A Preliminary Phylogenomic Analysis of Adesmiini (Coleoptera: Tenebrionidae) and Study of Pimeliinae Heat Shock Protein Functional Genomics

Kali L Swichtenberg, Purdue University

Abstract

Deserts, such as the Namib, Sonoran, and Saharan, are regions that are unsuitable habitats for many organisms. However, darkling beetles (Tenebrionidae), specifically Pimeliinae, have appeared to flourish in otherwise inhospitable environments. All organisms have heat shock proteins protecting cellular components from degradation due to environmental stress such as desert heat. Modifications to heat shock proteins may provide more efficient cellular protection allowing desert-dwelling beetles to survive in regions where few other organisms are found. I performed a study which analyzed heat shock protein 40 (Hsp40) homologs across Pimeliinae by using targeted enrichment and high-throughput sequencing of seven genetic loci from 142 taxa (25 tribes) to examine protein functionality and evolution. I determined that the critical J domain of Hsp40 is conserved across pimeliine taxa. Additionally, there were a variety of cysteine shifts within different pimeliine tribes throughout six of the seven homologs, indicating possible protein structure alterations. Maximum likelihood analyses of Hsp40 homologs determined that despite the relationships between the tribes shuffling, taxa remained within their respective tribes. In an effort to examine how Hsp40s may have evolved alongside other behaviors and life histories, the tribe Adesmiini (Tenebrionidae: Pimeliinae) was examined in detail. Adesmiines thrive in the arid regions of sub-Saharan Africa, northern Africa, and the Palearctic. Despite having a few genera (i.e., Onymacris) which have been the subject of extensive life history analyses, Adesmiini has undergone few modern taxonomic studies. As a result, Adesmiini is a good candidate for phylogenetic investigation. To investigate evolutionary relationships, 510 targeted loci across 47 specimens (41 species, 10 genera) were used to produce a well-supported phylogeny. Current generic concepts were not in agreement with the resulting topology. In addition to producing a molecular phylogeny, two adesmiine traits of interest, activity time (diurnal/nocturnal) and substrate usage (psammophily), were also examined. Since Adesmiini is a predominantly diurnal tribe within a primarily nocturnal family, the activity time was mapped to the topology. From this study’s tree, it was determined that there were at least three shifts from diurnal to nocturnal throughout Adesmiini. Several charismatic adesmiines occur on the dunes of southern Africa, so the shift to inhabiting sand hills (psammophily) devoid of vegetation was also investigated. Psammophily was determined to have arisen multiple times within Adesmiini, and the topology revealed no clear indication to a single radiation of adesmiine substrate usage. Finally, a study was performed on Adesmiini using the same seven Hsp40 homologs as in the pimeliine functional genomics investigation. The resulting phylogenies indicate a correlation between Hsp40 modification and diurnal, psammophilous adesmiines.

Degree

M.Sc.

Advisors

Smith, Purdue University.

Subject Area

Morphology|Ecology|Forestry|Genetics|Systematic biology|Wood sciences

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