For the second year running, five EEB graduate students were awarded Doctoral Dissertation Improvement Grants from the National Science Foundation. Hats off to: Katherine Crocker,Thomas Jenkinson, Tristan McKnight, Carlos Muñoz-Ramirez and Clara Shaw.
Their research, which has conservation and biodiversity implications in a changing world, is underway in campus labs, in Midwestern lakes and in locales as far-flung as the Atlantic forest of southern Brazil where amphibian populations are being driven to extinction by an emerging fungal disease.
Crocker’s project is titled “Does hormone provisioning link maternal social environment and offspring phenotype?” Her advisor is Professor Elizabeth Tibbetts.
“In a world full of other animals, individuals must match their bodies to their environment to maximize their success,” explained Crocker. “Animals often rely on steroid hormones to adapt, but small differences in the concentration of these hormones can profoundly alter offspring development, survival and behavior. A mother’s steroid hormone levels determine those of her developing offspring, and can therefore affect more than her immediate survival. Animals must balance their need to survive with their need to produce high-quality offspring. Many studies have tested the idea that the steroid hormones provided by mothers to their eggs could help optimize developing offspring. However, these studies have used animals that take care of their offspring after birth.
“Can mothers use steroid hormones to optimize offspring, or is parenting behavior also necessary? This project will answer that question by measuring the effects of different steroid hormone concentrations on offspring development and survival in a species that provides no parental care to its offspring. The results will show whether mothers can use steroid hormones to prime their offspring for future competition without relying on parental care. Because every mother influences her offspring’s hormones, the results of this study will change our general understanding of how hormones function across multiple generations.” Crocker was awarded nearly $16,000.
Jenkinson’s project is “Evolutionary consequences of pathogen strain competition in an emerging fungal disease.” His advisor is Professor Timothy James.
“A global pandemic is devastating amphibian populations worldwide and driving entire frog species extinct in some cases,” said Jenkinson. “The recently discovered, amphibian-killing chytrid fungus causes this spreading disease. My project will investigate a region of high chytrid genetic diversity in the Atlantic Forest of southern Brazil to understand how competition among different genetic strains determines the success and evolution of these pathogens. Prior research suggests that divergent amphibian-killing chytrid strains in Brazil's Atlantic Forest are competing for hosts. According to the principle of competitive exclusion, competing disease strains should evolve to have faster rates of growth and increased virulence until a single most successful strain has eliminated all others. My project will investigate how these chytrid disease strains initially came into contact, and the ecological and evolutionary outcomes of this contact.
“Newly discovered, emerging diseases are a significant threat to biological diversity and human health. Many of these emerging diseases are caused by fungal pathogens, yet few studies have addressed the evolutionary ecology of disease-causing fungi. A detailed understanding of how emerging fungal pathogens evolve virulence will be critical to both mitigating the destructive effects of this current pandemic, and informing the prevention of future diseases outbreaks.” Jenkinson received just over $20,000.
McKnight’s project is called “Speciation, niche divergence, and character displacement at multiple scales in Lasiopogon robber flies (Diptera: Asilidae.” His advisor is Professor Lacey Knowles.
“Species occupy niches that are the product of their own phylogenetic history and their interactions with other community members,” according to McKnight. “Robber flies in the genus Lasiopogon are a group of small insect predators that hunt in many environments across the continent, such as dunes, beaches, mountain meadows or riversides; further specializations in niche use such as perching habits or seasonal emergence times may provide a way for species with overlapping ranges to reduce competition.
“The goal of this project is to use genetic data, museum specimens and my own sampling to compare diversification patterns and similarities in geographic range, niche, and morphology among the approximately 60 species of North American Lasiopogon. This will reveal not just when and where a given species split, but how regional communities (i.e., who it evolved with) influenced diversification. Understanding the processes of adaptation at regional and local scales will help show how environmental cues and species interactions maintain and promote biodiversity, and how evolution along different axes of variation can fuel character displacement and competitive specialization. Due to the highly specialized habitat requirements of Lasiopogonspecies, this work may also be useful for studying biodiversity in changing environments, particularly in communities vulnerable to urban spread, irrigation and climate change.” McKnight received just over $20,000.
Muñoz is working on “Can the degree of mimicry predict levels of genetic structure among populations? A test using mimetic ground beetles" with his advisor Professor Knowles.
“Mimicry systems, where multiple species evolve mutual resemblance to reduce predation, are excellent natural laboratories to study processes driving biodiversity,” described Muñoz. “Species in these systems are often very diverse and exhibit multiple geographic morphs, which raises questions about how this diversity originated and is maintained. By analyzing spatial patterns of genetic diversity in a novel mimicry system from South America, this project will investigate whether the processes driving resemblance in mimicry systems can also promote diversity within species. Addressing this question will not only shed light on whether natural selection can promote and maintain genetic differentiation among populations, but it will also provide a basis for using morphological traits to predict levels of genetic structure. The latter will be especially useful for conservation purposes, particularly in groups or systems in which genetic data might not be available, as phenotypic traits could be informative about patterns of genetic differentiation.
“These goals will be addressed by conducting a fine scale landscape genetic study on mimetic beetles from the genus Ceroglossus, using next generation sequencing data. Samples will be collected across areas with different geographic morphs and levels of phenotypic matching, and from two or three different species. Correlation tests between color differences and genetic differentiation will inform whether selection for mimicry can impact levels of genetic structure, whereas model-based demographic inferences will provide statistical rigor to distinguish between specific mechanisms driving such patterns. This project will encourage collaborative work with Chilean researchers and students on the study of a new and fascinating model system.” Muñoz was awarded just over $20,000.
Shaw’s is working on the project “Do interactions between ultraviolet radiation and dissolved organic carbon modulate disease in aquatic systems?” with her advisor Professor Meghan Duffy.
“Environmental change alters ecosystems by changing the physical characteristics of a habitat, affecting which organisms can thrive in a given community,” explained Shaw. “Because interactions in communities are complex and numerous, it can be difficult to predict outcomes of environmental change. This project focuses in particular on how disease outbreaks change in Midwestern lakes as a result of the lakes becoming darker. This darkening occurs due to increases in terrestrially derived organic matter washing into lakes as a result of increased precipitation and storm severity. This process affects both nutrient levels and the penetration of ultraviolet and photosynthetically active light into the water. The impacts of this change on disease levels will depend on how disease agents (parasites), hosts, and the rest of interacting lake community members are impacted by these changing environmental factors.
"This project will examine the mechanisms by which lake darkening can affect disease inDaphnia hosts. Daphnia are very important members of lake food chains, serving as a key link between primary producers (e.g., algae) and consumers such as fish and insect larvae. This work will give mechanistic insight into how altering environmental factors can influence disease in lake communities.” Shaw received just over $20,000.
The NSF awards DDIGs in selected areas of the biological sciences. These grants provide partial support of doctoral dissertation research to improve the overall quality of research including costs for doctoral candidates to participate in scientific meetings, to conduct research in specialized facilities or field settings, and to expand an existing body of dissertation research.