Sympatric speciation

Definition

Sympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographical region. This occurs without physical barriers, often driven by factors like ecological niches, behavioral changes, or genetic divergence within a population. Understanding sympatric speciation is crucial as it contrasts with other modes of speciation and highlights the role of biogeographical processes in shaping biodiversity.

5 Must Know Facts For Your Next Test

1. Sympatric speciation can occur through mechanisms like disruptive selection, where extreme phenotypes are favored over intermediate ones, leading to reproductive isolation.
2. One well-known example of sympatric speciation is seen in cichlid fish in African lakes, where different species evolved by adapting to specific niches despite living in the same water body.
3. Polyploidy is a common way through which sympatric speciation happens, especially in plants; this can result from errors during cell division leading to organisms with multiple sets of chromosomes.
4. Behavioral changes, such as differing mating calls or preferences within the same area, can lead to reproductive isolation and thus contribute to sympatric speciation.
5. Unlike allopatric speciation, where geographical barriers separate populations, sympatric speciation emphasizes that new species can emerge without such physical separations.

Review Questions

• How does sympatric speciation differ from allopatric speciation in terms of geographical barriers?
  • Sympatric speciation occurs without geographical barriers, meaning that new species evolve while still inhabiting the same area as their ancestor. In contrast, allopatric speciation requires a physical separation of populations by geographical barriers such as mountains or rivers. This fundamental difference highlights how species can adapt to similar environments through various mechanisms like ecological niches or behavioral differences, leading to new species formation even in close proximity.
• Discuss how polyploidy contributes to the process of sympatric speciation and provide an example.
  • Polyploidy contributes to sympatric speciation by creating individuals with multiple sets of chromosomes that cannot breed with their diploid relatives. This condition is particularly common in plants, where a polyploid individual can occupy a different ecological niche than its parental species. A classic example is found in wheat, which evolved from multiple hybridizations resulting in polyploid forms that led to the development of new wheat species adapted to various environments.
• Evaluate the role of behavioral changes in promoting sympatric speciation and how this might impact biodiversity.
  • Behavioral changes play a significant role in sympatric speciation by facilitating reproductive isolation among individuals within the same environment. For instance, if certain individuals develop distinct mating preferences or feeding behaviors, these differences can lead to reduced interbreeding. This promotes genetic divergence and eventually results in the emergence of new species. Such processes increase biodiversity by allowing multiple species to coexist and adapt to diverse ecological roles within the same habitat, enriching overall ecosystem complexity.

Related terms

Ecological Niche:

The role and position a species has in its environment, including all interactions with biotic and abiotic factors.

Polyploidy: A condition in which a species has more than two complete sets of chromosomes, commonly observed in plants and often leading to sympatric speciation.

Reproductive Isolation: The mechanisms that prevent different species from interbreeding, thus maintaining species boundaries and promoting speciation.