Adaptive Radiation
Adaptive radiation refers to the evolutionary process in which a single species diversifies into multiple species, each adapted to occupy different ecological niches. It occurs when a species encounters new and diverse environmental conditions, leading to the development of various adaptations that allow it to exploit these new resources.

Key Points:
- Adaptive radiation occurs when a single ancestral species gives rise to multiple descendant species.
- It is driven by environmental changes and the availability of new ecological niches.
- Adaptive radiation leads to the formation of species with different traits and adaptations to exploit various resources.

Process and Examples:
- Adaptive radiation starts with a common ancestor species that colonizes a new environment or encounters new ecological opportunities.
- Over time, the descendants of the ancestral species undergo divergent evolution, developing unique adaptations to exploit specific resources.
- This process often leads to the formation of different species with distinct characteristics.
- An example of adaptive radiation is the evolution of Darwin's finches in the Galapagos Islands. The common ancestor of these finches arrived on the islands and diversified into multiple species with different beak shapes, allowing them to feed on various food sources.

Divergent Evolution
Divergent evolution refers to the process in which two or more species with a common ancestor evolve and accumulate differences over time, resulting in the development of distinct characteristics and adaptations. It occurs when species face different environmental pressures or occupy different ecological niches, leading to their divergence from a common ancestor.

Key Points:
- Divergent evolution occurs when species with a common ancestor become increasingly different from each other over time.
- It is driven by environmental factors, natural selection, and genetic variation.
- Divergent evolution leads to the formation of new species with unique traits and adaptations.

Process and Examples:
- Divergent evolution begins with a common ancestor species that splits into multiple lineages due to environmental changes or the occupation of different ecological niches.
- Each lineage faces distinct selection pressures, leading to the accumulation of genetic variations and the development of unique traits.
- Over time, these differences can become significant enough for the lineages to be classified as separate species.
- An example of divergent evolution is the evolution of the polar bear and the brown bear from a common ancestor. The polar bear adapted to the Arctic environment, developing traits such as a white fur coat and webbed feet, while the brown bear retained its characteristics adapted for other habitats.

In summary, adaptive radiation refers to the diversification of a single species into multiple species, each adapted to different ecological niches. Divergent evolution, on the other hand, describes the accumulation of differences between species with a common ancestor. Both processes are driven by environmental factors and natural selection, leading to the formation of new species with distinct characteristics and adaptations.