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Shannon McCauley, Postdoctoral Fellow

Department of Ecology and Evolutionary Biology
University of Toronto

Now Assistant Professor at Cal Poly State University, San Luis Obispo smccaule@calpoly.edu

B.A.

Bowdoin College, Maine

M.Sc.

Department of Zoology, University of Florida Thesis: Effects of dietary dilution in chelonians: implications for their ecology and conservation

Ph.D.

Ecology and Evolutionary Biology, University of Michigan Thesis: Species distributions in anisopteran odonates: effects of local and regional processes. Advisor: Earl Werner.

Postdoctoral Fellow

(2006 – June 2008) Center for Population Biology, University of California, Davis. Postdoctoral mentors: Sharon Lawler and Andy Sih.

2008-2010

Department of Ecology and Evolutionary Biology, University of Toronto. Postdoctoral
Advisors: Locke Rowe, Marie-Josee Fortin

Current Position Assistant Professor

Cal Poly State University, San Luis Obispo
new e-mail is: smccaule@calpoly.edu

 

Research interests

One of the central challenges in ecology is to understand how processes operating at different spatial scales act, and interact, to determine the structure of ecological communities. In my graduate work at the University of Michigan, I addressed questions about the roles of dispersal limitation and niche requirements on community structure. I examined how the ecological interactions of dragonflies in their aquatic larval habitat combined with their adult dispersal behavior to produce large-scale patterns in community structure within this group. This work combined large-scale natural habitat surveys (McCauley 2008a), landscape-level experiments, and lab experiments to address questions about the mechanisms structuring species distributions and the consequences of these for community structure. Species distributions and community structure depended on both larval niche requirements and dispersal behavior. Neither factor alone was sufficient to explain the observed community structure of this system (McCauley 2006, 2007). I also discovered pervasive adaptive trade-offs in activity levels between species that differed in the breadth of their habitat distributions: optimal activity level depended on the identity of the top predators in the habitat (McCauley 2008).

As a postdoctoral researcher, I have focused on questions about dispersal behavior itself as our understanding of this process is extremely limited in most systems and better data on movement behavior will provide new insights into the role of dispersal in structuring species distributions and community structure. While at UC Davis I conducted research on phenotype dependent dispersal. In a mark-release-resight study of adult male dragonflies, I found that dispersers were not a random subset of the population and that both behavior and morphology was related to the decision to disperse and the distance traveled. These results suggest that phenotype dependent dispersal may modify the level of genetic and demographic connectivity that exists between habitat patches. I also conducted a collaborative study on the potential consequences of phenotype dependent dispersal, examining the relationship between the isolation of artificial pools and the behavior of larval colonists from those pools. We found that even after being in common lab conditions for approximately half of their developmental period, dragonfly larvae from more isolated pools had higher foraging rates than larvae from less isolated pools (McCauley et al., accepted at The American Naturalist). This result indicates that variation in dispersal distances between individuals may result in correlations between habitat isolation and the phenotypic composition of the community, with important implications for how spatial structure may affect food-web structure in these systems.

Currently my research has two main components both of which are focused on the potential interactions between processes occurring at different spatial scales. The first project explores the potential for carry-over effects to result in important linkages between local conditions and regional processes including landscape connectivity. Organisms can display a remarkable level of behavioral and morphological plasticity in response to the conditions they experience within their developmental environment and these responses can in turn influence adult phenotypes and have impacts on their dispersal behavior (Benard and McCauley 2008). My research at the Koffler Scientific Reserve is exploring how developmental conditions influence adult phenotypes and the consequences of this for the ability and propensity of adults to disperse between sites. This work is being conducted using the dragonfly, Leucorrhinia intacta, which exhibits morphological plasticity in response to fish predators as a potential model for these effects (McCauley et al. 2008b). At KSR we have also begun addressing questions about predator-induced dispersal in notonectids (backswimmers). We found Notonecta undulata respond to non-lethal (caged) fish predators by increasing their rate of dispersal out of the aquatic environment and that this response is risk-sensitive (McCauley & Rowe 2010). These results suggest that predation risk within a habitat can affect dispersal among habitats, and thus affect community structure on a much greater scale than the direct effect of predation itself (e.g. ‘remote-control predator effects’ Orrock et al. 2008). While at U of T, I have also been working on questions about the processes that determine species’ range sizes. This work has tested some of the central hypotheses about factors affecting range size including how niche breadth, dispersal capacity, dispersal behavior, body size, and local abundance are related to range size. Our preliminary results indicate that dispersal behavior at the landscape scale is strongly related to the extent of species’ distributions across North America.

I am part of a collaborative project exploring the evolution of phenotypic plasticity within a holoarctic genus of dragonflies, Leucorrhinia. So far two species within this genus, one North American (McCauley et al. 2008b) and one European (Arnqvist and Johansson 1998), have been shown to exhibit morphological plasticity in response to the presence of fish predators. By testing for morphological, behavioral, and physiological plasticity across the whole genus we can examine the relationship between plasticity and habitat distributions at local and regional scales within a phylogenetic context. This work will provide new insights into the evolution and maintenance of plasticity. It will also allow us to examine the relationship between species distributions and plasticity and assess the resilience of species to ecological perturbations including changes in the top predator community.

 

Marked dragonfly (Pachydiplax longipennis) in Pope Valley, CA

marked fragonfly

Dragonfly larvae (Hagenius brevistylus) with attached zebra mussels, UMBS, University of Michigan. (McCauley and Wehrly 2007)

marked fragonfly

Notonecta undulata from the Koffler Scientific Reserve

marked fragonfly


Publications

  • McCauley, Shannon J. and K. E. Mabry. 2011. Climate change, body size, and phenotype dependent dispersal. Trends in Ecology and Evolution 26.11 (2011): 554-555. http://dx.doi.org/10.1016/j.tree.2011.06.017.

  • McCauley, Shannon J., Locke Rowe, and Marie-Josée Fortin. 2011. The deadly effects of “nonlethal” predators. Ecology 92: 2043–2048. [doi:http://dx.doi.org/10.1890/11-0455.1]

  • McCauley, S.J. and L. Rowe. 2010.  Notonecta exhibit threat-sensitive, predator-induced dispersal. Biology Letters 6: 449-452. Published on-line doi: 10.1098/rsbl.2009.1082 (pdf)

  • McCauley, S.J. 2010.  Body size and social dominance influence breeding dispersal in male Pachydiplax longipennis (Odonata). Ecological Entomology 35: 377-385. Published on-line DOI: 10.1111/j.1365-2311.2010.01191.x

  • McCauley, S.J., T. Brodin, and J.I. Hammond. 2010.  Foraging rates of larval dragonfly colonists are positively related to habitat isolation: results from a landscape-level experiment. The American Naturalist 173: E66-E73. (pdf)

  • McCauley, S.J., C.J. Davis, J. Nystrom, E.E. Werner. 2009.  A hump-shaped relationship between isolation and abundance of Notonecta irrorata colonists in aquatic mesocosms. Ecology 90: 2635-2641 (pdf)

  • McCauley, S.J., C.J. Davis, R.A. Relyea, K.L. Yurewicz, D.K. Skelly, E.E. Werner. 
    2008a.  Metacommunity patterns in larval odonates. Oecologia 158: 329-342. (pdf)

  • Benard*, M.F. and S.J. McCauley*. 2008.  Integrating across life-history stages: 
    consequences of natal habitat effects on dispersal.  American Naturalist 171: 553-567. (pdf)
    *both authors contributed equally to this work

  • McCauley, S.J., C.J. Davis, E.E. Werner.  2008b.  Predator induction of spine length in
    larval Leucorrhinia intacta (Odonata).  Evolutionary Ecology Research 10: 435-447. (pdf)

  • McCauley, S.J.  2008.  Slow, fast and in between: habitat distribution and behaviour of larvae in nine species of libellulid dragonfly.  Freshwater Biology 53: 253-263. (pdf)

  • McCauley, S.J.  2007. The role of local and regional processes in structuring larval
    dragonfly distributions across habitat gradients.  Oikos 116 (1): 121-133. (pdf)

  • Boyce, W.M., S.P. Lawler, J. Schultz, S. McCauley, L. Kimsey, M. Niemala, W. Reisen, C. Nielson, D. Brown.  2007.  Nontarget effects of the mosquito adulticide pyrethrin applied aerially during a West Nile virus outbreak in an urban California environment.  Journal of the American Mosquito Control Association 23(3): 335-339.

  • McCauley, S.J. and K. E. Wehrly.  2007.  Zebra mussel, Dreissena polymorpha, attachment to Odonata larvae.  Odonatologica 36(1): 63-69.

  • McCauley, S.J.  2006.  The effects of dispersal and recruitment limitation on community structure of odonates in artificial ponds.  Ecography, 29(4): 585-595. (pdf)

  • McCauley, S.J.  2005.  Relationship between habitat distribution, growth rate, and plasticity in congeneric larval dragonflies.  Canadian Journal of Zoology, 83: 1128-1133. (pdf, Erratum)

  • McCauley, S.J.  2005.  Differential dispersal propensities between individuals in male Leucorrhinia intacta (Hagen).  International Journal of Odonatology, 8(2): 223-232. (pdf)

  • McCauley, S.J., S.S. Bouchard, B.J. Farina, K. Isvaran, S. Quader, D. W. Wood, C. M. St. Mary.  2000.  Energetic dynamics and anuran breeding phenology: insights from a dynamic game.  Behavioral Ecology, 11(4): 429-436. (pdf)

  • McCauley, S.J. and K.A. Bjorndal.  1999.  Response to dietary dilution in an omnivorous freshwater turtle: implications for ontogenetic dietary shifts.  Physiological and Biochemical Zoology, 72(1): 101-108.

  • McCauley, S.J. and K.A. Bjorndal.  1999.  Assessing the effects of anthropogenic debris ingestion on juvenile sea turtles.  Conservation Biology, 13(4): 925-929.

Public seminar


Literature cited

  • Arnqvist, G. and Johansson, F. 1998. Ontogenetic reaction norms of predator-induced defensive morphology in dragonfly larvae. Ecology, 79: 1847-1858.

  • Orrock JL, Grabowski JH, Pantel JH, Peacor SD, Peckarsky BL, Sih A, and Werner EE. 2008. Consumptive and nonconsumptive effects of predators on metacommunities of competing prey. Ecology 89: 2426-2435.