Behavioral variation within species: environmental drivers and ecological consequences
Variation in traits among species is widely understood to influence the role of species in communities and ecosystems. Substantial variation in traits also occurs within species, but this variation is typically not considered by ecologists. Human activities are rapidly altering the traits within species at a global scale. Therefore, it is critical to determine whether intraspecific variation is important for community and ecosystem processes.
Behavioral traits, in particular, respond rapidly to environmental change and vary considerably both within and among populations. Past research in our lab has demonstrated substantial variation in behavioral traits including activity, boldness and feeding rate across the geographic range of freshwater crayfish. Therefore, the ecological impacts of crayfish are likely to vary across their range and between native and invasive populations. In addition, we found that crayfish from active, bold populations have substantially faster growth rates.
Currently, we are investigating whether intraspecific variation in behavioral traits across the biogeographical range of two crayfish species: (1) affects stream ecosystem functions including leaf litter decomposition, nutrient cycling and ecosystem metabolism and (2) is predictably associated with differences in local (resource availability, predation) and regional (climate) environmental variables. We are conducting this work in collaboration with Lauren Pintor at Ohio State University and AJ Reisinger at the University of Florida. This project is supported by a National Science Foundation EAGER grant.
Behavioral variation within species: environmental drivers and ecological consequences
Variation in traits among species is widely understood to influence the role of species in communities and ecosystems. Substantial variation in traits also occurs within species, but this variation is typically not considered by ecologists. Human activities are rapidly altering the traits within species at a global scale. Therefore, it is critical to determine whether intraspecific variation is important for community and ecosystem processes.
Behavioral traits, in particular, respond rapidly to environmental change and vary considerably both within and among populations. Past research in our lab has demonstrated substantial variation in behavioral traits including activity, boldness and feeding rate across the geographic range of freshwater crayfish. Therefore, the ecological impacts of crayfish are likely to vary across their range and between native and invasive populations. In addition, we found that crayfish from active, bold populations have substantially faster growth rates.
Currently, we are investigating whether intraspecific variation in behavioral traits across the biogeographical range of two crayfish species: (1) affects stream ecosystem functions including leaf litter decomposition, nutrient cycling and ecosystem metabolism and (2) is predictably associated with differences in local (resource availability, predation) and regional (climate) environmental variables. We are conducting this work in collaboration with Lauren Pintor at Ohio State University and AJ Reisinger at the University of Florida. This project is supported by a National Science Foundation EAGER grant.
(A) Experimental arena used to test crayfish shelter use and competition (B) Measuring benthic and water column metabolism in a stream
Invasive species and parasitism
Understanding the conditions that affect the success and impacts of invasive species is essential for managing today’s ecosystems, but invasions also provide natural experiments that are powerful tools for investigating questions in ecology and evolution. For example, invasions can provide insight into the importance of parasites in ecological communities.
Past research in our lab has focused on the impacts of parasites on the behavior and demography of invasive crayfish. For example, we have investigated the impacts of a trophically-transmitted, trematode parasite on crayfish behavior. This parasite reduces crayfish antipredator behavior and has different behavioral effects on novel crayfish hosts compared to those with which it shares a long evolutionary history. We are interested in how this alters interactions between native and invasive crayfish and their impacts in freshwater ecosystems.
Our current research in this area is focused on diseases in three closely related species of crayfish that inhabit north temperate lakes. These species differ in their ecological impacts and how long they have been present in the region. We are screening these crayfish for a wide variety of diseases (from viruses and bacteria to flukes and worms) in lakes with different patterns of crayfish species coexistence and population dynamics. These data will enhance our understanding of the role of parasites in invasions and crayfish species replacements. We will also investigate the potential to use native parasites as a management tool to control invasive crayfish populations. We are conducting this work in collaboration with Don Behringer and Jamie Bojko at the University of Florida. This project is supported by an Aquatic Invasive Species grant from the Wisconsin Department of Natural Resources.
Mesocosms at Trout Lake Research Station to test the effects of trematode parasites on freshwater communites
(A) Crayfish surveys in northern Wisconsin (B) A trematode metacercaria in a virile crayfish hepatopancreas (digestive organ) (C) A microsporidian infection in rusty crayfish abdominal muscle
Crayfish conservation and invasions
Freshwater crayfish are a diverse group that contains many species of conservation concern with limited distributions as well as numerous invasive species and have recently undergone dramatic range expansions. Crayfish often play a central role in freshwater ecosystems, where they are typically dominant consumers of leaf litter, periphyton, and benthic invertebrates. Thus, they can have large effects on ecosystem functions, such as leaf litter decomposition and nutrient cycling. Crayfish are also a critical food resource for many recreationally and economically important centrarchid fishes. Because of their central role in freshwater ecosystems, crayfish additions and deletions often have large ecological impacts.
We are currently partnering with researchers at the Florida Fish and Wildlife Conservation Commission to investigate the range expansion of the white tubercled crayfish into the Black Creek drainage in Florida. This drainage contains a rare crayfish of conservation concern, the black creek crayfish. Preliminary data suggest that the white tubercled crayfish has already replaced the black creek crayfish throughout most of its range.
Crayfish conservation and invasions
Freshwater crayfish are a diverse group that contains many species of conservation concern with limited distributions as well as numerous invasive species and have recently undergone dramatic range expansions. Crayfish often play a central role in freshwater ecosystems, where they are typically dominant consumers of leaf litter, periphyton, and benthic invertebrates. Thus, they can have large effects on ecosystem functions, such as leaf litter decomposition and nutrient cycling. Crayfish are also a critical food resource for many recreationally and economically important centrarchid fishes. Because of their central role in freshwater ecosystems, crayfish additions and deletions often have large ecological impacts.
We are currently partnering with researchers at the Florida Fish and Wildlife Conservation Commission to investigate the range expansion of the white tubercled crayfish into the Black Creek drainage in Florida. This drainage contains a rare crayfish of conservation concern, the black creek crayfish. Preliminary data suggest that the white tubercled crayfish has already replaced the black creek crayfish throughout most of its range.
Benthic invertebrate community ecology
Benthic macroinvertebrates are commonly used as indicators of water quality, and they are critical for energy flow through food webs and nutrient cycling in freshwater ecosystems. Therefore, part of the research in our lab focuses on benthic invertebrate abundance, diversity, and community composition to examine how human impacts and environmental change alter freshwater ecosystems.
For example, we have examined whether benthic invertebrate communities in urban stormwater ponds are influenced by human management (vegetation control). Stormwater ponds are commonly constructed to control pollution, flooding and erosion caused by human development, but they also support freshwater organisms. Understanding how management of these ponds affects benthic invertebrate communities may help managers maintain biodiversity in urban landscapes.
In addition, we are interested in the effects of prescribed fire on wetland ecosystems. While prescribed fire is instrumental in managing forest ecosystems in the southeastern USA, our knowledge of its impacts on freshwater ecosystems is severely limited. Research in the lab will continue to examine benthic invertebrate communities to assess environmental impacts, and this approach can be adapted to new questions and freshwater ecosystems of interest.
(A) Dragonfly larvae from an urban stormwater pond (B) A stormwater pond in Gainesville, FL (C) A wetland in a landscape managed by prescribed fire