Biology subjects

St Laurent, R. A.

Publications and source records attributed to St Laurent, R. A..

4 recordsLinked to original sources

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↗

bioRxiv2022

Diversification is correlated with temperature in white and sulfur butterflies

Temperature is thought to be a key variable explaining global patterns of species richness. However, to investigate this relationship carefully, it is necessary to study clades with broad geographic ranges that are comprised of species inhabiting diverse biomes with well- characterized species ranges. In the present study, we investigate the link between temperature and diversification in the butterfly family Pieridae (sulfurs and whites) by combining Next Generation sequences and published molecular data with fine-grained distribution information. After building the most comprehensive phylogeny of the group, with almost 600 species and all higher taxa (subfamilies, tribes and subtribes), we found strong support for the following relationships within the family: Dismorphiinae + (Coliadinae + (Pseudopontiinae + Pierinae)). With a curated distribution dataset of over 800,000 occurrences, we conducted multiple comparative phylogenetic analyses that provided strong evidence that species in environments with more stable daily temperatures or with cooler maximum temperatures in the warm seasons have higher diversification rates. We also found a positive correlation between speciation and extinction with paleotemperature: as global temperature decreased through geological time, so did diversification rates. Although many studies demonstrate higher diversity in the tropics, we have been able to identify specific climate variables associated with changes in diversification, while also inferring the most robust and well sampled phylogenomic framework for Pieridae to date.

evolutionary biology↗

bioRxiv2022

Evolution and diversification dynamics of butterflies

Butterflies are a diverse and charismatic insect group that are thought to have diversified via coevolution with plants and in response to dispersals following key geological events. These hypotheses have been poorly tested at the macroevolutionary scale because a comprehensive phylogenetic framework and datasets on global distributions and larval hosts of butterflies are lacking. We sequenced 391 genes from nearly 2,000 butterfly species to construct a new, phylogenomic tree of butterflies representing 92% of all genera and aggregated global distribution records and larval host datasets. We found that butterflies likely originated in what is now the Americas, [~]100 Ma, shortly before the Cretaceous Thermal Maximum, then crossed Beringia and diversified in the Paleotropics. The ancestor of modern butterflies likely fed on Fabaceae, and most extant families were present before the K/Pg extinction. The majority of butterfly dispersals occurred from the tropics (especially the Neotropics) to temperate zones, largely supporting a "cradle" pattern of diversification. Surprisingly, host breadth changes and shifts to novel host plants had only modest impacts.

evolutionary biology↗

bioRxiv2019

Phylogenomics reveals major diversification rate shifts in the evolution of silk moths and relatives

The silkmoths and their relatives (Bombycoidea) are an ecologically and taxonomically diverse superfamily that includes some of the most charismatic species of all the Lepidoptera. Despite displaying some of the most spectacular forms and ecological traits among insects, relatively little attention has been given to understanding their evolution and the drivers of their diversity. We heavily sampled (both in taxa and loci) all major lineages of the Bombycoidea, producing a well-supported phylogeny that identified important evolutionary patterns (e.g., morphology, biogeography, and differences in speciation and extinction). Importantly, analysis of diversification rates highlights the stark increases that exist within the Sphingidae (hawkmoths) and Saturniidae (wild silkmoths). We postulate that these rate shifts are due to differences in the intense selective pressures from insectivorous bats. The study also introduces a new Bombycoidea-specific Anchored Hybrid Enrichment (AHE) probe set, a modified DNA extraction protocol for Lepidoptera specimens from natural history collections, and additional information on the existing AHE bioinformatics pipeline. Our research highlights the flexibility of AHE to generate genomic data from a wide range of museum specimens, both age and preservation method, and will allow researchers to tap into the wealth of biological data residing in natural history collections around the globe.

evolutionary biology↗