Transcript Ecological Perspective BIOL 346/ch4 revised 22 Jan 2012

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?

Adaptive traits

Human weaknesses

Opposable thumbs

Walk upright

Intelligence

Environmental impacts
p. 67
Origins of Life

Chemical evolution

Biological evolution
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 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
Biological Evolution

Evolution

Theory of evolution

Microevolution

Macroevolution
Microevolution

Gene pool

Genetic variability

Mutations

Mutagens

Natural selection
A human body contains trillions
of cells, each with an identical
set of genes.
Genetic
Materials
There is a nucleus inside each
human cell (except red blood cells).
Each cell nucleus has an identical
set of chromosomes, which are
found in pairs.
A specific pair of chromosomes
contains one chromosome from
each parent.
Each chromosome contains a long
DNA molecule in the form of a coiled
double helix.
Genes are segments of DNA on
chromosomes that contain instructions
to make proteins—the building blocks
of life.
The genes in each cell are coded
by sequences of nucleotides in
their DNA molecules.
Fig. 2-5 p. 33
Natural Selection

Differential reproduction

Adaptation (adaptive trait)

Coevolution
Ecological Niches and
Adaptation

Ecological niche

Habitats

Fundamental niche

Realized niche
Specialized Feeding Niches for
Birds
Black skimmer
seizes small fish
at water surface
Scaup and other
diving ducks feed on
mollusks, crustaceans,
and aquatic vegetation
Flamingo
feeds on
minute
organisms
in mud
Herring gull is a
tireless scavenger
Brown pelican dives for fish,
which it locates from the air
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Louisiana heron wades into
water to seize small fish
Dowitcher probes deeply
into mud in search of
snails, marine worms,
and small crustaceans
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Ruddy turnstone
searches
under shells and
pebbles for small
invertebrates
Knot (a sandpiper) picks up
worms and small crustaceans
left by receding tide
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Fig. 4-10, p. 72
Broad and Narrow Niches and
Limits of Adaptation

Generalist species

Specialist species

Limits of adaptation
Number of individuals
Niches of Specialist and
Generalist Species
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Fig. 4-4, p. 68
Cockroaches: Nature’s Ultimate
Survivors
Fig. 4-A, p. 69
Evolutionary Divergence of
Honeycreepers
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Kona Grosbeak
Crested Honeycreeper
Akiapolaau
Maui Parrotbill
Unknown finch ancestor
Apapane
Fig. 4-6, p. 70
Misconceptions of Evolution

“Survival of the fittest”

“Progress to perfection”
Speciation

What is speciation?

Geographic isolation

Reproduction isolation
Geographic Isolation can Lead to
Speciation
Arctic Fox
Northern
population
Early fox
population
Spreads northward
and southward
and separates
Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Gray Fox
Southern
population
Adapted to heat
through
lightweight fur
and long ears,
legs, and nose,
which give off
more heat.
Fig. 4-9, p. 70
Factors Leading to Extinction

Plate tectonics

Climatic changes over time

Natural catastrophes

Human impacts
Extinctions

Background extinctions

Mass extinctions

Mass depletions

Human impacts
“Continental Drift” (Plate Tectonics): The
Breakup of Pangaea
LAURASIA
225 million years ago
135 million years ago
EURASIA
AFRICA
65 million years ago
Present
Fig. 4-8, 4-9 p. 69
Mass Extinctions of the Earth’s Past
Fig. 4-9, p. 73
Changes in Biodiversity over
Geologic Time
Terrestrial
organisms
Cretaceous
400
Quaternary
Marine
organisms
Tertiary
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
800
Cambrian
1200
Pre-cambrain
Number of families
1600
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

Artificial selection

Genetic engineering (gene splicing)

Genetic modified organisms (GMOs)

Cloning

Ethical concerns
Genetic Engineering
Phase 1
Make Modified Gene
E. coli
Cell
Extract
plasmid
Extract DNA
Gene of
interest
Identify and extract
gene with desired trait
DNA
Identify and remove
portion of DNA
with desired trait
Genetically
modified
plasmid
plasmid
Remove plasmid
from DNA of E. coli
Insert extracted DNA
(step 2) into plasmid
(step3)
Insert modified
plasmid into E. coli
Grow in tissue
culture to
make copies
Fig. 4-11, p. 75
Genetic Engineering
Phase 2
Make Transgenic Cell
E. coli
A. tumefaciens
(agrobacterium)
Foreign DNA
Host DNA
Nucleus
Transfer plasmid copies to
a carrier agrobacterium
Transfer plasmid
to surface
microscopic metal
particle
Agrobacterium inserts foreign
DNA into plant cell to yield
transgenic cell
Use gene gun
to inject DNA
into plant cell
Fig. 4-11, p. 75
Genetic Engineering
Phase 3
Grow Genetically Engineered Plant
Transgenic cell
from Phase 2
Cell division of
transgenic cells
Culture cells
to form plantlets
Transfer
to soil
Transgenic plants
with new traits
Fig. 4-11, p. 75
Genetically Engineered Mouse
p. 71