Objective(s):
• SWBAT describe the concept of biodiversity, including how it
is measured.
• SWBAT discuss how genetic diversity is created.
• SWBAT describe the four components of earth’s
biodiversity.
• SWBAT describe the ways in which evolution can occur.
• SWBAT compare and contrast artificial selection and natural
selection.
• SWBAT summarize Darwin’s theory of natural selection.
•SWBAT differentiate between a fundamental niche and a
realized niche.
• SWBAT differentiate between a generalist species and a
specialized species.
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.
Functional Diversity- energy
flow & matter recycling
needed for survival
Evolution- a change in the genetic
composition of a population over time;
depends on genetic diversity. Occurs in
three ways: artificial selection, natural
selection and random processes.
Microevolution- evolution below the species
level. Ex. Different varieties of apples
Macroevolution- Evolution which gives rise
to new species or new genera, family, class
or phyla.
Mutations: random changes in the structure of
DNA; can be caused by an insertion or deletion of
a nucleotide or an entire gene. Many mutations
are detrimental
**major source of genetic variation on a population**
Recombination: occurs as chromosomes are
duplicated during cell division. Ex. Provides new
immune defenses
Sexual reproduction leads to recombination of
alleles through a process called crossing over.
As a result, each individual in a population has a
different combination of alleles.
Without this genetic variation, evolution could
not occur. (1st step in biological evolution)
What are the advantages to sexual reproduction
vs. asexual reproduction?
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter3/animation__unique_features_of_meiosis.html
HMS Beagle (1831-1836)
Began work on natural
selection as a mechanism
of evolution in 1830’s
1859 On the Origin of
Species by means of
Natural Selection
1858 proposed concept
of natural selection as a
mechanism for evolution
Father of biogeography
Wallace effect
Fossil Record: Helps tell the story of evolution
Skeletons, bones, teeth, shells, leaves
Some forms of life leave no fossils, others decompose
Natural Selection favors any combinations of
traits that improves an individual’s fitness.
Fitness: an individual’s ability to survive and
reproduce.
Adaptations: traits that improve an individual’s
fitness. A heritable trait that enables organisms
to better survive and reproduce under a given
set of environmental conditions.
Natural selection: acts on individuals
Second step in biological evolution
Adaptation may lead to differential reproduction
Genetic resistance
When environmental conditions change,
populations
Adapt
Migrate
Become extinct
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.
Evolution by means of Natural Selection
Certain combinations of traits make individuals
better able to survive and reproduce.
Three human adaptations
Strong opposable thumbs
Walk upright
Complex brain
Tectonic plates affect evolution and the location
of life on earth
Location of continents and oceans
Species physically move, or adapt, or form new
species through natural selection
Earthquakes
Volcanic eruptions
A wide variety of edible plants has been
produced from a single mustard species
Certain temperature range
Dependence on water
Rotation on its axis
Revolution around the sun
Enough gravitational mass
Speciation: Formation of two species from one
species as a result of divergent natural selection
in response to changes in environmental
conditions. Usually takes thousands of years;
may happen faster with species with short life
cycles and high reproductive rates.
http://www.youtube.com/watch?v=rlfNvoyijmo
Evolution creates new species via geographic and
reproductive isolation.
The Grand Canyon is a great example of
speciation.
If two separated habitats differ in environmental
conditions (temperature, precipitation, difference
in predators), natural selection will favor different
phenotypes in each habitat.
If individuals cant move between the two
populations, they become more and more
genetically distinct from one another until they can
no longer reproduce with one another.
Reproductive Isolation: two populations can no
longer interbreed and produce viable offspring.
Mass extinction- when large numbers of
species went extinct over a relatively short
period of time.
Scientists feel that we are in our sixth mass
extinction, occurring in the last two decades.
Estimates of extinction rates vary widely, from
2% to 25% by 2020.
In contrast to previous mass extinctions,
scientists agree that this one is caused by
humans.
Species richness- the number of species in a
given 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.
Although both communities has the same number of species,
community one has a more even distribution of species. Therefore, it is
more diverse than community 2.
Phylogenies: the branching patterns of
evolutionary relationships. Scientists organize
species based on how closely related to one
another they are.
Phylogenetic
Tree: this
one is a
simplified
version for
vertebrates
Ecological Niche – Total way of life or role of a
species in an ecosystem.
Generalist Species – species with broad
ecological niches; they can live in many
different places, eat a variety of foods, and
tolerate a wide range of environmental
conditions.
Examples: bears, mice, rats,
flies, raccoons, cockroaches
Specialist Species – species with narrow ecological
niches; may be able to live in only one type of habitat
and tolerate only a narrow range of environmental
conditions. **more likely to suffer from habitat loss
or small environmental changes.
Examples: tiger salamander, spotted owls
Native species
Nonnative species; invasive, alien, or exotic
species
May spread rapidly
Not all are villains
Indicator species – provide early warning signs
of damage
Can monitor environmental quality
Trout
Birds
Butterflies
Frogs
Habitat loss and fragmentation
Prolonged drought
Pollution
Increase in UV radiation
Parasites
Viral and fungal diseases
Climate change
Overhunting
Nonnative predators and competitors
Importance of amphibians
Sensitive biological indicators of environmental
changes
Adult amphibians
Important ecological roles in biological communities
Genetic storehouse of pharmaceutical products
waiting to be discovered
Keystone species
Pollinators
Top predator
Foundation species
Create or enhance their habitats, which benefit
others
Elephants
Beavers
Keystone species
Eat dead and dying fish in the ocean
Strong immune systems
Wounds do not get infected
Almost never get cancer
Could help humans if we understood their
immune system