Glossary
Adaptive Radiation
The rapid diversification of a lineage into many new forms, often occurring when new habitats become available or after mass extinction events, filling vacant ecological niches.
Example:
After the extinction of dinosaurs, mammals underwent a period of adaptive radiation, evolving into a vast array of forms to occupy the newly available ecological roles.
Biodiversity
The variety of life on Earth at all its levels, from genes to ecosystems, determined by the balance between speciation and extinction rates.
Example:
Protecting rainforests is crucial for maintaining global biodiversity because these ecosystems harbor an immense number of unique plant and animal species.
Cretaceous-Paleogene Extinction
A mass extinction event that occurred about 66 million years ago, famously leading to the extinction of non-avian dinosaurs, primarily caused by a large asteroid impact.
Example:
The impact that triggered the Cretaceous-Paleogene Extinction created a global 'nuclear winter' effect, blocking sunlight and collapsing food chains.
Ecological Stress
Environmental changes or pressures that make it difficult for species to survive and thrive within their ecosystem.
Example:
When a forest experiences prolonged drought, the trees and animals face significant ecological stress, potentially leading to widespread die-offs.
Extinction
The complete termination of a species, which can occur naturally but is currently accelerated by human activities.
Example:
The dodo bird's disappearance from Mauritius is a classic example of human-driven extinction due to overhunting and habitat destruction.
Niche
The specific role or functional position of a species within an ecosystem, including its habitat, resource use, and interactions with other species.
Example:
A hummingbird's niche involves pollinating specific flowers while feeding on their nectar, a role no other local bird might fill.
Permian-Triassic Extinction
The most severe mass extinction event in Earth's history, occurring approximately 252 million years ago, primarily caused by massive volcanic eruptions.
Example:
Scientists believe the 'Great Dying' Permian-Triassic Extinction led to the loss of over 90% of marine species, fundamentally reshaping life on Earth.
Speciation
The evolutionary process by which new and distinct species are formed from existing ones, often through reproductive isolation.
Example:
The diverse finch species on the Galápagos Islands are a prime example of speciation, as different populations adapted to unique food sources on each island.