Research Interests
I am an ecologist interested in understanding current and predicting future patterns of biodiversity in the face of global environmental change. I use scenarios of climatic change, remote-sensing datasets, and various modeling techniques to predict how global change may alter both terrestrial and aquatic ecosystems with the goal of managing these impacts. My dissertation research centers on two major themes: (1) the use of bioclimatic models to predict biological invasions and range shifts under climatic change and (2) understanding and reducing the sources of uncertainty within such projections. My work has addressed a diverse set of research questions regarding Western Australian plants, North American ants, and biological invasions in the Great Lakes
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Are species-climate relationships conserved across space and time? Distinguishing the relative roles of climatic and non-climatic factors in determining current distributions of species is key to predicting future distributions of both native and non-native species. How these factors vary across space and time is particularly relevant to projections derived from bioclimatic models because their validity rests on the assumption that species-climate relationships will be conserved despite adaptation, shifting interactions with other species, and differing opportunities for dispersal. My analysis of the invasion of the
fire ant in North America was some of the first to demonstrate that invasive
species can occupy different environments in their native and exotic ranges.
My findings suggest that both biological invasions and range shifts under
climatic change may not be predictable using simple species-climate relationships
because biotic changes may allow species to occupy new environments. |
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| Fitzpatrick MC, Weltzin JF, Sanders NJ, Dunn RR (2007) The biogeography of prediction error: Why does the introduced range of the fire ant over-predict its native range? Global Ecology and Biogeography 16:24-33 | |
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To what extent do impacts of global change depend on dispersal ability? I am also interested in projecting the potential impacts of climatic change on biodiversity. In particular, I am intersted in adressing two key uncertaitnites in this area: (1) How different scenarios of future climatic change may alter distributions of species and (2) The ability of species to attain projected range shifts by dispersal. My research on Western Australian plants suggests that the pattern and severity of climatic change may represent a greater uncertainty than migration rates in this region. Projections varied most across climate scenarios and mainly in the degree rather than in the pattern of impact. Variation in migration rate had little influence on projected impacts because ranges of species tended to contract rather than shift. These results suggest that conservation efforts in this biodiversity hotspot should focus on protecting core areas of ranges of species rather than improving landscape connectivity. |
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| Fitzpatrick MC, Gove AD, Sanders NJ, Dunn RR (Accepted) Climate change, plant migration and range collapse in a global biodiversity hotspot: The Banksia (Proteaceae) of Western Australia. Global Change Biology | |
What is the relative importance of historic, biotic, and environmental factors in determining current patterns of biodiversity? |
| Understanding how species
may respond to future global environmental change requires an understanding
of the relative importance of historic, biotic, and abiotic factors in mediating
present-day patterns of biodiversity. Despite the fact that studies have
demonstrated strong influences of non-environmental factors on current patterns
of biodiversity, bioclimatic models are often applied broadly across taxa
with little consideration of whether climate exerts a similar degree of
influence on all species.
Bioclimatic models generally assume that species have attained their full potential distributions and that geographic ranges are determined by climate alone (i.e., species are in equilibrium with climate). The validity of this assumption should vary across species and by region, but few studies examine whether species differ in the degree to which they attain equilibrium. This is a crucial component in understanding and predicting the responses of species to climate change because models will be least reliable for groups that are least able to attain equilibrium with present-day climate. My latest research (in collaboration with Simon Ferrier, NSW Department of Environment and Conservation) investigates whether seed-dispersal mutualisms influence the degree to which climate determines the geographic ranges of plants in Western Australia. The prediction is that the distribution of poor-dispersers should reflect the influence of dispersal limitation and therefore should be less influenced by climate and less able to attain equilibrium than vagile species. In cases where dispersal is limiting, species can be expected to not reach all unoccupied areas and thus to not attain the maximum distribution possible given their environmental tolerances. Preliminary results suggest, somewhat paradoxically, that poorly-dispersing plants may be more constrained by climate than vagile plants – apparently because poor-dispersers are more narrowly-adapted and attain a greater degree of equilibrium within their narrow ranges than vagile species. These findings lead to two conclusions relevant to predicting the responses of plant species to future global change: (1) present-day distributions of vagile species may not reflect their full climatic tolerances and therefore predicted changes in distribution for such groups are least certain and (2) poor-dispersers may be at greater risk due to climate change, not necessarily because of an inability to track changes in climate, but rather because they are more narrowly adapted.
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