Seed and pollen flow in expanding a species' range

Area of Science:

• Ecology
• Evolutionary Biology
• Population Genetics

Background:

• Species range expansion involves distinct gene flow mechanisms via seeds and pollen.
• Seed dispersal initiates colonization, followed by combined seed and pollen flow effects.
• Understanding these processes is crucial for predicting species' responses to environmental changes.

Purpose of the Study:

• To investigate the influence of seed and pollen gene flow on shaping species distribution in a one-dimensional model.
• To differentiate the roles of seed and pollen flow in the context of species range expansion.

Main Methods:

• Theoretical modeling of gene flow in one-dimensional space.
• Analysis of seed and pollen dispersal dynamics.
• Simulation of adaptive and maladaptive gene introgression.

Main Results:

• Pollen flow accelerates range expansion when immigrating genes are adaptive.
• Maladaptive immigrating genes via pollen can contract species' ranges.
• Incomplete purging of maladaptive genes at the gametophyte stage creates barriers to expansion.
• Linkage disequilibrium amplifies the negative effects of maladaptive gene flow.

Conclusions:

• Pollen flow's impact on range expansion is context-dependent, influenced by gene adaptiveness.
• Genetic factors, particularly maladaptive gene flow, can significantly limit species' geographic distribution.
• Theoretical insights clarify pollen flow's role, even in non-colonizing scenarios, for range dynamics.