Ants are shifting to new habitats to cope with climate change

A recent study led by the University of Colorado, Boulder (CU Boulder) has found that, over the span of sixty years, climate change has pushed certain ant species beyond their traditional boundaries in Gregory Canyon near Boulder, Colorado. 

This shift, leading ant species unable to cope with rising temperatures to vacate their original habitats, signals a profound alteration in biodiversity that could have far-reaching consequences for local ecosystems. 

Valuable indicators of climate change

Ants, being ectothermic organisms, rely heavily on environmental temperatures for their metabolism and other vital functions, rendering them particularly susceptible to the effects of climate change. This feature makes ants valuable indicators for studying ecosystem responses to temperature shifts. 

The foundation for this study was laid more than six decades ago by CU Boulder entomologist Robert Gregg and his student John Browne. Intrigued by their pioneering work, lead author Anna Paraskevopoulos and her research team embarked on a mission to examine how the ant community in Gregory Canyon has evolved since then.

Isolated impacts of climate change 

Despite the significant urban expansion of Boulder, Gregory Canyon has remained relatively untouched, offering a unique window into the isolated impacts of climate change. 

“This gave us an opportunity to study the isolated impacts of climate change. In many other studies, the effect of land use and climate change are often entangled,” Paraskevopoulos said.

Dynamic shift in ant populations 

The researchers discovered a dynamic shift in ant populations, noting the emergence of some species not previously recorded in the canyon alongside the expansion and dominance of others. Conversely, certain species documented by Browne and Gregg have either dwindled in prevalence or vanished entirely. 

“Across the different environments and habitats in the canyon, we’re seeing the composition of ant species becoming more similar,” said senior author Julian Resasco, an expert in ecology and evolutionary biology at CU Boulder.

Ants and ecosystem stability 

The significance of ants as crucial ecosystem engineers cannot be overstated. They play essential roles in enhancing soil aeration, accelerating the decomposition process, and dispersing seeds. Different ant species contribute uniquely to the ecosystem, affecting various ecological processes. 

The shift in ant biodiversity observed in Gregory Canyon raises questions about the broader implications of these changes. “If the ecosystem has only a single type of ant, it could mean that the animal is only contributing to ecosystem functioning in one way, potentially reducing ecosystem stability,” Paraskevopoulos explained.

Widespread decline in insect populations 

This study contributes to the growing body of evidence pointing to a global decline in insect populations, a phenomenon many scientists have termed an “insect apocalypse.” It underscores the urgent need for a deeper understanding of the mechanisms driving these changes and their potential impact on ecosystem functioning. 

“In response to climate change, species are changing the ranges where they’re occurring. Some of them are spreading and becoming winners, while others are crashing and becoming losers. This work helps us understand how those communities reshuffle, which could have implications on how ecosystems function,” Resasco concluded.

Ants as bioindicators of climate change 

Ants serve as bioindicators of climate change due to their sensitivity to changes in their environment, making their behaviors, distributions, and community compositions useful indicators of shifts in climate conditions. Here’s how ants can reflect changes in the climate:

Sensitivity to temperature

Ants are ectothermic, meaning they rely on external sources of heat to regulate their body temperature. Changes in temperature and humidity can directly affect their survival, foraging behavior, reproduction, and distribution. For example, warmer temperatures might lead to shifts in ant species distributions, with some species moving to higher elevations or latitudes in search of suitable conditions.

Diverse ecological roles 

Ants play various crucial roles in ecosystems, such as soil aeration, seed dispersal, and predation. Climate change can alter these roles and affect the broader ecosystem. For instance, changes in precipitation patterns and temperature can impact ant-mediated seed dispersal, potentially affecting plant community composition.

Community composition 

Changes in climate can lead to shifts in ant community composition and diversity. Some species may thrive under new conditions, while others decline or disappear, leading to altered interactions among species. Monitoring these changes can provide insights into the impacts of climate change on local and broader ecosystems.

Symbiotic relationships

Ants engage in symbiotic relationships with plants and other insects, such as aphids. Climate change can disrupt these relationships by shifting the phenology (timing of biological events) of the involved species, potentially impacting ecosystem health and function.

By studying changes in ant populations and communities, scientists can gain valuable insights into the impacts of climate change on ecosystems. This data can inform conservation strategies and help predict future changes in biodiversity and ecosystem services.

The study is published in the journal Ecology.

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