Innovative method predicts the effects of climate change on cold-blooded animals

A research team led by Penn State has created a statistical model that enhances estimates of habitat suitability and extinction probability for cold-blooded animals as temperatures rise. This is in response to a warming climate that is having a significant impact on global biodiversity and will change the distribution and abundance of many animals.

The majority of species on Earth are cold-blooded animals, a diverse group that includes fish, reptiles, amphibians, and insects. The temperature of their surroundings has a significant impact on the body temperature of cold-blooded animals. Climate change poses a serious threat to them because their survival, reproductive success, and growth are all strongly correlated with environmental temperatures.

According to Tyler Wagner, the head of the research team and a scientist with the U.S. Department of Energy, understanding how climate change will affect biodiversity in the future is a top priority. S. Fisheries Ecology is an adjunct faculty member at Penn State and the Geological Survey. But he added that it is extremely difficult to predict where a species will live and how common it will be given future temperatures because, for many species, doing so would require guessing how they would react to temperatures that they have not yet encountered and that scientists have not yet observed.

“The problem was figuring out how to combine these two sources of information and use laboratory-derived information to assist inform landscape-scale forecasts under future temperatures that animals in their current ranges would not experience,”

Wagner, who is assistant unit leader of the Pennsylvania Cooperative Fish.

In a recent study, the researchers created a statistical technique to combine data gathered in the field describing the distribution and abundance of many cold-blooded animals with laboratory-derived data about species-specific temperature performance and tolerance. This allowed the researchers to more accurately estimate the effects of climate change on cold-blooded animals.

Wagner and colleagues report the creation of an original statistical modeling strategy in findings that were just published in the Proceedings of the National Academy of Sciences. Their recently created model, which they refer to as the “Physiologically Guided Abundance Model,” or PGA Model, can be used with almost all cold-blooded animals and is thought to have a great deal of promise for guiding the development of climate adaptation and management strategies.

The challenge, according to Wagner, an assistant unit leader at the Pennsylvania Cooperative Fish and Wildlife Research Unit in the College of Agricultural Sciences, “was how to combine these two sources of information and use laboratory-derived information to help inform landscape-scale predictions under future climates not experienced by animals in their current ranges.”. “The model we developed achieves that.”.

The PGA model predicts species geographic distributions and abundance in response to a warming world by fusing observations of species abundance and environmental conditions with laboratory-derived data on the physiological response of cold-blooded animals to temperature. Wagner argues that it is challenging to accurately predict the future of cold-blooded animals without taking species’ physiological preferences into account in a model.

Scientists now frequently only use data that describes relationships between abundance and distributions and temperature under current conditions “when trying to predict, or extrapolate, the effects of climate change on animal distribution and abundance.”. Then, under future temperature conditions, extrapolation is done using these relationships.

This method, however, makes the crucial assumption that species-environment relationships are biologically significant under projected temperatures and, more importantly, disregards the close relationship between environmental temperatures and the physiology of cold-blooded animals, according to Wagner.

“Cold-blooded animals are relatively well-studied when it comes to laboratory-derived information about how changes in environmental temperatures affect physiology and performance,” he said. “However, cold-blooded animals are understudied when it comes to understanding how their distributions and abundance will respond to climate change.”. In actuality, most cold-blooded animals exhibit a functional response that is consistent across a wide range of taxa in terms of how they perform relative to rising temperatures.”.

The data from three fish species, which have different thermal preferences and tolerances across more than 1,300 lakes in the U.S., were used by the researchers to create their PGA model. S. Midwest. They contrasted the outcomes of the PGA model with those of a conventional model that excludes the physiological responses of the species. The fish used in the study were bluegill, a warmwater fish; yellow perch, a coldwater fish; and cisco.

According to current conditions and increases in mean July water temperatures of 1, 2, 3, and 4 degrees Celsius, the researchers predicted species distributions and abundances at each lake. The Midwest region’s average regional air temperature is expected to rise by 7.2 degrees F (4 °C) between the years 2017 and 2100.

The PGA model showed that cold-adapted fish would become extinct in 61 percent of their current habitat with rising temperatures, in contrast to the traditional model’s findings that none of the fish species would be extirpated or locally driven out by climate change.

Gretchen Hansen, an assistant professor at the University of Minnesota and a co-author on the study, suggested that models that exclude physiological preferences may result in underestimations of the risk that climate change may pose to species that are adapted to the cold.

We demonstrated that when physiological information was incorporated into the model, temperature-driven changes in distribution, local extinction, and abundance of cold-, cool-, and warm-adapted species varied significantly, she said. “The PGA model has great potential for more realistically estimating the effects of climate change on cold-blooded species. Compared to traditional approaches, the PGA model provided more realistic predictions under future climate scenarios.”.

Christopher Custer, a doctoral candidate in the Department of Ecosystem Science and Management at Penn State, Erin Schliep from the Department of Statistics at North Carolina State University, Joshua North from the Climate and Ecosystem Sciences Division at Lawrence Berkeley National Laboratory, Holly Kundel and Jenna Ruzich from the Department of Fisheries, Wildlife, and Conservation Biology at the University of Minnesota, and others also contributed to the study.

More information: Wagner, Tyler, Predicting climate change impacts on poikilotherms using physiologically guided species abundance models, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/

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