Year

2021

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr Anthony Rossi

Second Advisor

Dr Dale Casamatta

Rights Statement

http://rightsstatements.org/vocab/InC/1.0/

Third Advisor

Dr Adam E. Rosenblatt

Abstract

Asphondylia borrichaie is a small fly (Diptera: Cecidomyiidae) that is currently undergoing host-associated sympatric divergence. Asphondylia borrichaie is an ambrosia galler, these insects utilize a host plant for oviposition, but its offspring also rely on a symbiotic fungus (or fungal community) to promote the formation of the gall as well as serve as a food source for the developing larvae. Previous studies indicate that A. borrichaie consists of two host- associated populations based on its original host plant Borrichia frutescens (Asterales: Asteraceae), and another one from the two Iva species (I. frutescens (Asterales: Asteraceae) and I. imbricata (Asterales: Asteraceae)). Differences in development time suggest allochronic isolation as the primary mechanism promoting host-associated sympatric divergence of midge populations and A. borrichiae has been shown to display fidelity to its natal host plant genus (e.g. Borrichia vs. Iva). Effects of host range expansion on the endophytic fungal community of the galls the midge’s two primary host plants (B. frutescens and I. frutescens) have never been compared. In the current study, olfactometery trials utilizing field-collected galls/midges demonstrated a weak association for a midge’s natal host; overall midges chose their natal host plant 56.1% percent of trials compared to 43.9% for the alternative (novel) plant. However, no significant differences were found in the time taken for a midge to choose natal vs novel host. Moreover, male midges showed a stronger preference for their natal host genus than females suggesting that gene flow between host-associated populations is more likely to be limited through males than females. Although clones of B. frutescens (collected from different localities) exhibited significant differences in leaf size (but not number of serrations after more 18 months of being cultured in a common greenhouse environment, suggesting at least a partial genetic control for leaf morphology, no association was detected for midges to their specific clone of B. frutescens from the midge’s natal locality. Lastly, this study successfully cultured and sequenced the ITS region of fungi extracted from gall chambers which could then be identified it down to fungal genera using BLAST searches. These data suggest a possible association of fungal genera with each host plant: specifically, with Cladosporium spp. which was more commonly found from galls collected from B. frutescens, while Fusarium spp. was more likely to be found in galls collected from I. frutescens.

Available for download on Tuesday, March 29, 2022

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