Sympatric speciation

Definition

Sympatric speciation is the process by which new species evolve from a single ancestral species while inhabiting the same geographic region. This form of speciation often occurs due to factors like polyploidy, habitat differentiation, and sexual selection that lead to reproductive isolation without physical barriers. As a result, populations may adapt to different ecological niches or develop distinct mating preferences, ultimately giving rise to new species within the same area.

5 Must Know Facts For Your Next Test

1. Sympatric speciation is particularly common in plants, where polyploidy can lead to immediate reproductive isolation and the formation of new species.
2. Habitat differentiation can cause sympatric speciation when subpopulations exploit different resources or occupy distinct habitats within the same area.
3. Sexual selection plays a key role in sympatric speciation as preferences for different traits can lead to reproductive isolation among individuals in overlapping populations.
4. In many cases, sympatric speciation involves gradual changes over time rather than sudden shifts, making it harder to observe in nature compared to allopatric speciation.
5. Examples of sympatric speciation can be found in cichlid fish in African lakes, where diverse feeding strategies and mating preferences have led to a rich variety of species in a single habitat.

Review Questions

• How does polyploidy contribute to sympatric speciation, particularly in plant species?
  • Polyploidy contributes to sympatric speciation by creating individuals with multiple sets of chromosomes, which can lead to instant reproductive isolation. In plants, when a diploid individual undergoes a mistake during cell division, it can produce a tetraploid that cannot successfully breed with its diploid ancestors. This chromosomal difference effectively creates a new species that can occupy the same environment as its progenitor without competing for mates.
• Discuss the role of habitat differentiation in driving sympatric speciation within the same geographical area.
  • Habitat differentiation drives sympatric speciation by allowing subpopulations within the same geographic area to exploit different ecological niches. When these groups adapt to their specific environments or resource uses, they may develop unique traits that help them thrive. Over time, these adaptations can lead to reproductive isolation due to varying preferences for mates or breeding habitats, resulting in the emergence of new species.
• Evaluate how sexual selection influences reproductive isolation in sympatric speciation and provide examples of this process.
  • Sexual selection influences reproductive isolation in sympatric speciation by favoring individuals that exhibit traits preferred by mates within specific subpopulations. For instance, if a group of organisms starts favoring particular colors or patterns during mate selection, those traits may become pronounced over generations. This preference creates two distinct groups within the same area that do not interbreed due to differing mate choices. An example can be seen in various butterfly species where color patterns influence mate attraction and ultimately lead to speciation.

Related terms

Polyploidy: The condition of having more than two complete sets of chromosomes, which can lead to the formation of new species, especially in plants.

Ecological niche: The role or function of an organism within its environment, including how it obtains resources and interacts with other organisms.

Reproductive isolation: A collection of mechanisms that prevent interbreeding between different species, maintaining distinct species over time.