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203 Pages·2013·4.38 MB·English

FOOD WEBS IN SPACE!

A Dissertation
Presented to the Faculty of the Graduate School
of Cornell University
In Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy

by
Joseph Lawrence Simonis
January 2013
© 2013 by Joseph Lawrence Simonis
FOOD WEBS IN SPACE!

Joseph Lawrence Simonis, Ph. D.
Cornell University 2013

All organisms engage in trophic interactions, as consumers of or as resources for other
organisms in a food web. And all organisms move through space, sometimes dispersing to a
new location, where they still engage in trophic interactions, but in a different food web. As a
result, dispersal connects not just populations of organisms across space, but also the food
webs in which they exist. This dissertation comprises five studies examining how dispersal
and trophic interactions combine to influence the spatial dynamics of populations and food
webs. In addressing this topic, I utilize theoretical and empirical approaches, with the
empirical component focused on a system of freshwater rock pools on Appledore Island,
Maine, USA.
In Chapter One, I use a set of mathematical models describing a simple two-patch
predator-prey metapopulation to show that the inherent variation in the timing of demographic
events (called demographic stochasticity) qualitatively alters the effect of dispersal on trophic
interactions. Chapter Two describes the dominant food chain in the Appledore rock pools and
shows how the age structure of the apex predator (Trichocorixa) population drives within-
pool trophic dynamics through allometric increases in per capita consumption rates. I begin
exploring dispersal in the Appledore pools in Chapter Three, where I examine the ability of
Larus gulls to disperse invertebrates between pools. I combine experimental and
observational studies to show that gull-mediated dispersal occurs frequently enough to
homogenize the taxonomic composition of the pools and may be the main mode of dispersal
for many taxa that cannot actively disperse. The apex predator Trichocorixa, however, can
fly among pools, and their flight is the focus of Chapter Four, where I show that
Trichocorixa’s high, yet variable, dispersal rate combines with high, and variable, rates of
population turnover to cause complex spatial population dynamics. And in Chapter Five, I
explore how Trichocorixa’s actions as a frequent disperser and a voracious predator may
combine to drive the spatial dynamics of their prey Moina. In particular, because
Trichocorixa emigrates frequently more when Moina are in lower densities, they are not
likely to drive local Moina populations extinct, potentially promoting spatial food-web
persistence.
BIOGRAPHICAL SKETCH

Joseph Lawrence Simonis was born July 30, 1984 in Libertyville, Illinois to Lawrence
Lee and Sandra Hope Thomson Simonis, the youngest of three children. Joe grew up in
Northern Illinois, spending most of the first 18 years of his life in Mundelein, a quiet(ish)
town on the edge of the Chicago suburbs, passing his time by being a general nerd, playing
sports, drumming, and enjoying the outdoors.
After graduating from Mundelein High School in 2002, Joe headed west to start
college at the University of California: San Diego, determined to become a biomedical
engineer. That determination was short-lived, however, and Joe found himself switching
majors to Ecology, Behavior, and Evolution after two quarters. Joe studied at UCSD for two
years before deciding it was time to move back to the Midwest, and transferred to the
University of Illinois: Urbana-Champaign at the start of his junior year, where he majored in
Integrative Biology. While at UIUC, Joe became engaged in research for the first time as an
assistant in Andy Suarez’s Lab, helping Chad Tillberg on a project looking at food web
position of an invasive ant using stable isotopes. From that moment on, Joe knew he wanted
to be an ecologist. Joe conducted his senior honors project in the lab of Carol Shearer, with
assistance from Huzefa Raja, looking at the enzymatic capabilities of freshwater fungi.
During his time at UIUC, Joe also had the opportunity to be a summer REU researcher at the
Kellogg Biological station, working with Carla Cáceres and Spencer Hall to examine host-
parasite interactions in Daphnia. That summer, Joe went to his first Ecological Society of
America meeting (that year in Montreal), where he met Carla’s former PhD advisor, and the
man who would later become Joe’s own PhD advisor, Nelson Hairston, Jr. But before he and
Nelson would work together, Joe took a year off from school and moved down to Tallahassee,
Florida to work as a technician in Nora Underwood’s lab at Florida State University, on a
project examining population density effects in plant-insect interactions using Solanum.
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Joe entered Cornell University in Fall 2007 as a graduate student in Ecology and
Evolutionary Biology, passing his candidacy exam in May 2009. Joe had always intended to
study spatial community ecology in aquatic systems for his PhD, but a chance conversation
with former Shoals Marine Laboratory (SML) director Jim Morin took Joe’s mind off of
vernal ponds in Upstate New York and moved it to freshwater rock pools on an island off the
coast of Maine. Joe visited Appledore Island (home of SML) with Jim for the first time in
May 2008 and was hooked on the place and the rock pools. Joe spent four summers (2008 –
2011) on Appledore studying dispersal and trophic interactions in the pools and those studies
are the empirical focus of this thesis.
Never a system-focused person and having spent enough time in the Eastern Time
Zone for now, Joe is ready to move back to Illinois and on to another project. She begins a
post-doctoral position at the Alexander Center for Applied Population Biology at the Lincoln
Park Zoo in Chicago, Illinois as soon as this dissertation is accepted.

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To my parents, for everything.
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ACKNOWLEDGMENTS

“It takes a village to raise a child.”

In whatever capacity I am allowed to use this analogy, as I have never had a child
before, this dissertation is my baby. And I didn’t raise it alone. This was a multi-team effort,
and so I have lots of folks to thank for making this work possible.
My thesis committee was incredibly awesome, and I am honored to have gotten the
opportunity to work with them for these past five-plus years. Nelson Hairston, Jr. was the
best advisor I could have hoped for, exactly the balance of support and laissez faire I needed
to get through graduate school with a sense of who I am as an independent scientist. Nelson
is an inspiration both as an ecologist and as a person, and I will cherish everything I learned
from him (including that predate is actually a word that means “eat”). Steve Ellner has been a
fantastic mentor, specifically with respect to quantitative skills, but more generally, as well.
Steve is an incredibly intelligent and eloquent ecologist and one of the nicest people I have
ever met. I came to Cornell with the hopes of learning how to combine theoretical and
empirical ecology from Steve and Nelson, and I am so thankful that they took me under their
wings. I hope I’m ready to fledge. Alex Flecker was incredibly invaluable and just awesome
to work with. Perhaps the most enjoyable, critical, and productive discussions I had in
graduate school took place in Alex’s office. I tell you, get two circuitously talking ecologists
in a room together and magic happens (although it can take a while…). Alex also provided
field equipment and training and a home-away-from-home in the Flecker lab, all of which I
am incredibly thankful for. Anurag Agrawal is the closest thing I have to an outside member
on my committee, and I am grateful for the alternative viewpoints he always brought to the
table, forcing me to step out of my comfort zone and think about things from a different angle.
More generally, the faculty of Cornell’s EEB Department are all top-notch researchers
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and wonderful people, and I am thankful for everything that they have taught me. In
particular Monica Geber, David Winkler, Jed Sparks, and Harry Greene were all great
mentors and friends.
This department is just the latest set in a life full of really fantastic science teachers. I
am the product of a public school education (well, plus whatever Cornell counts as), and I am
thankful for all of the teachers at Mechanics Grove Elementary School, Carl Sandburg Middle
School, Mundelein High School, the University of California: San Diego, the University of
Illinois: Urbana-Champaign, Florida State University, and Cornell University who imparted
upon me the wisdom, curiosity, and critical thinking skills that I have today. Having grown
up in a family of teachers, I am inspired by those who give of themselves to impart
knowledge. Teachers make the world go ‘round.
I was also the member of a number of really awesome ecology labs that helped me get
to Cornell. At UIUC, Andy Suarez and Chad Tillberg gave me my first lab job, and I am so
thankful for the opportunity. Carol Shearer was a fantastic undergraduate mentor and she and
Huzefa Raja were very helpful in getting me my first first-authored scientific paper. Carla
Cáceres was an incredible teacher and mentor. I am thankful that the stars aligned for me to
take Limnology with Carla, otherwise I would never have gotten the opportunity to be an
REU at Kellogg Biological Station and work with her and Spencer Hall, nor would I have met
Nelson at ESA in Montreal. Spencer is perhaps the best science role model I have ever had,
seemingly seamlessly combining rigorous math with cool natural history to answer interesting
questions, and I am grateful to have had the opportunity to work with and learn from him
while at Kellogg. At Florida State, the Underwood Lab provided me with a stimulating job,
an opportunity to take a break from school for a year, and a nice respite from freshwater
research! Stacey Halpern and Nora Underwood were both fantastic bosses and mentors.
While at Cornell, I’ve been lucky to call the Hairston Zoo home. All of the members
past and present have been supportive, intelligent, helpful folks. In particular, I cannot thank
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Colleen Kearns and Lindsay Schaffner enough for all that they did and do to make the lab run
smoothly and effectively. Lindsay was also an immense rock star of a helper with formatting
this thesis. It would not have been done on time without her. Oh, and she’s one of my best
friends, and arguably my derby wife. We’re not in a relationship, but seriously, she rocks.
All of the post-docs and grad students have also made the Hairston Lab a fantastic place to get
science done. Lutz Becks, Mikael Gyllstrom, Aldo Barreiro, Teppo Hiltunen, Masato
Yamaichi, Brooks Miner, Becky Doyle-Morin, Rebecca Dore, Mike Booth, Cayelan Carey,
Sarah Collins, Chris Dalton, and Katie Siriani, you rock! The Flecker lab was also a great
sister-lab, and I thank Krista Capps, Jen Moslemi, and Marita Davidson for welcoming me.
Both labs were great places to get feedback on ideas, talks, and papers. Never again I worry
about formatting a talk as much as I did before presenting at the Flecker lab.
I resided in three different offices in Corson Hall, each full of fantastic people that
kept me distracted, happy, and entertained, as well as provided great sounding boards for all
of my hair-brained ideas. Although the giant office was a difficult place to work sometimes, I
enjoyed sharing a space with Erica Larson, Fin Ransler, Mike Booth, Paulo Llambias, Marissa
Weiss, Morgan Mouchka, and Chris Dalton. I found a great, and more productive, home with
April Melvin, Susan Cook, and Danica Lombardozzi, all of whom shared sage advice on
finishing grad school and were awesome officemates. Finally, MG Weber and Colin Edwards
were fantastic foster officemates after I got moved for my final semester. I am so happy to
have had even just a few months working together, and wish I could have had more.
I had the pleasure of spending work (and not-work) time with an incredible group of
friends including (but not limited to…sorry if I forgot!) Sarah Collins, Rayna Bell, Chris
Dalton, Dave Baker, Morgan Mouchka, Willie Fetzer, Ben Dalziel, MG Weber, Jon DeCoste,
Nancy Chen, Jen Koslow, Stuart Campbell, Mike Stastny, Mike Booth, Sam Chamberlain,
Lindsay Schaffner, Yula Kapetanakos, Anna Forsman, Ezra Lencer, Ginny Howick, Sarah
States, April Melvin, Susan Cook, Danica Lombardozzi, Krista Capps, Erica Larson, Findley
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