Question

Species that have overlapping geographic ranges but do not interbreed in nature are said to be a. geographically isolated. b. reproductively isolated. c. influenced by genetic drift. d. hybrids.

Short answer

b. reproductively isolated.

Step-by-step solution

Understand the concept

Species that occupy the same geographic area but do not interbreed are not prevented from doing so by physical barriers. Instead, the reason they do not interbreed must be explored.

Define the options

Look at the definitions: a) Geographically isolated: Physical barriers separate populations. b) Reproductively isolated: Biological factors prevent interbreeding. c) Influenced by genetic drift: Random changes affect gene frequencies in small populations. d) Hybrids: Offspring of crosses between different species.

Process of elimination

Eliminate the options that don't fit the situation. Since the geographic ranges overlap, they can't be geographically isolated. Genetic drift doesn't address breeding directly. Hybrids would imply interbreeding occurs.

Identify the correct term

With other options ruled out, the term 'reproductively isolated' fits best. This term means that despite overlapping ranges, biological barriers prevent them from interbreeding.

Conclusion

The species are prevented from interbreeding due to reproductive isolation, not geographical isolation, genetic drift, or hybridization.

Key concepts

species interbreeding

Species interbreeding means that two different species are capable of reproducing together. In biology, interbreeding is often a sign that the species may share a close genetic relationship. However, some species with overlapping habitats do not interbreed. When interbreeding does not occur despite geographic proximity, it's usually due to certain biological factors. These factors are explored in concepts like reproductive isolation. Interbreeding can lead to the creation of hybrids, but even in overlapping geographic ranges, various mechanisms can prevent this. Understanding why interbreeding does or does not happen is key to studying species diversity.

geographic overlap

Geographic overlap occurs when two or more species share the same physical space or habitat. This can happen in many environments, such as forests, oceans, or grasslands. Despite living in the same location, geographic overlap does not guarantee that species will interact or interbreed. Some species evolve to coexist without mating due to different behaviors, ecological niches, or reproductive strategies. This phenomenon is crucial in studying ecosystems and how different species maintain their identities and contribute to biodiversity. It's important to recognize how geographic overlap differs from geographic isolation, where physical barriers like mountains or rivers keep species apart.

biological barriers

Biological barriers are mechanisms that prevent species from interbreeding, despite geographic overlap. These barriers can be prezygotic, meaning they occur before fertilization, or postzygotic, meaning they occur after fertilization. Examples of prezygotic barriers include temporal isolation, where species breed at different times, and behavioral isolation, where differences in mating rituals prevent mating. Postzygotic barriers might involve hybrid inviability, where the hybrid offspring do not survive, or hybrid sterility, where the hybrid cannot reproduce. Reproductive isolation is often the result of these biological barriers, which help maintain the integrity and identity of species by preventing the mixing of gene pools. These barriers are essential for understanding how species evolve and remain distinct.