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My
research currently involves five main themes:
- The
Evolution of Cooperation
- Parental
care and breeding system evolution
- Sperm
Competetition
- Effects
of contaminant exposure
- Species
introductions and extinctions
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| Photo
credit: Michael Taborsky |
1.
The Evolution of Cooperation
In many species of animals, some individuals will forgo opportunities to reproduce in order to help others. Such apparent altruistic behaviour has long puzzled evolutionary scientists because natural selection is thought to favour self-interest. In the past, it was believed that such helping behaviour in animals occurred mainly between relatives. We have been using a series of field and laboratory studies on a small cooperatively breeding fish Neolamprologus pulcher (from Lake Tanganyika in
Africa), to investigate why ‘helpers’ help. |
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Past
research: Groups are composed of anywhere from 1-14 helpers
of both sexes and group size is related to territory quality
(Balshine et al 2001). Breeders living in large groups feed
more and work less (Balshine et al 2001). Helpers can take
over a vacant breeding spot and helping behaviour may be a
signal group membership (Balshine-Earn et al 1998).
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Genetics: We use microsatellite markers to investigate
relatedness and skew patterns among groups of fish on a single
territory or subpopulation and explore the relationship between
helping effort and relatedness.
Students and Collaborators: Kelly Stiver, Lisle Gibbs,
Jim Quinn
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Physiology:
We have been exploring the physiological basis for variation
in helping effort and social status among group members. We
examine differences between the sexes and social positions
in terms of growth, plasma cortisol and androgen levels as
well other physiological measures. have been examining variation
in brain gene expression. We relate this variation to differences
between males and females, among dominance ranks and among
individual variation in parental/helping effort.
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Students and Collaborators: Julie Desjardin, Nadia
Aubin-Horth, Hans Hoffman, Katherine Sloman, Glen Van der
Kraak
Field Work: we investigate the effects of ecological
factors on the social dynamics in N. pulcher groups.
Students and Collaborators: Julie Desjardin, Kelly
Stiver, John Fitzpatrick |
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| Photo
credit: Ad Konings |
2.
Parental care and
breeding system evolution
A
cost/benefit or life history approach has been widely employed
to investigate the evolution of parental care and mating systems
in animals. However, to date most empirical tests of these
theories have been hampered by the fact that current species
may have fixed behaviour patterns and ecological conditions
may have changed over time from those that initially led to
the evolution of a particular mating or care system. To overcome
these problems, we use species with labile care patterns,
to test evolutionary models of parental care evolution (Balshine-Earn
1995, 1996, 1997; Balshine-Earn & Earn 1997; 1998).
This work has recently been expanded in two directions:
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A)
Comparative analyses using the entire family of cichlid fishes
(over 1400 species). We have constructed the first family-wide
composite phylogeny and the first supertree for this family
of fish. We have discovered that there have been numerous
transitions in parental care patterns are now analyzing life
history traits associated with these transitions (Goodwin
et al 1998; Goodwin et al 2001; Goodwin & Balshine in
prep).
Students and Collaborators: Nick Goodwin, John Reynolds
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B)
Experimental field and laboratory studies with another cichlid
fish from Lake Tanganyika with a peculiar breeding pattern,
Eretmodus cyanostictus. Using this species we have
been investigating the factors that maintain monogamy. Although
males could easily desert their mates, we have discovered
that they are both socially and genetically monogamous (Neat
and Balshine 1999; Morley & Balshine 2002; Morley &
Balshine 2003; Taylor et al 2003).
Students and Collaborators: Francis Neat, Josephine
Morley, Martin Taylor
 3.
Sperm Competetition
It is well established that in situations where females mate
with multiple mates (e.g. Baboons), males have evolved larger
testes and more sperm as a response to sperm competition.
However, it remains unclear what size of sperm is evolutionarily
stable in various situations. It has long been assumed that
large sperm swim faster but die more quickly, leading to a
debate about whether males undergoing
sperm
competition should invest in large versus small sperm. Using
cichlid fishes, we have found that males with higher sperm
competition tend to have longer sperm (Balshine et al 2001).
These results corroborate comparative studies of mammals,
birds and insects, but they sharply contrast the only published
comparative study of fish species. We are now examining long
held assumptions about sperm morphology and exploring the
life history trade-offs within ejaculates. We are also investigating
the role of breeding systems, fertilization location and social
status on the degree of sperm competition and ejaculate characteristics.
Students and Collaborators: John Fitzpartrick, Brenda
Leach, Bob Montgomerie
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4.
Effects of Contaminant Exposure in Great Lakes Fishes.
Anthropogenic pollutants are a serious concern in aquatic
systems, with the potential to negatively impact many species
of fish, amphibians, birds and mammals, including humans.
Rarely are the consequences of in situ exposure to industrial
effluents examined on behavioural, developmental and physiological
levels. We have begun to explore the changes in endocrinology,
anatomy, histology and behaviour in fishes of Hamilton Harbour,
a region with a long industrial history. Our work focuses
on the invasive round goby, Neogobius melanostomus, a benthic
fish found on both contaminated and relatively clean sediments
throughout the Harbour.
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Due
to their sheer numbers and diet of dreissenid mussels, round
gobies have the potential to mobilize bioaccumulated toxins
through Great Lakes foodwebs, so changes in contaminated round
gobies may serve as a red flag for possible impacts in sportfish
and waterfowl, and even facilitate accelerated mobilization,
if contaminated round gobies can no longer act adaptively
in a variety of behaviours affecting predator avoidance, foraging
and reproduction. We use a combination of fieldwork, behavioural
experiments and laboratory techniques to understand the extent
of contaminant-associated effects in our focal species.
Students and Collaborators: Julie Marentette, Greg
Slater, Joanna Wilson, Jim Quinn, Chris Wood, Environment
Canada
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5.
Species introductions
and extinctions.
The round goby, Neogobius melanostomus, was accidentally
introduced with ballast water to Lake Erie in 1993. Since
then this species has rapidly spread into the Great Lakes
and the first goby was caught in Lake Ontario in the autumn
of 1998. We have established that this species has become
one of the most abundant species in the littoral zone of
Hamilton Harbour and have discovered that it has entered
a sensitive fish breeding ground in Lake Ontario, known
as Cootes Paradise. We are currently embarked on a comprehensive
ecological and behavioural research program with this species
to establish food, habitat and breeding preferences as well
as quantify its density differences across habitats in Hamilton
Harbour. Finally, using competition experiments we are investigating
whether the round goby will deleteriously affect any of
the particular native species in Lake Ontario.
Students and Collaborators: John Fitzpartrick, Julie
Marentette, Brenda Leach, Bob Montgomerie
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Tristramella
is a cichlid genus from the Middle East for which the exact
number of taxa is uncertain. Moreover, at least two Tristramella
species have become extinct as a result of recent habitat
destruction by humans. We have embarked on a number of studies
(taxonomy, ecology and genetics) on this genus. Our results
show that another species has disappeared. We hope to raise
awareness of this problem in the governments involved (Israel,
Syria and Jordan) and to highlight the need to conserve the
remaining species and their environments.
We have also been using genetics and systematic techniques
to investigate a similar question for a group of species known
as the Neolamprologus pulcher/brichardi complex. As
with the genus Tristramella, the number of species in this
complex remains unknown. Our results to date suggest that
N. brichardi and N. pulcher may be sub-species.
Students and Collaborators: Adam Ben-Tuvia, Daniel
Golani, Axel Meyer, Petra Dierkes, Eva Skubic, Michael Taborsky |
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