Ole Shelton

Broadly, I am interested in how to document and account for the massive variability observed in nature. For populations, what are the impacts of having variability in vital rates (e.g. yearly survivorship or growth) to population growth and stability? For management purposes, what are the consequences of not explicitly incorporating natural variability?

My thesis research centers on connecting the life history and demography of the seagrass genus Phyllospadix (surfgrasses) to the community affiliated with these habitat forming plants. Phyllospadix spp. are dioecious (have separate male and female individuals) with female-biased sex ratios (>90% of plants are female). Male rarity appears to result in massive variation in pollination rates and seed production between sites. Sites with many males produce and recruit many more seedlings than sites with few males. Using this natural variation in male abundance as well as manipulative experiments, I am developing a demographic model that will allow me to understand the relative importance of sexual and asexual reproduction to surfgrass populations. In particular I am interested in if the importance of asexual reproduction may help explain the ubiquity of male rarity despite its measuarable cost.

An important aspect of the demography of surfgrasses is identifying when during the life cycle male rarity develops. To determine the source of skewed sex ratios, I have developed a sex-linked genetic marker (AFLP) that allows me to determine the sex of plants that are not flowering. By using this marker on plants at various life stages (seedlings, small pre-flowering patches, and leaves of large individuals), I hope to understand when during the surfgass life cycle male rarity develops and how this timing influences surfgass populations.

A final aspect of my project is examining the impact of surfgrass on intertidal communities. Specifically, I am experimentally manipulating surfgrass abundance in tide pools to understand surfgrass' impact on the thermal environment of tide pools and how this change may affect the community composition of tide pools.

Other projects:

1. I am collaborating with biologists at the Alaska Department of Fish and Game in Juneau to develop sampling methods and population models for stocks of pacific herring (Clupea pallasi) in Southeastern Alaska.
2. With Prof. Fiorenza. Micheli at Hopkins Marine Station I am working to describe the effects of marine reserves on the recovery of black and red abalone populations in Central California.

Publications:
Micheli, F., A.O. Shelton, S.M. Bushinsky, A.L.Chiu, K.W. Heiman, C.V. Kappel, M.C. Lynch, and J. Watanabe. 2008. Persistence and recovery of depleted marine invertebrates in marine reserves of central California. In press. Biological Conservation.

Shelton, A.O., D.A. Woodby, K. Hebert, and J. Witman. 2006 Age determination and spatial patterns of growth of the red sea urchin (Strongylocentrotus franciscanus) in southeast Alaska. Transactions of the American Fisheries Society 135:1670-1680.

Hebert, K.P. and A.O. Shelton. 2001. Red sea urchin (Strongylocentrotus fransiscanus) growth and mortality rates in Southeast Alaska. Proceedings of the 2001 Alaska Chapter American Fisheries Society Annual Meeting, Sitka, Alaska, November 12-15, 2001, page 44.

In review:
Shelton, A.O. Skewed sex ratios, pollen limitation, and reproductive failure in the dioecious seagrass genus Phyllospadix.

Ma, L., M.L. Stein, M. Wang, A.O. Shelton, C.A. Pfister and K.J. Wilderk. Species abundance along a curvy margin: correcting sampling biases for coastlines, rivers, and other convoluted edges.