Why do California and Chile have scrublands with similar structures but different ancestral species?

California and Chile possess scrublands with remarkably similar structures despite being geographically isolated and composed of different ancestral species because of a process known as convergent evolution.12

In this process, unrelated species living in similar physical environments are shaped by natural selection to develop comparable morphological, physiological, and life-history characteristics. Because both California and Chile feature a Mediterranean climate—characterized by mild, moist winters and hot, dry summers—the environmental pressures on their vegetation are nearly identical.3451

As a result, plants in both regions have evolved to become "ecological equivalents". They share similar adaptations, such as the development of sclerophyll vegetation (hard, leathery foliage) to minimize water loss during the arid summer months. Research comparing these regions has revealed that this convergence extends beyond individual plant morphology to include the overall structure of the vegetation, patterns of plant physiology, and the adaptations of associated fauna. These similarities demonstrate how consistent environmental demands can drive evolution toward parallel outcomes, even when starting from different ancestral lineages.2416