Undergraduate Honors Theses

Connecting Herbivore Effects to Population Dynamics of Common Milkweed (Asclepias syriaca) Using an Integral Projection Model

Sivan Yair, College of William and MaryFollow

Date Thesis Awarded

4-2016

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Drew LaMar

Committee Members

Joshua Puzey

Leah Shaw

Harmony Dalgleish

Abstract

Plant defense mechanisms and their effects on plant performance have been extensively studied in common milkweed (Asclepias syriaca). No studies, however, have investigated the relevance of these responses to its population dynamics. Common milkweed are clonal plants that exhibit both an induced defensive chemical response and mechanisms of resource allocation upon herbivore damage. Milkweed population decline has been implicated as a major contributing factor to the decline of monarch butterflies. We examined how herbivores affect the survival, growth, and fecundity of the ramets of common milkweed, and whether those effects were meaningful at the population level. By using an integral projection model to connect individual variation in size and foliar damage to population dynamics, we show that herbivores affect the milkweed's sexually reproductive output and clonal propagation, both pathways that the population growth rate is sensitive to. Our results provide insight on the herbivore effects that have greater influence on population growth and indicate future directions to improve the currently limited knowledge of how environmental factors drive population dynamics in common milkweed.

Recommended Citation

Yair, Sivan, "Connecting Herbivore Effects to Population Dynamics of Common Milkweed (Asclepias syriaca) Using an Integral Projection Model" (2016). Undergraduate Honors Theses. William & Mary. Paper 895.
https://scholarworks.wm.edu/honorstheses/895