Biology 2485B Lecture 20: Species Extinction

68 views10 pages

Document Summary

Spe(cid:272)iatio(cid:374) is o(cid:374)ly o(cid:374)e pa(cid:396)t of the e(cid:395)uatio(cid:374) that (cid:272)o(cid:374)t(cid:396)i(cid:271)utes to ea(cid:396)th(cid:859)s spe(cid:272)ies di(cid:448)e(cid:396)sity. Extinction: the disappearance of a species from earth, extinction is irreversible: once a species is lost, it is lost forever, but is currently occurring at accelerated rates as a result of human activities. Extirpation: the disappearance of a species from one part of its normal range. Population dynamics: population growth rate = births + immigration - deaths - emigration, the balance of these processes determines whether the population grows, stays the same, or declines. Major current threats to biodiversity decrease births and increase deaths. Invasive species: habitat alteration (loss, fragmentation, degradation, pollution, overharvesting, climate change. Other reasons why a population might not rebound when its size is pushed too low: random demographic events (e. g. , skew in sex ratio, genetic effects (loss of genetic variation and inbreeding) **these can also set up positive feedback loops that reduce population size further.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents