• Welcome

• Introduce Zoology

• Syllabus

• Lecture – Evolution, and Zoology– Theory of Evolution by Natural Selection– Origin of Species– Properties of Life Origins of Life– Prokaryotic and Eukaryotic – Levels of organization– Cell division and inheritance

• Biology is the study of Life

• Single cell to multicellular organisms

• Cell is the basic unit of life

• Unique plant cell and animal cell

• Zoology- zoon, animal + logos, to study – is the study of Animals

• Is one of the broadest fields in all of science– Variety of animals– Complexity of and the processes

Specializations in Zoology

• Anatomy

• Ecology

• Genetics

• Parasitology

• Physiology

• Entomology-

• Ichthyology-

Ichthyologist-work to understand structure, function, ecology and evolution of fishes

Studies have uncovered an amazing diversity of fishesCichlid (‘sick-lid’)- freshwater perch-like fishes• 1000 species in Africa• 300 in South America• 3 in India• 1 in North America

Members of this group

• Variety of color patterns

• Habitats

• Body forms

• Feeding habits

Eretmodus

Nip algae with chisel-like teeth

Tanganicodus

Insect pickers

Perissodus

Scale eaters

• Brood their young

• Dogtooth cichlid

The Fontosa

Body form

An Evolutionary Perspective

• Share a common evolutionary past and evolutionary forces that influence their history – Resulted in 4 to 100 million species of animals

• Understand evolutionary process to understand – What it is – How it originated

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

Fossils, Cuvier, and Catastrophism

• 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

Figure 22.3

• 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

EnglandEUROPE

NORTHAMERICA

GalápagosIslands

Darwin in 1840,after his return

SOUTHAMERICA

Cape ofGood Hope

Cape Horn

Tierra del Fuego

AFRICA HMS Beagle in port

AUSTRALIA

TasmaniaNewZealand

PACIFICOCEAN

An

des

ATLANTICOCEAN

Darwin’s Focus on Adaptation

• As Darwin reassessed all that he had observed during the voyage of the Beagle– He began to perceive 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 indeed what

happened to the Galápagos finches

Figure 22.6a–c

(a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp.

(c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground.

(b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects.

• In 1844, Darwin wrote a long essay on the origin of species and natural selection– But he was reluctant to introduce his theory publicly,

anticipating the uproar it would cause

• In June 1858 Darwin received a manuscript from Alfred Russell Wallace– Who had developed a theory of natural selection

similar to Darwin’s

• Darwin quickly finished The Origin of Species– And published it the next year

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

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)

Yea

rs a

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illio

ns

of y

ea

rs a

go Dei

no

ther

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Ma

mm

ut

Ste

go

don

Ma

mm

uth

us

Pla

tyb

elo

don

Bar

yth

eriu

m

Mo

eri

ther

ium

Elephasmaximus

(Asia)

Loxodontaafricana(Africa)

Loxodontacyclotis(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

Terminalbud

Lateralbuds

Brussels sproutsCabbage

Flowercluster

Leaves

Cauliflower

Flowerandstems

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

• Natural selection can produce an increase over time– In the adaptation of organisms to their environment

Figure 22.11

(a) A flower mantidin Malaysia

(b) A stick mantidin Africa

• If an environment changes over time– Natural selection may result in adaptation to these new

conditions

• Darwin’s theory explains a wide range of observations

• Darwin’s theory of evolution– Continues to be tested by how effectively it can

account for additional observations and experimental outcomes

Evolutionary Processes

• Organic evolution- change in the genetic makeup of populations over time. – Source of animal diversity– Explains family relationships within animal groups

• Charles Darwin

• Published evidence of evolution 1859

• Proposed a mechanism

• Understanding diversity of animal structure and function arose is one of the many challenges

• i.e cichlid scale eaters of Africa

Animal classification and Evolutionary Relationship

• Evolution not only explanation why animals appear and function as they do

• It explains family relationships

• i.e cichlid species– Groups share more of their DNA– Thus resemble each other

– Genetic studies suggest• Oldest African cichlid found in Lakes Tanganyika and Kivu

• These fish invades rivers, lakes Malawi, Victoria and others

• Most rapid known origin of species of any animal groups

Figure 1.3

• 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 Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species

• In order to understand why Darwin’s ideas were revolutionary– We need to examine his views in the context of other

Western ideas about Earth and its life

• 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 19001795 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.1837Darwin writes his essay on the origin of species.1844

Wallace sends his theory to Darwin.1858

The Origin of Species is published.1859Mendel publishes inheritance papers.1865

Homology, Biogeography, and the Fossil Record

• Evolutionary theory– Provides a cohesive explanation for many kinds of

observations

Homology

• Homology– Is similarity resulting from common ancestry

Anatomical Homologies

• Homologous structures between organisms– Are anatomical resemblances that represent variations on

a structural theme that was present in a common ancestor

Figure 22.14Human Cat Whale Bat

• Comparative embryology– Reveals additional anatomical homologies not visible in

adult organisms

Figure 22.15

Pharyngealpouches

Post-analtail

Chick embryo Human embryo

• Vestigial organs– Are some of the most intriguing homologous structures– Are remnants of structures that served important

functions in the organism’s ancestors

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

Homologies and the Tree of Life

• The Darwinian concept of an evolutionary tree of life– Can explain the homologies that researchers have

observed

• 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

Lamprey14%

54%

69%

87%

95%

100%

Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide

Biogeography

• Darwin’s observations of the geographic distribution of species, biogeography– Formed an important part of his theory of evolution

Sugarglider

AUSTRALIA

NORTHAMERICA

Flyingsquirrel

Figure 22.17

• Some similar mammals that have adapted to similar environments– Have evolved independently from different ancestors

The Fossil Record

• The succession of forms observed in the fossil record– Is consistent with other inferences about the major

branches of descent in the tree of life

Binomial nomenclature

• Karl von Linne (1707-1778)

• Named and classified plants into hierarchy of relatedness

• Binomial Nomenclature- systematic way of naming organisms- – Two part name describes each kind of organism– First part- indicates the genus– Second part indicates the species to which the organism

belongs.

– i.e. Perissodus microlepis

• 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

Figure 1.4

Hierarchy of Relatedness

• Evolutionary concepts hold the key to understanding – why animals look and act – Habitat– Characteristics

Ecological Perspective

• Ecology- (Gr. okois, house + logos, to study)

• Study of the relationships between organisms and their environment

• Human dependence on animals (food, medicine, clothing)

• Humans upset the delicate ecological balances that has evolved

In the 1950’s in an attempt to increase the lake’s fishery

• Nile perch introduced into Lake Victoria

• Reduced cichlid population from 99% to <1%

• Most cichlid feed on algae, the algae grew

• Algae died and decayed

• Lake depleted of oxygen

• Introduced nonnative plant (water hyacinth)

• Water hyacinth has overgrown and resulted in further habitat loss

Figure 1.6 (a)

Figure 1.6 (b)

EC Figure

Chapter 1 Evolution, Ecology and

Zoology

Chapter 4Theory of Evolution by

Natural SelectionMicroevolution and

Macroevolution

Chapter 2Properties of Life Origins of

LifeProkaryotic and Eukaryotic

Levels of organizationCell division and inheritance

Chapter 3MitoticMeiosis