Download CH 4 Biodiversity

Biodiversity
Vocabulary
1. Biodiversity: the variety of
earth’s species & the genes
they carry
2. Species: group of individuals
that can mate and have fertile
offspring
 Estimated that there are 10-14
million species
 Up to ½ of world’s plants &
animals in tropical rainforest
 Most unidentified organisms live
in tropical rainforest and oceans
3. Natural capital: stock of
natural ecosystems that yields
a flow of valuable ecosystem
goods or services into the
future
Importance of Biodiversity
1. At least 40% of the world’s economy and
80% of the needs of the poor are
derived from biological resources.
2. The richer the diversity of life, the
greater the opportunity for medical
discoveries, economic development,
and adaptive responses to such new
challenges as climate change.
 Greater species diversity ensures natural
sustainability for all life forms
 Healthy ecosystems can better withstand
and recover from a variety of disasters
Organisms live by
mutually
supporting other
organisms.
Ecosystem Services of Biodiversity
1. Biodiversity underlies all
ecosystem services
2. Ecosystem services contribute
to making human life both
possible and worth living
 We derive most of our essential
food & fibers from animals &
plants
 Biodiversity preserves air and
water quality
 Biodiversity helps to maintain
health topsoil
 Biodiversity decomposes &
recycles nutrients
Biological Evolution
1. Biological evolution: descent
with modification
 Includes small-scale evolution
(changes in gene frequency in
a population from one
generation to the next)
 Include large-scale evolution
(the descent of different species
from a common ancestor over
many generations)
2. All life on Earth shares a
common ancestor
Darwin &
Wallace
Charles Darwin wrote The
Origin of Species in 1858
1. Ideas behind Darwin's theory had been known for
decades
2. Geologists and paleontologists:
 life had been on Earth for a long time
 life had changed over that time
 many species had become extinct
3. Darwin showed how all this evidence favored the
evolution of species from a common ancestor
 proposed the mechanism for evolution was natural selection
 Fitness: those with traits best suited to the environment survive
and leave more offspring to the next generation
Darwin’s Theory
1.
2.
3.
4.
5.
Evolution is gradual; occurs
over vast amount of time
Variation occurs among
individuals within a population
Organisms produce more
offspring than will survive to
reproduce for the next
generation
Those with the most favorable
traits will survive and
reproduce (fitness)
Darwin DID NOT know about
“genetics” and did NOT know
about mutations leading to
genetic variation
Variation within a population
Genetic Variability
1. Genetic variability: variety of the genetic make-up of
individuals within a population
 Arise from mutations in DNA (usually can’t detect the change in
the physical appearance of the organism)
2. Human blood types: an example
Blood Type
Type O
Type A
Susceptible to
cholera
Resistant to
malaria
cholera
3. Having natural genetic resistance gives an advantage
when confronted with an infectious agent or other
environmental factor.
Endemic Species and Islands
1. Endemic species: lives no where
else in the world


evolved from something else.
considered at-risk; some are so
endangered, researchers count
individuals
2. Many live on islands such as
Galapagos, Hawaiian, &
Madagascar

Islands are geographically isolated
from the mainland, interbreeding is
nearly impossible
3. Endemic species are vulnerable
to habitat destruction and
habitat loss
Geologic Time
Scale
Extinction
The last Trilobites
went extinct about
245 mya
1. Extinction: irreversible loss of a species
2. Biological extinction: an entire species is lost
3. Local extinction: species is extinct over a large area, but not globally
lost
4. Background extinction: low rate of species disappearance (1-5
species / year for each million species on Earth)
5. Mass extinction: an extinction of a significant proportion of the world's
biota in a geologically insignificant period of time
 evidence of such an event is contained in the fossil record
 fossil record is most complete from ~542 mya to present.
 Organisms whose structure includes hard parts (shells & bones) formed
beginning about ~ 542 mya
Major Mass
Extinctions
Break up of Pangaea
resulted in the
greatest mass
extinction of time
5 mass extinctions show up in fossil
record
 450 MYA (Late Ordovician) ~ 85% of
marine species became extinct
 374 MYA (Late Devonian) ~ 70-80% of
marine species became extinct
 251 MYA (end of the Permian) ~ 90% of all
species became extinct, perhaps 99% of all
animals Greatest mass extinction in history
 200 MYA (end of the Triassic) most
ammonites, half the genera of bivalves,
many brachiopods and gastropods, 20% of
foraminifera families, 80% of quadrupeds,
and all conodonts became extinct
 65 MYA (end of the Cretaceous) dinosaur
extinction, along with ~2/3 of all species
and perhaps 80% of all individual
organisms
Climate Change and Extinction
1. Polar Bears are threatened by:
 habitat destruction
 human encroachment
 by exposure to persistent organic pollutants
 greatest threat to them is from the melting of sea ice due to global warming
because large areas of open water make it easier for seals to escape
2. Climate change is a threat because species have evolved to live within
certain temperature ranges
 Polar bears do not experience bone loss during 7 months of hibernation (we would
lose ⅓ of bone mass) –model for treating osteoporosis?
 Polar Bears don’t urinate during the several months of hibernation and yet don’t
become ill. (We can’t go for more than a few days without eliminating waste or else we
die) – model for studying kidney failure
 Polar bears gain a lot of weight prior to hibernation, but don’t develop Type II diabetes
Niche
1. Niche: how a species interacts with its environment
 Includes: what it eats, how much it eats, when it hunts, when it
reproduces
2. What’s the difference between competitive exclusion &
coexistence?
A. Eating same size seeds so blue
out-competes red
B. Blue eats a larger seed than red;
resource partitioning
Genetic Resistance
1. Genetic resistance: ability of 1
or more organisms in a
population to tolerate a chemical
designed to kill it
2. Many plants contain chemicals
that deter herbivores from eating
them
3. Milkweed contains cardenolides
which is a cardiac arrester
 When a Monarch caterpillar eats the
leaves from the Milkweed, it ingests
the cardenolides.
 This makes the Monarch toxic to
many vertebrate predators.
Generalist
Species
1. Characteristics include:




Broad niche
can live in many different places
Eat a variety of foods
Tolerate a wide range of ecological conditions
2. Examples:

Flies, cockroaches, raccoons, mice, rates, white tailed deer,
humans
3. Not as likely to become endangered, unless overhunted
Specialist Species
1. Characteristics




Narrow niches
Might live in only one type of habitat
Use just one resource
Tolerate narrow range of environmental conditions
2. Examples:

flamingos, Giant panda, Koala
Indicator Species
Environmental Examples
1. Indicator species: plant or animal that
is very sensitive to environmental
changes in its ecosystem
 Affected almost immediately by damage to
the ecosystem
 Give early warming that ecosystem is
suffering
 Damage from air pollution, water pollution,
or climate change show first in indicator
species
2. Environmental Examples:
 Euglena thrive in eutrophic water
 Paramecium are indicators of biological
toxins
 Lichen very sensitive to SO2 in air
Amphibians as
Indicators
1. Why amphibians are so sensitive:
 Breathe through their skin, so they are much more directly affected
by changes to the chemistry of air & water associated with pollution
 sensitive to fungi & diseases which can infect them through their
skin
 require aquatic habitats for reproduction
 directly affected by changing water levels and qualities
 complex life cycles; often have to move between habitats
 makes them sensitive to changes in the specific habitats that they
need for food and shelter as well as all the places they travel
through to get to their preferred habitats
Northern Spotted Owl
1. The northern spotted owl lives in old-growth forests.
 Very territorial & intolerant of habitat disturbance.
 Prefer old-growth forests with tree canopies that are high & open
enough for the owls to fly between & underneath the trees.
 Each nesting pair needs a large amount of land for hunting & nesting
2. Scientists study the northern potted owl because its
presence in an old grow forest means the forest is healthy
Keystone and Foundation Species
1. A keystone species is one whose impact on its community
or ecosystem is disproportionately large relative to its
abundance
2. Foundation species: can cause physical changes that acts
as facilitators of biodiversity in the community
Keystone Species
1. Keystone species: roles have large effect on the types
and abundance of other species in the ecosystem
2. Characteristics:
 Often limited in numbers
 Limited numbers makes them more vulnerable to extinction
 Play critical roles in ecosystems
 Pollinators: butterflies, hummingbirds, bats
 Top predators: feed on and help regulate population of other
species – wolves, lions, leopards, & sharks
3. Disappearance of the keystone species affects other
members of the habitat
 Remove the wolf, and deer and rabbit population overpopulate,
then starve
Sea Otters are
Keystone Species
1. Sea Otters are one of the few
animals that can eat sea
urchins.
2. Hunted to near extinction for
pelts
 Treaty passed in 1911 to help
protect sea otter
 Sea urchins eat brown kelp
 Kelp beds are very important to
many fish as a place to have
their young
 If kelp beds disappear, then fish
do not have a safe place to
spawn
Foundation Species
1. Foundation species: can cause physical changes that
acts as facilitators of biodiversity in the community
2. Examples:
 Beavers: Build dams and create ponds; transform forests into
wetlands
 Alligators: Dig deep depressions (gator holes) that hold
freshwater during dry season
 Other aquatic life drawn to gator holes
 Elephants: push over, break, uproot trees; creates opening in
grasslands & wooded areas
 Corals: produce the reef structure