Graduation Year


Graduation Month


Document Type


Degree Name

Bachelor of Science

School or Department

Biological Sciences, Division of


Biology – Ecology and Organismal Biology

Faculty Mentor

Lila Fishman

Faculty Mentor Department

Biological Sciences, Division of


Milkweed, local adaptation, qst fst, asclepias speciosa

Subject Categories

Biology | Ecology and Evolutionary Biology


Many plant species show variation in phenotypic traits, such as traits related to growth and defense against herbivores, across environmental gradients. Differences in phenotypic traits can be due to selection, leading to local adaptation, or due to the random process of genetic drift. To examine the driver of phenotypic variation, I conducted a Qst (a measure of phenotypic variation among populations) vs. Fst (a measure of genetic variation among populations) analysis for 13 populations of A. speciosa grown in a common garden, using five growth and defense traits and seven microsatellite markers. I found relatively low differentiation at the neutral markers (mean Fst = 0.005), and population differentiation of plant height, leaf shape, and latex production traits (but not trichome density or specific leaf area). These results suggest that the three highly differentiated growth and defense traits are responding to population-specific selection pressures, indicating local adaptation of A. speciosa distributed across an environmental gradient.

Honors College Research Project




© Copyright 2017 Kira I. Sussman