Evolution and systematics.ppt

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Descent with Modification: A Darwinian View of Life


•  The Origin of Species

–  Focused biologists’ attention on the great diversity of organisms

Figure 22.1


•  Darwin made two major points in his book

–  He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral species

–  He proposed a mechanism for the evolutionary process, natural selection


•  The historical context of Darwin’s life and ideas

Figure 22.2

Linnaeus (classification) Hutton (gradual geologic change)

Lamarck (species can change) Malthus (population limits)

Cuvier (fossils, extinction) Lyell (modern geology)

Darwin (evolution, nutural selection) Mendel (inheritance) Wallace (evolution, natural selection)

1750 American Revolution French Revolution U.S. Civil War

1800 1850 1900 1795 Hutton proposes his theory of gradualism.

1798 Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution.

1830 Lyell publishes Principles of Geology. 1831–1836 Darwin travels around the world on HMS Beagle.

Darwin begins his notebooks on the origin of species. 1837 Darwin writes his essay on the origin of species. 1844

Wallace sends his theory to Darwin. 1858 The Origin of Species is published. 1859

Mendel publishes inheritance papers. 1865


Resistance to the Idea of Evolution

•  The Origin of Species

–  Shook the deepest roots of Western culture

–  Challenged a worldview that had been prevalent for centuries


The Scale of Nature and Classification of Species

•  The Greek philosopher Aristotle

–  Viewed species as fixed and unchanging

•  The Old Testament of the Bible

–  Holds that species were individually designed by God and therefore perfect


•  Carolus Linnaeus

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

–  Was a founder of taxonomy, classifying life’s diversity “for the greater glory of God”


Theories of Gradualism

•  Gradualism

–  Is the idea that profound change can take place through the cumulative effect of slow but continuous processes


•  Geologists Hutton and Lyell

–  Perceived that changes in Earth’s surface can result from slow continuous actions still operating today

–  Exerted a strong influence on Darwin’s thinking


Lamarck’s Theory of Evolution

•  Lamarck hypothesized that species evolve

–  Through use and disuse and the inheritance of acquired traits

–  But the mechanisms he proposed are unsupported by evidence

Figure 22.4


•  Darwin’s interest in the geographic distribution of species

–  Was kindled by the Beagle’s stop at the Galápagos Islands near the equator west of South America

Figure 22.5

England EUROPE NORTH AMERICA

Galápagos Islands

Darwin in 1840, after his return

SOUTH AMERICA

Cape of Good Hope

Cape Horn

Tierra del Fuego

AFRICA HMS Beagle in port

AUSTRALIA

Tasmania New Zealand

PACIFIC OCEAN

And

es

ATLANTIC OCEAN


The Origin of Species

•  Darwin developed two main ideas

–  Evolution explains life’s unity and diversity

–  Natural selection is a cause of adaptive evolution


Descent with Modification

•  The phrase descent with modification

–  Summarized Darwin’s perception of the unity of life

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


•  In the Darwinian view, the history of life is like a tree

–  With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms

Figure 22.7

Hyracoidea (Hyraxes)

Sirenia (Manatees

and relatives)

Year

s ag

o M

illio

ns o

f yea

rs a

go

Dei

noth

eriu

m

Mam

mut

Ste

godo

n

Mam

mut

hus

Pla

tybe

lodo

n

Bar

ythe

rium

Moe

rithe

rium

Elephas maximus

(Asia)

Loxodonta africana (Africa)

Loxodonta cyclotis (Africa)


Natural Selection and Adaptation

•  Evolutionary biologist Ernst Mayr

–  Has dissected the logic of Darwin’s theory into three inferences based on five observations


•  Observation #1: For any species, population sizes would increase exponentially

–  If all individuals that are born reproduced successfully

Figure 22.8


•  Observation #2: Nonetheless, populations tend to be stable in size

–  Except for seasonal fluctuations

•  Observation #3: Resources are limited

•  Inference #1: Production of more individuals than the environment can support

–  Leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving


•  Observation #4: Members of a population vary extensively in their characteristics

–  No two individuals are exactly alike

Figure 22.9


•  Observation #5: Much of this variation is heritable

•  Inference #2: Survival depends in part on inherited traits

–  Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals


•  Inference #3: This unequal ability of individuals to survive and reproduce

–  Will lead to a gradual change in a population, with favorable characteristics accumulating over generations


Artificial Selection

•  In the process of artificial selection

–  Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits

Figure 22.10

Terminal bud

Lateral buds

Brussels sprouts Cabbage

Flower cluster

Leaves

Cauliflower

Flower and stems

Broccoli Wild mustard Kohlrabi

Stem

Kale


Summary of Natural Selection

•  Natural selection is differential success in reproduction

–  That results from the interaction between individuals that vary in heritable traits and their environment


•  If an environment changes over time

–  Natural selection may result in adaptation to these new conditions


The Evolution of Drug-Resistant HIV

•  In humans, the use of drugs

–  Selects for pathogens that through chance mutations are resistant to the drugs’ effects

•  Natural selection is a cause of adaptive evolution


•  Researchers have developed numerous drugs to combat HIV

–  But using these medications selects for viruses resistant to the drugs

Figure 22.13

Patient No. 1

Patient No. 2

Patient No. 3

Per

cent

of H

IV re

sist

ant t

o 3T

C

Weeks


Molecular Homologies

•  Biologists also observe homologies among organisms at the molecular level

–  Such as genes that are shared among organisms inherited from a common ancestor


•  Anatomical resemblances among species

–  Are generally reflected in their molecules, their genes, and their gene products

Figure 22.16

Species

Human

Rhesus monkey

Mouse

Chicken

Frog

Lamprey 14%

54%

69%

87%

95%

100%

Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide


•  The Darwinian view of life

–  Predicts that evolutionary transitions should leave signs in the fossil record

•  Paleontologists

–  Have discovered fossils of many such transitional forms

Figure 22.18


What Is Theoretical about the Darwinian View of Life?

•  In science, a theory

–  Accounts for many observations and data and attempts to explain and integrate a great variety of phenomena


•  New information has revised our understanding of the tree of life

•  Molecular Data

–  Have provided new insights in recent decades regarding the deepest branches of the tree of life


Previous Taxonomic Systems

•  Early classification systems had two kingdoms

–  Plants and animals


•  Robert Whittaker proposed a system with five kingdoms

–  Monera, Protista, Plantae, Fungi, and Animalia

Figure 26.21

Plantae Fungi Animalia

Protista

Monera


Reconstructing the Tree of Life: A Work in Progress

•  A three domain system

–  Has replaced the five kingdom system

–  Includes the domains Archaea, Bacteria, and Eukarya

•  Each domain

–  Has been split by taxonomists into many kingdoms


•  One current view of biological diversity

Figure 26.22

Pro

teob

acte

ria

Chl

amyd

ias

Spi

roch

etes

Cya

noba

cter

ia

Gra

m-p

ositi

ve b

acte

ria

Kor

arch

aeot

es

Eur

yarc

haeo

tes,

cre

narc

haeo

tes,

nan

oarc

haeo

tes

Dip

lom

onad

s, p

arab

asal

ids

Eug

leno

zoan

s

Alv

eola

tes

(din

ofla

gella

tes,

api

com

plex

ans,

cili

ates

)

Stra

men

opile

s (w

ater

mol

ds, d

iato

ms,

gol

den

alga

e, b

row

n al

gae)

Cer

cozo

ans,

radi

olar

ians

Red

alg

ae

Chl

orop

hyte

s

Cha

roph

ycea

ns

Domain Archaea Domain Eukarya

Universal ancestor

Domain Bacteria

Chapter 27 Chapter 28


Bry

ophy

tes

(mos

ses,

live

rwor

ts, h

ornw

orts

)

Plants

Fungi

Animals

See

dles

s va

scul

ar p

lant

s (fe

rns)

Gym

nosp

erm

s

Ang

iosp

erm

s

Am

oebo

zoan

s (a

moe

bas,

slim

e m

olds

)

Chy

trids

Zygo

te fu

ngi

Arb

uscu

lar m

ycor

rhiz

al fu

ngi

Sac

fung

i

Clu

b fu

ngi

Cho

anof

lage

llate

s

Spo

nges

Cni

daria

ns (j

ellie

s, c

oral

)

Bila

tera

lly s

ymm

etric

al a

nim

als

(ann

elid

s,

arth

ropo

ds, m

ollu

scs,

ech

inod

erm

s, v

erte

brat

es)

Chapter 29 Chapter 30 Chapter 28 Chapter 31 Chapter 32 Chapters 33, 34

Figure 26.21


•  Concept 25.2: Phylogenetic systematics connects 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


Binomial Nomenclature

•  Binomial nomenclature

–  Is the two-part format of the scientific name of an organism

–  Was developed by Carolus Linnaeus


•  The binomial name of an organism or scientific epithet

–  Is latinized

–  Is the genus and species


Hierarchical Classification

•  Linnaeus also introduced a system

–  For grouping species in increasingly broad categories

Figure 25.8

Panthera pardus

Panthera

Felidae

Carnivora

Mammalia

Chordata

Animalia

Eukarya Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species


Linking Classification and Phylogeny

•  Systematists depict evolutionary relationships

–  In branching phylogenetic trees

Figure 25.9

Panthera pardus

(leopard)

Mephitis mephitis

(striped skunk)

Lutra lutra (European

otter)

Canis familiaris

(domestic dog)

Canis lupus (wolf)

Panthera Mephitis Lutra Canis

Felidae Mustelidae Canidae

Carnivora

Ord

er Fa

mily

G

enus

Sp

ecie

s


•  Each branch point

–  Represents the divergence of two species

Leopard Domestic cat

Common ancestor


•  “Deeper” branch points

–  Represent progressively greater amounts of divergence

Leopard Domestic cat

Common ancestor

Wolf


•  Concept 25.3: Phylogenetic systematics informs the construction of phylogenetic trees based on shared characteristics

•  A cladogram

–  Is a depiction of patterns of shared characteristics among taxa

•  A clade within a cladogram

–  Is defined as a group of species that includes an ancestral species and all its descendants

•  Cladistics

–  Is the study of resemblances among clades


Cladistics

•  Clades

–  Can be nested within larger clades, but not all groupings or organisms qualify as clades


•  A valid clade is monophyletic

–  Signifying that it consists of the ancestor species and all its descendants

Figure 25.10a

(a) Monophyletic. In this tree, grouping 1, consisting of the seven species B–H, is a monophyletic group, or clade. A monophyletic group is made up of an ancestral species (species B in this case) and all of its descendant species. Only monophyletic groups qualify as legitimate taxa derived from cladistics.

Grouping 1

D

C

E G

F

B

A

J

I

K H


•  A paraphyletic clade

–  Is a grouping that consists of an ancestral species and some, but not all, of the descendants

Figure 25.10b

(b) Paraphyletic. Grouping 2 does not meet the cladistic criterion: It is paraphyletic, which means that it consists of an ancestor (A in this case) and some, but not all, of that ancestor’s descendants. (Grouping 2 includes the descendants I, J, and K, but excludes B–H, which also descended from A.)

D

C

E

B

G H

F

J

I

K

A

Grouping 2


•  A polyphyletic grouping

–  Includes numerous types of organisms that lack a common ancestor

Figure 25.10c

(c) Polyphyletic. Grouping 3 also fails the cladistic test. It is polyphyletic, which means that it lacks the common ancestor of (A) the species in the group. Further- more, a valid taxon that includes the extant species G, H, J, and K would necessarily also contain D and E, which are also descended from A.

D

C

B

E G

F

H

A

J

I

K

Grouping 3


Shared Primitive and Shared Derived Characteristics

•  In cladistic analysis

–  Clades are defined by their evolutionary novelties


•  A shared primitive character

–  Is a homologous structure that predates the branching of a particular clade from other members of that clade

–  Is shared beyond the taxon we are trying to define


•  A shared derived character

–  Is an evolutionary novelty unique to a particular clade

Apomorphies for taxa B&C

A B C D E F

TIME

Cladogram or Phylogenetic Tree

TAXA

Apomorphy for taxon D

Apomorphy for taxa B-F

Similarity due to common ancestry- similar DNA sequences

Intraindividual homology? Similarity by common ancestry of features within

an individual, e.g., carpels and leaves (common ancestry by genes)

Similarity not by common ancestry.

Types? Convergence - independent evolution of a

similar feature in 2 or more lineages. Reversal - loss of a derived feature with re-

establishment of ancestral feature.

Convergence - Stem succulence and “spines” in Cactaceae and Euphorbia spp.

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