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RESEARCH INTERESTS
Evolutionary ecology and genetics
Evolutionary genetics of whale lice (Amphipoda, Cyamidae)
Evolution of selfish genetic systems, especially coccoid chromosome elimination
Evolution of vertebrate odorant receptors
Sex allocation, especially in Hymenoptera
PUBLICATIONS
Posters
Do island endemics suffer increased genetic loads?
Why so many cryptic species of ant-decapitating flies?
People in my lab use a wide range of techniques including phylogenetic
analysis, field observations of behavior, and mathematical modeling, to
address a wide range of problems in evolutionary ecology and evolutionary
genetics. Often the problem is to understand how an adaptation evolves
under constraints of various kinds. For example, sex ratios evolve under
constraints on the allocation of nutrients and other resources to male and
female offspring; resources allocated to male offspring are not available
for females or for growth of the parent. In such cases, there is
typically a tradeoff between the costs and benefits of incompatible
alternatives; the optimal balance between these alternatives usually
depends on particular aspects of the individual's or species' current
ecological situation. Often it is informative to analyze the responses of
related species in a comparative, phylogenetic framework. This requires
that the evolutionary relationships of the species be understood in
detail. Like other evolutionary biologists, we increasingly turn to DNA
sequences for the data needed to infer phylogenetic relationships, and we
increasingly seek to understand how mutation, selection, and other
evolutionary processes guide the evolution of those sequences.
I have specific interests in the evolutionary ecology of aculeate
(stinging) Hymenoptera, including insect sociality and sex allocation, the
biology of solitary hunting wasps in the Philanthinae, and the structure
of bee communities. Glenn Herrick (in the Department of Oncological
Sciences) and I share an interest in the chromosome-elimination systems of
scale insects, and other "selfish" genetic phenomena cued by genomic
imprints. Aron Branscomb and I are studying the evolution of mammalian
odorant receptors, which are encoded by the largest known family of genes.
Some members of this family evolve very rapidly, but others (including
some expressed in the testis) evolve very slowly. This finding raises
many questions about the evolutionary diversification and maintenance of
large gene families that include many non-essential members. We plan to
address some of these questions by studying how odorant-receptor genes
vary within and among natural populations of mice.
Students now or recently in my lab work on colony structure, relatedness,
and sex allocation in social insects, and on various aspects of molecular
evolution. For example, Jay Evans studied patterns of relatedness and
parentage in polygynous (multiple-queen) colonies of the ant Myrmica
tahoensis, using highly polymorphic microsatellite markers to
determine pedigree relationships among the members of individual colonies.
He showed that workers apparently assess their average relatedness to the
siblings they are helping to rear, before deciding whether to devote most
of their effort to rearing males or females. In colonies where the
workers are especially closely related to other females, they specialize
in rearing females, while in colonies where they are relatively more
closely related to males, they produce only males. Janice Ragsdale is
studying primitive sociality in carpenter bees of the genus
Xylocopa. Unrelated females often join together to construct and
defend a nest, but one of the females lays most or all of the eggs. This
behavior poses a challenge to current theories for the evolution of
sociality. Janice is testing the hypothesis that "worker" females often
live long enough to inherit the valuable nest from their "reproductive"
partners. Mark Beilstein constructed a molecular phylogeny of plants in
the genus Draba. He showed that many western North American
species are very young, and that flower colors and trichome ("hair")
morphologies have changed more often than previously believed. Pat
Corneli is developing methods for more accurately estimating phylogenetic
relationships (and branch lengths) from DNA sequences of limited length.
She plans to use these more powerful methods to attack some long-standing
problems in mammalian phylogeny. Vicky Rowntree and Ada Kaliszewska (an
undergraduate) are using molecular phylogenetic and population-genetic
methods to study the relationships of "whale lice" (small amphipod
crustaceans that live on the skin of whales) and thereby to infer patterns
of interaction and association among the whales within a
population.
Selected publications
Seger J, Stubblefield JW (2002) Models of sex ratio evolution. In
Sex Ratios: Concepts and Research Methods (ed ICW Hardy), pp 2-25.
Cambridge University Press.
Johnson KP, Seger J (2001) Elevated rates of nonsynonymous
substitution in island birds. Molecular Biology and Evolution
18:874-881.
Morehead SA, Seger J, Feener DH Jr, Brown BV (2001) Evidence for a
cryptic species complex in the ant parasitoid Apocephalus
paraponerae (Diptera: Phoridae). Evolutionary Ecology Research
3:273-284.
Branscomb A, Seger J, White RL (2000) Evolution of odorant receptors
expressed in mammalian testes. Genetics 156:785-787.
Seger J (1999) Is sex in the details? Journal of Evolutionary Biology
12:1050-1052.
Eckhart VM, Seger J (1999) Phenological and developmental costs of male
sex function in hermaphroditic plants. In Life History Evolution in
Plants (ed TO Vuorisalo, PK Mutikainen), pp 195-213. Kluwer.
Herrick G, Seger J (1999) Imprinting and paternal genome elimination in
insects. In Genomic Imprinting: An Interdisciplinary Approach (Results
and Problems in Cell Differentiation, vol. 25) (ed R Ohlsson) pp 41-71.
Springer-Verlag.
Berrigan DB, Seger J (1998) Information and allometry. Evolutionary
Ecology 12:535-541.
Seger J, Stubblefield JW (1996) Optimization and adaptation. In
Adaptation (ed GV Lauder, MR Rose) pp 93-123. Academic Press.
Seger J, Eckhart VM (1996) Evolution of sexual systems and sex allocation
in plants when growth and reproduction overlap. Proc R Soc Lond B
263:833-841.
Richards MH, Packer L, Seger J (1995) Unexpected patterns of parentage
and relatedness in a primitively eusocial bee. Nature
373:239-241.
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