Notes Natural Selection September

8/6/2019 Notes Natural Selection September

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The Theory of

Evolution


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A theory

Explains the current observations andpredicts new observations.

Explains: Present day organisms are

similar, but not identical, to fossilorganisms.

Explains: Biodiversity

Explains: Populations are well suitedto their environments; molecules,organelles and cells specialized.

Predicts?


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What is a species?

A speciesis a group of organisms that can mateand produce fertile offspring.


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Are all dogs the same species with

variationsorarethey differentspecies ?

German Shepherd DachshundGreat Dane

Cana German Shepard and a GreatDanemateand produceoffspring ?


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APuggle!!


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ALaboradoodle. Of course.

So, dogs of different breeds are members of the same

species. They canproduce fertile offspring.


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Variation and Adaptation

Populations are groups of organisms of the samespecies living together.

Variation exists among members of everypopulation

A population/species has adaptations for survivalin a particular niche

Whats the difference between variation and

adaptation?


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forcapturinginsects

4)longstickytongue


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Types ofA

daptationsAnything that helps an organism

Hide from/defend against predators

Attract a mate/reproduce (sexual selection)

Catch food


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Attract a mate/reproduce

Male-male contest

Mate selection AnoleElephant Seal

Peacock

PeahenIrish Elk


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Catch Food


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Throughadaptations,populationsoftenbecomesuited toaspecifichabitatorniche.

Duck foot chickadee


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Broadlyspeaking,a niche isahabitatandtheroleapopulationplaysinthathabitat.


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Insect eaters

Bud eater

Seed eaters

Cactus

eater

Darwin &

Evolution by

Natural Selection


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Beginninginthe late1700spaleontologistswerebeginningto discoverfossils of

animalsthatno longerexisted.


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The irsts stemati explanati n ev l ti nasput rth by the Frenchscientist Jean-

Baptiste Lamarckin18 9. Inhistheory,Lamarck describedamechanism orevolutionknownas theinheritanceofacquired

characteristics.

Jean-Baptiste amarck (1774-1829)


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Jean-Baptiste Lamarck

Lamarckbelieved thatfossilsofextinctanimals werethe

ancestors ofanimalslivingtoday.


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3. Onceastructure wasmodified byuseor disuse,modificationisinherited byoffspring. Thisthird

principleiscalled the inheritance of acquired

characteristics

(Lamarkstated thatagiraffesneckgraduallybecame longerduetostretchingit duringits lifetime. Their longernecks

could thenbepassed ontotheiroffspring.)


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Lamarkshypothesis

abouttheinheritance of

acquired

characteristicswas laterdisproved by

GermanbiologistAugust

Weismann


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DespiteLamarckbeing wrong,thesearchforamechanismhad

begun.Theindividual tofinally discoverthe

mechanism

of

ev

olution

wou

ldbe . . .


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Charles Darwin

Proposed a way how

evolution works

How did creatures change

over time? by natural selection

Collected a lot of

evidence to support hisideas

1809-1882

ritish naturalist


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LaMarck

evolution by acquired traits

creatures developed traits

during their lifetime

give those traits to their

offspring

example

in reaching higher

leaves giraffes stretch their

necks & give the acquired

longer neck to offspring

not accepted as valid

Earlier ideas on Evolution


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Darwins view of Evolution

Darwin

giraffes that already

have long necks

survive better leave more offspring who

inherit their long necks

variation

selection & survival

reproduction &

inheritance of more

fit traits


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Robert FitzroyRobert Fitzroy

Voyage of the HMS eagle Invited to travel around the world

1831-1836 (22 years old!)

makes many observations of nature

main mission of theBeagle was to chartSouth American coastline


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Voyage of the HMS eagle

Stopped in Galapagos Islands 500 miles off coast of Ecuador


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GalapagosRecently formed volcanic

islands. Most of animals on

the Galpagos live nowhere

else in world, but they look

like species living on South

American mainland.

800 km west of Ecuador


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Darwins journal givesa detailed descriptionofthehistoric journeyand hasbeenpublished as

"The Voyageofthe Beagle.


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Manyof Darwins observations made

him wonder Why?

Darwin asked:

Whywere these creatures found only

on the Galapagos Islands?

Darwin foundmany unique

species


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present day Armadillos

Darwin found:Darwin found:

Evidence that creaturesthat creatures

have changed over timehave changed over time

ancient Armadillo

Darwin asked:Darwin asked:

Why should extinctWhy should extinct

armadillos & modernarmadillos & modern

armadillos be found onarmadillos be found on

same continent?same continent?

Darwin foundclues in the

fossils


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Darwin found:

Different shells on tortoises on different islands


Is there a relationshipIs there a relationship

between the environmentbetween the environment

& what an animal& what an animal

looks like?looks like?


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D

arwin found birds

Finch? Sparrow?

Woodpecker? Warbler?

Darwin found:Darwin found:

Many different birds onMany different birds on

the Galapagos Islands.the Galapagos Islands.

He thought he foundHe thought he found

very different kindsvery different kinds


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Darwin was amazed tofind out:

All14 species of birds

were finches

Finch? Sparrow?

Woodpecker? Warbler?

But Darwin found a lot offinches

Large ground

finchSmall ground

finch

Warblerfinch Tree finch

Butthere is only one

species of finch on the

mainland!


If the GalapagosIf the Galapagos

finches came from thefinches came from the

mainland, why are theymainland, why are theyso different now?so different now?


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Relationship between species (beaks) & food


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Darwins finches

Darwins conclusions

variations in beaks

differences in beaks in the original flock

adaptations to foods available on islands natural selection for most fit

over many generations, the finches were selected for

specific beaks & behaviors

offspring inherit successful traits accumulation of winning traits:

both beaks & behaviors

separate into different species


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Warbler finch

Woodpecker finch

Small

insectivorous

tree finchLarge

insectivorous

tree finch

Vegetariantree finch

Cactus finch

Sharp-beaked finch

Small

ground

finch

Medium

ground

finch

Large

groundfinch

Insect eaters

Bud eater

Seed eaters

Cactus

eater

variationnatural selection forbest

survival & reproduction

From 1 species to 14 species


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Darwins Theory ofNatural Selection

1. There is variation withinpopulations. Somevariations are favorable.

2. More offspring are bornthan can possibly survivedue to limited resource.

3. Individuals that surviveand reproduce are thosewith favorable traits.


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Natural Selection

variation Differences

in fitness

Changes in

a population


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On

Nov

ember24,1 5 ,

Darwins

book,On theOriginof

Species is published.


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Corn has been selected to produce

larger and larger ears over thepast 200 years.


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All dogs breeds were created from wolves byhumans over a 10,000 year period.


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Classification

Taxonomy: The scienceof naming organisms.


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What variety! What similarity! Diversity of Life

there are so many different creatures onEarth

why are there differences? Unity of life

all creatures havesimilarities

common characteristics

why are they so alike?


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Aristotle

Plant or animal?

If an animal, does it

Fly

Swim

Crawl

Simple classifications

Used common names


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Carolus Linnaeus

Swedish botanist, 1750s Developed binomial nomenclature

First word = genus name

Second word = species name

Must be underlined or in italics

Genus capitalized

ex.Homo sapiens


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Why binomial nomenclature?

Much easier than a 10+ word name under

old polynomial system

Less confusion

Binomial = SCIENTIFIC NAME


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Organizing systems Making sense out of the differences

Eastern gray squirrel

Sciurus carolinensis


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Taxonomic hierarchy Names organisms and their relationships

from very broad to very specific


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How many are out there?

Scientists currently estimate that

There are 10 million species worldwide

Over 5 million live in the tropics

Most unnamed species are small or microscopic


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Why is taxonomy useful?

Helps to show how organisms are related

Can be used to reconstruct phylogenies

evolutionary histories of an organism or

group


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Cladograms Graph showing when different groups diverged

from a common ancestral line

Points where they diverge are often noted with a

feature that was different between ancestral group

and a new feature in the group that split off.


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Phylogeneti Systemati s - Characters and Taxa

orangutan Gorilla Pan H. sapien

time

upright posture

use of tools

reduced

hairiness

bipedal

complexlanguag

The common ancestral

lineage to Pan (chimps)and H. sapien eventually

splits to form the

ancestors to

chimpanzees and H.

sapien.


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How are Phylogenic Relationships

Determined?

D

NA

: a geneticcode

More closelyrelated organisms

have moresimilarities in theirDNA code

S


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Structure

Closely related organisms may have similar

(homologous) structures, adapted to theirparticular niches


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Embryology and Development

Closely related

organisms will have

similar embryo

development


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Organizing the world of

organisms

The Tree of Life

organize creatures

by structure &function

how they are built

how they live

organize them intogroups of closely

related creatures


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Three Domains, 6 KingdomsDomain Archaea

Contains 1 kingdom the Archaebacteria

Domain BacteriaContains 1 kingdom the Eubacteria

Domain Eukarya

Contains 4 Kingdoms:-Protista-Fungi-Animalia-Plantae

Prokaryotes


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KingdomProtist

Kingdom

Fungi

Kingdom

Plant

Kingdom

Animal

KingdomArchaebacteria

KingdomBacteria

Prokaryotes

Eukaryotes


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Bacteria

&

Archaebacteria

Classification

6 Kingdom system Prokaryotes

No separate organelles in their cells

Bacteria

Archaebacteria

Eukaryotes

Separate organellesin their cells

Protists Plants

Fungi

Animals

Prokaryote

Eukaryote


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Prokaryotes Bacteria

one-celled organisms

microscopic

no organelles

have cell membrane have DNA

most common form of life on Earth

incredible number of different kinds


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Archeabacteria

Ancient bacteria live in extreme environments

high heat

high salthot spring in which archaea

are found similar to bacteriabut have differentcell wall compounds


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Prokaryotic = no

nucleus

DNA is not in a nucleus

as in eukaryotes.

plasmids are

small loops of DNA

cell wall composition determines gram-positive and

gram-negative types.TRUE BACTERIA -

MORPHOLOGY

Eubacteria

Most common bacteria,found everywhere!


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Eukaryotes - Morphology

Nucleus

DNA organized

into chromosomes.

Many organelles(cell parts)


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Eukaryotes can be unicellular or multicellular.

All have nuclei and organelles within cells.

Eukaryotes

Plants: autotrophic,

multicellular, cell

walls made of

cellulose

Fungi: heterotrophic,

decomposers, cell

walls made of chitin


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ANIMALIA PHYLA

Porifera Cnidaria Platyhelminth AnnelidaM

ollusca Arthropoda Echinodermata Chordata

Animals: Multicellular, heterotrophic


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Animals: Chordates

E k


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EukaryotesProtists: Eukaryotic organisms that are less

organized than plants, animals, fungi.

Some are plant-like

Some are animal-like

Some are fungus-like

Slime mold

paramecium

algae

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Notes Natural Selection September

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