Multiple large-scale gene and genome duplications during the evolution of hexapods.

Polyploidy or whole genome duplication (WGD) is a major contributor to genome evolution and diversity. Although polyploidy is recognized as an important component of plant evolution, it is generally considered to play a relatively minor role in animal evolution. Ancient polyploidy is found in the ancestry of some animals, especially fishes, but there is little evidence for ancient WGDs in other metazoan lineages. Here we use recently published transcriptomes and genomes from more than 150 species across the insect phylogeny to investigate whether ancient WGDs occurred during the evolution of Hexapoda, the most diverse clade of animals. Using gene age distributions and phylogenomics, we found evidence for 18 ancient WGDs and six other large-scale bursts of gene duplication during insect evolution. These bursts of gene duplication occurred in the history of lineages such as the Lepidoptera, Trichoptera, and Odonata. To further corroborate the nature of these duplications, we evaluated the pattern of gene retention from putative WGDs observed in the gene age distributions. We found a relatively strong signal of convergent gene retention across many of the putative insect WGDs. Considering the phylogenetic breadth and depth of the insect phylogeny, this observation is consistent with polyploidy as we expect dosage balance to drive the parallel retention of genes. Together with recent research on plant evolution, our hexapod results suggest that genome duplications contributed to the evolution of two of the most diverse lineages of eukaryotes on Earth.

Most Compositae (Asteraceae) are descendants of a paleohexaploid and all share a paleotetraploid ancestor with the Calyceraceae.

PREMISE OF THE STUDY: Like many other flowering plants, members of the Compositae (Asteraceae) have a polyploid ancestry. Previous analyses found evidence for an ancient duplication or possibly triplication in the early evolutionary history of the family. We sought to better place this paleopolyploidy in the phylogeny and assess its nature. METHODS: We sequenced new transcriptomes for Barnadesia, the lineage sister to all other Compositae, and four representatives of closely related families. Using a recently developed algorithm, MAPS, we analyzed nuclear gene family phylogenies for evidence of paleopolyploidy. KEY RESULTS: We found that the previously recognized Compositae paleopolyploidy is also in the ancestry of the Calyceraceae. Our phylogenomic analyses uncovered evidence for a successive second round of genome duplication among all sampled Compositae except Barnadesia. CONCLUSIONS: Our analyses of new samples with new tools provide a revised view of paleopolyploidy in the Compositae. Together with results from a high density Lactuca linkage map, our results suggest that the Compositae and Calyceraceae have a common paleotetraploid ancestor and that most Compositae are descendants of a paleohexaploid. Although paleohexaploids have been previously identified, this is the first example where the paleotetraploid and paleohexaploid lineages have survived over tens of millions of years. The complex polyploidy in the ancestry of the Compositae and Calyceraceae represents a unique opportunity to study the long-term evolutionary fates and consequences of different ploidal levels.

A new species of whip spider, Weygoldtia hainanensis sp. nov., from Hainan, China (Arachnida: Amblypygi: Charinidae).

To date, only one species of whip spider has been recorded in China. Here, we describe a new species, Weygoldtia hainanensis sp. nov., from Hainan, China. The new species is morphologically similar to W. davidovi (Fage, 1946) and W. consonensis Miranda et al. 2021, but can be distinguished with a combination of the following characters: 26 segments in tibia I, 6-7 teeth on chelicerae, distitibia IV trichobothria sc and sf series each with 10-11 trichobothria. To validate our morphological inferences and support the erection of W. hainanensis sp. nov. as a new species, we sequenced the COI gene region for two individuals and performed molecular phylogenetic analyses. The inferred phylogenetic trees placed the new species within Weygoldtia and highlighted the evolutionary distinction between W. hainanensis sp. nov. and currently described whip spiders. The type specimens are deposited in the Museum of Biology, East China Normal University (ECNU).