Just thought I would share with all of you; this is what has been keeping me off the grid and water changes to the minimum over the past many months (and really over the past many years). Several of you have also played a role in supporting this research as well as providing a valuable perspective on these fishes with which we are so fascinated, and I thank you all for that!
Here is the abstract of my dissertation (see below), and I'll keep you all posted with how things go and when the dissertation is available online (in case any of you would like to dig deeper into spotted gar and other lepisosteid research).
I must also mention that Richard Kik (polypterus, pejelajarto, ...so many names!) was beyond integral in this research and it definitely would not have happened without him. We connected via predatory fish forums many years ago, so that in and of itself is an important value of forums like this - connecting people to learn more about the given subjects.
The attached image is the flyer that our school's media person made for my defense.
Title:
"Life history, growth, and genetic diversity of the spotted gar (Lepisosteus oculatus) from peripheral and core populations"
Abstract:
Peripheral populations occupy the edge of a species’ range and are considered to be exceptionally important in terms of a species’ ecology, biogeography, evolution, and conservation. Peripheral populations often persist under different environmental conditions from the species’ central or “core” populations, and may exhibit genetic and morphological adaptations to potentially “harsher” marginal environments. Peripheral populations also often experience low gene flow and high degrees of genetic drift, further increasing likelihood of divergence from core populations. Because of differing environmental conditions related to geographical factors such as latitude, populations may also exhibit different life history characteristics such as size and age at maturity, growth rate, and mortality schedules. Conserving distinct peripheral populations is therefore an integral and important component of conserving global biodiversity.
To further explore and better understand these issues, I studied the ecology and biogeography of the spotted gar (Lepisosteus oculatus) from core and peripheral populations. Although relatively common in drainage basins of the southern United States, the spotted gar is poorly studied and its ecology and status comparatively unknown in the Great Lakes basin. I used common garden experiments, life history analyses, and phylogeography to address the overall hypothesis that spotted gars from peripheral, Great Lakes Basin populations exhibit different life history characteristics and genetic diversity than spotted gars from core populations. My findings suggest Great Lakes Basin populations have adapted to life at higher latitudes (shorter growing season) and exhibit countergradient variation in growth as well as lower mortality rates. Analysis of mitochondrial DNA from core and peripheral populations indicated genetic diversity was highest in the Mississippi River Basin, lowest in the Great Lakes Basin, and most divergent in the western Gulf Coast Basin. Genetic structure and low diversity in the Great Lakes Basin were likely related to recent post-glacial colonization from Mississippian refugia, founder effects, and low gene flow. The Great Lakes Basin population of spotted gars was shown to be a unique component of the overall species, and can serve as a case study to inform conservation strategies and better understand the evolution and maintenance of vertebrate life history patterns and genetic diversity.
--solomon
Here is the abstract of my dissertation (see below), and I'll keep you all posted with how things go and when the dissertation is available online (in case any of you would like to dig deeper into spotted gar and other lepisosteid research).
I must also mention that Richard Kik (polypterus, pejelajarto, ...so many names!) was beyond integral in this research and it definitely would not have happened without him. We connected via predatory fish forums many years ago, so that in and of itself is an important value of forums like this - connecting people to learn more about the given subjects.
The attached image is the flyer that our school's media person made for my defense.
Title:
"Life history, growth, and genetic diversity of the spotted gar (Lepisosteus oculatus) from peripheral and core populations"
Abstract:
Peripheral populations occupy the edge of a species’ range and are considered to be exceptionally important in terms of a species’ ecology, biogeography, evolution, and conservation. Peripheral populations often persist under different environmental conditions from the species’ central or “core” populations, and may exhibit genetic and morphological adaptations to potentially “harsher” marginal environments. Peripheral populations also often experience low gene flow and high degrees of genetic drift, further increasing likelihood of divergence from core populations. Because of differing environmental conditions related to geographical factors such as latitude, populations may also exhibit different life history characteristics such as size and age at maturity, growth rate, and mortality schedules. Conserving distinct peripheral populations is therefore an integral and important component of conserving global biodiversity.
To further explore and better understand these issues, I studied the ecology and biogeography of the spotted gar (Lepisosteus oculatus) from core and peripheral populations. Although relatively common in drainage basins of the southern United States, the spotted gar is poorly studied and its ecology and status comparatively unknown in the Great Lakes basin. I used common garden experiments, life history analyses, and phylogeography to address the overall hypothesis that spotted gars from peripheral, Great Lakes Basin populations exhibit different life history characteristics and genetic diversity than spotted gars from core populations. My findings suggest Great Lakes Basin populations have adapted to life at higher latitudes (shorter growing season) and exhibit countergradient variation in growth as well as lower mortality rates. Analysis of mitochondrial DNA from core and peripheral populations indicated genetic diversity was highest in the Mississippi River Basin, lowest in the Great Lakes Basin, and most divergent in the western Gulf Coast Basin. Genetic structure and low diversity in the Great Lakes Basin were likely related to recent post-glacial colonization from Mississippian refugia, founder effects, and low gene flow. The Great Lakes Basin population of spotted gars was shown to be a unique component of the overall species, and can serve as a case study to inform conservation strategies and better understand the evolution and maintenance of vertebrate life history patterns and genetic diversity.
--solomon
