Download video slide - Your School

Evolution
The Origin of Species
Classification
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The origin of new species, or speciation
• Species: Is a Latin word meaning “kind” or
“appearance”
– Is at the focal point of evolutionary theory,
because the appearance of new species is the
source of biological diversity
• Evolutionary theory
– Must explain how new species originate in
addition to how populations evolve
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Biological Species Concept
• The biological species concept
– Defines a species as a population or group of
populations whose members have the
potential to interbreed in nature and produce
viable, fertile offspring but are unable to
produce viable fertile offspring with members
of other populations
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Reproductive Isolation
• Reproductive isolation
– Is the existence of biological factors that
impede members of two species from
producing viable, fertile hybrids
– Is a combination of various reproductive
barriers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Reproductive barriers
• barriers impede mating or hinder fertilization if
mating does occur
Habitat
isolation
Behavioral
isolation
Temporal
isolation
Individuals
of different
species
Mechanical
isolation
Mating
attempt
HABITAT ISOLATION
TEMPORAL ISOLATION
BEHAVIORAL ISOLATION
(b)
MECHANICAL ISOLATION
(g)
(d)
(e)
(f)
(a)
(c)
Figure 24.4
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Some barriers reduces hybrid vitality and fertility if mating
does occur
Gametic
isolation
Reduce
hybrid
fertility
Reduce
hybrid
viability
Hybrid
breakdown
Viable
fertile
offspring
Fertilization
REDUCED HYBRID
VIABILITY
GAMETIC ISOLATION
REDUCED HYBRID FERTILITY HYBRID BREAKDOWN
(k)
(j)
(m)
(l)
(h)
(i)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Once geographic separation has occurred
– One or both populations may undergo
evolutionary change during the period of
separation
A. harrisi
Figure 24.6
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
A. leucurus
Habitat Differentiation and Sexual Selection
– Can also result from the appearance of new
ecological niches
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Adaptive Radiation
• Adaptive radiation
– Is the evolution of diversely adapted species
from a common ancestor upon introduction to
new environmental opportunities
Figure 24.11
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Darwin’s Finches
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Hawaiian archipelago
– Is one of the world’s great showcases of
adaptive radiation
Dubautia laxa
1.3 million years
MOLOKA'I
KAUA'I
MAUI
5.1
million
years O'AHU LANAI
3.7
million
years
Argyroxiphium sandwicense
HAWAI'I
0.4
million
years
Dubautia waialealae
Figure 24.12
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Dubautia scabra
Dubautia linearis
Changes in Spatial Pattern
• Substantial evolutionary change
– Can also result from alterations in genes that
control the placement and organization of body
parts
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Homeotic genes
– Determine such basic features as where a pair
of wings and a pair of legs will develop on a
bird or how a flower’s parts are arranged
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The products of one class of homeotic genes called
Hox genes
– Provide positional information in the
development of fins in fish and limbs in
tetrapods
Chicken leg bud
Zebrafish fin bud
Figure 24.18
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Region of
Hox gene
expression
The evolution of vertebrates from invertebrate
animals
– Was associated with alterations in Hox genes
Hypothetical vertebrate
ancestor (invertebrate)
with a single Hox cluster
First Hox
duplication
1 Most invertebrates have one cluster of homeotic
genes (the Hox complex), shown here as colored
bands on a chromosome. Hox genes direct
development of major body parts.
2 A mutation (duplication) of the single Hox complex
occurred about 520 million years ago and may
have provided genetic material associated with the
origin of the first vertebrates.
3 In an early vertebrate, the duplicate set of
genes took on entirely new roles, such as
directing the development of a backbone.
Hypothetical early
vertebrates (jawless)
with two Hox clusters
Second Hox
duplication
Figure 24.19
Vertebrates (with jaws)
with four Hox clusters
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
4 A second duplication of the Hox complex,
yielding the four clusters found in most present-day
vertebrates, occurred later, about 425 million years ago.
This duplication, probably the result of a polyploidy event,
allowed the development of even greater structural
complexity, such as jaws and limbs.
5 The vertebrate Hox complex contains duplicates of many of
the same genes as the single invertebrate cluster, in virtually
the same linear order on chromosomes, and they direct the
sequential development of the same body regions. Thus,
scientists infer that the four clusters of the vertebrate Hox
complex are homologous to the single cluster in invertebrates.
What is evolution?
• One common misconception about evolution is
that individual organisms evolve, in the
Darwinian sense, during their lifetimes
• Natural selection acts on individuals, but
populations evolve
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Natural Selection
• Different traits make some organisms more
successful in reproduction than other
organisms
– Results in certain alleles being passed to the
next generation in greater proportions
– Examples: Pesticide resistance in insects- If
some insects have a natural resistance to
pesticides, then those insects won’t die when
sprayed and will have a chance to pass on
their genes.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Genetic variations in populations
– Contribute to evolution
Figure 23.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Gene Pools and Allele Frequencies
• A population
– Is a localized group of individuals that are capable of
interbreeding and producing fertile offspring
MAP
AREA
•
Fairbanks
Fortymile
herd range
•
Whitehorse
Figure 23.3
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The gene pool
– Is the total of genes in a population at any one
time
– Consists of all alleles in all individuals of the
population
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mendelian inheritance
– Preserves genetic variation in a population
Generation
1
CW CW
genotype
CRCR
genotype
Plants mate
Generation
2
All CRCW
(all pink flowers)
50% CR
gametes
50% CW
gametes
Come together at random
Generation
3
25% CRCR
50% CRCW
50% CR
gametes
25% CWCW
50% CW
gametes
Come together at random
Generation
4
25% CRCR
Figure 23.4
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
50% CRCW
25% CWCW
Alleles segregate, and subsequent
generations also have three types
of flowers in the same proportions
Why so much variation?
• Two processes, mutation and sexual
recombination
– Produce the variation in gene pools that
contributes to differences among individuals
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mutation
• Mutations
– Are changes in the nucleotide sequence of DNA
– Cause new genes and alleles to arise
Figure 23.6
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Sexual Selection
• Sexual selection
– Is natural selection for mating success
– Can result in sexual dimorphism, marked
differences between the sexes in secondary
sexual characteristics
Figure 23.15
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Which is better? Sexual or Asexual Reproduction?
• Sexual reproduction
– Produces fewer reproductive offspring than asexual
reproduction, a so-called reproductive handicap
Sexual reproduction
Asexual reproduction
Generation 1
Female
Female
Generation 2
Male
Generation 3
Generation 4
Figure 23.16
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
If sexual reproduction is a handicap, why has it
persisted?
– It produces genetic variation that may aid in
disease resistance
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
What is common ancestry? How is it determined?
– Morphological, biochemical, and molecular
comparisons to infer evolutionary relationships
Figure 25.2
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Inferred from:
• Fossil Evidence
• Morphological Evidence
• Molecular Evidence
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Biologists draw on the fossil record
– Which provides information about ancient
organisms
Figure 25.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Fossil Record
• Sedimentary rocks
– Are the richest source of fossils
– Are deposited into layers called strata
1 Rivers carry sediment to the
ocean. Sedimentary rock layers
containing fossils form on the
ocean floor.
2 Over time, new strata are
deposited, containing fossils
from each time period.
3 As sea levels change and the seafloor
is pushed upward, sedimentary rocks are
exposed. Erosion reveals strata and fossils.
Younger stratum
with more recent
fossils
Figure 25.3
Older stratum
with older fossils
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The fossil record
– Is based on the sequence in which fossils have
accumulated in such strata
• Fossils reveal
– Ancestral characteristics that may have been
lost over time
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Though sedimentary fossils are the most common
– Paleontologists study a wide variety of fossils
(c) Leaf fossil, about 40 million years old
(b) Petrified tree in Arizona, about
190 million years old
(a) Dinosaur bones being excavated
from sandstone
(d) Casts of ammonites,
about 375 million
years old
(f) Insects
preserved
whole in
amber
Figure 25.4a–g
(g) Tusks of a 23,000-year-old mammoth,
frozen whole in Siberian ice
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(e) Boy standing in a 150-million-year-old
dinosaur track in Colorado
Morphological and Molecular Homologies
• In addition to fossil organisms
– history can be inferred from certain
morphological and molecular similarities
among living organisms
• In general, organisms that share very similar
morphologies or similar DNA sequences
– Are likely to be more closely related than
organisms with vastly different structures or
sequences
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Evaluating Molecular Homologies
• Systematists use computer programs and
mathematical tools
– When analyzing comparable DNA segments from
different organisms
1
Ancestral homologous
DNA segments are
identical as species 1
and species 2 begin to
diverge from their
common ancestor.
1 C C A T C A G A G T C C
2 C C A T C A G A G T C C
A C G G A T A G T C C A C T A G G C A C T A
T C A C C G A C A G G T C T T T G A C T A G
Deletion
2
3
4
Figure 25.6
Deletion and insertion
mutations shift what
had been matching
sequences in the two
species.
Homologous regions
(yellow) do not all align
because of these mutations.
Homologous regions
realign after a computer
program adds gaps in
sequence 1.
1
C C A T C A G A G T C C
2
C C A T C A G A G T C C
G T A
Insertion
1
C C A T
C A
2
C C A T
G T A
1
2
A G T C C
C C A T
C C A T
G T A
C A G
A G T C C
C A
A G T C C
C A G
A G T C C
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 25.7
Classification with evolutionary history
• Taxonomy
– Is the ordered division of organisms into
categories based on a set of characteristics
used to assess similarities and differences
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Binomial Nomenclature
• Binomial nomenclature
– Is the two-part format of the scientific name of
an organism
– Was developed by Carolus Linnaeus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The binomial name of an organism or scientific
epithet
– Is latinized
– Is the genus and species
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Hierarchical Classification
• Linnaeus also introduced a system
– For grouping species in increasingly broad
categories
Panthera
Species pardus
Panthera
Genus
Felidae
Family
Carnivora
Order
Class
Phylum
Kingdom
Figure 25.8
Domain
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mammalia
Chordata
Animalia
Eukarya
Linnaeus’ classification system:
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Linnaean classification system has limitations.
• Linnaeus taxonomy doesn’t account for
molecular evidence.
– The technology didn’t exist during Linneaus’
time.
– Linnaean system based only on physical
similarities.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Linking Classification
Species
Panthera
Figure 25.9
Felidae
Order
Family
Panthera
pardus
(leopard)
Genus
• depict evolutionary relationships In branching
phylogenetic trees
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mephitis
mephitis
(striped skunk)
Mephitis
Lutra lutra
(European
otter)
Lutra
Mustelidae
Carnivora
Canis
familiaris
(domestic dog)
Canis
lupus
(wolf)
Canis
Canidae
Each branch point
– Represents the divergence of two species
Leopard
Domestic cat
Common ancestor
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
“Deeper” branch points
– Represent progressively greater amounts of
divergence
Wolf
Leopard
Common ancestor
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Domestic cat
–
The length of a branch reflects the number of genetic changes
that have taken place in a particular DNA or RNA sequence in
that lineage
Figure 25.12
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cladistics is classification based on common
ancestry.
• Phylogeny is the evolutionary history for a
group of species.
– evidence from living species, fossil record, and
molecular data
– shown with branching tree diagrams
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Derived characters are traits shared in different
degrees by clade members.
– more closely
related species
share more
derived
characters
1 Tetrapoda clade
2 Amniota clade
3 Reptilia clade
4 Diapsida clade
5 Archosauria clade
FEATHERS &
TOOTHLESS
BEAKS.
SKULL OPENINGS IN
FRONT OF THE EYE &
IN THE JAW
OPENING IN THE SIDE OF
THE SKULL
SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
FOUR LIMBS WITH DIGITS
DERIVED CHARACTER
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The three domains in the tree of life are Bacteria,
Archaea, and Eukarya.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Bacteria: includes prokaryotes in the
kingdom Bacteria.
– one of largest
groups on Earth
– classified by
shape, need for
oxygen, and
diseases
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Archaea includes prokaryotes in the
kingdom Archaea.
– cell walls chemically
different from bacteria
– differences discovered
by studying RNA
– known for living in
extreme environments
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Bacteria and archaea can be difficult to classify.
– transfer genes among themselves outside of
reproduction
– blurs the line
bridge to transfer DNA
between “species”
– more research
needed to
understand
prokaryotes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Prokaryotes thrive almost everywhere
– Including places too acidic, too salty, too cold,
or too hot for most other organisms
Figure 27.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Eukarya includes all eukaryotes.
– kingdom Protista
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Eukarya includes all eukaryotes.
– kingdom Protista
– kingdom Plantae
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Prokaryotes play crucial roles in the biosphere
Prokaryotes are so important to the biosphere
that if they were to disappear
– The prospects for any other life surviving
would be dim
– Play a major role in chemical recycling (many
are decomposers
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
But they can also be dangerous!
• Prokaryotes cause about half of all human
diseases
– Lyme disease is an example
Figure 27.16
5 µm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Eukarya includes all eukaryotes.
– kingdom Protista
– kingdom Plantae
– kingdom Fungi
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Domain Eukarya includes all eukaryotes.
– kingdom Protista
– kingdom Plantae
– kingdom Fungi
– kingdom Animalia
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
But what about Viruses? Are they alive or not?
• Recall that bacteria are prokaryotes
– With cells much smaller and more simply
organized than those of eukaryotes
• Viruses
– Are smaller and simpler still
Virus
Bacterium
Animal
cell
Animal cell nucleus
0.25 m
Figure 18.2
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Recall the Characteristics of Life:
• A virus has a genome but can reproduce only
within a host cell!
It is NOT living, but exhibits many of the
characteristics of life.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Origin of HIV
• Analysis shows that HIV
– Is descended from viruses that infect
chimpanzees and other primates
• A comparison of HIV samples from throughout
the epidemic
– Has shown that the virus has evolved in a
remarkable fashion
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Phylogenetic Tree of HIV-1 Strain
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings