Abstract
Understanding how biodiversity evolves is a major goal in evolutionary developmental biology because changes in developmental processes are tightly linked with evolutionary diversification. Heterochrony--alteration to the rate or timing of development--can significantly alter the appearance of descendant species. Heterochronic shifts in gene expression and associated morphological change may explain the morphological divergence between the threatened June sucker (Chasmistes liorus) and the sympatric Utah sucker (Catostomus ardens) in Utah Lake, UT, USA. June sucker are endemic to Utah Lake and have subterminal mouths adapted for pelagic feeding, while Utah sucker (Catostomus ardens) have ventral mouths adapted for benthic feeding. As larvae, both June sucker and Utah sucker have terminal mouths. However, within the first 14 weeks of development, the Utah sucker's mouth shifts to a ventral position, whereas the June sucker's mouth only shifts to a subterminal position. Using geometric morphometrics and RNA-seq time courses, we document a difference in the timing of shape development and a corresponding change in the timing of gene expression between June sucker and two Utah sucker lineages. Our results suggest that the distinctive mouth morphology in June sucker may be the result of paedomorphosis in which adult June sucker exhibit an intermediate mouth morphology between that of the larval (terminal) and ancestral (ventral) states. On a broader scale, additional Chasmistes / Catostomus pairs exist in the Intermountain West that are also morphologically divergent, but genetically similar. These pairs could be the result of repeated convergent evolution driven by differential expression of genes in response to environmental cues.
Degree
MS
College and Department
Life Sciences; Biology
Rights
https://lib.byu.edu/about/copyright/
BYU ScholarsArchive Citation
Searle, Peter C., "Introgression or Incipient Speciation? Using Geometric Morphometrics and Gene Expression to Characterize Mouth Development in Larval June Sucker and Utah Sucker" (2022). Theses and Dissertations. 10130.
https://scholarsarchive.byu.edu/etd/10130
Date Submitted
2022-08-04
Document Type
Thesis
Handle
http://hdl.lib.byu.edu/1877/etd12968
Keywords
Catostomidae, geometric morphometrics, transcriptomics, differential expression
Language
english