Date of Award

2022

Document Type

Honors Thesis (Open Access)

Department

Colby College. Biology Dept.

Advisor(s)

David R. Angelini

Second Advisor

Christina Cota

Third Advisor

Tariq Ahmad

Abstract

Phenotypic plasticity is the ability of an organism to integrate information from environmental cues to inform the development of its phenotype and remains understudied in biology. Models of plasticity are needed because evolution in the presence of plasticity is poorly understood. Jadera haematoloma, a hemimetabolous true bug, is an excellent animal model of plasticity, exhibiting a non-linear plastic response to juvenile nutrition that biases adult development into groups with differences in flight capability, wing shape, and fecundity. However, there is a lack of literature consensus regarding the range of developmental outcomes in the species. Some publications report the presence of long-wing adults that develop without flight muscle, while others take the presence of short or long wings to be an absolute indicator of flight capability. Even within publications, there is uncertainty as to whether variation in flight muscle development is discrete or continuous. Moreover, it is unclear how beak length, a trait central to the study of J. haematoloma’s rapid population divergence on introduced host plants, is affected by the species’ developmental plasticity, and whether environmental factors beyond juvenile nutrition influence development. Therefore, I used geometric morphometric analysis, functional analysis of flight capability, and anatomical study of thoracic interiors to investigate whether wing shape predicts flight capability and flight muscle development. In addition, I took linear measurements of beak length to determine how the trait varies by sex and wing shape. I concluded by attempting to bias development by manipulating environmental conditions and gene expression. I find that wing shape does not completely predict flight capability and that the range of adult J. haematoloma phenotypes cannot be encapsulated by a simple two-morph system, resulting in significant implications for the future study of development in the species and the study of developmental plasticity in general.

Keywords

Geometric Morphometrics, Evolutionary Developmental Biology, Phenotypic Plasticity, Polyphenism, Flight-Fecundity trade-off, Field Study

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Click below to download supplemental content.

Michael_Yorsz_Thesis_Analysis_Script.R (17 kB)
Flight Day Test Data (0-3) - 59_specimens (5).csv (8 kB)
JH GMM - 21 categorical food (1).csv (165 kB)
JH GMM - ATG RNAi uc (1).csv (17 kB)
JH GMM - Day 3 Flight Tests (23).csv (205 kB)
JH GMM - flight + jsan (1).csv (160 kB)

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