Download Biodiversity Diversity 10/27/2014

10/27/2014
Biodiversity
October 27, 2014
Mr. Alvarez
Diversity
Ecosystem Diversity- the variety of
ecosystems within a given region
Species Diversity- the variety of species in a
given ecosystem
Genetic Diversity- the variety of genes within
a given species
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How Many Species Are There?!?!
• Scientists have currently named 2 million
species
• Current estimates of the total number of
species range from 5 million to 100 million
• Most Scientists agree the estimate is close to
10 million species
Richness vs Evennesss
Species Richness- the number of different species
in an area
Species Evenness- the measure of whether a
particular ecosystem is numerically dominated by
one species or are all represented by similar
numbers of individuals.
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Phylogenies
• Phylogenies- The branching patterns of
evolutionary relationships
Forest
ECOTONE
Species Richness & Edge Effect
Grassland
Where edge effect occurs
Typically greater species richness
Forest Ecotone
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Evolution
 Evolution- a change in the genetic composition of
a population over time
 Microevolution- Evolution below the species
level
Evolution of different varieties of apples or potatoes
 Macroevolution- Evolution which gives rise to
new species or new genera, family, class or phyla.
Genetic Diversity
Genes- physical locations on chromosomes
within each cell of an organism
Nucleus  Chromosomes  Strand of DNA  Genes
Genetic Diversity cont.
Genotype- the complete set of genes in an
individual
Mutation- a random change in a genetic code
Most of the time bad
Sometimes they do nothing
Very rarely can be beneficial
**In order for a mutation to be passed down,
the mutation must occur to sperm or egg.
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Recombination
Recombination- occurs as chromosomes are
duplicative during reproductive cell division
and a piece of one chromosome breaks off
and attaches to another chromosome
Phenotype
• Phenotype- the actual set of traits expressed
in that individual.
– Genotype = Genetic Code
– Phenotype = Physical Trait
Artificial Selection
Artificial Selection- Humans determine which
individuals breed, typically with a
preconceived set of traits in mind
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Artificial Selection of Plants
Artificial Selection & Resistance
• PROBLEMS! Repeated application of chemicals
breeds resistance in to the target population
(unintentional artificial selection)
• Herbicide resistant weeds
• Drug-resistant bacteria
• Pesticide-resistant pests
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Natural Selection
• Natural Selection- The environment
determines which individuals survive and
reproduce
– Members of a population naturally vary in their
traits
– Certain combinations of traits make individuals
better able to survive and reproduce
Darwin’s Theory of Evolution
• On the Origin of Species by Means of Natural
Selection
– Individuals produce an excess of offspring
– Not all offspring can survive
– Individuals differ in their traits
– Differences in traits can be passed on from
parents to offspring
– Differences in traits are associated with
differences in the ability to survive and reproduce
Natural Selection
Fitness- an organisms
ability to survive and
reproduce
Adaptations- traits
that improve an
individual’s fitness
Gradual change
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Random Process
• (1) Mutation-occur randomly and can add to the
genetic variation of a population.
• (2) Genetic Drift- a change in the genetic composition
of a population over time as a result of random mating
• (3) Bottleneck Effect- a reduction in the genetic
diversity of a population caused by a reduction in its
size
• (4) Founder Effect- a change in a population
descended from a small number of colonizing
individuals.
(1) Mutation
(2) Genetic Drift
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(3) Bottleneck Effect
(3) Bottlenecks
• Human caused:
– Habitat loss
– Hunting
– Changes to the environment
• Natural:
– Natural disaster
• Outcome
– Decreased genetic variation, increased diseases, low
fertility
(3) Bottleneck Effect
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(4) Founder Effect
Allopatric
Speciation:
• Geographic Isolation
• Reproductive Isolation
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Sympatric speciation: no physical
isolation
Pace of Evolution
Genetically Modified Organisms
Genetically Modified Organisms- An organism
produced by copying genes from a species
with a desirable trait an inserting them into
another species
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All species have a range of tolerance
for temperature, salinity, pH, etc
Ecological Niche
• An organisms’ “place” in its environment
• Takes into account all aspect of an organisms
existence
– Physical, chemical, biological factors needed to
survive
– Habitat
– Abiotic components of the environment
• Ex: Light, temperature, moisture
Ecological Niche
• Fundamental niche
– Potential idealized ecological niche
• Realized niche
– The actual niche the organism occupies
• Ex: Green Anole and Brown Anole
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Ecological Niche
• Green Anole and Brown Anole
– Fundamental niches of 2 lizards initially
overlapped
– Brown anole eventually out-competed the green
anole- reduced the green anole’s realized niche
Realized Niche
Realized Niche- the range of abiotic and biotic
conditions in which a species actually lvies
Niche Generalist- species that live under a wide
range of conditions.
Niche Specialist- species that live only in specific
habitats.
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Fossils
Fossils- remains of organisms that have been
preserved in rock. Much of what we know
about evolution comes from the fossil record.
The Fossil Record Tells All!
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The SIXTH Mass
Extinction
• Anthropogenic
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Habitat Destruction
Overharvesting
Invasive Species
Climate Change
Emerging Diseases
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