Extinction occurs when the last existing member of a given species diesIn other words…there aren’t any more left!
Genetics and DemographicsSmall populations = increased riskMutations
Causes a flux in natural selectionBeneficial genetic traits are overruled
Loss of Genetic DiversityShallow gene pools promote massive inbreeding
Habitat DegradationOne of the most influentialHas many causesSome due to humansSome due to other factors
ToxicityKills off species directly through food/waterIndirectly via sterilizationCan occur in short spans (a single generation)Can occur over several generations
Increasing toxicityIncreasing competition for habitat resources
Destruction of Habitat“Save the Rainforests!”Elimination of living spaceChange in habitat
Rainforest to pasture landsLeads to diminishing resources
Increases competitionCan be caused by natural processes
Volcanoes, floods, drought, etc…
Introduction of predatorsInvasive alien speciesTransported by humans
Cattle, rats, zebra muscles, etc…Sometimes on purpose, sometimes not
Can eat other speciesEat food sourcesIntroduce diseases
The loss of one species leads to the loss of another
Chain of extinctionCan be caused by small impacts in the
beginningA predator looses its food sourceAffected by interconnectedness in nature
Aka: an extinction eventA sharp decrease in the number of species on
Earth in a short period of timeCoincides with a sharp drop in speciation
The process by which new biological species arise
There have been at least 5Last one was 65M years ago
Nearly 2/3rds (or more) of all animal species that ever existed on the planet are now gone.
With contemporary extinction being attributed to HUMAN activity.
Numerous factors go into the extinction of a specific species.
Though all point the finger to climate change.
Began about three-million years ago (Continental Glaciations).
Hypotheses for initial extinction:Sea level depletion vs. Temperature decrease
Though these hypotheses aren’t mutually exclusive, they may have conspired together.
1. Cretaceous-Tertiary Extinction (65). 2. End Triassic Extinction (200). 3. Permian Triassic Extinction (250).4. Late Devonian Extinction (364). 5. Ordovician-Silurian Extinction (440).
(#= millions of years ago)
Human controlledThought of to help humansDeadly viruses
SmallpoxExtinct in the wild
PolioNear extinct (only in small parts of the world)
Causes complete devastationFlattening and crater at
or around impact site-hundreds of miles wide
Reverberations felt around the world
Natural factors usually occur at a slower rate and therefore cause a low extinction rate. Human activities occur at a faster rate and cause higher extinction rates. Human activities are mostly responsible for the present extinction rates.
http://www.gov.mb.ca/conservation/sustain/extinct.pdf
Top Human Causes of Extinction:
Increased human population
Destruction/Fragmentation of habitat
Pollution
Climate change/Global warming
Based on these, and other studies done by The international Union for Conservation of Nature and Natural Resources (IUCN), human induced extinctions are not necessarily a new phenomena. However, extinction by humans today is becoming much more rapid.
The rapid loss of species today is estimated by some experts to be between 100 and 1,000 times higher than the natural extinction rate, while others estimate rates as high as 1,000-11,000 times higher.
Habitat Degradation
Habitat loss and degradation affect 86% of all threatened birds, 86% of mammals and 88% of threatened amphibians
Biodiversity is the variation of taxonomic life forms for a given biome or ecosystem
Boosts Ecosystem productivityMeasure of the health of a biological
system
Food and drinkMedicinesIndustrial materialsEcological servicesLeisurely, cultural, and aesthetic values
PollutionLoss of tropical forestSpread of urban areasWarfareLarge dam
constructionRoad buildingTourismLoss of traditional
lifestyles
Loss of foodDecrease in biomassCollapse of food webLoss of keystone speciesReduction of ecosystem
efficiency and community productivity
Loss of medicinal supplies
Increased vulnerability of species to disease and predation
Monoculture of crops lets the yield become susceptible to pests or viruses 75% of crop varieties are extinct Due to the spread of modern agriculture