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Most species are found only in certain parts of the world, with clear boundaries marking where their populations begin and end. Scientists have long wondered why these geographic limits exist, often assuming species don’t occur where they can’t survive, or occupy habitats they can’t reach.

A new study led by Chris Eckert (Biology) and Master’s students Graydon Gillies and Michael Dungey provides the first-ever evidence to support a different explanation, and their findings could reshape how scientists and conservationists understand the boundaries of where species live, and how to protect them in a changing world. 

To better explain what might truly determine range limits, Eckert, Gillies, and Dungey set out to explore a more nuanced hypothesis called metapopulation dynamics, which looks at how species occupy scattered patches of suitable habitat within their range limits.

“Metapopulation dynamics suggests that a species doesn’t occupy all suitable patches of habitat at the same time,” says Gillies. “To persist on a landscape, a species must colonize vacant patches of suitable habitat at least as fast as it goes extinct from patches it occupies. We set out to test the idea that this balance breaks down near the edges of a species’ range.”

The team studied the Pacific coastal plant C. cheiranthifolia (beach evening primrose), tracking its presence across more than 900 kilometres of coastal dunes, from San Francisco to its northern range limit in southern Oregon. They observed that habitat colonization of new habitat patches occurred less frequently near the range limit, supporting the idea that metapopulation dynamics play a key role in shaping where species boundaries form.
 

What does this mean for conservation and species protection?

As climate change causes temperatures to rise, many species are expected to shift their range limits northward. With the team’s new observations about how these limits are determined, we could use it to help adapt our approaches to environmental conservation.

“Our findings show that protecting species means more than just preserving where they live now,” says Eckert. “We also need to safeguard nearby vacant habitat that could support future populations in an evolving climate.”

This task is especially challenging in southern Canada, where most Canadian species at risk already meet their northern range limits, and where suitable habitats are already heavily fragmented by urbanization and agriculture. As species shift northward to survive, they will need access to nearby, connected habitats. Without this continuity, they may not be able to colonize new areas quickly enough to offset losses in parts of their range where changing conditions are driving them to extinction.

By uncovering new insights into where species live and why, Eckert, Gillies, and Dungey hope their findings help support efforts to preserve biodiversity as natural environments continue to change.

To learn more about research by Gillies, Dungey, and Eckert visit their .