Lecture 24: Biodiversity & Global Ecology: Biodiversity and humans Flashcards
To understand modern patterns of biodiversity decline, we must ______________________________________________
understand historical patterns of extinction
The historical pattern of extinction is one of a relatively ___________________________ punctuated by _______________________.
- low level of background extinction
- mass extinction events
There have been ______________________________________ in the history of life on earth.
five documented mass extinctions
define mass extinction
The extinction of 75% or more of existing species over a period of 2 million years or less
_____________________________________, but, _____________ evolve, and __________________________ are established.
- Existing ecological systems collapse
- new species
- new ecological systems
Nevertheless, __________________________________________ than at any other period in history
more species are coexisting on earth today
History of biodiversity is one of __________________. But, _______________________________________, because the ______________________________________________________.
- collapse and recovery
- few individual species make it through a biodiversity collapse
- ecological systems they depend on also collapse
The ______________________________________, the _______________________________________________ is likely
- larger the extent of the extinction
- more the collapse of ecological systems
What happened to mammal biodiversity after the arrival of humans?
- Lower species richness of mammals in the presence of humans.
- Stronger divergence at smaller scales = more local extinctions?
____________ have been established to _____________________.
- New efforts
- track extinction
categories for how close species are to extinction defined by International Union for Conservation of Nature
- extinct
- extinct in the wild
- threatened
- near-threatened
- least concern
categories for how close species are to extinction - extinct
known to be in the wild in the year 1500 (recent recorded human history) but no individuals are known to be alive today
categories for how close species are to extinction - extinct in the wild
Only known individuals are in captivity
categories for how close species are to extinction - threatened
Populations at high risk of extinction
categories for how close species are to extinction - near-threatened
Species likely to become threatened soon
categories for how close species are to extinction - least concern
Currently show no sign of population decline.
We are now monitoring extinction status in real-time. Some groups are particularly well known and therefore ______________________.
good for monitoring
what is found when monitoring non-extinction categories
- Threatened status differs substantially among groups.
- High proportion in some threatened status across groups
- Status of fish is particularly concerning for humans in near-term
experimental reduction in plant species richness results in what?
less plant biomass in the ecological system
what happens to primary production as biodiversity declines?
Primary production is lost as biodiversity declines
Biodiversity loss means ____________________
less genetic diversity
_________ genetic diversity means _________________ for long-term survival.
- Lower
- less variation
Humans rely primarily on _________________________________ (cows, pigs, sheep, goats, buffalo, horses, and donkeys) for food and labor, and _______________ (chickens, turkeys, ducks, and geese)
- seven species of mammals
- four species of birds
Worldwide, original wild species are extinct or unknown, and many domesticated breeds are now extinct. — _________________________________________________________
We rely on a small number of genetically inbred breeds for much of our food.
