Robbins, R. K. | Search bioRxiv

bioRxiv2023

Hiding in Plain Sight: Phylogenomics Reveals a New Branch on the Noctuoidea Tree of Life

We present the results of the first phylogenomic analyses based on anchored hybrid enrichment (AHE) data from densely sampled tribes and subfamilies of Notodontidae (Prominent Moths). Our analyses reveal the familys polyphyly with respect to an assemblage of genera related to Scrancia Holland that has been variously recognized at the tribal or subfamilial rank. We propose and re-describe Scranciidae, stat. nov., and recognize 21 genera and approximately 100 species--distributed in Africa, Asia, and Australia and not represented in previous phylogenomic studies--from the six recognized noctuoid families (Noctuidae, Erebidae, Euteliidae, Nolidae, Notodontidae, and Oenosandridae). We further re-interpret morphological synapomorphies previously proposed for Notodontidae (including Scranciidae) and for the trifid Noctuoidea, viz. the ventral-facing tympanum and trifid forewing venation-- characters previously called into question when Doidae were transferred from Noctuoidea to Drepanoidea. Deep-level relationships within Noctuoidea are not firmly established outside the clade comprising the four quadrifid families (Noctuidae, Erebidae, Euteliidae, and Nolidae), and in attempting to establish the phylogenetic position of Scranciidae relative to Notodontidae, Oenosandridae, and the quadrifids, we obtain conflicting results depending on data type (amino acid vs. nucleotide) and analytical framework (maximum likelihood, multi-species coalescent, and parsimony). We also demonstrate that discordant topologies among these ancient lineages yield drastically different divergence time estimates, highlighting the need for caution when interpreting phylogenetic dating of uncertain topologies. Following multiple analyses of several datasets designed around the distribution of missing data, and an evaluation of strict support measures at the deepest nodes of the noctuoid tree, we provisionally conclude that this ambiguity is a function of character conflict amplified by missing data and short branch lengths, and that in the topology best supported by the available data, Scranciidae is placed well outside Notodontidae and sister to the remaining Noctuoidea.

evolutionary biology↗

bioRxiv2021

Whole-genomes from the extinct Xerces Blue butterfly reveal low diversity and long-term population decline

The Xerces Blue (Glaucopsyche xerces) is considered to be the first butterfly to become extinct at global scale in historical times. It was notable for its chalky lavender wings with conspicuous white spots on the ventral wings. The last individuals were collected in their restricted habitat, in the dunes near the Presidio military base in San Francisco, in 1941. We sequenced the genomes of four 80 to 100-year-old Xerces Blue, and seven historical and one modern specimens of its closest relative, the Silvery Blue (G. lygdamus). We compared these to a novel annotated genome of the Green-Underside Blue (G. alexis). Phylogenetic relationships inferred from complete mitochondrial genomes indicate that Xerces Blue was a distinct species that diverged from the Silvery Blue lineage at least 850,000 years ago. Using nuclear genomes, both species experienced population growth during the Eemian interglacial period, but the Xerces Blue decreased to a very low effective population size subsequently, a trend opposite to that observed in the Silvery Blue. Runs of homozygosity and deleterious load in the Xerces Blue were significantly greater than in the Silvery Blue, suggesting a higher incidence of inbreeding. These signals of population decline observed in Xerces Blue could be used to identify and monitor other insects threatened by human activities, whose extinction patterns are still not well known.

evolutionary biology↗