BIO311Dlecture5

8/13/2019 BIO311Dlecture5

1/25

Announcements

Discussion sections start this week. You willtake a short pre-concept test-bring a pencil (itwill not influence your grade in the course).

First Faculty Fellows Dining with Students lunch

tomorrow, Tuesday, Sept. 10, Noon, Jester CityLimits.

Reminder: Lecture attendance is expected andto your benefit. I will take attendanceperiodically, as I did last Friday, and there willbe graded lecture activities throughout thesemester.


2/25

The Origin of Species

A new era of biology began in 1859 whenCharles Darwin published The Origin ofSpecies.

The Origin of Speciesfocused biologistsattention on the great diversity of organisms.

And in fact, it is this knowledge of diversity thatlead to the development of evolutionary theory

and our understanding of the processes ofevolution today.


3/25


The book that shook the worldOne long argument for evolution

20 years in the making

http://darwin-online.org.uk/
http://darwin-online.org.uk/http://darwin-online.org.uk/http://darwin-online.org.uk/http://darwin-online.org.uk/


4/25

Darwin noted that current species are

descendants of ancestral species. Evolution can be defined by Darwins

phrase descent with modification.

Evolution can be viewed as both apattern and a process.


5/25

Figure 22.2

1809

1798

1812

1795

1830

17901809 183136

1844

18591870

Lamarck publishes hishypothesis of evolution.

Malthus publishes

Essay on the Principleof Population.

Hutton proposeshis principle of

gradualism.

Charles Darwinis born.

Darwin travels aroundthe world on HMS

Beagle.

The Galpagos Islands

Darwin writes hisessay on descentwith modification.

On the Origin ofSpeciesis published.

While studying species inthe Malay Archipelago,Wallace (shown in 1848)sends Darwin his hypothesisof natural selection.

1858Cuvier publishes his extensivestudies of vertebrate fossils.

Lyell publishesPrinciples of Geology.


6/25

Afred Russel Wallace (1823-1913)

1858Wallace sent letterto Darwin describing histheory of evolution

Naturalist & collector

Explored Amazon/SouthPacific

Independently developednotion of natural selection

and species change


7/25

Chapter 1: Variation under domestication

Domestic species are variable

This variability is heritable

Small changes accumulate to make bigdifferences

Breeders have made changes > than differencesbetween species


8/25


9/25


10/25

Chapter 2: Variation in nature

Things are the same way in nature

Population vs. typological approach

Variation is a natural state

Variation makes taxonomy difficult


11/25

The struggle for existence & the tendency for

population to increase

Competition and predation EVERYWHERE,variation can be related to success

Darwin calculated that 1 pair of elephants (veryslow breeders) will leave 15 million descendentsin 500 years

Thus, most individuals do not survive(or the planet would be overrun with elephants)

Chapter 3: The struggle for existence


12/25


13/25

Chapter 4: Natural selection

Can we doubtthat individuals havingany advantage, however slight, over others,would have the best chance surviving and of

procreating their kind? On the other hand,we may feel sure that any variation in theleast degree injurious would be rigidlydestroyed. This preservation of favorable

variations and the rejection of injuriousvariations, I call Natural Selection.


14/25

Chapter 4: Natural selection

Discusses the potential strength of naturalselection

Discusses the possibility of sexual selection

Variation, inheritance, and the struggle forexistence inevitably lead to evolution


15/25

Some doubt about the permanence of

species preceded Darwins ideas

Descent with modification by naturalselection explains the adaptations of

organisms and the unity and diversity oflife


16/25

Darwins Focus on Adaptation

In reassessing his observations, Darwinperceived adaptation to the environmentand the origin of new species as closely

related processes. From studies made years after Darwins

voyage, biologists have concluded that

this is what happened to the Galpagosfinches.

Fi 22 6


17/25

Figure 22.6

(a) Cactus-eater (b) Insect-eater

(c) Seed-eater


18/25

In 1844, Darwin wrote an essay on naturalselection as the mechanism of descent with

modification,but did not introduce his theorypublicly.

Natural selection is a process in which individualswith favorable inherited traits are more likely to

survive and reproduce. In June 1858, Darwin received a manuscript from

Alfred Russell Wallace, who had developed atheory of natural selection similar to Darwins.

Darwin quickly finished The Origin of Speciesandpublished it the next year.


19/25


Darwin explained three broadobservations:

The unity of life

The diversity of life The match between organisms and their

environment


20/25

Descent with Modification

Darwin never used the word evolutionin thefirst edition of The Origin of Species.

The phrase descent with modificationsummarized Darwins perception of the unity

of life.

The phrase refers to the view that allorganisms are related through descent from

an ancestor that lived in the remote past.


21/25

In the Darwinian view, the history oflife is like a tree with branchesrepresenting lifes diversity.

Darwins theory meshed well with thehierarchy of Linnaeus.

Figure 22 7


22/25

Figure 22.7

Figure 22 8


23/25

Figure 22.8Hyracoidea(Hyraxes)

Sirenia(Manateesand relatives)

Deinotherium

Mammut

Platybelodon

Stegodon

Mammuthus

Elephas maximus(Asia)

Loxodonta africana(Africa)

Loxodonta cyclotis(Africa)

Moeritherium

Barytherium

60

Millions of years ago

34 24 5.521040

Years ago


24/25

Recommended books


25/25

For next lecture

Read Chap. 23 and answer:

- What is a gene pool?

- Define a biological population.

- What is Hardy Weinberg equilibrium?

Documents

BIO311Dlecture5