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Lecture 12

Lec12 - Conservation of Biodiversity.docx

Biological Sciences
Course Code
Mary Olaveson

of 4
Conservation of Biodiversity
1 conservation of biodiversity
What is biodiversity
What is extinction?
What is conservation biology?
What strategies do conservation biologists use?
2 what is biodiversity?
Biodiversity = sum total of all organisms in an area including:
o Diversity of species
o Genes
o Communities
o Ecosystems
Biodiversity determined by
3 what is extinction?
The disappearance of an entire species from earth
Occurs when a species cannot adapt quickly enough to a changing environment
o Extinction is a natural process
It is irreversible
Average time for a species on earth is ~1 10 million years
Species currently on earth
o the number formed by speciation number formed by extinction
i.e. speciation extinction
4 background extinction rate
extinction usually occurs one species at a time
earth has had several mass extinctions
o ~ five events in earth’s history that killed off massive numbers of species at once
50 95% of all species went extinct
Four of five events due to climatic / tectonic / geological events
Ordovician period
Devonian period
Permian period
Triassic period
One of five events was due to asteroid impact
o i.e. extraterrestrial means
o at the end of cretaceous period (K)
5 asteroid impact
asteroid impact killed off dinosaurs
led to the rise of mammals
6 projected sixth mass extinction
due to human impact
o concern that humans may cause the extinction of many species
o current extinction rate is higher than background rates
o resource depletion
habitat destruction
invasive species
resource overexploitation
network disruption
o population growth
o development / consumption
e.g. tropical forests
contain some of the greatest concentrations of species
are being destroyed at an alarming rate
7 most species loss can be traced to four major threats from humans
habitat destruction
invasive species
overexploitation of resources
disruption of interaction networks
8 habitat destruction
human alteration of habitat is the single greatest threat to biodiversity throughout the biosphere
massive destruction of habitat brought about by many types of human activity
many natural landscapes have been broken up
o fragmenting habitat into small patches
in almost all cases
o habitat fragmentation and destruction leads to loss of biodiversity
9 habitat destruction
species confined to islands vulnerable to extinction because they are not used to predators
10 invasive species
species that humans move the locations of species’ native locations to new geographic regions
gains foothold in new habitat
disrupts adopted community because it has no predator
11 overexploitation
refers to human harvesting of wild plants or animals at rates exciting ability of populations of those
species to rebound
12 overexploitation
species reductions / extinctions due to
o over fishing of desired species
o over hunting of game
13 disruption of interaction networks
extermination of keystone species by humans
o climate change pollution etc
can lead to major changes in community structure
14 what is conservation biology
integrates many fields of biology to conserve biological diversity at all levels
appreciate that biodiversity is crucial natural resource needed for proper ecosystem structure and
o loss of species means loss of genes and genetic diversity
o enormous species diversity of organisms on earth has potential for great human benefit
crops / fibres/ medicines
o many pharmaceuticals contain substances originally derived from plants
15 what strategies do conservation biologists use?
Biologists focuse on conservation at population / species levels
Small population approach
o Focuses on processes that can cause very small populations to become extinct
E.g. endemic species
16 biologists focus on conservation at population and species levels
Declining population approach
o Focuses on threatened and endangered populations that show a downward trend;
regardless of population size
o Emphasizes environmental factors causing population decline
17 biologists classify species in order to decide proper action