I am broadly interested in isolating mechanisms that prevent gene flow between populations that differ in migratory behavior. I have investigated the roles of both behavioral and physiological isolating mechanisms in seasonal sympatry.
Currently, I am interested in the molecular basis of isolating mechanisms in hybrid zones. I am interested in how gene expression varies across a hybrid zone and how selection acts against hybrids.
Currently, I am interested in the molecular basis of isolating mechanisms in hybrid zones. I am interested in how gene expression varies across a hybrid zone and how selection acts against hybrids.
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Seasonal sympatry is a population distribution, in which populations that differ in migratory behavior are living in the same geographic space for part of the year, but are otherwise geographically isolated. Since "seasonal sympatry" can be often described as a migratory divide, when populations are in sympatry during the breeding season, this term is more often used to describe migrant and resident populations that overlap in the winter and into early spring until migrants depart for their breeding grounds. Due to potential differences in reproductive timing, this overlap in early spring could create an opportunity for gene flow. A great species for studying seasonal sympatry is the dark-eyed junco, as shown in the comic to the right and the photo below.
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Reproductive Timing as a Temporal Barrier
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Differences in reproductive timing could serve as a temporal barrier and prevent interbreeding between seasonally sympatric populations. Females become reproductive later in the calendar year than males, and likely make the final mating decisions, determining whether interbreeding occurs. Therefore, I am focused on differences between migrant and resident female reproductive timing.
In order to determine how females differ in reproductive timing, despite exposure to the same environmental cues, I have analyzed differences in transcript abundance of genes associated with reproduction using quantitative PCR (qPCR). Our results suggest that resident and migrant females differ in timing of reproductive development. Differential transcript abundance of receptors may also explain the mechanisms for how females differ in timing of reproductive development. |
The hypothalamic-pituitary-gonadal (HPG) axis: the reproductive cascade of hormones
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Be sure to check out the related papers:
1. Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbird. Functional Ecology 2019.
2. Seasonally sympatric songbirds that differ in migratory strategy also differ in neuroendocrine measures. General and Comparative Endocrinology 2019.
1. Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbird. Functional Ecology 2019.
2. Seasonally sympatric songbirds that differ in migratory strategy also differ in neuroendocrine measures. General and Comparative Endocrinology 2019.
Mate Preferences in Seasonal Sympatry
Residents that initiate breeding prior to the departure of migrants may avoid interbreeding with migrants by exhibiting mate preferences for local individuals. Although most mate choice research focuses on female preferences, choosing a mate with similar reproductive timing in seasonal sympatry may be critical for both males and females.
In order to study male mating preferences, I conducted Simulated Courtship Interaction (SCI) trials, by presenting free-living resident males with either a caged migrant or resident female stimulus. I quantified courtship behavior early in the breeding season, when residents have initiated breeding prior to the departure of migrants.
Resident males preferentially court resident females. We can conclude that males distinguish between migrants and residents during seasonal sympatry when risk of interacting with a non-reproductive migrant is high. Read the paper here.
In order to study male mating preferences, I conducted Simulated Courtship Interaction (SCI) trials, by presenting free-living resident males with either a caged migrant or resident female stimulus. I quantified courtship behavior early in the breeding season, when residents have initiated breeding prior to the departure of migrants.
Resident males preferentially court resident females. We can conclude that males distinguish between migrants and residents during seasonal sympatry when risk of interacting with a non-reproductive migrant is high. Read the paper here.
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Molecular Basis of Divergent Migratory Behavior in a Hybrid Zone
I started my postdoctoral position at Texas A&M in August 2019. I will be studying migratory gene expression across a hybrid zone. Return later to learn more once the project is underway!
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