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.
Large numbers of ____________ of food species used to be maintained, to _______________________________, keeping genetic diversity high.
- local varieties
- tolerate local conditions
____________________ has favored only a few varieties, resulting in huge ________________________________
- Mass production
- loses of genetic diversity
seed vaults
used to preserve seeds to protect biodiversity
Categories of human activities driving biodiversity decline
- Habitat loss.
- Over-harvesting.
- Species introductions.
- Pollution.
- Global Climate change
Habitat loss is seen as the ______________________________________________
largest driver of human-caused biodiversity decline
__________ of habitat loss are _________ when areas have _________________.
- Impacts
- greater
- high endemism
define Endemism
species distributions that are limited to a small geographic area or ecologically distinct region
Deforestation continues in some regions, but _____________________________________________ that experienced past forest loss from human activity.
forest cover is recovering in some locations
Impact of _______________ has escalated with ________________________.
- over-harvesting
- technological advances
___________________ has outpaced natural ________________________
- Capacity for harvesting
- capacity for recovery
Today, _____________represent the species that are most in _________________________________________ of wild populations.
- fisheries
- danger of extinction from over-harvesting
what is the global pattern regarding collapsed fisheries?
Steady increase in percentage of collapsed fisheries
Introduction is happening at an ___________________________, and in a way that __________________________________________ — immediate introduction in a new range, instead of initial contact zone and geographic spread
- exceptionally high frequency
- differs from natural patterns of invasion
what is shown in documented species introductions
- No sign in slowing down bc of increases
- so extinctions from introduction are likely to increase over time.
define biomagnification
The process by which the concentration of a contaminant increases as it moves up the food chain
____________ are particularly potent as agents of extinction.
Pesticides
why are pesticides potent as agents of extinction?
Toxicity increases as the pesticide travels up the food chain
Each consumer level of the food chain eats ______________________________________________________, with each consumed individual adding to the ____________________ in the body of the consumer
- many individuals from the trophic level below
- toxin accumulation
Human-driven climate change is likely to be ____________________________________ - A very active area of ecological research
quicker than the capacity of many species to move and/or adapt
