Topic 26 Flashcards
Extinction of animal and plant species is often linked to..
human activities
3 types of extinction
- background extinction
- mass extinction
- anthropogenic mass extinction
Background extinction
species disappear and others take their place as environmental conditions change
Mass extinction
dying off of large numbers of species as result of natural catastrophes
Anthropogenic mass extinction
dying off of a large numbers of species as a result of human activities
Information from fossil record (long term perspective) tells us
- background rate: 1 species/year
- present anthropogenic
Extinction
disappearance of all individuals of a species (elimination of a species)
Extirpation
the disappearance of population of a particular species from a local area (elimination of a population)
A population may be extirpated but..
spices is not extinct
Extirpation is a natural process that expresses the..
failure of a species to adapt to changing environmental conditions (change may happen too quick for adaptions to occur)
Deaths > births =
populations decline r < 0
Smaller populations have a greater risk of extinction than larger ones because
genetic drift, inbreeding and the allee effect
Allee effect
with species that derive benefits from naturally aggregating smaller populations sizes can further decrease their chances of success
Extinction vortex
cyclic chain of events that result in small population continues to get smaller as a result of being small
The larger the geographical range of a space the lower..
risk of extinction
Ubiquitous
widespread over larger area
Endemic
only occur in a small area
Loss of habitat in one region leads to
loss of the species
The more age structure of a species the lower
the risk of extinction
European shag
Farne islands (England) 1968 fish abundance decline an most parents and offspring died. age structure buffered extinction
Large endothermic animals have a lower risk of
extinction than smaller endothermic animals
Ectothermic animals have a higher risk of ..
extinction than endothermic animals
K selected species have a lower…
population resilience and so an increases risk of extinction
Conservation biology
integrative discipline that applies the principles of ecology to the protection of biodiversity (actual scientific discipline only since 80s)
International union fro the conservation of Nature and Natural resources (IUCN)
Red list of species. >26,000 species at risk of extinction and 1% of species worldwide. but based on 5% of described species (so likely an understatement)
Advantage of the IUCN classification system
provides a standard quantifiable method of classifying species
Problem of IUCN classification system
often don’t have complete information
Precautionary principle
absence of complete scientific data, uncertainty will not be used as a reason to postpone conservation efforts of species when the species is faced with the threat of serious or irreversible harm
Defining the extinction risk of species is important for species
conservation on a global scale
3 levels of IUCN classification
- critically endangered
- endangered
- vulnerable
Critically endangered
have > 50% of chance of extinction within 10 years (or 3 generations)
Endangered
have 20% change within 20 years (or 5 generations)
Vulnerable
have >10% chance of extinction within 100 years
3 conservation strategies
- habitat management
- genetic recombination
- ex-situ rehabilitation
Habitat management
preserve the natural habitat of the threatened species and hope it can restore its population sizes naturally (prairie chicken)
Genetic recombination
mix remnant populations with will populations of related species with which breeding may occur naturally to preserve genes (Florida panthers)
Ex-situ rehabilitation
raise populations of species in captivity when they become extinct in the wild preparing them for reintroduction (california condor)
Function based biodiversity species
keystone species: conserve the species that are active determinants of biological structure
Non function based species
- endangered/threatened species
- indicator species
- flagship species
Indicator species
status reflects the status of other species
Flagship species
cute and cuddle, gets publics attention
Protect target areas which have
high biodiversity
Biodiversity hotspot approach
Myers 2000. Identified concentrated areas of high species richness
Primary biodiversity hotspot approach based on
plant species assuming would reflect insect species.
Secondary biodiversity hotspot approach based on..
vertebrate spices (birds, mammals, etc)
Defined hotspots based on 2 criteria
- exceptional concentration of endemic (rare) species
- exceptional loss of habitat
Exceptional concentration of endemic species used endemism because of low
scientific inforuairton on number of species
Endemic species are highly..
vulnerable to habitat loss
Biodiversity hotspot approach is the most..
cost effective way of conserving the largest number of species with littlest scientific information
