Amphibian Ecology

The fundamental goals of ecology are to understand the factors that determine the abundance, distribution and diversity of organisms in nature.  The urgency of this task is increasing because of mounting losses of species due to degradation and destruction of habitats.  Human alterations of landscapes have fragmented many habitats which has resulted in direct area loss and reduced distribution of species.  This artificial patchiness impedes the movements of individual organisms among local populations and increases the chances of species loss.  The ultimate result of fragmentation of formerly continuous habitats is a loss of biodiversity.

Amphibians play a vital role in nature because they act as both important predators and prey in the food webs of many ecosystems, and they use habitats on both land and in water.  Amphibians may also be sensitive to environmental changes because of biological characteristics such as their skin and dependence on water.  Because of these attributes, amphibians make excellent indicators of ecosystem health by acting as proverbial 'canaries in coalmines'.  My research provides valuable insights into amphibian ecology and conservation in Canada at a time when there are serious concerns regarding the global decline of amphibian populations.  This research also contributes to Canada's obligations as a signatory of the United Nations Convention on Biological Diversity.

Above photo of Hyla versicolor Gray Treefrog

 

The goal of my research is to document and explain patterns of species richness, species turnover, and spatial dynamics of amphibian communities and regional faunas.  I am interested in determining the relative importance of local and regional processes, and discovering how historical and contemporary human landscape practices structure amphibian populations and communities.  My students and I take an empirical field-based approach and use multiscaled perspectives in our research.  Our field methods involve using repeated visits of numerous local sites within annual activity seasons to construct accurate local species lists.  We compare these 'snapshots' of communities among sites with physical, habitat, and landscape variables to determine how environmental factors structure local populations and communities.  Comparison of these 'snapshots' through time allows us to determine how local communities and patterns of regional incidence change.  Developing our research approach played a seminal role in shifting field studies in amphibian ecology from a focus on individual populations or manufactured communities to studying 'metapopulations', 'metacommunities', and regional faunas.  We have made valuable contributions to, and continue to advance, the understanding of the roles of water chemistry, wetland characteristics, landscape features, fish predation, and historical and contemporary landuse practices in structuring amphibian populations and communities (see Publication list).  Contemporary ecologists recognize the importance of large scale and long-term studies because the processes that structure natural systems often function on these scales.  Despite this knowledge, most field studies still tend to be restricted to small local areas and to be short-term (1-3 years).  Because of the paucity of these studies, we began long-term studies of amphibians in several regions in Ontario in 1992.  This research is providing valuable insights to understanding stability and trends in regional faunas and the scale of factors that affect amphibian communities.  Besides contributing to advancing knowledge basic knowledge of amphibian ecology it is also providing valuable insights into understanding large-scale amphibian declines.  This research was funded through an NSERC Discovery Grant until 2010 and past support from a PREA award.  It continues through university support and personal funding.

 

• Long-term Spatial Dynamics of Amphibians - We have been studying trends in amphibian incidence and metacommunity dynamics as regional environmental changes occur over the past 25 years in the Stratford Region of Southwestern Ontario.
• Long-term Trends of Abundance in Green Frog Populations - We have been studying trends in Green Frog abundance across a network of 35 ponds over the past 25 years in the Stratford Region of Southwestern Ontario.  
  
• Long-term Effects of Climate Change on Amphibian and Reptile Phenology - With the help of staff at the Ojibway Prairie Nature Centre in Windsor, Ontario we are studying how initiation of amphibian breeding calls and date of emergence from hibernation for reptiles has changed over the past 40 years with respect to climate change.
•  Geographic Distribution of Axanthic Green Frogs - With the help of colleagues we are collecting records of the rare 'Blue' colour morph of Green Frogs and investigating the range-wide distribution of the trait.