Speakers

Randall Hughes

Randall Hughes

Associate Professor
Marine and Environmental Sciences
Marine Science Center
Northeastern University
https://cos.northeastern.edu/faculty/randall-hughes/

"Ecological consequences of clonal identity and diversity in marine foundation species"

Changes in diversity due to human and natural forces can alter ecosystem functioning, including productivity, nutrient cycling, and resistance to disturbance, with consequences for the delivery of ecosystem services. While diversity research has commonly focused on the species level, I will highlight the importance of diversity within clonal marine foundation species for population, community, and ecosystem responses. I will argue that ecological effects of genetic identity and/or diversity are particularly common for abundant and widely distributed clonal species, such as seagrasses and salt marsh plants. For example, seagrass (Zostera marina) clonal diversity enhances the plant response to natural and experimental disturbances. Additionally, the consequences of lower primary production in low diversity plots extend beyond seagrass to the community of organisms it supports. Similarly, clonal diversity in the marsh grass Spartinaalterniflora enhances plant production and macroinvertebrate abundance, though the strength of these effects varies across elevation and resource gradients. To predict when and where these effects are likely to occur, and to harness their benefits for conservation and restoration efforts,we need a better understanding of factors driving the relative importance of sexual vs. clonal reproduction, as well as the spatial distribution of clonality, in natural populations.

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Karen Mock

Karen Mock

Professor
Utah State University
Assistant Department Head of the Wildland Resources Department
https://qcnr.usu.edu/directory/mock_karen

"Landscape clonal patterns as clues to ecological and evolutionary mechanisms"

The extent of sexual vs. asexual reproduction in perennial plants is a reflection of ecological factors, which in turn reflect the outcome of evolutionary and demographic tradeoffs. Therefore, landscape patterns of clonal size and distribution can be a rich source of information about past ecological conditions, and can help target questions about future persistence and resilience.  Sexual reproduction is expected to dominate when new landscapes become available for colonization and when climate and/or ecological changes require rapid evolution.  Asexual reproduction is expected to dominate when the conditions for seedling establishment are rare and/or when ecological conditions are stable.  Using trembling aspen (Populus tremuloides) as a case history, I will summarize how landscape patterns of clonal sizes are helping us understand short- and long-term ecological landscape histories and how these patterns guide future research.  Aspen is the most broadly distributed forest tree in North America, and an important foundation species, particularly in western North America. Aspen is also highly clonal, and one particularly large clone in central Utah has been touted as the world’s largest living organism. An unusual and recently discovered feature of North American aspen is its high rate of naturally occurring triploids.  I will discuss landscape patterns of aspen clonal sizes and triploidy in the context of phylogeographic boundaries, local landscape histories, and how these patterns can guide research questions about future forest vulnerabilities and resilience in the face of climate change. 

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Lawrence (Larry) J. Weider

Lawrence (Larry) J. Weider

Professor
Department of Biology
University of Oklahoma
http://www.ou.edu/cas/biology/people/
faculty/lawrence-weider.html

"Send in the clones: Daphnia as a model clonal organism"

Across the tree-of-life, the two major modes of reproduction – asexual and sexual – have evolved numerous times. The evolutionary significance of these reproductive modes has been the subject of much research ever since the time of Darwin, and has centered on the “evolution of sex” debate. In a number of taxa, most notably plants, a combination of these reproductive modes has evolved, whereby distinct phases of the life cycle are either asexual or sexual. Among the Animalia, a number of groups (i.e., cladocerans, aphids) also exhibit asexual (clonal) and sexual (recombinant) phases to their life cycles - termed “cyclical parthenogenesis”. I will present an overview of one such model animal system, the keystone aquatic herbivore, Daphnia (Cladocera, Anompoda – a.k.a. water fleas). These organisms are critical players in the food webs of many aquatic ecosystems, since they graze on primary producers (i.e., phytoplankton), and in turn, serve as important prey items for secondary consumers (e.g., fish). They inhabit a wide range of freshwater habitats world-wide (i.e., they are found on all continents, including Antarctica), ranging from very large lakes (e.g., North American Great Lakes) to ephemeral woodland wetlands to arctic rock pools and tundra ponds. My presentation will examine the ecology and evolution of the Daphnia system and how it can serve as a good “animal model” of a clonal organism that can be compared/contrasted with clonal plant systems. More information about the research being done in my lab can be found at http://waterfleaworld.oucreate.com/.

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