Lecture 23 notes

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Published on 7 Jun 2011
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UTSG
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Biology
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BIO120H1
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BIO120 LECTURE 23
BIODIVERSITY, EXTINCTION, AND CONSERVATION BIOLOGY
E.O. Wilson: founder of biodiversity science
Todays global environmental problems
GLOBAL WARMING & CLIMATE CHANGE
LOSS OF BIODIVERSITY
Environmental pollution
Human famine
Spread of infectious diseases
Human population growth
Keeling: realized greenhouse gas emissions were increasing
Fluctuations because of seasonal changes
How do organisms respong to climate change?
Migration to favourable environment (ecology)
Adapt to environmental conditions (evolution
Extinction (evolution)
Art Weiss : field mustard in southern California
Measured natural selection
oFound evidence for directional selection in two population
oFavoured plants that flowered early
oSet seed
oFlower late, hit by drought and seeds are not set
Resurrection paradigm
Collected seeds in 1997 and 2004 and compared them
Made a cross between them
www.notesolution.com
Biodiversity
Interspecific species diversity
Intraspecific genetic diversity
Loss of biodiversity is irreversible; most important process of environmental change.
Consequences are the least predictable
Most biodiversity is in poor, developing countries tropics
David Tillman: the ecological function of biodiversity
Measuring biodiversity in individual plant plots
Manipulate amount of biodiversity
How resilient are these plots to things such as drought
DIVERSITY GIVES RESILIENCE TO ENVIRONMENTAL PERTURBATION
TYPES OF EXTINCTION
Background extinction – low rate; approx 1 species per year
Mass extinction – due to natural catastrophes
Anthropogenic extinction –caused by humans
Main cause of extinction is habitat destruction
Keystone species
Example: nitrifying bacteria
oMight not have many landscapes
Fig trees in trop forests
oKeep animal pops alive because they produce fruit for a long period of time
MVP
oMinimal viable population size
oNumbers of individuals needed to maintain or increase numbers in a region
oThe smallest pop that can sustain itself suring environmental change
www.notesolution.com
Heterozygosity and fitness:
Everyone has lethal, recessive genes
When pops become smaller inbreeding prevention (inbreeding depression)
oRecessive lethal genes can become homozygous and dominant
oFixation of deleterious genes
Example: cheetah
o52 enzymes indicating monomorphism in gel tests
oCheetahs affected by bad sperm low sperm counts
Genetic result of inbreeding
Population fell population bottleneck
Loss in variability
Inbreeding biggest problem in zoos
oLimited number of founding individuals
oPopulation bottlenecks
oWill animals be able to survive in the wild? Low genetics diversity
o
www.notesolution.com

Document Summary

Today"s global environmental problems: global warming & climate change, loss of biodiversity, environmental pollution, human famine. Spread of infectious diseases: human population growth. How do organisms respong to climate change: migration to favourable environment (ecology, adapt to environmental conditions (evolution, extinction (evolution) Art weiss : field mustard in southern california: measured natural selection, found evidence for directional selection in two population, favoured plants that flowered early, set seed, flower late, hit by drought and seeds are not set. Resurrection paradigm: collected seeds in 1997 and 2004 and compared them, made a cross between them www. notesolution. com. Loss of biodiversity is irreversible; most important process of environmental change: consequences are the least predictable. Most biodiversity is in poor, developing countries tropics. David tillman: the ecological function of biodiversity: measuring biodiversity in individual plant plots, manipulate amount of biodiversity, how resilient are these plots to things such as drought, diversity gives resilience to environmental perturbation.