evolution a change in successive generations of organisms, due to random mutation and changes in the...

EvolutionA change in successive generations

of organisms, due to random mutation and changes in the

organisms’ surroundings

Evolution takes place through a set of processes

• including: – mutation– adaptation– natural selection – extinction

Mutation

Genetic mutations & variety produced by sexual reproduction allow for

diversity within a given population.Many factors can cause a change in a

gene over time.

Mutation• Mutations are

important in how populations change over time because they result in genetic changes to the gene pool.

• Mutations are inheritable changes because a mutation is a change in the DNA code

Mutation = change in DNA

Mutations can be: favorable change or adaptation in genetic information that improves a species’ ability to exist in its environment


Mutations can be: unfavorable change that does not improve a species’ ability to exist in its environment.


Mutations can be: changes in the genetic information that neither harms nor helps the species.

Adaptation

• Adaptations are structures, functions, or behaviors that enable a species to survive.

Adaptation

• Depending on the rate of adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.

Adaptations…Activity: How Handy? The Human Hand

DARWIN’S PHRASE FOR EVOLUTION:“Descent with Modification”

He meant that present-day species arose from a succession of ancestors. Descendents of

ancient ancestors that spread into new environments and accumulated diverse

modifications, or adaptations that allowed them fit into specific ways of life.

Copyright © 2009 Pearson Education, Inc.


Introduction: Clown, Fool, or Simply Well Adapted?

• What is an adaptation?– Adaptations are behaviors, structures or functions that

enable a species to survive.

Haltere


CHARLES DARWIN: Father of Evolution


Jean Baptiste Lamarck: Mechanism of Evolution

– Lamarkians would say:– Use or disuse – Inheritance of acquired

characteristics

– Example…giraffes STRETCH THEIR NECKS BY REACHING and SO THEY HAVE BABIES WITH LONGER NECKS.

– Principles of Geology


Charles Lyell:

Father

of

Geology

Lynell’s view: Formation of Sedimentary Rock

EARTH is VERY, VERY OLD!

• Darwin realized Earth was very, VERY, VERY, VERY old & that, over time (LOTS OF TIME), present day species have arisen from ancestral species by natural processes

• sedimentary rock is very old – therefore the species that are represented in this rock must also be old.

• Most fossils are found in sedimentary rock.• Older fossils will be found below younger fossils.

NorthAmerica

ATLANTICOCEAN

GreatBritain

Brazil

TheGalápagosIslands

PACIFICOCEANPinta

MarchenaGenovesa

Santiago

Fernandina Pinzón

IsabelaSan

Cristobal

EspañolaFlorenza

DaphneIslands

SantaCruz

SantaFe

40 miles

Equator

40 km0

0

Europe

Africa

SouthAmerica

Ande

s

Argentina

Cape Horn

Cape ofGood Hope

PACIFICOCEAN

Equator

NewZealand

Australia

Tasmania

At the age of 22, Darwin joined a 5 year expedition aboard the HMS Beagle to map the coast of South America…not all who wander are lost!

• Darwin observed that– Organisms vary in many traits– More offspring produced than the environment can support


Darwin’s Idea of Natural Selection

• Individuals with traits that increase their chance of surviving & reproducing leave more offspring

• As a result, favorable traits accumulate in a population over generations


13.2 Darwin proposed natural selection as the mechanism of evolution

• Darwin found convincing evidence for his ideas in the results of artificial selection, the selective breeding of domesticated plants and animals



Terminalbud

Lateralbuds

Leaves

Kale

Stem

Brussels sprouts

Cauliflower

Cabbage

Kohlrabi

Wild mustard

Flowerclusters

Flowersand stems

Broccoli

Artificial Selection: Dog Breeding

German shepherd Yorkshire terrier English springerspaniel

Mini-dachshund Golden retriever

Hundreds tothousands of years

of breeding(artificial selection)

Ancestral dog

– In 1859, Darwin published On the Origin of Species by Means of Natural Selection, presenting a strong, logical explanation of descent with modification, evolution by the mechanism of natural selection


13.1 A sea voyage helped Darwin frame his theory of evolution

• Note these important points – Individuals do not evolve: populations evolve– Natural selection can amplify or diminish only heritable

traits; acquired characteristics cannot be passed on to offspring

– Evolution is not goal directed and does not lead to perfection; favorable traits vary as environments change



• Will natural selection act on variation in hair style in a human population?



• Will natural selection act on tongue rolling in a human population?

(Note: Tongue rolling is an inherited trait, caused by a dominant allele)



• Will natural selection act on eye number in a human population?



evolution a change in successive generations of organisms, due to random mutation and changes in the...

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species ability

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mutation adaptation

ancestral species

presentday species

evolutiona change

unfavorable change

environment mutation