I am broadly interested in life history evolution, theoretical population / community ecology, and mechanisms of diversity. A little more specifically, I am deeply interested in how populations / species / communities evolve in seasonal systems and other fundamentally (temporally) autocorrelated environments. I am a fan of combining mathematical models, field work, and experiments.Below is a list of my research projects (most recent to oldest) in more detail.
Projects
Phenological diversity, temporal axis of diversity, conceptualization of seasonal turnovers of biodiversity
I am interested in how entities within complex ecological communities, such as species, partition themselves into different temporal 'niches'. Tackling this question requires a marriage of community ecology theory and life history evolution theory. How is diversity of life histories created and maintained as a result of species-to-species interactions? The deep literature on species diversity is heavily concerned with drivers of patterns in space. But (how) can we study time as another axis of diversity & distribution? Predictable and repeatable species turnover patterns in seasonal systems certainly suggest that time is an important dimension for organization and coexistence, and occurrence timing (phenology) is adaptive. Particularly in a changing climate - with shifts in phenology and mismatched ecological interactions - can a quantitative treatment of how communities of phenologies evolve help us think about the maintenance of diversity in nature?
To formalize these questions and provide a conceptual roadmap for future research, I am currently collaborating with Dr. Eric Post (UC Davis). Updates coming soon.
I am interested in how entities within complex ecological communities, such as species, partition themselves into different temporal 'niches'. Tackling this question requires a marriage of community ecology theory and life history evolution theory. How is diversity of life histories created and maintained as a result of species-to-species interactions? The deep literature on species diversity is heavily concerned with drivers of patterns in space. But (how) can we study time as another axis of diversity & distribution? Predictable and repeatable species turnover patterns in seasonal systems certainly suggest that time is an important dimension for organization and coexistence, and occurrence timing (phenology) is adaptive. Particularly in a changing climate - with shifts in phenology and mismatched ecological interactions - can a quantitative treatment of how communities of phenologies evolve help us think about the maintenance of diversity in nature?
To formalize these questions and provide a conceptual roadmap for future research, I am currently collaborating with Dr. Eric Post (UC Davis). Updates coming soon.
Life history evolution in cyclical environments
Cycles are ubiquitous in nature. Familiar examples include seasons and tides. Climate change is altering parameters of cycles such as season lengths in many natural systems, driving shifts in phenology (e.g. changing flowering time) around the planet with profound consequences on ecosystems. Phenology is the study of how life cycle transition patterns repeat from year to year, i.e. fit within seasonal cycles. Yet, surprisingly, we lack a general quantitative theory of how cycles shape life history evolution. This gap has hindered our ability to explain mechanisms behind disparate phenological shifts and predict future change. To add to the confusion, different species in the same community often exhibit different shifts when faced with the same change in cycles. To tackle this problem, I have developed a general demographic framework that gives a mechanistic basis for the relationship between environmental cyclicality and life history optimization. The theory is agnostic to timescale and can accommodate different life history architectures.
In order to test my theoretical predictions, I tuned the model for the intertidal copepod Tigriopus californicus, a species that is ubiquitous along the Pacific coast of North America from Baja California to southeast Alaska. Isolated populations of T. californicus live in small rock pools of the upper intertidal zone. Depending on pool height and local tide patterns, populations are subject to varying tide cycle periods. When tidal waves reach the pools, populations experience decline and structural perturbations. Given these features, along with quick generation times and ease of sampling, T. californicus provide an ideal system for studying life history evolution as a function of environmental cycle parameters. I measured life history traits and quantified cycle periodicity across 19 populations in northwest Washington. Inter-population life history variation follows theoretical predictions very closely, suggesting that life history optimization mechanisms underlying the theory may hold water.
Second, I am in the middle of a long-term life history evolution experiment using T. californicus. I have devised a way to isolate the variable of environmental periodicity by rearing replicate populations in common garden settings in the laboratory and inducing population perturbations at varying periods. Updates coming soon.
Third, I am testing the theory across a global database of plant populations (COMPADRE). Updates coming soon.
Cycles are ubiquitous in nature. Familiar examples include seasons and tides. Climate change is altering parameters of cycles such as season lengths in many natural systems, driving shifts in phenology (e.g. changing flowering time) around the planet with profound consequences on ecosystems. Phenology is the study of how life cycle transition patterns repeat from year to year, i.e. fit within seasonal cycles. Yet, surprisingly, we lack a general quantitative theory of how cycles shape life history evolution. This gap has hindered our ability to explain mechanisms behind disparate phenological shifts and predict future change. To add to the confusion, different species in the same community often exhibit different shifts when faced with the same change in cycles. To tackle this problem, I have developed a general demographic framework that gives a mechanistic basis for the relationship between environmental cyclicality and life history optimization. The theory is agnostic to timescale and can accommodate different life history architectures.
In order to test my theoretical predictions, I tuned the model for the intertidal copepod Tigriopus californicus, a species that is ubiquitous along the Pacific coast of North America from Baja California to southeast Alaska. Isolated populations of T. californicus live in small rock pools of the upper intertidal zone. Depending on pool height and local tide patterns, populations are subject to varying tide cycle periods. When tidal waves reach the pools, populations experience decline and structural perturbations. Given these features, along with quick generation times and ease of sampling, T. californicus provide an ideal system for studying life history evolution as a function of environmental cycle parameters. I measured life history traits and quantified cycle periodicity across 19 populations in northwest Washington. Inter-population life history variation follows theoretical predictions very closely, suggesting that life history optimization mechanisms underlying the theory may hold water.
Second, I am in the middle of a long-term life history evolution experiment using T. californicus. I have devised a way to isolate the variable of environmental periodicity by rearing replicate populations in common garden settings in the laboratory and inducing population perturbations at varying periods. Updates coming soon.
Third, I am testing the theory across a global database of plant populations (COMPADRE). Updates coming soon.
Eco-evolutionary feedback between Daphnia and phytoplankton, and consequences on temporal phytoplankton community composition
The Post Lab at Yale has shown intraspecific life history divergence in alewife (a freshwater fish) populations in anadromous (connected to sea) and landlocked lakes. This divergence has been shown to further drive life history divergence in Daphnia (an important zooplankton prey for alewife and keystone grazer of phytoplankton) populations in these lakes. Using this system, I asked if Daphnia ambigua life history divergence influences the temporal (seasonal) species turnover in phytoplankton communities. I reared genetic clones of Daphnia ambigua from the two lake types, and designed short- and long-term lab mesocosm experiments with five algae and diatom species to explore multitrophic interactions. LH divergence in Daphnia was associated with grazing preference differences, and altered temporal phytoplankton community dynamics. Thus, we showed that predator intraspecific divergence can influence community dynamics two trophic levels below.
Park & Post (2017) Ecology & Evolution, doi: https://doi.org/10.1002/ece3.3678
The Post Lab at Yale has shown intraspecific life history divergence in alewife (a freshwater fish) populations in anadromous (connected to sea) and landlocked lakes. This divergence has been shown to further drive life history divergence in Daphnia (an important zooplankton prey for alewife and keystone grazer of phytoplankton) populations in these lakes. Using this system, I asked if Daphnia ambigua life history divergence influences the temporal (seasonal) species turnover in phytoplankton communities. I reared genetic clones of Daphnia ambigua from the two lake types, and designed short- and long-term lab mesocosm experiments with five algae and diatom species to explore multitrophic interactions. LH divergence in Daphnia was associated with grazing preference differences, and altered temporal phytoplankton community dynamics. Thus, we showed that predator intraspecific divergence can influence community dynamics two trophic levels below.
Park & Post (2017) Ecology & Evolution, doi: https://doi.org/10.1002/ece3.3678
Tundra mosquito life history strategies in a race against time
Excessive grubbing (shoot-pulling) by growing snow goose populations in the Canadian Arctic denudes the vegetation cover above the permafrost and triggers long-term destructive processes that force irreversible alternate stable-states. Less known are the indirect effects this disturbance has on the hydrology of the seasonal ephemeral bodies of water that are truly ubiquitous across the tundra landscape, and on other (smaller) organisms that obligatorily utilize these aquatic habitats. Mosquitoes are a striking presence and source of great petulance during the Arctic summer, after they develop as larvae in these seasonal pools and emerge as flying adults. What is also striking is that, when one takes the time (ex. a whole field season in the middle of nowhere) to observe the temporal turnovers of species during the summer, they appear to characterize the aerial landscape in dramatic and distinct waves, even among closely related species with very similar developmental time requirements. I designed emergence traps that sampled the different mosquito species as they emerged out of ponds throughout the summer, and conducted a dehydration survey which showed that tundra surface degradation by snow goose increases the evaporation rate of ephemeral pools. This results in the constriction of the temporal template available for mosquito development and limits those species with late-season emergence life histories. Thus diversity spread across time is restricted by an unexpected, indirect ecological interaction.
Park (2017) Polar BIology, doi: 10.1007/s00300-016-1978-y
Excessive grubbing (shoot-pulling) by growing snow goose populations in the Canadian Arctic denudes the vegetation cover above the permafrost and triggers long-term destructive processes that force irreversible alternate stable-states. Less known are the indirect effects this disturbance has on the hydrology of the seasonal ephemeral bodies of water that are truly ubiquitous across the tundra landscape, and on other (smaller) organisms that obligatorily utilize these aquatic habitats. Mosquitoes are a striking presence and source of great petulance during the Arctic summer, after they develop as larvae in these seasonal pools and emerge as flying adults. What is also striking is that, when one takes the time (ex. a whole field season in the middle of nowhere) to observe the temporal turnovers of species during the summer, they appear to characterize the aerial landscape in dramatic and distinct waves, even among closely related species with very similar developmental time requirements. I designed emergence traps that sampled the different mosquito species as they emerged out of ponds throughout the summer, and conducted a dehydration survey which showed that tundra surface degradation by snow goose increases the evaporation rate of ephemeral pools. This results in the constriction of the temporal template available for mosquito development and limits those species with late-season emergence life histories. Thus diversity spread across time is restricted by an unexpected, indirect ecological interaction.
Park (2017) Polar BIology, doi: 10.1007/s00300-016-1978-y
Snow goose phenology in a changing Arctic
NSF-REU work with collaborator Dr. David Koons at Utah State University, and involvement with the Hudson Bay Project with Dr. Robert Rockwell at the American Museum of Natural History took me to the Canadian low Arctic to investigate snow goose gosling morphology, life history strategies, and survival on the tundra affected by long-term degradation from overgrazing. We investigated the simultaneous effect of spatio-temporal variation in habitat degradation and the mismatch between goose hatching phenology and plant phenology on early-life growth, and consequences on population dynamics. This involved living on the tundra for a few months at a time among polar bears, jumping out of helicopters, and sprinting after flocks of geese alongside herds of caribou. Coincidentally, it provided a unique opportunity to observe the seasonal transition of a system patiently (as there was a lot of free time), inspiring theoretical questions about life history evolution, temporal niches, and fluctuating interactions in ecological communities that still drive my research.
NSF-REU work with collaborator Dr. David Koons at Utah State University, and involvement with the Hudson Bay Project with Dr. Robert Rockwell at the American Museum of Natural History took me to the Canadian low Arctic to investigate snow goose gosling morphology, life history strategies, and survival on the tundra affected by long-term degradation from overgrazing. We investigated the simultaneous effect of spatio-temporal variation in habitat degradation and the mismatch between goose hatching phenology and plant phenology on early-life growth, and consequences on population dynamics. This involved living on the tundra for a few months at a time among polar bears, jumping out of helicopters, and sprinting after flocks of geese alongside herds of caribou. Coincidentally, it provided a unique opportunity to observe the seasonal transition of a system patiently (as there was a lot of free time), inspiring theoretical questions about life history evolution, temporal niches, and fluctuating interactions in ecological communities that still drive my research.
