Fuller Evolutionary Biology Program

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We use field studies and the powerful tools of molecular biology to explore the earth’s biodiversity and the processes that have generated it. As a research and training unit, we send students and scientists around the world in search of answers to scientific questions about the history and current complexities of life, and we use traditional and cutting-edge technological tools to inventory biodiversity and address conservation issues. We accomplish this research in large part by training students and early career scholars from Cornell University and partner institutions worldwide.

Visit the Fuller Evolutionary Biology Program website.

Project Highlights

Ancient-DNA Projects

By examining "ancient DNA," or DNA from old specimens, we can ask fascinating questions about extinct species or populations. But working with ancient DNA is technically demanding because degradation sets in soon after an animal's death. The Fuller Evolutionary Biology Program includes a dedicated ancient-DNA lab that we use when working with old or degraded specimens. We have successfully retrieved and analyzed old genetic material ranging from bird museum skins collected in the 1800s, to 5,000-year-old plant material recovered from receding glaciers in the Andes. Ancient DNA techniques also enable us to study materials from places that are difficult to access, and to examine the genetics of extremely rare, protected, or extinct species.

How Many Genes Does It Take to Make a Good Evolutionary Tree?

Many questions remain about how best to uncover evolutionary relationships among species. This is partly because a phylogenetic tree resolved from a single gene sequence will differ somewhat from trees of other genes sampled from the same species. We are exploring this problem by analyzing many genes from small groups of birds such as North American chickadees. These studies help us better understand the relationships of these birds and how best to deploy our laboratory and analytical resources.

Starlings, Mockingbirds and Oxpeckers: Evolutionary History and Behavior

We recently generated detailed phylogenetic trees for nearly all species of starlings, mynas, oxpeckers, mockingbirds, and thrashers. These trees have revealed many otherwise hidden aspects of the evolutionary histories of these avian groups, and they are influencing how these groups are classified. In a broader sense, these trees have guided our exploration of the diverse behaviors of these birds. For example, we have shown that the social systems of starlings and the song complexities of the mockingbirds are both strongly influenced by the predictability of each species’ environment.

The Wood-Warbler Tree of Life

Our work on the evolutionary tree of the wood-warblers has yielded information on when and how this group of songbirds diversified. We have used this information to explore why some warbler species occur together in breeding communities, whereas others compete so strongly that they don't co-occur. We have shown that some wood-warbler lineages appeared rapidly early on in the group’s evolution, but diversification declined thereafter. This supports the idea that wood-warbler communities arose via “adaptive radiation” in which speciation slows as ecological niches fill. We have also taken an evolutionary approach to studying the life history, migration, and ecology of warbler species. We've found that warbler species living in taller trees or more open forest canopies tend to have higher frequency flight calls.

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Origins of Biodiversity

pipettingMembers of our lab’s research community explore the biological diversity of birds and other organisms. We seek a better understanding of the processes that underlie the diversification and differentiation of populations and species, we generate improved reconstructions of their evolutionary histories, we conduct novel comparative and experimental tests of ecological and behavioral adaptations, and we inform scientific and public audiences about real-world issues relating to diversity and conservation genetics.

Visit the Fuller Evolutionary Biology Program website.

Understanding the Maintenance of Biodiversity

baltimore oriole paintingIn addition to investigating the origins of diversity, we explore how closely related species maintain their uniqueness. When two species interbreed, they may produce offspring that look, sound, and act intermediate between the parent species. So why, despite this occasional hybridization, do most species remain distinct? We are investigating the genetic reasons for this in pairs of species that often hybridize, such as Baltimore and Bullock’s orioles, and Indigo and Lazuli buntings.

Monogamy

More than 90 percent of all bird species behave as if they are monogamous, but genetic work reveals that, in most species, chicks in the same nest can have different fathers. This "extra-pair paternity" varies substantially among species, populations, and years. Our research examines the costs, benefits, and likelihood that individuals will engage in extra-pair copulations. We test hypotheses that birds choose mates because of “good genes” that confer higher survivorship on offspring, increase their fitness, or are dissimilar to avoid inbreeding and produce high genetic variability. These are some of the species we have studied:

Black-throated Blue Warbler

Climate change is predicted to increase weather extremes. In species that engage in extra-pair copulations, adverse weather could cause males to spend less time and effort looking for mates, and reduce the incidence of extra-pair paternity. But the effects of weather on reproductive behavior remain poorly understood. We are examining the influence of weather on rates of extra-pair paternity in Black-throated Blue Warblers along an elevational gradient with a range of climatic conditions.

Western Bluebird (Sialia mexicana)—California

We are analyzing more than 20 years of data from a Western Bluebird population to discover the costs and benefits of extra-pair mating from the perspective not just of females, but of their extra-pair and social mates as well. We are investigating how nongenetic factors affect offspring survival and reproduction as a way to distinguish who benefits from multiple matings. We are also examining lifetime survival and reproductive success of offspring, a crucial comparison that will help us find out whether within-pair young are genetically superior to extra-pair young, and whether the tendency to mate outside the pair is inherited.

Eusociality

Many social insects have a “haplodiploid” genetic system in which workers are females and are more closely related to their sisters than to their offspring. However, in colonies with multiple queens or sires the situation is more complex. We examine relatedness of workers in one such system, as a way of understanding how inclusive fitness and ecological factors contributed to the evolution of sociality in insects.

Cooperative Breeding

In some birds, helpers assist breeding pairs in raising offspring. Helpers are typically male and either do not breed at all or sire some of the young. We use molecular markers to determine how adults and young are related at these complicated nests. We study how cooperative breeding evolved by examining the benefits of cooperation and the costs of delaying reproduction in helpers. Further, we investigate how environmental constraints have promoted this unique mating system. Some of the species we have studied include:

Florida Scrub-Jay

When molecular tools first showed that most birds mate with others besides their social mate, it came as a great surprise. Twenty years later, the discovery of a truly monogamous species is the surprise that begs explanation. The Florida Scrub-Jay is one such rare example. We are exploring whether this species deviates from monogamy in some parts of its range, which might help us to understand why genetic monogamy occurs in the first place.

Red-backed Fairywren (Malurus melanocephalus)—Queensland, Australia

Male Red-backed Fairywrens have fascinating breeding strategies: Some males breed in bright plumage, whereas others breed in dull, female-like plumage. We are studying the function of elaborate sexual signals and the hormonal mechanisms that underlie them. In particular, we are exploring the extent to which genetic and environmental factors influence whether a male is showy or dull, and the cascading effects of breeding strategy on survival and reproduction. This work will lead to a better understanding of how organisms use social and environmental cues as their behavior develops.

American Crow (Corvus brachyrhynchos)—New York

Parentage analysis of the socially monogamous American Crow have revealed that some offspring are sired incestuously, usually by the adult “helper” sons of breeding females. These incestuous matings are costly: genetically derived inbreeding coefficients suggest that disease probability is higher, and survival probability lower, for the most inbred birds in this population.

Habitat Fragmentation and the Florida Scrub-Jay

The Florida Scrub-Jay is a federally threatened species found in the few remaining patches of oak scrub in Florida. Habitat fragmentation, development, and fire suppression have contributed to a steep population decline in this species. By studying its genetics, we’ve learned about the species’ movement patterns between habitat patches. With this information, we can preserve what remains of the genetic variation in the species by translocating birds as well as conserving and restoring habitat.

Hybridization as a Conservation Threat

blue-winged warbler researchThe Golden-winged Warbler (Vermivora chrysoptera) is declining precipitously, due in part to the expansion of the closely related Blue-winged Warbler (V. pinus) into its range. The incursion of blue-wings has led to widespread interbreeding between the two species, followed by the rapid disappearance of golden-wings. We are using genetic approaches to map the pattern of hybridization throughout the past and present range of Golden-winged Warblers. One objective of this survey is to identify the most genetically “pure” remaining golden-wing populations, which have special priority for conservation.

Genetics and House Finch Eye Disease

Another way we study House Finch eye disease is by examining the genetic diversity of House Finches in relation to their susceptibility to this disease. We’ve discovered that the introduced population of House Finches in eastern North America is substantially less genetically diverse than the native population in western North America. We are also studying the numerous strains of the bacteria, to learn where the strain infecting finches may have arisen.

Avian Malaria

Students working in the Fuller Evolutionary Biology Lab have investigated the ecology and evolution of avian malaria. Studies have surveyed the host distributions of particular avian malaria species and tested the ability of various mosquito species to transmit avian malaria among hosts. Work done in collaboration with the Chicago Field Museum used sequenced DNA from 170 strains of malaria to clarify the genetic evolution of this single-celled organism that originated at least half a billion years ago.

Mosquito Feeding Ecology

Many diseases and parasites are transmitted (or vectored) by insects and other arthropods, creating a complex transmission cycle involving the pathogens, the vector species, and the host species. To better understand this cycle we study the feeding patterns of one of the most notorious of all insect vectors, the mosquito. Using wild mosquitoes captured locally in Sapsucker Woods at the Cornell Lab of Ornithology, we use DNA bar-coding to analyze mosquito blood meals. After identifying each mosquito to species, we extract the blood meal from its abdomen to identify the species of bird or mammal the mosquito fed from.

Inbreeding and Disease in Crows

American Crows in Ithaca, New York, suffer from a suite of infectious diseases, including West Nile virus, avian pox, and numerous other bacterial, fungal, and viral infections. We have found evidence that there is a genetic basis for infection risk: Inbred crows have a higher probability of dying with disease symptoms than crows with unrelated parents. Inbreeding is rare and disadvantageous in nearly all animals, so it's a mystery why inbreeding is commonplace in these crows. We are now exploring the potential benefits of breeding with kin that might balance some of these disease costs.

The Research Group at the Fuller Evolutionary Biology Program

labworkThe Fuller Evolutionary Biology Program includes a core group of permanent research staff and a much larger group of undergraduate, graduate student, postdoctoral, and visiting researchers. The program is overseen by Dr. Irby Lovette, who is also an associate professor in Cornell’s Department of Ecology and Evolutionary Biology. Members of our lab group come and go on cycles dictated by fieldwork schedules and graduations, but at any given time about two dozen people are typically at work here.

Our program is the primary institutional and intellectual home for about half of our lab group members. The others come to us from elsewhere at Cornell, and beyond, to gain help with the molecular-genetic aspects of their research. Many of our lab group members arrive with little or no previous molecular biology experience. We take pride in helping them become accomplished at both benchwork and the statistical techniques of genetic analysis. All of us enjoy the rich and ever-changing diversity of organisms, projects, and perspectives that characterizes our research group.

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