Research Interests

My research interests fall under the broad category of behavioral ecology. More specifically, I am interested in mating systems, sex allocation and extreme life-history adaptations of marine birds. In 2004, I completed my M.S. in Biology at Bucknell University in the lab of Dr. Donald C. Dearborn. My master's research involved offspring sex ratios and the influence of three factors (age, body condition, and food availability) on adaptive sex allocation in Great Frigatebirds (Fregata minor) breeding in the northwest Hawaiian Islands. As part of this project, I collaborated with Dr. Mark Haussmann and Dr. Carol Vleck from Iowa St. University on a
telomere-based technique for estimating ages of individual frigatebirds in wild populations.

Background

Sex allocation: Modern sex-allocation theory predicts that
if ecological or social conditions differentially influence the fitness
benefits gained from producing male or female offspring, parents
should correspondingly adjust their production of sons and
daughters to maximize their fitness. Theoretical and empirical
research supports the theory, though the empirical data have
centered around organisms where a clearly defined mechanism
of adjustment exists, such as in haplodiploid insects. Sex-ratio
studies conducted on organisms with chromosomal sex
determination are especially intriguing because they underscore
the complex tradeoffs between evolutionary adaptation and genetic
constraint. Chromosomal sex determination would seemingly
constrain the evolution of adaptive manipulation of offspring sex
ratios in many vertebrates. Although the mechanisms for
circumventing any constraints set by chromosomal sex
determination remain unclear, increasing evidence now suggests
that some vertebrates, including birds, are capable of adjusting
their offspring sex ratio.

Telomere Aging: Telomeres are protein-DNA complexes that cap the ends of linear eukaryotic chromosomes. By nature of the linear DNA replication process, DNA polymerase is unable to complete the replication of the 3' end. Therefore, during each replication cycle of a cell, some telomeric repeats are left as single stranded ends that are eventually lost to breakage or degradation. Telomere restriction fragments (TRFs) have been shown to serve as a fairly reliable marker for age in several bird species, though the rate of TRF shortening has been directly related to the lifespan of each species. Obtaining information about individual age and age structure for a population of wild animals is often not possible due to the time and expense involved in long-term mark-recapture studies, particularly for long-lived species. If the ages of some, but not all, individuals of a given population were known, it should be possible to calibrate the rate of TRF shortening for that population and then make age estimates of other population members for which there is no known history.

Overview

For my dissertation research, I plan to continue exploring
various aspects of Great Frigatebird breeding biology in the
northwest Hawaiian Islands. One potential avenue of
research involves the link between genes and behavior.
Specifically, this would involve a suite of genes called the
major histocompatibility complex (Mhc) as a basis for mate
choice. Mhc genes influence immunological self/non-self
recognition, and play a critical role in disease resistance. It
has been postulated that these genes may also play an
important role in mate choice and kin recognition.
Mhc -dependent mating preferences may have evolved as a
mechanism for inbreeding avoidance, as well as for
enhancement of offspring fitness through heterozygousity of
Mhc genes. Hypotheses relating to both “good genes” and
“optimal compatibility” with respect to Mhc and a chosen
mate have been proposed. Currently, there is some evidence
for Mhc -influenced mating in mammals and fish, though very
little evidence exists for birds. Great Frigatebirds may provide
a good opportunity for exploring the role of Mhc in mate choice,
as males exhibit exaggerated secondary sexual traits which
may correlate with particular Mhc genotypes, and thus convey
indirect benefits through “good genes” that could influence
female mate choice.

Publications

Juola FA, Haussmann MF, Dearborn DC , and Vleck CM.  Telomere shortening in a long-lived marine bird: cross-sectional analysis and test of an aging tool.  In press. Auk.

Juola FA, and Dearborn DC . Does the differential cost of sons and daughters lead to sex ratio adjustment in great frigatebirds (Fregata minor)? In review.  Journal of Avian Biology.

Anderson DJ, Huyvaert KP, Apanius V, Townsend H, Gillikin CL, Hill LD, Juola FA, Porter ET, Wood DR, Lougheed C, Vargas H, 2002. Population size and trends of the waved albatross Phoebasteria irrorata . Marine Ornithology 30:63-69.

Carsten LD, Juola FA, Male TD, Cherry S, 2002. Host Associations of Lianas in a Southeast Queensland Rainforest. Journal of Tropical Ecology 18:107-120.


Frans' C.V.