Biogeography Flashcards
What does the geological record indicate?
5 mass extinction events
What is most recent extinction event?
K-Pg event marking end of Cretaceous and beginning of Tertiary period
Despite mass extinction,
species diversity has increased over time and extinction rates were generally low
What are modern extinction rates?
100-1000x higher than the average rate across the last 1/2 billion years
What is modern extinction mainly attributed to?
human activity
What is the latitudinal gradient?
species richness higher near equator
What are the biographic regions?
-Holarctic
- Holotropical
- Aostral
What is holarctic?
neoactic and paleacrtic
What is holotropical?
neotropical, afrotropical, oriental, austrotropical
What is aostral?
antarctica plus most southernly reaches of South America, Africa, and Australopacific islands
How is biodiversity assessed?
by destructive and non-destructive techniques
What is alpha diversity also called?
local
What is alpha diverity?
number of species in a particular location
How is alpha diversity sampled?
locale is sampled until further sampling effort fails to reveal new species
How can alpha diversity be addressed?
asymptote can help determine the max sample size needed to find nearly all of the species
What is the target of alpha diversity?
sample enough so that 95% of the species are recorded
What is beta diversity?
measure of variation in diversity among locales within a region
What is beta diversity related to?
species turnover (species differences among locales)
What may be more constrained (beta diversity)
species within narrow niches (or with less mobility) compared to species with wider niches (or more mobility)
What does gamma diversity mean?
all of the species in the region
What is gamma diversity affected by?
primarily by immigration and speciation
What does threatened mean?
may not survive without human intervention
What does endangered mean?
cannot survive without human intervention
What are the top extinction threats?
- habitat loss
- direct exploitation
- invasive species
Why should people care about extinction?
- to protect our “genetic library”
- to benefit from ecosystem services
- for esthetic and ethical obligations
What is conservation biology?
study of threats to biodiversity, and means to promote its maintenance and to enable restoration
What is the focus of island biogeography?
focus is on ecological reasons for variation in species diversity on islands
What are islands?
any isolated habitable areas surrounded by relatively inhospitable areas
What does species area curves do?
relate island size to the number of species found
What 3 processes interact to determine species number on islands
immigration, extinction, and evolution