Mosquitoes, bats... species migration caused by climate change

In these times of global warming, many species are on the move, causing headaches for decision-makers around the world.


As mosquito, tick, and disease-carrying bat habitat ranges shift, illnesses such as malaria and Lyme disease are invading new territories, catching healthcare systems off guard. Commercially important fish are also changing their territories, taking jobs with them and sparking trade disputes.

Seeking to understand this phenomenon and predict when it will occur for a given species, an international group led by a team from McGill University has identified factors that, over the past few decades, have either facilitated or hindered habitat changes in thousands of species worldwide.

As Jake Lawlor, a Ph.D. student at McGill University and lead author of a recently published article in Nature Reviews Earth & Environment, explains: "In most systems where humans use or interact with other species, it's assumed that the species in question will stay where they are. Due to climate change, we now need to take past and future redistributions into account in conservation and resource management plans."

Rising temperatures, yes... but what else?

The research team found that climate warming could predict the movements of most of the 26,000 species tracked in the global BioShifts database quite well. In fact, 59% of species moved to cooler regions.

However, in a significant percentage of cases, things aren't as clear. Indeed, 41% of species either didn't move at all or didn't go in the direction that warming temperatures would suggest. This indicates that temperature alone isn't the only factor.

The research team wondered if other species-specific or environmental factors could explain these unexpected movements or lack thereof.

"If researchers can understand these contrary shifts, they can create models to predict under what circumstances warming is likely to alter distribution boundaries," explains Jake Lawlor. "Based, for example, on an organism's life cycle, its sensitivity to warming, or landscape characteristics, we might be able to assess the likelihood of it moving, or even predict the paths it might take."

Incomplete data

However, the research team issues a caution: the existing data on distribution changes mainly covers Europe and North America, varies in completeness depending on plant and animal groups, and is nearly nonexistent for marine species. They believe these data should be interpreted with caution.

For instance, redistributions observed in regions with four seasons, such as Europe and North America, don't necessarily apply to regions with alternating rainy and dry seasons; moreover, species might be expected to react differently depending on their dispersal capacity (the ability to establish in a new territory) and growth rates.

"In other words, the average rates and general directions of movement we calculate from observations of birds and insects don't necessarily apply to kelp, crops, or fish. And given climate change, these data would, in many cases, be insufficient for developing conservation plans," notes Jennifer Sunday, lead author of the article and assistant professor in the Department of Biology at McGill University.

According to the research team, closer monitoring of distribution changes is needed to better understand the factors at play and to incorporate them into biodiversity preservation strategies in the era of climate change.

References:
The article “Mechanisms, detection and impacts of species redistributions under climate change” by Jake Lawlor et al in Nature Reviews Earth & Environment
DOI: https://doi.org/10.1038/s43017-024-00527-z