ORCID

Tajinder Singh: https://orcid.org/0009-0009-6744-0661

Degree

Bachelor of Science (B.S.)

Major(s)

Microbiology, Environmental Science in Agricultural Systems

Document Type

Immediate Open Access

Abstract

Hybridization is a key evolutionary mechanism for generating biological diversity, ultimately shaping diversification and adaptation of plant lineages in natural and agroecosystems.  Our understanding of the frequency, distribution, and significance of hybridization is rapidly increasing, but the external driving forces that dictate why certain species hybridize, and others do not remain obscure. The physical traits that shape gene flow and trait sharing among species are likely to be among the key factors that directly control hybridization. Gene flow in most plants is mediated by pollinating insects and thus by pollination syndromes, which are suites of floral traits that have evolved to attract and interact with specific groups of pollinators. Dissecting the genetic basis of syndromes is thus important for understanding the patterns of reproductive isolation and hybridization among plants. Using Heuchera (coral bells), which are prolific hybridizers in nature with numerous inter-specific differences in traits relevant to pollinator display, we aimed to develop a system to investigate traits that may relate to hybridization as a process. Specific pollinators in Heuchera are known and their link to morphological traits remains under investigation. Most importantly, Heucherapossesses the very rare property of multiple evolutionary transitions between floral symmetry modes; this architectural difference is central to syndrome evolution. Also diverse in this system are leaf ornamentation patterns, which likely relate to negative insect interactions instead. We hypothesized a single locus linked with each floral development and leaf ornamentation patterns. We further hypothesized that the species symmetry difference was due to a CYCLOIDEA-like, a member of the same gene subfamily as the master regulator initiating bilateral symmetry in snapdragon and other plants. We phenotyped an F2 population generated from crossing two Heuchera species, which segregated independently for the target floral traits and leaf ornamentation patterns. We genotyped the individuals by resequencing and conducted GWAS (genome wide association studies) to find candidate genes with functions inferred from a closely related genome annotation. We successfully discovered single locus candidates linked to segregating floral and leaf traits in the population. Our results suggest the genetic architecture of pollination traits in this system is relatively simple and amenable to manipulation.

Date Defended

4-30-2026

Funding Source

This work was supported by NSF CAREER grant (DEB-2337784) to Ryan A. Folk

Thesis Director

Ryan A. Folk

Second Committee Member

Daniel Peterson

Third Committee Member

Matthew Peaple

Rights Statement

Discovering the genetics underlying speciation traits in Heuchera (coral bells), Copyright 2025 by Tajinder Singh. This work is licensed under CC BY-NC-ND.

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Digital Object Identifier (DOI)

https://doi.org/10.54718/FPEX5161