Transcript Ch.5 - Evolution and Biodiversity

CH.5 - EVOLUTION AND
BIODIVERSITY
“Each species here today represents a long chain of
evolution and plays a unique ecological role (niche) in the
earth’s communities and ecosystems.”
5-1 Origins of Life
1) Chemical Evolution – organic
compounds and systems of chemical
reactions formed the first cells.
(took about 1 billion years!)
2) Biological Evolution – change from
single celled prokaryotes
single celled eukaryotes
multicellular organism
HOW DO WE KNOW???
•
Most left behind fossil records that
give us physical evidence of past
organisms and their internal
structures. Records are incomplete,
however, and actually only
represent about 1% of all species
ever lived.
5-2 Evolution and Adaptations
 Evolution – change in a POPULATION’S genetic
makeup over successive generations (not individuals!)
 Theory of Evolution- all species descended from earlier, ancentral
species
 Macroevolution
Microevolution
Long-term, large scale changes from 1
ancestral species to another where older
species is lost through extinction.
Small genetic changes in a population’s
gene pool that are past on to offspring.
Past organisms’ fossil records
5-2 Changes in a Gene pool
• Basics of Genetics• Alleles
• Mutations – environmental or
random; harmful or beneficial
• Create genetic diversity and
new combinations of alleles
Beneficial and Lethal Mutations
Natural Selection
- When individuals in a population have certain
genetic traits that enhance their ability to survive
and pass on these advantageous traits to their
offspring.
Adaptation- heritable trait that enables the
organisms to better survive under environmental
conditions.
When faced with changing environmental conditions
a species will either:
1) adapt through natural selection
2) migrate to areas with more favorable conditions
3) become extinct!
Coevolution
- Interactions between 2 populations of
different species over a long period of time
can lead to changes in their gene pools, like a
evolutionary contest of who can produce the
most offspring.
- Example: Bats and moths (echolocation)
5-3 Ecological Niches & Adaptations
 Niche– specific role in an ecosystem (occupation)
Includes:
 adaptive traits
 range of tolerance for physical/chemical conditions
(temperature/H2O availability)
 Types/amount of resources specie uses (food, space,etc)
 How it interacts with nonliving/living components in the
ecosystem
 Role specie plays in energy flow and matter cycling in the
ecosystem.
HABITAT- physical location where organism lives (address)
5-3 Ecological Niches & Adaptations
 Fundamental Niche – full potential range of
physical, chemical, and biological conditions and
resources a species could theoretically use if there
was no t direct competition from other species.
Realized Niche- specie only occupies part of its
fundamental niche to survive and avoid
competition
Broad vs. Narrow niches = Generalists vs. Specialists
Coastal wetlandsspecialized feeding niche
Limits to Adaptations
 Genetic trait that leads to an adaptation to changes
in the environmental condition must already be
present in the gene pool.
 If present, adaptation is limited by reproductive
rate. (humans would take thousands to millions of years to
adapt!)
Fitness = reproductive success, not strongest!
5-4 Speciation, Extinction, and
Biodiversity
 Allopatric speciation
Geographic isolation
(Physical barrier)
Reproductive isolation
(no longer produces fertile offspring)
 Sympatric Speciation
 Mutation or changes in behavior no longer allows
interbreed in close living species (insects)
Extinction
 99.9% of all species that ever existed are now
extinct.
 Background extinction- species disappear at a low
rate
 Mass extinction and mass depletion
Extinctions create new opportunities for other
species. Adaptive radiation sets in as new
species adapt to fill vacated ecological niches in
changed environments.
Human Activities are Decreasing
Biodiversity
 Richest areas of biodiversity- tropical forests,
coral reefs, and wetlands
5-5 What is the future of evolution?
 Artificial Selection
 Selective breeding
 Genetic engineering
 Genetically modified organisms (GMO’s) or transgenic organisms
 Gene splicing
 Biopharming- using genetically engineered animals
to produce a product for human use
(hormones, vaccines, antibodies, etc.)
Bioethics- governmental regulations and control
Genetic Engineering
Why Humans Thrive as a Species
 Strong opposable thumbs
 Complex brains
Extra credit! (5 points)
 See p. 100 Project #1 submit written assignment
to me through email by Monday!