1.
Physiological
basis of life-history traits and trade-offs
Over 70
years ago, Fisher highlighted the importance of an understanding of
physiological
mechanism to life-history theory, a point subsequently repeated by many
evolutionary biologists. Despite this frequent recognition the
physiological basis of most, if not all, trade-offs
remains unknown. The development of the field of "evolutionary
physiology" and more recently "evolutionary endocrinology"
has lead to significant, and very productive,
integration
of physiology and evolutionary biology, although much of this
work
has focused on performance-related traits (e.g. sprint speed, maximum
sustainable
metabolic rate), rather than life-history traits. Much of the work in
my lab is aimed at integration of physiology with evolutionary biology
to understand mechanisms underlying
variation in key LH traits (egg/offspring size and number) and
trade-offs between these traits, such as that between egg size
and clutch size, or the "cost of reproduction": the trade-off between
current
reproduction and future fecundity and/or survival.
We
mainly
focus on avian
reproduction
(though not
exclusively!) and specifically early stages of reproduction (e.g. egg
formation and laying)
since the importance of this phase of breeding has been neglected and
underestimated. Our research primarily combines laboratory studies,
using captive breeding zebra finches (Taeniopygia guttata), with
studies of a free-living, nest-box breeding, population of European
starlings
(Sturnus
vulgaris)
which are ideal for experimental studies in
the
field. However, we have been involved in other projects on a wide range
of species including Arctic-nesting ducks and
geese, seabirds, and even blue tits. Some recent or current projects
include:
Hormonally-mediated
maternal effects:
through correlative studies and experimental 
manipulations
we have been investigating the role of
non-androgens, especially estradiol and corticosterone, in mediating
maternal effects via transfer of maternal hormones to yolk, and
subsequent effects on offspring phenotype. For example, work by Love at
al. (2005) has suggested that maternal stress hormones such as
corticosterone provide a mechanistic link between maternal quality and
sex-biased maternal investment in offspring. In relation to estradiol,
the primary female reproductive hormone, we are investigating whether
negative pleiotropic effects of this hormone required for egg
production include anemia - which is commonly associated with
reproduction - and if this provides a potential physiological mechanism
for "cost of reproduction" (Williams et al. 2004).
Molecular basis of
individual variation in reproduction: with the availability of
the zebra finch genome http://www.ncbi.nlm.nih.gov/genome/guide/finch/
we have started to investigate individual variation in molecular and
cell-level processes involved in egg production. For example, we are
characterising 1) individual variation in vitellogenin receptor (VTG-R)
expression
in developing follicles in the ovary, in relation to different
stages of follicle development and individual variation in follicle
size;
and 2) individual variation in yolk-targeted very low density
lipoprotein (VLDLy)
expression in the liver as well as developing an ELISA for apoVLDL-II
to directly assay plasma VLDLy.
Costs of egg production in
song sparrows: Zanette et al. (2006 Ecology) reported a strong
negative 
correlation
between
clutch number and clutch
size in song sparrows breeding in the Gulf Islands, BC, indicative of a
cost of reproduction at the intra-specific level. In a collaborative
project with Drs. Liana Zanette and Mike Clinchy (UWO)
we will test
the hypothesis that this trade-off is due to an accumulated
physiological cost
of successive bouts of egg production, associated with pleiotropic
hormone
effects. Specifically we will compare reproductive success (including
egg and
offspring quality, sex ratio, etc) and physiological traits (including
anemia,
oxidative stress, plasma metabolites) in control females and females experimentally
forced to re-nest.
Individual
variation in reproductive effort
and fitness in lady beetles:
We have
initiated
some work with
lady
beetles (
Harmonia
axyridis) to provide a system where we can still take
physiological
approaches but where we can also measure recruitment,
lifetime reproductive success, or
survival of individual females (something that is more difficult in our
avian study systems). We are
characterising intra- and
inter-individual variability in egg and batch (clutch) size by
experimentally
manipulating resource level (aphid food supply), and have obtained
preliminary
data demonstrating a strong positive relationship between egg size and
larval
survival. As is the case with avian egg size advances in theory have
substantially outpaced empirical data with regard to evolution of
progeny size, and specifically the causes and consequences of large
inter-individual variation in egg size - which affect total
fecundity -
remain poorly understood.
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2. Physiology of
migration
Since
arriving at SFU I have been involved in a range of studies of
physiological mechanisms involved in long-distance
migration in Arctic-nesting shorebirds, focusing on the western
sandpiper (Calidris mauri). 
Projects have
included, a)
intraspecific variation in body composition
and organ masses in relation to variable energy demands during
migration;
b) the role of fatty acid binding protein (FABP) in migration, an
intracellular protein which facilitates
the delivery of fuel to the mitochondria during muscle function; this
has
involved isolation and characterization of avian FABP; c) the
functional significance
and regulation of seasonal and individual variation in fatty acid and
phospholipid
composition in plasma, adipose and muscle tissue, and d) the functional
significance,
and fitness consequences, of age-specific variation in gut morphology
and
physiology in first-year versus adult birds. Current work is mainly
aimed at using plasma metabolite profiles (triglycerides, etc) as a
tool to estimate fattening rates and provide
information
on habitat quality and habitat use by migratory shorebirds. I am
involved in many collaborative projects, with researchers from PRBO
Conservation Science, USGS and US F & W, at sites along the Pacific
Flyway from California to Alaska.
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3.
NSERC/CWS Chair in Wildlife Ecology: Applied Physiology CWE web site
The mandate
of the
NSERC/Environment Canada Chair in Wildlife Ecology (CWE) is to foster
high-quality graduate level research in wildlife ecology with
specializations in behavioral, population, and physiological ecology.
The central concept is to provide an interface between the
mission-orientated research and management policies of the Environment
Canada and the more basic-science approach of the Universities. My
contribution to the Chair's mandate has been based on the belief that a
rigorous understanding of the mechanisms underlying intraspecific
variability in physiological traits is essential in determining, and
hopefully predicting, the ability of individuals, populations and
species to respond to environmental change. Specifically I have an
on-going
interest in the effects of pesticides and other xenobiotics on avian
reproduction, in collaboration with Dr. John Elliott, Environment
Canada. Some recent projects have included:
Monitoring
of chlorinated hydrocarbons
and effects
in bald eagles
on the
British Columbia
coast. The
aim of this
project was to assess the impact of chlorinated hydrocarbon
concentrations on
nestling bald
eagles from
the Lower Fraser Valley and reference sites in the Georgia Basin. The
objectives of the study were to: (1) to revisit eagle nests sampled in
the early
1990s to assess burdens of pulp mill related contaminants (dioxins,
furans),
(2) to sample those same sites for “new” chemicals of concern such as
polybrominated
diphenyl ethers (flame retardents) and look for correlative evidence of
impairment
of thyroid hormone processes. Long
term trend monitoring of persistent contaminants
in local marine and estuarine food chains is valuable to a variety of
agencies
and NGOs in assessing chemical risks to ecosystems.
Impact
of use
of MSMA
(monosodium methanearsonate) for bark beetle control on cavity-nesting
birds in
B.C. forests.
The
infestation
of BC forests by bark beetles, particularly mountain pine beetle, is a
serious environmental
problem and one of the options for
controlling MPB is the arsenic-based insecticide MSMA. Toxicity
of MSMA to select mammals and aquatic
species is known but there are few studies on
insectivorous birds, particularly woodpeckers which are attracted to
beetle
outbreaks. We tackled this
problem through a
combination of field work on woodpeckers and chickadees in Merrit, BC,
and lab studies to investigate uptake,
elimination and toxicity of MSMA in adult zebra finches and sub-lethal
effects during growth in nestling zebra finches.
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