Topic 26 -Conservation: Extinction Flashcards
examples of extinction due to human activities
dodo, passenger pigeon, stellar’s sea cow, Sumatran rhino
what are the three types of extinction
Background Extinction
Mass Extinction
Anthropogenic Extinction
Background extinction
species disappear and others take their place as environmental conditions change
Mass Extinction
dying off large numbers of species as a result of natural catastrophes
Anthropogenic mass extinction
dying off of large number of species as a result of human activities
what have fossils told us about the background rate of extinction
1 species/year
present anthropogenic extinction is ______times the background rate
1000
Extinction is defined
disappearance of all individuals of a species (elimination of a species)
Extirpation
the disappearance of a population of a particular species from a local area (elimination of a population)
a population may be extirpated but the species is not extinct
what are the 6 types of extinction risks
smaller populations have a greater risk of extinction than larger ones
The larger the geographical range of a species- the lower the risk of extinction
the more age structure of a species -the lower risk of extinction
Large, endothermic animals have a lower risk than smaller endothermic animals
ectothermic animals have a greater risk than endothermic animals
k-selected species have a lower population resilience and so an increased risk of extinction
allee effect
with species that derive benefits from naturally aggregating (ie. safety from predators) smaller population sizes can further decrease chance of success
extinction vortex
a cyclic chain of events that result in a small population continuing to get smaller as a result of being small
ubiquitors
widespread over a large area
endemic
only occur in small areas
loss of habitat in one area leads to loss of species
Conservation Biology
an integrative discipline that applies the principles of ecology to the protection of biodiversity
actual scientific discipline only since 1980
international union for the conservation of nature and natural resources
Red list of threatened species
more than 26 000 species at risk of extinction
roughly 1% of species world wide
based off of 5% of described species (VERY LIKELY AN UNDERESTIMATE)
Advantage of the IUCN classification system
provides a standard, quantifiable method of classifying species
what is the problem with the classification system, what do they do to prevent this?
often do not have complete information
precautionary principle -in the absence of complete scientific date, 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
what are the three levels for the IUCN classification system
Critically endangered: have a 50% chance of extinction within 10 years (or 3 generations), whichever is longer
Endangered: have a 20% chance within 20years (or 5 generation)
Vulnerable: have a 10% chance of extinction within 100 years
three different conservation strategies
Ex-situ rehabilitation
Genetic recombination
Habitat management
Ex-situ rehabilitation
raise populations of species in captivity when they become “extinct in the wild” preparing for reintroduction ex california condor
Genetic recombination
mix remnant populations with wild populations of related species with which breeding may occur naturally to preserve genes ex florida panthers
Habitat management
preserve the natural habitat of the threatened species and hope it can restore its population sizes naturally ex prairie chicken
Biodiversity hotspot approach
myers et al. 2000 Nature identified concentrated areas of high species richness “hotspots”
primary based on plant species (reflect insects)
secondary based on vertebrates
myers defined hotspots based on 2 criteria
exceptional concentration of endemic (rare) species
used endemism because of low scientific info on number of species
exceptional loss of habitat -endemic species are highly vulnerable to habitat loss (extirpation can mean extinction)
cost effective way of conserving the largest number of species -with the littlest scientific information
