Biodiversity Graduate Student Research Enhancement Grants

Following several decades of lethal control, lions were restored to the Laikipia Plateau of central Kenya in response to increased tolerance by pastoralists, but they now are suppressing population growth for several species of antelopes (e.g., Jackson’s hartebeest, greater kudu, eland; hereafter simply “antelopes”) via apparent competition. Because tourists place a premium on viewing a diversity of antelopes, pastoralists have considered reimplementing lethal control (shooting and poisoning) of lions to stabilize their populations. Antelopes are selectively consumed by lions, particularly when they occur in close proximity to zebra, which are the primary prey of lions and the most common wild ungulate in Laikipia. Importantly, zebra are unique among wild ungulates in aggregating around glades—lush grazing lawns derived from nutrient inputs of livestock following the rotation of corrals. Because zebra aggregate near glades, lions target their hunting activity near glades, thus increasing predation risk for any antelopes in the vicinity. Strategically placing livestock corrals (which transition into glades over the course of ~1 year) away from territories of antelopes provides a spatial refuge by enticing lions to hunt (and thus kill) zebra far from antelopes. Thus, informed placement of livestock corrals offers a rare win-win: antelope diversity is conserved without resorting to lethal control of lions, through active collaborations with pastoralists on a centuries-old livestock husbandry practice.

An unresolved challenge that limits our ability to conserve antelope diversity concerns the density and time at which the attractive effect of glades begins to attenuate. This knowledge gap is critical: if glades persist for longer periods of time than it takes for them to disappear, they will eventually accumulate on the landscape, thereby diluting their ability to attract zebra and to create spatial separation between zebra and antelopes. Through my dissertation, I will (1) quantify strategies for corral rotation to maximize the attractive effect of glades for zebra (and thus conservation potential for antelopes); and (2) conduct structured questionnaires to understand the determinants of support for implementing such corral rotation by pastoralists. Support for corral rotation is strong on at least some properties in Laikipia, so these data will form the foundation for additional projects implementing such proactive methods across Laikipia.

Objectives:

Understand whether biophysical first principles that govern photosynthesis explain and predict the distribution of rare plants in Wyoming. Objective 1: Determine if Wyoming rare plants are able to better utilize resources than their common competitors. Objective 2: Determine if rare plants in Wyoming have limited distributions due to exploitation of small, stressful environments.

Background and Rational:

Wyoming’s wide diversity of ecosystems provides scientists with a unique opportunity to discover how natural systems operate. From Wyoming’s high alpine meadows crowded with innumerable wildflowers, to its expansive prairies blanketed by sage and rabbitbrush, our state exhibits an astounding diversity of vegetation. However, due to climate change, i.e. temperature increases, seasonal precipitation shifts, and ongoing changes from snow to rain driven systems, vegetation shifts are already occurring. Due to these vegetation shifts, rare plants with a high level of habitat specificity would be forced to make a series of improbable dispersal events spanning many kilometers. With very few plant species expected to be able to keep up with climate change through dispersal alone, conservation of rare plants under climate change requires predictive understanding of their rarity mechanisms, especially their physiological tolerances.

Objectives:

I will quantify the pathways by which positive abundance-occupancy relationships arise. Specifically, I will isolate the role of dispersal (immigration) and niche (diet) difference sin maintaining positive abundance-occupancy relationships in a species-rich community of small mammals

Background:

Have you ever wondered why some species are abundant and widespread, while others are rare and occur in only a few places? This macroecological pattern—known as the abundance-occupancy relationship (AOR)—is among the most general in all of ecology. From North American songbirds to helminth parasites, widely distributed species tend to be common where they occur, while those with restricted distributions tend to be locally rare. Because AORs have been noted across a diversity of taxa, geographic locales, and sampling regimes, this macroecological pattern begs for a mechanistic explanation.

Objective:

This research aims to fill a key knowledge gap in the promise of trait-based ecology by empirically linking population fitness in different environments to plant functional traits. Although functional traits have been shown to differ across environmental gradients, strong empirical links between traits and vital rates are lacking. A link between these will be necessary if we hope to use traits to understand and predict the response of plant communities under climate change. Moreover, traits conferring fitness in different environments may further differ depending on biotic interactions with the neighbor community. In my M.S. research I showed that the more dissimilar the traits of a focal species are from the traits of the community the better that species did under drought stress. This current research will elucidate how both trait by environment and trait by neighbor interactions effect demographic performance. The differential performance of cooccurring species directly influences realized community assembly and biodiversity.

Background:
It is well-supported that fitness varies along environmental gradients. Different species are successful in different environments because they have characteristics that make them suitable for their environment and less suitable for others. Our understanding and ability to predict community assembly through
environmental filtering is enhanced by considering how particular plant traits, instead of whole species, preform across environments. These plant functional traits are broadly defined as morpho-, physio-, phenological characteristics and have been posed as a holy grail for plant community ecology. A
strong link between traits and demographic performance under different conditions would allow us to make strong predictions about the future of grasslands under climate change for example. Despite the strong theoretical connection between traits and fitness in different environments, empirical tests for the net effects of traits on fitness are still lacking. 

Objective:
The objective of my dissertation is to quantify the influence of an unregulated predator on an endangered keystone species, the Sierra Nevada bighorn sheep. Our findings will aid in the management and recovery of this keystone species as the long-term implications of predation for this endangered species is currently unknown.

Background:
 A keystone species is a species that has a disproportionate influence on its environment relative to its abundance. The endangered Sierra Nevada bighorn sheep (Ovis canadensis sierrae, hereafter Sierra bighorn) is an endemic subspecies of bighorn sheep only found in the Sierra Nevada mountains of California. Like many herbivores, bighorn sheep play a role in regulating alpine plant diversity through selective foraging. Further, bighorn sheep serve as a food source for predators and scavengers. Prior to the near extinction of the Sierra bighorn, the population likely provided an important prey and scavenging source for wolverines (Gulo gulo), the extirpated grizzly bear (Ursus arctos), the endangered Sierra Nevada red fox (Vulpes vulpes necator) and multiple bird species. Unfortunately, the role of this species for the ecosystem is dwindling as the population was driven to near extinction by commercial hunting and disease from domestic sheep. The species was listed as endangered in 2000, and there are currently 600 Sierra bighorn in the wild as of 2020.

Objectives:

We will compare movement behaviors among and within a diversity of migratory strategies in a mule deer herd and develop management recommendations to benefit climate - and disturbance - resilience. Specifically, we will test predictions of ecological theory, promote public engagement with citizen science and accessible presentations, engage early science education, and create novel tools for managers to monitor migration in real time.

Background: Animal migration is a global phenomenon of high subsistence, economic and cultural value. Migratory ungulates bolster rural and indigenous economies and provide multiple ecosystem services. To support this important role, regional managers use migration-specific protocols to maintain migratory herds. For instance, Wyoming managers install wildlife-friendly fencing, conduct habitat enhancement efforts, and adapt harvest regulations according to seasonal occurrence. However, while managers strive to adjust hunting quotas to spread harvest evenly throughout the herd, determining the precise level of harvestable surplus that limits unintended population effects is difficult. As a result, there are often mismatches between hunting quotas and their desired effect on harvested populations.

Objective:

I will assess the effects of ecosystem engineers on the compositional biodiversity and functional connectivity of dependent species. To achieve this goal, I will test if beaver-medited habitat change has significant, positive impacts on amphibian occupancy, genetic diversity,and connectivity.

Background:

Biodiversity across organismal, community, and biotic process scales, is critical to maintain resilient and multifunctional ecosystems. While biodiversity is often a priority of conservation and management organizations the emphasis is often placed on one aspect of biodiversity -compositional diversity, or the variety of elements in a system (such as number of species). Focusing solely on compositional diversity without considering structural (e.g. habitat patches/clusters) and functional diversity (ecological processes, such as gene flow or disturbance regimes) overlooks areas and components of biodiversity essential to ecosystem services. Keystone species are organisms whose removal can cause biodiversity loss, loss of ecosystem services, and possibly ecosystem collapse. Ecosystem engineers, organisms that alter resource availability, can be keystone species due to their disproportionately large impact on the community or ecosystem. While ecosystem engineers’ effect on compositional diversity is well documented, their impacts on functional and structural diversity, especially at the genetic level, are not well understood13. Species that rely on ecosystem-engineered habitat are mostly strongly affected. Ecosystem engineers may facilitate colonization, gene flow, and larger population sizes (leading to the maintenance of genetic diversity); conversely, loss of ecosystem engineers could limit colonization and gene flow, reducing population sizes, diversity, and adaptive capacity.

Questions and hypotheses:

Given that resources are not always clumped together in space, a fundamental challenge of mobile animals is to develop some sort of representation of the location of their goals (refuges, food, mates, etc.) and how to get to them. Indeed, animals across a broad array of taxa express impressive spatial and navigational skills in complex environments. While learning and memory are not required for movement, it is becoming increasingly clear that they play an important role in how animals exploit their environment. Understanding how animals learn their environment and incorporate that knowledge into movement decisions is particularly important for restorative ecology programs, such as reintroduction efforts, where success is often tied to how populations move and settle in new environments.

One behavior that exposes animals to the conditions for spatial learning is exploration (i.e., going to a new place and experiencing it). The motivation and decision to explore may arise from a change in internal state (hunger), competition, resource depletion, or other environmental factors (e.g., seeking thermal refuge). In a novel environment where individuals do not have prior information, however, exploration is likely driven by the interest and need to reduce uncertainty and gain information about their environment. Where an animal chooses to explore is likely influenced by information gathered from their immediate surroundings through sight, smell, or other cues. The recent re-introduction of naïve bison into Banff National Park, a novel ecosystem for this population, represents an invaluable opportunity to test hypotheses surrounding how populations explore novel habitats. Specifically, we will evaluate the mechanisms underlying the decision to explore. This work will have key implications for understanding the success or failure of re-introduction efforts by increasing our understanding of post-release exploration behavior and habitat selection.

Reintroductions are a critical method for recovering threatened species and restoring biodiversity. The success rate of reintroduction programs, however, remain low. Due to the increased number of reintroduction efforts, high implementation costs, and animal welfare, it is essential that reintroduction programs are evaluated and reported on to aide future program success. My research seeks to not only elevate our theoretical understanding of animal exploration, dispersal, and decision making but also through this understanding improve future reintroduction efforts.

Project Objectives:

My research will direct the development of microbiome-based conservation strategies (e.g., probiotics and habitat manipulation) for amphibians impacted bychytridiomycosis. Using the Wyoming toad as a focal species, I will (A) determine the relationship between cutaneous microbial diversity and chytridiomycosis outcome, (B) identify microbial biodiversity linked to chytridiomycosis resilience in the wild, (C) note putatively Bd-inhibitory bacteria missing from captivity, and (D) documentbiotic and abiotic factors associated with a beneficial microbiome.

Background and Rationale:

Considered the most threatened vertebrate taxa globally, amphibians have experienced severe declines in both abundance and range in recent decades, largely due to the synergistic effects of infectious disease and habitat degradation. Chytridiomycosis (hereafter “chytrid”) is an

amphibian disease caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd). Chytrid has been linked to the extinction of at least 90 species and the and decline of over 500 worldwide, which is the largest estimated loss of biodiversity attributed to a single pathogen to date. Unfortunately, no practical method to treat or eliminate chytrid in the wild exists. In response,many highly susceptible species were transferred to captive assurance populations to counter extinction,with the ultimate goal of repatriation.However, recovery efforts for these species remains challenging as Bd has become endemic in many native habitats. The microbiome, or symbiont microbes (i.e., bacteria) present on amphibian skin, offer innate protection against Bd and could be manipulated via probiotic application or habitat manipulation to improve chytrid mitigation for captive release programs. 

Background:

Migration is common in animals because it allows them to move between different seasonal ranges to meet their year-round foraging requirements (Kauffman et al., 2021). Migration in Wyoming is prominent because many ungulate taxa must migrate across Wyoming’s landscape to escape the harsh winters and short summers to find sufficient resources. Moose (Alces alces), elk (Cervus canadensis), bighorn sheep (Ovis canadensis), pronghorn antelope (Antilocapra americana), mule deer (Odocoileus hemionus) all migrate across the state in diverse ways. We have learned so much from studying migration across taxa that we identified mechanisms about why ungulates migrate during different seasons. For example, movement studies support the Green Wave Hypothesis (Aikens et al., 2017), which describes how migrating ungulates follow plant growth that occurs in the spring and moves as a wave across the landscape. In the early winter, ungulates are thought to migrate ahead of the coming snow to avoid moving through snow that would deplete energy resources (Monteith et al., 2011, Rodgers et al., 2021) . The Frost Wave has only been applied to avian migrants but is referred to as the phenomenon of migration that is in response to snow and cold temperatures that also traverse the landscape as a wave (Xu and Si 2019).

Despite this progress to understand migration ecology, migration has often eluded scientists. Most tracking data comes from adult migrants, while movement data from younger animals is limited. Migration knowledge is thought to transcend generations by younger individuals learning where and when to migrate from their parents or other conspecifics (Nelson 1998). Jesmer et al. (2018) has shown that after a period of extinction from an area, reintroduced bighorn sheep and moose failed to migrate in the first generation because they lacked cultural knowledge of their new habitat (Jesmer et al., 2018). But after multiple generations populations learned the landscape and the timing of the green wave and through social learning gained the ability to migrate once again. Although social learning is assumed to be the mechanism, how learning happens has been little studied. For example, in White-tailed deer (Odocoileus virginianus), Nelson (1998) showed that the white tailed deer teach their offspring to migrate by having them accompany them along their migration route (Nelson 1998). When their offspring get older, they occupy the same migration route as their mothers, showing evidence of social learning where young learn from their mothers. These cases are important because the animals studied showed evidence of learning from their mothers and others by watching them how to migrate. This contrasts teaching it would imply that the mothers would have to show the fawns hot to migrate. Byholm et al, 2022 found that migration knowledge in Caspian terns (Hydroprogne caspia) was transmitted by the fathers who accompanied the young terns to their wintering range for their first migration. This shows evidence of the parents teaching their young how to migrate thus teaching migrational ability to the younger generation which is the basis for the Social Learning Hypothesis. The Social Learning Hypothesis is the mechanism by which organisms are taught how to migrate by watching and accompanying their parents with them during their migration seasons. Jakopak et al. (2019) showed that mule deer have the ability to omit their parent migration route after learning that route and could complete an entirely different migration after the abandonment of the animal by their mother (Jakopak et al., 2019). In this study, a female fawn migrated away from their parental home range and back to complete a full season of migration while having no prior knowledge of the landscape before migrating. This shows the importance of spatial memory as a key mechanism that underpins all types of migration learning. While previous studies have shown that the ability to migrate in ungulates must be learned (Jesmer et al. 2018), there is no context where the ability to migrate is innate thus showing that social learning or being taught by parents is not studied enough to be the predictor of how ungulates and animals learn how to migrate showing the gap in the current knowledge of how migration transcends generations.