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Evolution and Biodiversity. Chapter 4. Key Concepts. Origins of life Evolution and evolutionary processes Ecological niches Species formation Species extinction. How Did We Become Such a Powerful Species So Quickly?. Strong opposable thumbs Walk upright Intelligence. Fig. 4-1, p. 63.

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key concepts
Key Concepts
  • Origins of life
  • Evolution and evolutionary processes
  • Ecological niches
  • Species formation
  • Species extinction
how did we become such a powerful species so quickly
How Did We Become Such a Powerful Species So Quickly?
  • Strong opposable thumbs
  • Walk upright
  • Intelligence

Fig. 4-1, p. 63

origin evolution of life
Origin & Evolution of Life
  • Chemical evolution - 1st billion yrsorganic molecules, biopolymers & chemical rxns needed for formation of first cells (Age of Earth = 4.6 billion years)
  • Biological evolution - first life 3.7 bya (prokaryotes)“Populations - not individuals - evolve by becoming genetically different.”
animation chemical evolution
Animation- Chemical Evolution

Stanley Miller's experiment animation

biological evolution of life
Biological Evolution of Life

Modern humans

(Homo sapiens)

appear about

2 seconds

before midnight

Recorded human

history begins

1/4 second

before midnight

Origin of life

(3.6–3.8 billion

years ago)

Fig. 4-3, p. 66

how do we know which organisms lived in the past
How Do We Know Which Organisms Lived in the Past?
  • Fossil record
  • Radiometric dating
  • Ice cores
  • DNA studies

Fig. 4-2, p. 65

biological evolution
Biological Evolution
  • Evolution= change in populations genetic makeup over time (“Populations - not individuals - evolve by becoming genetically different.”)
  • “Theory” of evolution= All species descended from earlier, ancestral species
  • Microevolution= small genetic changes in a population
  • Macroevolution= long-term, large scale evolutionary changes (speciation, extinction)
natural selection
Natural Selection
  • Definition: Process where particular beneficial trait is reproduced in succeeding generations more than other traits
  • Three Conditions:1. Genetic Variability2. Trait must be inherited (selection occurs)3. Differential Reproduction - individuals w/ trait have more offspring
adaptations
Adaptations
  • Structural- coloration, mimicry, protective, gripping
  • Physiological - hibernate, chemical
  • Behavioral - ability to fly, migrate
animation
Animation

Change in moth population animation

“Genes mutate, individuals are selected, and populations evolve.”

animation1
Animation

Adaptive trait interaction

ecological niches and adaptation
Ecological Niches and Adaptation
  • Ecological niche= occupation (role)
  • Habitats= address
  • Fundamental niche = no competition
  • Realized niche = with competition
specialized feeding niches for birds
Specialized Feeding Niches for Birds

Herring gull is a

tireless scavenger

Brown pelican dives for fish,

which it locates from the air

Black skimmer

seizes small fish

at water surface

Ruddy turnstone searches

under shells and pebbles for small invertebrates

Dowitcher probes deeply

into mud in search of

snails, marine worms,

and small crustaceans

Avocet sweeps bill through

mud and surface water in

search of small crustaceans,

insects, and seeds

Scaup and other

diving ducks feed on

mollusks, crustaceans,

and aquatic vegetation

Knot (a sandpiper) picks up

worms and small crustaceans

left by receding tide

Flamingo

feeds on

minute

organisms

in mud

Oystercatcher feeds on

clams, mussels, and

other shellfish into which

it pries its narrow beak

Piping plover feeds

on insects and tiny

crustaceans on

sandy beaches

Louisiana heron wades into

water to seize small fish

Fig. 4-5, p. 68-69

broad and narrow niches and limits of adaptation
Broad and Narrow Niches and Limits of Adaptation
  • Generalist species - broad niche
  • Specialist species - narrow niche, more extinction-prone under changing environmental conditions. Which is better?
  • Limits of adaptation- gene pool & reproductive capacity

Refer to Spotlight, p. 69- cockroaches

niches of specialist and generalist species
Niches of Specialist and Generalist Species

Specialist species

with a narrow niche

Generalist species

with a broad niche

Niche

separation

Number of individuals

Niche

breadth

End Pt 1

Region of

niche overlap

Resource use

Fig. 4-4, p. 68

animation2
Animation

Stabilizing selection animation.

animation3
Animation

Disruptive selection animation.

evolutionary divergence of honeycreepers
Insect and nectar eaters

Fruit and seed eaters

Greater Koa-finch

Kuai Akialaoa

Amakihi

Kona Grosbeak

Crested Honeycreeper

Akiapolaau

Apapane

Maui Parrotbill

Unknown finch ancestor

Evolutionary Divergence of Honeycreepers

Fig. 4-6, p. 70

misconceptions of evolution
Misconceptions of Evolution
  • “Survival of the fittest”OK if: Fitness = reproductive success ≠ strongest
  • “Progress to perfection”
speciation
Speciation
  • What is speciation?
  • Geographic isolation
  • Reproduction isolationmutation & natural selection operate independently in gene pools of geographically isolated populationsoriginal populations become genetically distinct- unable to produce live, fertile offspring
geographic isolation can lead to speciation
Geographic Isolation can Lead to Speciation

Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage.

Arctic Fox

Northern

population

Spreads northward

and southward

and separates

Early fox

population

Different environmental

conditions lead to different

selective pressures and evolution

into two different species.

Gray Fox

Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat.

Southern

population

Fig. 4-7, p. 71

animation4
Animation

Speciation on archipelago animation

extinctions
Extinctions
  • Background extinctions= 1-5 species per million
  • Mass extinctions- five previous mass extinctions: 25% - 75% species go
  • Mass depletions- > background, but < mass
  • Human impacts - 6th major mass extinction???
factors leading to extinction
Factors Leading to Extinction
  • Plate tectonics
  • Climatic changes over time-most
  • Natural catastrophes
  • Human impacts
continental drift plate tectonics the breakup of pangaea
LAURASIA

PANGAEA

GONDWANALAND

225 million years ago

135 million years ago

NORTH AMERICA

EURASIA

AFRICA

INDIA

SOUTH AMERICA

MADA

GASCAR

AUSTRALIA

ANTARTICA

65 million years ago

Present

“Continental Drift” (Plate Tectonics): The Breakup of Pangaea

Fig. 4-8, p. 72

changes in biodiversity over geologic time
Changes in Biodiversity over Geologic Time

1600

Terrestrialorganisms

Silurian

Triassic

Permian

Jurassic

Devonian

Cambrian

Ordovician

1200

Cretaceous

Marineorganisms

Pre-cambrain

Carboniferous

Number of families

800

Tertiary

Quaternary

400

0

3500

545

500

440

410

355

290

250

205

145

65

1.8

0

Millions of years ago

Fig. 4-10, p. 74

future of evolution
Future of Evolution
  • Artificial selection (selective breeding)
  • Genetic engineering (gene splicing)
  • Genetic modified organisms (GMOs)
  • Cloning
  • Ethical concerns
genetically engineered mouse
Genetically Engineered Mouse

Mouse on right has human growth hormone gene- grows 3x faster and 2x larger

Fig. 4-12, p. 76

genetic engineering links
Genetic Engineering Links

Genetic Engineering and Society, Lecture 1a, Honors Collegium 70A, UCLA

http://www.youtube.com/watch?v=eg19FquatGo

Watch This Lecture. Take Notes and turn in for 10 activity points

Yale University online Lectures- Genetic Engineering

http://www.youtube.com/watch?v=uUddHabtAzk&feature=relmfu

Alternative to UCLA lecture.

Future of genetic engineering - by Futurist Dr Patrick Dixon.

http://www.youtube.com/watch?v=P_UoReSgz84

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