What is a characteristic of a ring species?

A ring species is a fascinating evolutionary concept that illustrates the complexities of speciation and genetic variation across populations. The characteristic identified is that adjacent populations can interbreed, but not the end populations. This scenario typically arises when populations of a species are distributed around a geographical barrier, forming a 'ring.'

As these populations spread in a circular manner, they may gradually diverge genetically due to differing environmental pressures and mutations. While neighboring populations can interbreed, it is often the case that the populations located at either end of the spectrum have diverged sufficiently over time that they can no longer produce viable, fertile offspring when they come into contact. This phenomenon results in a situation where genetic continuity is maintained among nearby populations, but the endpoints of the ring exhibit reproductive isolation despite being physically connected through the surrounding populations.

The other options do not accurately describe the complexities of ring species. For instance, stating that all populations can interbreed simplifies the biology of these species and overlooks the significant genetic divergence that can occur. The idea that all populations are geographically isolated contradicts the nature of a ring species, as they are inherently connected geographically. Lastly, the assertion that they exhibit no genetic variation overlooks the rich diversity present across the populations, which is essential to understanding how evolution operates