Evidence That Metapopulation Dynamics Maintain a Species' Range Limit.

Area of Science:

• Ecology
• Biogeography
• Plant Science

Background:

• The metapopulation hypothesis suggests that variations in local extinction and colonization rates can create abrupt species range limits.
• Understanding range limits is crucial for predicting species responses to environmental change.

Purpose of the Study:

• To investigate the role of metapopulation dynamics in shaping the northern range limit of Camissoniopsis cheiranthifolia.
• To quantify habitat availability and rates of colonization and extinction across the species' northern range.

Main Methods:

• Field surveys across 3485 plots to assess habitat suitability and plant abundance.
• Statistical analysis of colonization and extinction rates in relation to habitat and proximity to occupied plots.
• Development and application of a metapopulation model incorporating spatial variation in dynamic rates.

Main Results:

• Colonization rates increased with suitable habitat area and nearby plant abundance, declining towards the species' northern range limit.
• Extinction rates were higher in plots with less habitat and lower initial abundance but did not show a significant trend towards the range limit.
• The metapopulation model accurately predicted the observed decline in plot occupancy towards the range limit.

Conclusions:

• Spatial variation in metapopulation dynamics, particularly declining colonization, contributes to the northern range limit of Camissoniopsis cheiranthifolia.
• Habitat availability and local population density are key drivers of colonization and, consequently, range boundaries.