Transcript APES 4 Biodiversity and Evolution pptx

All we have yet discovered is but a
trifle in comparison with what lies
hid in the great treasury of nature.
Antoine Van Leeuwenhoek
Biodiversity and Evolution
Unit 4
Case Study: Why Should We Protect
Sharks?
• More than 400 known species.
• 6 deaths/yr.
• 79-97 million sharks killed every year:
-Fins, organs, meat, hides, fear, by-catch
• 32% shark species threatened with extinction.
• Reasons for protection: cancer resistant,
keystone species.
4-1
Importance of Biodiversity
• Biodiversity: the variety of Earth’s species,
their genes, the ecosystems where they live,
and the sustaining ecosystem processes
(nutrient cycling, energy flow).
• Vital to sustaining life on earth (supplies us
with food, wood, fiber, energy, and medicine).
Components of Biodiversity (cont’d)
• Functional diversity: bio/chemical processes
needed for survival of species & communities.
-energy flow & matter recycling.
• Ecosystem diversity: variety of terrestrial and
aquatic ecosystems.
-storehouse of genetic, species diversity.
Components of Biodiversity
Species diversity:
• Est. 8 million to 100 million species.
• 1.9 million identified.
-insects make up most of known species.
-unidentified are mostly in rain forests and
oceans.
Genetic diversity: variety of genetic material within
a population.
-enables life to adapt to environmental changes.
FYI: Why You Should Love Insects
Bad rep: compete for food, spread disease, bite
and sting, invade lawns.
Natural capital:
• pollination (allows flowering plants reproduce
sexually).
• free pest control: insects eat other insects.
E.O. Wilson: Biodiversity
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•
•
•
•
Loved bugs as a kid.
Specialized in ants.
Widened scope to
earth’s biodiversity.
Theory of island
biogeography.
• First to use “biodiversity”
in a scientific paper.
4-2
Evolution of Species
Biological evolution: change in the genetic makeup
of a species over generations.
Theory of evolution: organisms with adaptive traits
have an advantage over others.
• Alfred Russell Wallace
• Charles Darwin:
-studied beak shape in Galapagos finches.
-published On the Origin of Species by Means of
Natural Selection.
Natural Selection
Individuals with advantageous traits are more
likely to survive & transmit traits to succeeding
generations.
Steps of Selection
1. Genetic variability exists in a population.
-mutations (random changes to DNA) are source
of variation.
-mutations within gametes are inheritable.
2. Environmental factors favor survival of
individuals with adaptive trait over others.
3. Adaptive trait may lead to differential
reproduction, which enables individuals with
adaptation to produce more offspring.
Natural Selection and the Six
Kingdoms/Tree of Life
The Geologic Time Scale
Natural Selection & Genetic Resistance
• Ability of members of a population to resist a
chemical designed to kill it.
Evidence of Natural Selection
• Fossil record: entire
collection of preserved
species.
-represents ≈ 1% of all
species on Earth.
• Homologous structures:
-similar structures in
dissimilar species.
• DNA analysis
Limitations to Natural Selection
• Genetic change must precede change in the
environmental conditions.
• Reproductive capacity:
-Species that reproduce rapidly and in large
numbers are better able to adapt.
Common Myths about Evolution
through Natural Selection
• “Survival of the fittest” is not “survival of the
strongest” .
(Fittest is in terms of leaving behind the most
offspring )
• Organisms do not develop traits out of need or
want.
• No grand plan of nature for perfect adaptation
(evolution is not “goal oriented).
Case Study: How Did Humans Become
Such a Powerful Species?
Three human adaptations:
• Strong opposable thumbs
• Walk upright
• Complex brain: allows for weapon
development, creation of protective devices,
and technologies that extend our senses.
4-3 Geology and Natural Selection
• Tectonic plates affect evolution and the location
of life on earth.
-change the location of continents & oceans.
-influences climate & distribution of species.
-species became geographically isolated from one
another.
• Earthquakes: shifting of tectonic plates; may
isolate populations.
• Volcanic eruptions: occur near plate boundaries;
may wipe out populations.
Movement of the Earth’s Continents
over Millions of Years
Pangea’s breakup explained: Scrat’s Missing Adventure
Video Clip , Video Clip 2
Climate Change and Natural Selection
• Cyclical climate changes restrict location/
survival of populations.
-adapt, migrate or become extinct
Catastrophes and Natural Selection
• Collisions between the Earth & large asteroids
have occurred throughout history.
-caused destruction of ecosystems/species.
-created opportunities for new species.
4-4
Biodiversity, Speciation and
Extinction
• Biodiversity results from the interaction
between speciation and extinction.
Extinction
• Biological extinction: effects global population.
• Local extinction: widespread, but not global.
• Endemic species: found only in one area;
particularly vulnerable to extinction.
• Background extinction: typical low rate of
extinction.
-1-5 species per million species/year.
• Mass extinction: above background rate.
-3-5 over 500 million years.
Golden Toad of Costa Rica
Found in cloud
forests 2000 m
above sea level.
Climatic change, pollution, ultraviolet radiation, and/or fungal skin infections? No one
knows why it went extinct.
Mass Extinctions
Cenozoic
Era
Period
Quaternary
Millions of
years ago
Today
Bar width represents relative
number of living species
Extinction
Tertiary
65
Extinction
Mesozoic
Current extinction crisis caused
by human activities. Many species
are expected to become extinct
within the next 50–100 years.
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Cretaceous
Jurassic
Species and families
experiencing
mass extinction
Extinction
Triassic: 35% of animal families, including many
reptiles and marine mollusks.
250
Extinction
Permian: 90% of animal families, including over
95% of marine species; many trees, amphibians,
most bryozoans and brachiopods, all trilobites.
345
Extinction
180
Triassic
Permian
Paleozoic
Carboniferous
Devonian: 30% of animal families, including
agnathan and placoderm fishes and many
trilobites.
Devonian
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician: 50% of animal families,
including many trilobites.
Fig. 4-12, p. 93
FYI
The Passenger Pigeon - Gone Forever
• Once the most numerous
bird on earth.
• In 1858, Passenger Pigeon
hunting became a big
business.
• By 1900 they became
extinct from over-harvest
and habitat loss.
Figure 11-1
Global Extinction
• Some animals have become prematurely extinct
because of human activities.
Figure 11-2
Giant panda
Mountain gorilla
Black-footed
ferret
Whooping
crane
Northern spotted Blue whale
owl
Florida
panther
California
condor
Hawksbill sea Black
turtle
rhinoceros
Fig. 11-3, p. 224
Speciation
Evolutionary process by which new biological
species arise:
• Geographic isolation: physical isolation of
populations for a long period lead to…
• Reproductive isolation: mutations in
geographically isolated populations prevent
the production of viable offspring.
Geographic Isolation Can Lead to
Reproductive Isolation
Changing Genetic Traits
• Genetic engineering:
alters genes by adding,
deleting segments of
DNA for desired trait(s).
Normal mouse (left) vs. Transgenic mouse
with Human Growth Hormone
• Artificial selection: use
selective/crossbreeding
4-5
The Importance of Species
Diversity
• Species richness: number of different species
in a given area.
• Species evenness: the comparative number
of individuals of each species in an ecosystem.
-low evenness: few individuals of each
species.
-high evenness: many individuals of each
species.
FYI: Species Richness and Evenness
Which plot has a
higher species
richness? Each color
represents a different
species.
Which plot has a
greater species
evenness?
Variations in Species Richness and
Species Evenness
High species richness
Low species evenness
Low species richness
High species evenness
Species Richness on Islands
• Species equilibrium model, theory of island
biogeography.
• Rate of new species immigrating should balance
with the rate of species extinction
• Island size and distance from the mainland need
to be considered.
-small islands have a higher extinction rates.
-islands closest to the mainland have greater
species richness.
Effects of Species Richness
• Determined by two factors:
-plant productivity (more plant biomass)
-enhanced sustainability
FYI: Current hypothesis suggests that the more
species, the more nutrients, the more pathways for
energy flow. Our buddy, E O Wilson says,
“There’s a common sense to this: the more species
you have, the more likely you’re going to have an
insurance policy for the whole ecosystem”.
4-6 Roles of Species in an Ecosystem
• Ecological niche: role of species & everything
needed for its survival.
Generalists
Generalist species:
broad niches
• many different
locations
• varied diet
• tolerate wide range of
conditions
Specialists
Specialist species:
narrow niches
• restricted habitat
• restricted diet
• narrow tolerance of
environmental
conditions
Five Major Species Roles in Ecosystems
1. Native: normal resident.
2. Nonnative: migrate, introduced into.
-AKA invasive, alien, exotic
3. Indicator: provide early warnings of damage
to communities.
4. Keystone: role determines types, abundance
of other species in community.
5. Foundation: create, enhance habitats for other
species.
Invasive Species
Deliberately Introduced Species
Purple loosestrife
European starling
African honeybee
(“Killer bee”)
Marine toad
(Giant toad)
Water hyacinth
Japanese beetle
Nutria
Hydrilla
Salt cedar
(Tamarisk)
European wild boar
(Feral pig)
Fig. 11-11a, p. 234
FYI: Invasive Species
• The Argentina fire
ant was introduced
to Mobile, Alabama
in 1932 from South
America.
– Most probably from
ships.
– No natural
predators.
Figure 11-12
Indicator Species
Keystone Species
Foundation Species
Exam Focus
• Role of shark/top predator in ecosystem.
• Components of biodiversity
• Link between biodiversity, speciation &
extinction.
• Most abundant identified species.
• Steps of natural selection, including the “raw”
material that drives it and its result.
• Basics of geologic time scale/resulting kingdoms.
• Role of plate tectonics in speciation
Exam Focus (cont’d)
• Genetic resistance.
• Importance of fossil record to evolution.
• Reasons for vulnerability to extinction of
endemic and specialist species.
• Sequence of order in speciation (geo or
repro).
• Species richness vs evenness.
• Ecological niche
Exam Focus
• Traits of generalists vs specialists.
• 5 species roles and examples.
• Expect questions from previous units.