Jon Davenport, Ph.D.
Associate Professor of Biology
Department of Biology
Appalachian State University
Current Research
Climate change and subarctic wetland communities
For the past 8 years, I have worked to establish a research program investigating the ecology of subarctic wetlands around Churchill, Manitoba. Environmental change is occurring rapidly at higher latitudes and freshwater ecosystems in the North are very susceptible to this environmental change. The Hudson Bay Lowlands garner the 2nd largest concentration of wetlands in the world. Along with this concentration of wetlands, Churchill is also home to polar bears and beluga whales (which I do not study), but also has fascinatingly simple wetland communities. They are composed of two freshwater fish species, several predatory dragonflies, and two species of frogs at the northern extent of their range.
We are conducting natural surveys alongside experimental mesocosms to shed some light on the mechanisms controlling the distribution and abundance of freshwater organisms (vertebrates and invertebrates) in these wetland communities. To date, we have a 6 year data set on natural ponds and over 5 years of experimental work.
Dispersal and movement ecology of non-game wildlife
While as a postdoc under Winsor Lowe at the University of Montana, I explored the link between species interactions and dispersal. I am continuing this line of research by using animal movement data to understand how dispersal affects the strength of species interactions and divergence among populations. I deploy a multi-faceted approach that integrates data from mark-recapture surveys, wildlife telemetry, population models, behavioral assays and mesocosm experiments. This work is being explored with stream salamanders (or spring lizards depending on where you’re from), frogs, and freshwater turtles. I am also very interested in understanding how habitat fragmentation can impact dispersal of non-game species.
Community ecology in freshwater systems
My Ph.D. training under David Chalcraft focused on factors that influenced the strength of intraguild interactions. Specifically, I conducted multiple experiments in mesocosms with larval amphibians and freshwater invertebrates. The intermediate predator that I used throughout my work was Ambystoma opacum, the marbled salamander, and the top predators were Aeshnid dragonflies of the genus Anax.
In one experiment, we analyzed the effects of food web simplification on an intermediate predator’s growth and survival. Larval dragonflies consumed larval salamanders no matter how much food (larval frogs) was available. However, we did find that in the most diverse food webs the larval salamanders that did metamorphose were up to 2.5 times larger than any other survivors from less diverse food webs.
In another experiment, we looked at the variation in larval salamander morphological traits throughout development when exposed to cues from a top predator and competitors. Larval salamanders do alter their torso length and tail fin depths when exposed to predators. Specifically, deeper tail fins with predators and shorter torsos (only found when the abundance of competitors was low). These trait changes led to important consequences for survival with top predators. Salamanders with deeper tail fins and shorter torsos had the lowest mortality rates with top predators out of the phenotypes that we evaluated.
I am still very fascinated with food webs in freshwater communities and still explore questions about them with my students. We have expanded our questions to investigate the impacts of non-native species in these food webs. Below are just some of the types of questions we are working on:
1) How does prey population source influence species interaction strength?
2) How do non-consumptive effects of predators interact with prey personality influence prey survival and growth?
3) How does a common contaminant ,Triclosan, affect tadpole growth and survival?
4) The effects of inter-Kingdom interactions within freshwater food webs
5) The effects of introduced predators/competitors and climate change on native stream fauna
Phenological shifts and their effects on freshwater wetland food webs
Climate change is impacting biological communities in many ways. One such way is by shifting phenological events (timing of breeding, flowering time, etc.) and their cascading effects. Recent funding from the DoD, in collaboration with the USGS and VA Tech, has provided my lab with the opportunity to examine how phenological shifts in salamander breeding times can influence wetland food webs. This work will take place at Fort Leonard Wood in Missouri and will include two fall breeding Ambystomatid salamanders (A. opacum and A. annulatum).
