Download Ch 13 evolution supliment - Elmwood Park Memorial High School

EVOLUTION &
SPECIATION
VOCABULARY REVIEW
• EVOLUTION – CHANGE OVER TIME
• NATURAL SELECTION - INDIVIDUALS
BETTER ADAPTED TO THE
ENVIRONMENT ARE ABLE TO
SURVIVE & REPRODUCE.
– A.K.A. “SURVIVAL OF THE FITTEST”
NEW VOCABULARY
• POPULATION – GROUP OF
INDIVIDUALS OF SAME SPECIES
THAT INTERBREED
• GENE POOL – COMMON GROUP OF
ALL GENES PRESENT IN A
POPULATION
Gene Pool
Combined genetic
info. of all
members
Allele frequency is
# of times
alleles occur
Variation in Populations
2 processes can
lead to this:
Mutations change in DNA
sequence
Gene Shuffling –
from sexual
reproduction
Genetic Drift changes populations…….
• Random change in allele
frequency causes an allele to
become common
• Founder Effect:
a cause of
genetic drift
attributable to
colonization by
a limited
number of
individuals from
a parent
population
• Nonrandom mating: inbreeding and
assortive mating (both shift
frequencies of different genotypes)
• Natural Selection:
differential
success in
reproduction;
only form of
microevolution
that adapts a
population to its
environment
Sexual selection
• Sexual
dimorphism:
secondary sex
characteristic
distinction
• Sexual selection:
selection towards
secondary sex
characteristics
that leads to
sexual
dimorphism
Evolution of Populations
Occurs when
there is a
change in
relative
frequency of
alleles
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
mutation!
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
Generation 3: 0.76 not resistant
0.24 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
Generation 3: 0.76 not resistant
0.24 resistant
Generation 4: 0.12 not resistant
0.88 resistant
Phenotype Expression
•Depends
on how
many
genes
control
that trait
Single-Gene vs. Polygenic Traits
Single-Gene:
2 Distinct Phenotypes (eg: tongue rolling)
Polygenic:
Many Phenotypes
Allele Frequencies
Natural Selection
Single Gene
Traits
Genetic Drift
Polygenic
Traits
Directional
Selection
Stabilizing Selection
Disruptive Selection
Natural Selection on Polygenic Traits
• Shifts to
middle range
• Shifts to
2 extremes
• Shifts to
1 extreme
Conditions needed for Genetic
Equilibrium
SPECIATION
• THE FORMATION OF NEW SPECIES
• AS NEW SPECIES EVOVLVE,
POPULATIONS BECOME
REPRODUCTIVELY ISOLATED
• REPRODUCTIVE ISOLATION –
MEMBERS OF 2 POPULATIONS
CANNOT INTERBREED & PRODUCE
FERTILE OFFSPRING.
Allopatric Speciation
• A few individuals of a species on the
mainland
– reach isolated island 1
– Speciation follows genetic divergence in a new
habitat.
Allopatric Speciation
• Later in time, a few individuals of the new
species colonize island 2
– In this new habitat, speciation follows genetic
divergence.
Allopatric Speciation
• Speciation may also follow colonization of
islands 3 and 4
• Invasion of island 1 by genetically different
descendants of the ancestral species!
Honeycreeper Speciation
• More than 20 species of Hawaiian
honeycreepers have evolved
– from a common ancestor as they adapted to
diverse food sources on the islands
3 ISOLATING MECHANISMS……..
• BEHAVIORAL ISOLATION- CAPABLE OF
BREEDING BUT HAVE DIFFERENCES IN
COURTSHIP RITUALS (EX.
MEADOWLARKS)
• GEOGRAPHICAL ISOLATION –
SEPARATED BY GEOGRAPHIC
BARRIERS LIKE RIVERS, MOUNTAINS,
OR BODIES OF WATER (EX. SQUIRREL)
• TEMPORAL ISOLATION – 2 OR MORE
SPECIES REPRODUCE AT DIFFERENT
TIMES.
Table 23.1a
Subspecies
• Separate populations of the same species
can exist in isolation.
• Over time the population of the same
species can differ genetically because of
adaptation to different living conditions.
• Eventually different populations can
become so different they can not
interbreed successfully.
• They are then considered to be separate
species.
Tigon
Result of male tiger
and female lion
mating incaptivity.
Offspring are infertile.
Separated both
geographically and
ecologically.
Liger
Result of male lion and female
tiger mating in captivity.
Offspring are infertile.
Table 23.1b
Fig. 23.6
Four species of leopard frogs: differ in their
mating calls. Hybrids are inviable.
These squirrels live on opposite sides of the Grand
Canyon. This is an example of allopatric speciation.
Galápagos Finches
• Darwin’s finches from the Galápagos
Islands
– arranged to show evolutionary relationships
Insect
eaters
Insect
eaters
Berry
eater
Seed Cactus
eaters eaters
– Notice that
beak
shape
– varies
depending
on diet
Hawaiian Honeycreepers
An example of adaptive radiation –
these species all diverged from a
common ancestor (founder species)
FOUNDER SPECIES
SPECIATION IN DARWIN’S
FINCHES
• SPECIAITON IN THE GALAPAGOS
FINCHES OCCURRED BY:
- FOUNDING OF A NEW POPULATION,
- GEOGRAPHIC ISOLATION which led to - REPRODUCTIVE ISOLATION and
CHANGES IN THE NEW POPULATION’S
GENE POOL due to COMPETITION.
Evidence of
Evolution
Fossil Record
provides
evidence that
living things have
evolved
Fossils show the
history of life on
earth and how
different groups
of organisms
have changed
over time
Flying
Squirrel
Sugar
Glider
Marsupial Mammals
Convergent
Evolution
and
Analogous
Structures
Placental mammals
Mammalia
Rat like
common
ancestor
Convergent Evolution
• Similarities can evolve in organisms
not closely related often because they
live in the same or similar habitat.
Ex. The wings of a bird and the wings
of a bat
These characteristics are called
analogous structures.
Analogous Structures
• Wings of insects, birds and bats
– serve the same function but differ
considerably
– in structure and embryological development
Divergent Evolution
• Divergent evolution of a variety
– of placental mammals from a common ancestor
• Divergence accounts for descendants
– that differ from their ancestors and from one
another
Convergent Evolution
• Convergent evolution takes place
– when distantly related organisms give rise to
species
– that resemble
one another
– because they
adapt
– in comparable
ways
Gradualism vs. Punctuated
Equilibrium
• Gradualism changes that take place
over a long period of time.
• Punctuated equilibrium are periods of
rapid change separated by little or no
change.
© 2008 Paul Billiet ODWS
Punctuated Equilibrium
Gradualism
Tempo of Evolution
Cladistics and Cladograms
• Traditionally, scientists have
– depicted evolutionary relationships
– with phylogenetic trees
• in which the horizontal axis represents
• anatomical differences
• and the vertical axis denotes time
• In contrast, a cladogram shows
– the relationships among members of a clade
• a group of organisms
• including its most recent common ancestor
• Cladistics focus on derived characteristics
• sometimes called evolutionary novelties
– as opposed to primitive characteristics
Phylogenetic Tree
• A phylogenetic
tree
– showing the
relationships
– among various
vertebrate animals
Cladogram
• A cladogram showing inferred relationships
• Some of the characteristics used
– to construct this cladogram are indicated
Evolutionary Novelties
All land-dwelling vertebrate
animals
– possess bone and paired limbs
– so these characteristics are
primitive
– and of little use in establishing
Cladograms
• Bats and birds fly,
– which might suggest
– a closer relationship
– than to dogs
• Dogs and birds
– do not appear closely
related
• Hair and giving birth to
live young
– indicate that bats and
dogs
– are more closely related
Linnaean Classification
Most inclusive
• Kingdom
– Phylum
• Subphylum
• the coyote, Canis
latrans
• Animalia
– Chordata
–Class
 Order
• Family
• Vertebrata
–Mammalia
• Canidae
»Carnivora
– Genus
• Species
Least inclusive
– Canis
• latrans
Classification —shared
Characteristics
• Subphylum
vertebrata
– including fishes,
amphibians,
reptiles, birds
and mammals,
– have a
segmented
vertebral
column
• Only warm-
blooded animals
with hair/fur
and mammary
glands are
mammals
Coyote, Canis latrans
• 18 orders of
•
•
•
mammals exist
including order
Carnivora
The Family
Canidae are
doglike carnivores
and the genus
Canis includes
only closely
related species
Coyote, Canis
latrans, stands
alone as a species
Cladistics for Fossils
• Cladistics and cladograms work
– well for living organisms,
– but are trickier for fossils
• Care must be taken in determining
– what are primitive verses derived
characteristics,
– especially in groups with poor fossil records
• Paleontologists must be especially careful
– of characteristics resulting
– from convergent evolution
Evolutionary Trends
• During evolution, all aspects of an organism
– do not change simultaneously
• A key feature we associate
– with a descendant group might appear
– before other features typical of that group
• For example, the oldest known bird
– had feathers and the typical fused clavicles of
birds,
– but it also retained many reptile characteristics
• Mosaic evolution is the concept that
– organisms possess recently evolved characteristics
– as well as some features of their ancestral group
Phylogeny
• Phylogeny is the evolutionary history
– of a group of organisms
• If sufficient fossil material is available,
– paleontologists determine the phylogeny
– and evolutionary trends for groups of
organisms
• For example, one trend in ammonoids
• extinct relatives of squid and octopus
– was the evolution
– of an increasingly complex shell
Evolutionary Trends
• Abundant fossils show the evolutionary
trends of
– the extinct
Eocene
mammals,
Titanotheres
• These
relative
of
horses and rhinoceroses
– evolved from small
ancestors
– to giants standing 2.4 m at
the shoulder
– developed large horns
– and the shape of their
skull changed
– Only 4 of the 16 known
genera are show
Evolutionary Trends
• Size increase is
– one of the most common evolutionary trends
• However, trends are complex
– they might reverse
– more than one can take place
– at the same time at different rates
• Trends in horses included
– generally larger size
• but size decreased in some now-extinct horses
– changes in teeth and skull
– lengthening legs
– reduction in number of toes
• These trends occurred at different rates
Adaptations
• Evolutionary trends are a series
of adaptations
– to changing environment
– or in response to exploitation of
new habitats
• Some organisms
– show little evolutionary change
– for long periods
• Lingula is a brachiopod
– with a shell, at least,
– that has not changed
– significantly since the Ordovician
“Living Fossils”
• Several organisms have shown
– little or no change for long periods
• If these still exist as living organisms today
– they are sometimes called living fossils
• For example:
– horseshoe crabs
– Latrimaria (fish)
– Gingko trees
• Some of these are generalized and can live
under a wide variety of enviroinments
A Living Fossil
• Latimeria
– belongs to a group of fish
– once thought to have gone extinct
– at the end of the Mesozoic Era
A specimen was caught
off the coast of East Africa in
1938
A Second Living Fossil
• Ginkgos
– have changed
very little
– for millions of
years
Vestigial Structures
• Vestigial structures are nonfunctional
remnants
– of structures in organisms that were functional
in their
• Why– do
dogs ancestors
have tiny,
– functionless toes on
their feet
• Ancestral
dogs had five
(dewclaws)?
toes
– on each foot,
– all of which contacted
the ground
• As they evolved
– they became toe-walkers with only four toes on
the ground
– and the big toes and thumbs were lost or reduced
Remnants of Rear Limbs in
Whales
• The Eocene-aged whale,
Basilosaurus,
– had tiny vestigial back
limbs
– but it did not use limbs
to support its body
weight.
Evolution in Living Organisms
• Small-scale evolution can be observed today.
• For example
•
– adaptations of some plants to contaminated
soils
– insects and rodents developing resistance to
new insecticides and pesticides
– development of antibiotic-resistant strains of
bacteria
Variations in these populations
– allowed some variant types
– to live and reproduce,
– bringing about a genetic change
What do We Learn from
Fossils?
• The fossil record consists
– of first appearances of various organisms
– through time
• One-celled organisms appeared
– before multicelled ones
– plants appeared before animals
– invertebrates before vertebrates
• Fish appeared first followed
– in succession by amphibians,
– reptiles, mammals, and birds
Advent of Various Vertebrates
• Times
when
major
groups of
vertebrates
appeared
in the
fossil
record
• Thickness
of spindles
shows
relative
abundance
Fossils Are Common
• Fossils are much more common
•
•
•
•
– than many people realize
However the origin and initial diversification
– of a group is generally the most poorly
represented
But fossils showing the diversification
– of horses, rhinoceroses, and tapirs
– from a common ancestor are known
as are ones showing the origin
– of birds from reptiles
and the evolution
– of whales from a land-dwelling ancestor
Horses and Their Relatives
• This cladogram shows the relationship
among
– tapirs, rhinoceroses, and horses
Horses and Their Relatives
• These might seem an odd assortment of animals
•
•
•
– but fossils and studies of living animals
– indicate that they shared a common ancestor
As we trace these animals back
– in the fossil record,
– differentiating one from the other
– becomes increasingly difficult
The earliest members of each group
– are remarkably similar,
– differing mostly in size and details of their
teeth
As their diversification proceeded
– the differences became more apparent
Never Enough
• Of course, we will never have enough fossils
•
•
– to document the evolutionary history
– of all living creatures simply because
fossilization
– is an incomplete process
The remains of some organisms
– are more likely to be preserved than those of
others
– and accumulation of sediments
– varies in both space and time
But several other kinds of evidence
– support the concept of evolution
– including molecular biology and paleontology
Big Question!!!
How did life arise on the big blue planet??
 Scientists attempt to answer this
question scientifically.
Big Bang Theory
 A cosmic explosion that hurled matter and in all
directions created the universe 10-20 billion
years ago
 Evidence: it explains why distant galaxies are
traveling away from us at great speeds.
Cosmic radiation from the explosion can be
observed
 The Big Bang theory probably will never be
proven; consequentially, leaving a number of
tough, unanswered questions.
What was early earth like?
Earth was Hot!!
Little or no oxygen
Gasses in atmosphere:
Hydrogen cyanide (poison to you!)
Hydrogen sulfide
Carbon dioxide
Carbon monoxide
Nitrogen
So how did the earth
get oxygen?
 Some of that oxygen was generated by
photosynthetic cyanobacteria
 Some came from the chemical
separation of water molecules into
oxygen and hydrogen.
 Oxygen drove some life
forms to extinction
 Others evolved ways of
using oxygen for respiration
How did life begin?
Miller and Urey’s
Experiment
 Passed sparks
through a mixture of
hydrogen methane
ammonia and water
 This produced
amino acids – the
building blocks of life
Miller’s
experiment
suggests that
lightning could
have produced
amino acids
How can simple amino
acids result in life?
1. Formation of microspheres
 Large organic molecules can
sometimes form tiny proteinoid
microspheres
 Store and release energy, selectively
permeable membranes, may have
acquired more characteristics of living
cells
nd
2
Hypothesis for Life
Evolution of RNA to DNA
• RNA was assembled
from simple organic
molecules in a
primordial soup
• RNA was able to
replicate itself and
eventually form DNA
• Not scientifically
proven to be possible
The Bubble Model
rd
3
Theory of Life
Endosymbiotic theory
eukaryotic cells
arose from living
communities formed
by prokaryotic
organisms
Ancient prokaryotes
entered primitive
eukaryotic cells and
remained there as
organelles
• Prokaryotes are chemosynthetic.
• Photosynthetic prokaryotes
(cyanobacteria) release oxygen into the
water, once saturated move into
atmosphere.
• Evolution of eukaryotes then multicelluar
organisms.
• Formation of ozone allowed organisms to
move to land