Dispersal vs Vicariance: Difference and Comparison

Key Takeaways

1. Definition: Dispersal is the movement of organisms to new areas, while vicariance involves the separation of populations by barriers.
2. Mechanisms and Factors: Dispersal occurs through various means, while geological or climatic events drive vicariance.
3. Implications: Dispersal allows colonization and gene flow, while vicariance can lead to speciation and shape species distribution.

What is Dispersal?

Dispersal refers to the movement of individuals or propagules (such as seeds, spores, or larvae) from their birthplace to a new location where they establish a new population. Dispersal can occur through various means, including migration, wind, water, or hitchhiking on other organisms.

Dispersal is an essential process in ecology and evolution because it affects populations’ distribution and genetic diversity. It can allow people to colonize new areas, escape from unfavorable conditions, or increase genetic diversity by mixing populations.

Dispersal can occur over short or long distances and can be either active (such as walking or flying) or passive (such as being carried by wind or water). Different organisms have different dispersal abilities and strategies, which can influence their survival and success in different environments.

What is Vicariance?

Vicariance is a process in biogeography that occurs when a previously continuous geographic range of a species or group of organisms is split by a barrier such as a mountain range, sea, or other physical or environmental factors. This separation can lead to the divergence of the two populations on either side of the barrier as they adapt to their different environments and accumulate genetic differences over time.

Vicariance is contrasted with dispersal when organisms move from one place to another without a barrier or geographical separation. In vicariance, the geographical separation of populations is the result of long-term geological or climatic changes, such as tectonic movements or changes in sea levels.

Difference Between Dispersal and Vicariance

1. Dispersal involves the active or passive movement of individuals or propagules from one location to another, while vicariance results from a previously continuous range’s physical or environmental separation.
2. Dispersal can occur at any point in an organism’s life cycle, while vicariance is a historical process that occurred in the distant past.
3. Dispersal can occur over short or long distances, while vicariance involves the separation of populations over large geographical areas.
4. Dispersal can result in the mixing of populations and the transfer of genetic variation between them. At the same time, vicariance can lead to the divergence of populations and the accumulation of genetic differences over time.
5. Dispersal can allow organisms to colonize new habitats or escape from unfavorable conditions. At the same time, vicariance can lead to the formation of distinct biotic regions and the evolution of unique ecological communities.

Comparison Between Dispersal and Vicariance

Parameters of Comparison	Dispersal	Vicariance
Definition	Can frequently occur throughout the lifespan of individuals	Separation of a previously continuous range due to a barrier or environmental change
Frequency	Can occur frequently throughout the lifespan of individuals	Typically a historical process that occurred in the distant past
Distance	Can occur over short or long distances	Typically involves the separation of populations over large geographical areas
Cause	Can be due to various factors such as resource availability or competition	Often due to geological or climatic changes
Ecological Impact	Can lead to the formation of new populations in new areas or the mixing of genetic variation between populations	Can lead to the divergence of populations and the formation of distinct biotic regions and ecological communities

References

1. https://www.sciencedirect.com/science/article/pii/S1055790306000935
2. https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-8137.2006.01795.x