Regents Biology 2006-2007

Evidence for Evolutionby

Natural Selection

Regents Biology

A BRIEF HISTORY...

Charles Darwin The person who was most

influential to our understanding of evolution.

In 1831, at age 22, he joined the crew of the HMS Beagle as a naturalist for a 5 year voyage around the world.

Regents Biology

Darwin’s Findings

After Darwin returned to England in 1836 he filled notebooks with his ideas about species diversity and the process that he would later call evolution.

He did not rush to publish his ideas because they disagreed with the fundamental scientific beliefs of his day.

He asked his wife to publish his ideas when he died.

Regents Biology

Wallace’s Essay

In 1858, another naturalist, Alfred Russell Wallace wrote an essay describing his work in Malaysia that summarized the same ideas Darwin had been thinking about for 25 years.

Regents Biology

Origin of Species

Suddenly Darwin had incentive to publish the results of his work.

In 1859, his book On the Origin of Species presented evidence and proposed a mechanism for evolution that he called natural selection.

Regents Biology

EVOLUTION IS CHANGE OVER A PERIOD OF TIME!

Regents Biology

Evolution is NOT goal-oriented§An evolutionary trend does not mean that evolution is goal-oriented.

§Surviving species do not represent perfection.

§There is random chance involved as well

§Traits happen—Well suited to anenvironment, OR NOT!

Evolution is the survival of the fittest, but

sometimes it is survival of the just good

enough.

Regents Biology

Evidence supporting evolution Fossil record

shows change over time

Anatomical record comparing body structures

homology & vestigial structures embryology & development

Molecular record comparing protein & DNA

sequences

Artificial selection Human-caused evolution

Regents Biology

1. Fossil record Layers of rock contain fossils

new layers cover older ones creates a record over time

fossils show a series of organisms have lived on Earth (over a long period of time)

Regents Biology

Fossils tell a story…

the Earth is oldthe Earth is old

Life is oldLife is old

Life on Earth has changedLife on Earth has changed

Regents Biology

Fossil of Archaeopteryx lived about 150 mya links reptiles & birds

Today’s birds descended from ancestral species

Today’s birds descended from ancestral species

Evolution of birds

Regents Biology

Transition from sea to land 2006 fossil discovery of early tetrapod

4 limbs Missing link from sea to land animals

Regents Biology

Land Mammal

?

???

Where are the

intermediate

fossils?Where are the

intermediate

fossils?

Ocean Mammal

Complete seriesof transitional

fossils

We found the fossil — no joke!

Regents Biology

2. Anatomical recordAnimals with different structures on the surfaceAnimals with different structures on the surface

But when you look under the skin…But when you look under the skin…

It tells an evolutionary story of common ancestorsIt tells an evolutionary story of common ancestors

Regents Biology

Compare the bones The same bones under the skin

limbs that perform different functions are built from the same bones

How could thesevery different animals

have the same bones?

Regents Biology

Homologous structures Structures that come from the same origin

homo- = same -logous = information

Forelimbs of human, cats, whales, & bats same structure on the inside same development in embryo different functionson the outside evidence of common ancestor

Regents Biology

But don’t be fooled by these…

Analogous structures look similar on the outside same function different structure & development on

the inside different origin no evolutionary relationship

Solving a similar problem with a similar solutionSolving a similar problem with a similar solution

How is a birdlike a bug?

Regents Biology

Analogous structures Dolphins: aquatic mammal Fish: aquatic vertebrate

both adapted to life in the sea

not closely related

Watch the tail!

Regents Biology

Vestigial organs Structures on modern animals that have

no function remains of structures that were functional

in ancestors

evidence of change over time

eyes on blind cave fish

human tail bone

Regents Biology

Vestigial organs Hind leg bones on whale fossils pelvis on

snakeWhy would whales have pelvis & leg bones if they were always sea creatures?

Why would whales have pelvis & leg bones if they were always sea creatures?

Because they used to

walk on land!

Regents Biology

Convergent evolution 3 groups with wings

Does this mean they have a recent common ancestor?

Flight evolved 3 separate times — evolving similar solutions to similar “problems”

Flight evolved 3 separate times — evolving similar solutions to similar “problems”

NO!

They justcame up with the

same answer!

Regents Biology

Convergent evolution led to mimicry Why do these pairs look so similar?

Monarch malepoisonous

Viceroy maleedible

fly bee moth bumblebee

Which is the fly vs. the bee? Which is the moth vs. the bee?

Regents BiologyToo close to call for hungry birds!!

Regents Biology

Yuck!!!

Regents Biology

Comparative embryology Development of embryo tells an

evolutionary story similar structures during development

all vertebrate embryos have a “gill pouch” at one stage of development all vertebrate embryos have a “gill pouch” at one stage of development

Regents Biology

3. Molecular record

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

Comparing DNA & protein structure everyone uses the same genetic code!

DNA

compare common genes compare common proteins

compare common genes compare common proteins

number of amino acids different from human hemoglobinnumber of amino acids different from human hemoglobin

Regents Biology

Building “family” treesClosely related species are branches on the tree — coming from a common ancestorClosely related species are branches on the tree — coming from a common ancestor

Regents Biology

How do we know natural selection can change a population? we can recreate a similar process “evolution by human selection”

4. Artificial selection

“descendants” of wild mustard“descendants” of wild mustard

Regents Biology

Selective BreedingHumans create the change over time

Humans create the change over time

“descendants” of the wolf“descendants” of the wolf

Regents Biology

Artificial Selection…and the examples keep coming!

I liked breeding pigeons!

Regents Biology

Unexpected consequences of artificial selection

Pesticide resistancePesticide resistance

Antibiotic resistanceAntibiotic resistance

Regents Biology

Insecticide resistance Spray the field, but…

insecticide didn’t kill all individuals variation

resistant survivors reproduce

resistance is inherited insecticide becomes

less & less effective