Unit A Biological Diversity: Section 4.0 Flashcards
What is extinction?
Extinction is the disappearance of every individual of a species from then entire planet
What percent of species do scientist think are extinct?
Scientists estimate that 99% of all the species that have ever existed are now extinct. Extinction is natural.
What were most mass extinctions caused by?
Catastrophic events
When was the last major environmental change?
1.8 million years ago, called the ice age
What is extirpation?
Extirpation is a local extinction or the disappearance of a species from a particular area.
What are endangered species?
Endangered species are ones that are in immediate danger of extinction or extirpation.
What are threatened species?
Threatened species are likely to become endangered if their current declines are not reversed
What are species of special concern?
Species that are of special concern are ones that are particularly vulnerable to natural events or human activities.
Overspecialization
When organisms have adaptations that suit them to only a narrow set of environmental conditions.
Why does overspecialization happen?
This probably happens because the environment that the organism inhabits remains unchanged for a very long time.
What are the natural causes of extinction?
- catastrophic events such as volcanic eruptions, floods, or fires
- lack of food due to overpopulation
- disease
Human causes of extinction and extirpation?
Habitat Destruction
Introduction of Non-Native Species
Over-Hunting
Explain habitat destruction
Construction of buildings, agricultural development, logging, and the damming of rivers all change environments. These activities are necessary to meet human needs
Explain introduction of a non-native species
When introduced species use the same resources as native species, they compete with the native species and cause the number of native species to decline, simply because there is less of everything.
Explain Over-hunting
Over-hunting was the major cause of the decline and eventual extirpation and extinction. Basically when people killed certain species until they all died