Research Interests

Research interests of the Loiselle lab are in the area of evolutionary ecology with a particular emphasis on plant-animal interactions and mating systems of tropical lek-breeding birds. When possible, we take experimental approaches to mechanistically address process-oriented hypotheses, but often experimental manipulations are not possible and we rely on comparative approaches and long-term studies to provide insight about ecological and evolutionary processes. Currently, research in the Loiselle lab is focused in three areas: (1) ecology and evolution of fruit-frugivore mutualisms, (2) evolutionary ecology of lek-breeding systems in tropical birds and, (3) applications of Geographic Information Systems technology for spatial-related questions in ecology and conservation. Our research has been funded by a variety of sources, but, most importantly, National Science Foundation and National Geographic Society have generously supported our research over the past years.

Ecology and Evolution of Fruit-frugivore Mutualisms

In tropical wet forests where Loiselle has focused her research for the past 25 years, the vast majority of plants (>90% of species) rely on animals to disperse their seeds. Seeds that remain un-dispersed (i.e., fall below the parent plant) suffer nearly 100% mortality, frequently as a result of pathogens, seed predators, or other causes. Yet, unlike pollination systems, evolution between plants and their seed dispersers is thought to be less coupled and, thus, few examples of tight co-evolutionary relationships between plants and their seed dispersers exist. A research question Loiselle has long been interested in is the degree to which animal seed dispersers or suites of dispersers can influence the ecology and evolution of plant populations. In tropical systems, the selective force of individual animal species on plants is thought to be low as many animals are adapted to feed on the fleshy fruits of plants and plants have apparently little control over who removes seeds. Moreover, selective forces acting on seeds may not be the same as those operating on later plant stages (e.g., seedlings) and, consequently, the fate of seeds among plant stages in response to the environment may become uncoupled. The greater the degree of uncoupling among plant stages, the lower the probability that selective forces operating on seed removal and dissemination (actions directly affected by fruit-eating animals) are likely to shape plant population dynamics and the evolution of plant traits. Few studies have examined in detail the individual actions of fruit-eating animal species and their impact on plant populations, both along temporal and spatial gradients. Loiselle's and a number of her past and present students' research programs have focused on providing detailed ecological information on the relationship between plants and their seed dispersers, which mean detailed studies of the foraging and spatial ecology of animals and the post-dispersal establishment of plants. Only by teasing apart individual relationships between animal dispersers and stages of plant recruitment (seed removal, dissemination, and establishment) will we be able to understand the potential selective role animals play in influencing plant population dynamics.

Current projects are focused on plant-bird interactions in Amazon forests of Ecuador (collaborators include John Blake, Kimberly Holbrook, Pedro Blendinger, and Gonzalo Rivas), Bolivia (PhD student Andrea Loayza), and a comparison of effective seed dispersal of Miconia species in the Amazon where plants are native and in Australia where the same plants have recently invaded tropical forests (collaborators include Kimberly Holbrook, Denise Hardesty, David Westcott, John Blake, and Gonzalo Rivas).

Evolutionary Ecology of Lek-breeding Systems in Tropical Birds

Loiselle's interest in fruits and fruit-eating animals has long drawn her attention to the Pipridae or manakins, a bird family characterized by obligate fruit-eating birds. As a consequence of their fruit-feeding behavior, males have been “emancipated” from parental care duties and lek breeding systems have evolved in the group. Unlike most birds which have monogamous breeding systems, manakin males gather in display areas where they attract females through often elaborate singing and dancing displays. The social organization and spatial structure of manakin leks varies from tight clusters of males that may cooperate and have dominance hierarchies, to more loose assemblages where males can hear each other, but not necessarily see each other. In most studies of manakins, strong reproductive skew in male mating success has been noted based on behavioral observations of copulations at the lek sites. A compelling question is why do males join leks when their potential for reproductive success is so low? We have initiated a long-term study to examine exactly this question using a comparative approach and molecular genetic techniques. In particular, we examine reproductive skew in male mating success of manakin species using both observation and paternity analyses as a function of social organization (number of males at a lek, genetic relatedness of males at leks, dominance hierarchies or cooperative behavior), spatial structure of males within and among leks, and the spatial movement patterns of female manakins. This research, a collaboration of the Loiselle, Blake and Parker labs, is being conducted at the Tiputini Biodiversity Station in Yasuni Biosphere Reserve in the Ecuadorian Amazon where six species of manakins, which show different patterns of lek structure and organization, coexist in the same environment. To date, our research team has made significant headway in testing hypotheses about male reproductive skew which have provided insight regarding the evolution of mating systems in these tropical birds. Collaborators in this project are John Blake, Patricia Parker, Brandt Ryder, Renata Duraes, Wendy Tori, and Jose Hidalgo.

Applications of Geographic Information Systems

A third research interest revolves around the application of Geographic Information Systems (GIS) technology for ecology and conservation. GIS has become a powerful and essential tool for the ecologist and conservationist toolbox and, more recently, is being used by evolutionary biologist to test hypotheses in phylogeographic studies. Many of the research questions being addressed in Loiselle's lab have strong underlying spatial components (e.g., movement patterns of fruit-eating birds; seed and seedling shadows created by frugivores; distribution of manakin leks in the environment) and GIS has allowed for much greater sophistication in analyzing spatial patterns in ecology. Loiselle's initial interest in GIS was to investigate fine-scale spatial patterns related to fruit abundance, fruit-eating animal movements, plant recruitment, and plant genetic structure. In addition, we were interested in how GIS could inform conservation decisions. A current challenge in conservation is using our rather sparse knowledge regarding the distribution of plant and animals in an effective way to set conservation priorities at a scale most appropriate for conservation action. Loiselle's research lab began to address this question for the highly endangered Atlantic forests of Brazil using birds as a model system. The long history of deforestation in the region meant that we had little understanding of the true area of occupancy for most bird species since many of the major expeditions occurred after areas had undergone large-scale habitat alteration. As part of this research effort, we also began investigating how modeling algorithms may lead to different predictions and impact conservation decisions. Collaborators on these projects include past and present students and post-docs (especially T. Patricia Feria, C. Daniel Cadena, C. Howell), as well as colleagues at the Center for Conservation and Sustainable Development at the Missouri Botanical Garden, especially Trisha Consiglio, Ivan Jimenez, Peter Jorgensen, and Olga-Martha Montiel, and Catherine Graham at SUNY-Stony Brook.