© 2014 pearson education, inc. how could you not love this face?

© 2014 Pearson Education, Inc.

How could you not love this face?


Scala Naturae and Classification of Species

Aristotle: (way long ago)

Viewed species as fixed and arranged them on a scala naturae

The Old Testament holds that species were individually designed by God and therefore perfect


Interpreted organismal adaptations as evidence that the Creator had designed each species for a particular purpose

Founder of taxonomy:

the branch of biology concerned with classifying organisms

Developed the binomial format for naming species (for example, Homo sapiens)

Carolus Linnaeus (1707 – 1778)


Georges Cuvier: (1769 – 1832)

Speculated that each boundary between strata represents a catastrophe that destroyed many species

Paleontology, the study of fossils

James Hutton (1726 – 1797)

Charles Lyell (1797 – 1875)

Changes in Earth’s surface can result from slow, continuous actions still operating today

Lyell further proposed that the mechanisms of change are constant over time


Ideas About Change over Time

The study of fossils helped to lay the groundwork for Darwin’s ideas

Fossils are remains or traces of organisms from the past, usually found in sedimentary rock, which appears in layers or strata

Video: Grand Canyon


Lamarck’s Hypothesis of Evolution

Lamarck: (1744 – 1829)

Hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics

The mechanisms he proposed are unsupported by evidence


The Voyage of the Beagle

Darwin collected (and sometimes ate) specimens of South American plants and animals

He observed that fossils resembled living species from the same region, and living species resembled other species from nearby regions


Darwin was influenced by Lyell’s Principles of Geology and thought that Earth was more than 6,000 years old

His interest in geographic distribution of species was kindled by a stop at the Galápagos Islands west of South America

He hypothesized that species from South America had colonized the Galápagos and speciated on the islands


Figure 19.5c

Genovesa

PACIFICOCEAN

Equator

Pinta

Marchena

Fernandina

Florenza

Pinzón

SantiagoDaphneIslands

SantaCruz

SantaFe

Isabela

Española

SanCristobal

Kilometers

0 4020

TheGalápagosIslands


Darwin’s Focus on Adaptation

In reassessing his observations, Darwin perceived adaptation to the environment and the origin of new species as closely related processes

From studies made years after Darwin’s voyage, biologists have concluded that this is what happened to the Galápagos finches


Figure 19.6

(b) Seed-eater

(a) Cactus-eater (c) Insect-eater


Darwin wrote an essay on natural selection as the mechanism of descent with modification

the view that all organisms are related through descent from an ancestor that lived in the remote past

Natural selection: Process in which individuals with favorable inherited traits are more likely to survive and reproduce because of those traits

Alfred Russell Wallace, had developed a theory of natural selection similar to Darwin’s


Figure 19.8


Figure 19.9

Moeritherium†

†Barytherium

Hyracoidea(Hyraxes)

Sirenia(Manateesand relatives)

†Deinotherium

†Mammut

†Platybelodon

†Stegodon

Elephas maximus(Asia)

Mammuthus†

Loxodonta cyclotis(Africa)

Loxodonta africana(Africa)

Millions of years ago Years ago

60 34 24 5.5 2104 0


Artificial Selection, Natural Selection, and Adaptation

Darwin noted that humans have modified other species by selecting and breeding individuals with desired traits, a process called artificial selection

Darwin argued that a similar process occurs in nature


Figure 19.10

Wild mustard Kohlrabi

Cabbage

Kale

Broccoli

Selectionfor leaves

Selectionfor stems

Selectionfor flowersand stems

Selection foraxillary (side)buds

Selection forapical (tip) bud

Brusselssprouts


Darwin drew two inferences from two observations

Observation #1:

Members of a population often vary in their inherited traits

Observation #2:

All species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce


Figure 19.11


Figure 19.12

Sporecloud


Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals

Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations


Thomas Malthus:

Noted the potential for human population to increase faster than food supplies and other resources (was he fully correct?)

If some heritable traits are advantageous, these will accumulate in a population over time, and this will increase the frequency of individuals with these traits

This explains the match between organisms and their environment


Natural Selection: A Summary

Individuals with certain heritable traits survive and reproduce at a higher rate than other individuals

Over time, natural selection increases the match between organisms and their environment

If an environment changes over time, natural selection may result in adaptation to these new conditions and may give rise to new species


Note that individuals do not evolve; populations evolve over time

Natural selection can only increase or decrease heritable traits that vary in a population

Adaptations vary with different environments

Ideas to keep in mind


Evolution is supported by scientific evidence

There are four types of data that document the pattern of evolution

Direct observations

Homology

The fossil record

Biogeography


The Evolution of Drug-Resistant Bacteria

The bacterium Staphylococcus aureus is commonly found on people’s skin and nasal passages

Methicillin-resistant S. aureus (MRSA) strains are dangerous pathogens

S. aureus became resistant to penicillin in 1945, two years after it was first widely used

S. aureus became resistant to methicillin in 1961, two years after it was first widely used


Figure 19.15

Year

Chromosome mapof S. aureus clone USA300

An

nu

al

ho

sp

ita

l a

dm

iss

ion

sw

ith

MR

SA

(th

ou

sa

nd

s)

’05

400

’93 ’94 ’95 ’96 ’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04

350

300

200

250

100

150

50

0

Increased gene exchange(within species) andtoxin production

Increased disease severityAbility to colonize hosts

Methicillin resistance

Key to adaptations

250,000 base pairs

500,000

750,000

2,000,000

1,750,000

1,500,0001,250,000

1,000,000

2,250,000

2,500,000

2,750,000 1


Remember that mutations change an organisms DNA and are RANDOM

Natural selection does not create new traits, but edits or selects for traits already present in the population

The local environment determines which traits will be selected for or selected against in any specific population

These are super-important to get straight

© 2014 Pearson Education, Inc. Figure 19.16

Humerus

Carpals

Radius

Human

Ulna

Metacarpals

Phalanges

Whale Cat Bat

Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor

Keep in mind: 1 bone, 2 bones, little bones, fingers


Vestigial structures are remnants of features that served important functions in the organism’s ancestors (eg. Vestigal hind legs in whales)


Examples of homologies at the molecular level are genes shared among organisms inherited from a common ancestor

Homologous genes can be found in organisms as dissimilar as humans and bacteria


Convergent Evolution

Convergent evolution:

The evolution of similar, or analogous, features in distantly related groups

Analogous traits arise when groups independently adapt to similar environments in similar ways

Convergent evolution does not provide information about ancestry


Figure 19.18

AUSTRALIA

NORTHAMERICASugar

glider

Flyingsquirrel


The Fossil Record

The fossil record provides evidence of The extinction of species

The origin of new groups

Changes within groups over time

Important transitions

Cetaceans and even-toes ungulatesMost mammals

(d) Odocoileus (deer)(c) Sus (pig)(a) Canis (dog) (b) Pakicetus


Biogeography

The geographic distribution of species, provides evidence of evolution

Endemic species are species that are not found anywhere else in the world


What Is Theoretical About Darwin’s Ideas?

A theory accounts for many observations and explains and integrates a great variety of phenomena

Predictions made by a scientific theory must stand up to continual testing by experimentation and observation

Darwin’s theory of evolution by natural selection integrates diverse areas of biological study and stimulates many new research questions


Overview: Investigating the Evolutionary History of Life

• Legless lizards and snakes evolved from different lizards with legs

• Legless lizards have evolved independently in several different groups through adaptation to similar environments

ANCESTRALLIZARD(with limbs)

Eastern glass lizard

Monitor lizard

Snakes

Geckos

No limbs

Iguanas

No limbs


• Phylogeny: The evolutionary history of a species or group of related species

• Systematics: Classifies organisms and determines their evolutionary relationships

• Taxonomy: The ordered division and naming of organisms

Terms to keep straight


Binomial Nomenclature

• Two-part names for species and hierarchical classification• The first part of the name is the genus • The second part, is species within the genus


Hierarchical Classification

The taxonomic groups from narrow to broad are species, genus, family, order, class, phylum, kingdom, and domain

Taxonomic unit at any level of hierarchy is called a taxon

Species: Panthera pardus

Kingdom: Animalia Domain:

Archaea

Domain:Bacteria

Domain:Eukarya

Genus: Panthera

Order: Carnivora

Family: Felidae

Class: Mammalia

Phylum: Chordata


Linking Classification and Phylogeny

• Systematists depict evolutionary relationships in branching phylogenetic treesPanthera

pardus(leopard)

SpeciesOrder Family

Taxideataxus(Americanbadger)

Canislatrans(coyote)

Lutra lutra(Europeanotter)

Canislupus(gray wolf)

Pan

thera

Taxid

eaC

anis

Lu

tra

Felid

aeM

ustelid

ae

Carn

ivora

Can

idae

1

2


• Each branch point represents the divergence of two taxa from a common ancestor

• Sister taxa are groups that share an immediate common ancestor

• A rooted tree includes a branch to represent the most recent common ancestor of all taxa in the tree

• A basal taxon diverges early in the history of a group and originates near the common ancestor of the group

• A polytomy is a branch from which more than two groups emerge

Components of a phylogenetic tree


Figure 20.5

1

2

3

4

5

Branch point:where lineages diverge

This branch pointrepresents the commonancestor of taxa A−G.

This branch point forms apolytomy: an unresolvedpattern of divergence.

ANCESTRALLINEAGE

Sistertaxa

Basaltaxon

Taxon A

Taxon B

Taxon C

Taxon D

Taxon E

Taxon F

Taxon G


What Phylogenetic Trees Show

• Phylogenetic trees show patterns of descent, not phenotypic similarity

• Phylogenetic trees do not generally indicate when a species evolved or how much change occurred in a lineage

• It should not be assumed that a taxon evolved from the taxon next to it


Concept 20.2: Phylogenies are inferred from morphological and molecular data

• Systematists gather information about morphologies, genes, and biochemistry of living organisms

• The similarities used to infer phylogenies must result from shared ancestry


Morphological vs Molecular Homologies

• Phenotypic and genetic similarities due to shared ancestry are called homologies

• Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences


Sorting Homology from Analogy

• Need to distinguish whether a similarity is the result of homology or analogy– Homology is similarity due to shared ancestry– Analogy is similarity due to convergent evolution

• Example:– Bat and bird wings are homologous as forelimbs, but analogous as functional wings


• Analogous structures or molecular sequences that evolved independently are also called homoplasies– Molecular sequences called molecular homoplasies

• Homology can be distinguished from analogy by comparing fossil evidence and the degree of complexity

• The more complex two similar structures are, the more likely it is that they are homologous


Evaluating Molecular Homologies

• Molecular homologies are determined based on the degree of similarity in nucleotide sequence between taxa

• Computer programs analyze comparable DNA segments from different organisms

• Shared bases in nucleotide sequences that are otherwise very dissimilar are called molecular homoplasies

G A T C C AA C G A G T C T A G G C A C T A

C C G G G TT C A A C A C T T T G A C T A G


Concept 20.3: Shared characters are used to construct phylogenetic trees

• Once homologous characters have been identified, they can be used to infer a phylogeny

Cladistics classifies organisms by common descentA clade is a group of species that includes an

ancestral species and all its descendants

Clades can be nested in larger clades, but not all groupings of organisms qualify as clades


Figure 20.10

B

C

A

D

E

F

G

Group I

(a) Monophyletic group(clade)

1 1B

C

A

D

E

F

G

Group II

(b) Paraphyletic group (c) Polyphyletic group

B

C

A

D

E

F

G

Group III

22


Figure 20.11

Leopard

Turtle

Frog

Bass

Lamprey

Lancelet(outgroup)

Hair

Amnion

Four walking legs

Hinged jaws

Vertebralcolumn

Leo

par

d

Tu

rtle

Fro

g

Bas

s

Lam

pre

y

Lan

cele

t(o

utg

rou

p)

Hair

Amnion

Fourwalking legs

Hinged jaws

Vertebralcolumn

(backbone)

CH

AR

AC

TE

RS

TAXA

(b) Phylogenetic tree(a) Character table

0 10

1

0

1

0

1

0

10 1

0

1

0

1

0

1

0

1

0

10

10 1

0 10

1


Figure 20.UN07


• An outgroup is a species or group of species that is closely related to the ingroup, the various species being studied

• The outgroup is a group that has diverged before the ingroup

• Systematists compare each ingroup species with the outgroup to differentiate between shared derived and shared ancestral characteristics

• Characters shared by the outgroup and ingroup are ancestral characters that predate the divergence of both groups from a common ancestor


Phylogenetic Trees with Proportional Branch Lengths

• The length of a branch can reflect the number of genetic changes or time since divergence

Mouse

Human

Chicken

Frog

Zebrafish

Lancelet

Drosophila

Millions of years ago65.5 Present542

PALEOZOIC

251

MESOZOIC CENOZOIC


Maximum Parsimony

Maximum parsimony:Assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely


• Phylogenetic bracketing:

Predict features of ancestors and their extinct descendants based on the features of closely related living descendants


Molecular clocks help track evolutionary time

• To extend molecular phylogenies beyond the fossil record, we must make an assumption about how molecular change occurs over time

A molecular clock•Uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change

•The number of nucleotide substitutions in related genes is assumed to be proportional to the time since they last shared a common ancestor


From Two Kingdoms to Three Domains

• 5 kingdoms were recognized: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia

• More recently, the three-domain system, supported by DNA sequence data has been adopted:– Bacteria– Archaea– Eukarya

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The Important Role of Horizontal Gene Transfer

Horizontal gene transfer:

Movement of genes from one genome to another

Occurs via transposable elements and plasmids, viral infection, and fusion of organisms

© 2014 pearson education, inc. how could you not love this face?

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