feeding aphids and blood-feeding bed bugs, we present the genome sequence and comparative analyses centered on the milkweed bug Oncopeltus fasciatus, a seed feeder of the family Lygaeidae.\n\nResultsThe 926-Mb Oncopeltus genome is well represented by the current assembly and official gene set. We use our genomic and RNA-seq data not only to characterize the protein-coding gene repertoire and perform isoform-specific RNAi, but also to elucidate patterns of molecular evolution and physiology. We find ongoing, lineage-specific expansion and diversification of repressive C2H2 zinc finger proteins. The discovery of intron gain and turnover specific to the Hemiptera also prompted evaluation of lineage and genome size as predictors of gene structure evolution. Furthermore, we identify enzymatic gains and losses that correlate with feeding biology, particularly for reductions associated with derived, fluid-nutrition feeding.\n\nConclusionsWith the milkweed bug, we now have a critical mass of sequenced species for a hemimetabolous insect order and close outgroup to the Holometabola, substantially improving the diversity of insect genomics. We thereby define commonalities among the Hemiptera and delve into how hemipteran genomes reflect distinct feeding ecologies. Given Oncopeltus's strength as an experimental model, these new sequence resources bolster the foundation for molecular research and highlight technical considerations for the analysis of medium-sized invertebrate genomes.

genomics↗