BI SC 002 Lecture Notes - Lecture 39: Background Extinction Rate, Habitat Destruction, Speciation

• School: PSU
• Department: Biological Science
• Course: BI SC 002
• Professor: Louise Mc Gibbon

Document Summary

All members of a species have died. Root of extinction is always the same: the rate of evolution fails to meet the pace of environmental change. Can result form a variety of external triggers: examples: Background extinction rate : refers to the steady gradual loss of species due to: Fossil record indicates the rate is between 0. 1 to 1. 0 extinctions per year: per million species. In earth"s history: there have been 5 major mass extinctions. Huge numbers of species eliminated in a relatively short period of time. Have a major influence in terms of: creating vast new habitats. The few species that survive can: come forward, diversify in this new environment. Tectonic plate movements can explain some mass extinctions. Earth"s crust is made up of plates : gradually move in response to forces deep within the planet. Since the time of pangea, significant changes have taken place: climate, habitat. Species fail to adapt to radically different habitats.