Climate changes are causing a dizzying ride that seems to present opportunities for some creatures to thrive. Scientists who write supercharged scenarios caution that the difference between seasonal coping and long-term adaptation is huge and hard to predict.
Biologists at Michigan State University have studied damselflies, which resemble dragonflies and are abundant as both predators and prey in wetlands, to understand what happens throughout their life cycle, from nymph to the winged insect, along with what they eat when the summers get warmer and longer.
Your work this week Proceedings of the Royal Society B has a twist: It combines seasons of observational and experimental work in the field and in the lab with input from a theoretical ecologist, a mathematician by training with supersized modeling credentials.
The results: a more realistic look at what a hot summer can bring to a nearby pond, and a newfound respect for the blinding speed that global warming is bringing.
“We are seeing that the rate of climate change is much faster than organisms have endured in their evolutionary experience,” said co-author Phoebe Zarnetske, an associate professor of integrative biology.
PI of the Spatial and Community Ecology Laboratory (SpaCE) and director, IBEEM. “That rapid pace is going to be an even bigger problem with the increase in extreme events like heat waves.”
Work in “Life history responses to temperature and seasonality mediate ectothermal consumer resource dynamics under climate warming” finds that inserting the right level of data collected from field experiences, specifically the effects of seasonal changes in temperature in consumer life cycles, creates a more robust predator-prey simulation model. The work differs from findings from similar models with less biological realism that predicted warming trends that would doom predators. They see Michigan damselflies surviving climate warming by switching to a life cycle similar to their southern relatives, with two life cycles in a season instead of one.
The work developed from first author Laura Twardochleb’s work as a PhD student in Zarnetske’s lab. She had spent time observing the one-year life cycle of damselflies in Michigan. They emerge as adults from ponds in spring. They mate, reproduce, and the juveniles grow for a year in the pond eating zooplankton. They make good study subjects, she said, because they thrive both outdoors and in the lab.
Twardochleb, now with the California State Water Resources Control Board, was part of MSU’s Ecology, Evolution, and Behavior Program and, as part of that, took a class from Chris Klausmeier, Professor of Plant Biology and Integrative Biology at the MSU Foundation.
He saw that the first models that projected how a warming climate would affect ectothermic predators were significantly simpler than the nature he was looking at. On the one hand, the models did not allow for the change of seasons from the north. The models were also not tracking the size and growth rate of a predator and the changes in its life cycle with warming.
Meanwhile, Klausmeier, a theoretical ecologist, was recognizing the special sauce that an experimenter brings when creating mathematical models that make assumptions about how organisms behave, grow, are born, and die.
“I can invent any model I want without being limited by reality,” Klausmeier said. “But that’s a bit dangerous because of course you want something related to the real world. When you join an experimenter, you can bring not only the experimental results and parameters, but also bring deep natural history and knowledge into the system to know the key variables and limitations”.
The work, taking into account a warmer, but still seasonal climate, shows how damselflies can grow and reproduce more quickly. By creating a model that only allowed virtual damselflies to live a one-year life cycle in a warmer world, they burned to death. Extinction was on the horizon.
But allow insects the option of joining two generations in one season, and thriving was a possibility. “Many models said [predators] they were going to starve,” Twardochleb said. “That’s what’s exciting: that we can make more realistic models.”
Twardochleb said the work is a good foundation for understanding how other species will respond to a warmer world, particularly species like mosquitoes, which are nuisances and potentially carry disease.
Zarnetske added that the ongoing challenge will be beyond the idea that different species will adapt to a new world. Climate change is outpacing that kind of evolution in an unprecedented way. And climatic extremes (heat waves, droughts, floods) are quite a variable.
“That’s our next step,” Zarnetske said. “Unpredictability is hard.”
The work was supported by the National Science Foundation, NASA, the MSU Department of Fish and Wildlife and Environmental Science and Policy Program, the Kellogg Biological Station, and the Society for Freshwater Science.
—————————————————-
Source link