Regents Biology 2006-2007

Evidence for Evolutionby

Natural Selection

Regents Biology

What is evolution?Evolution is

the gradual change in a species over time.

Regents Biology

A theory is a ____________, _______, explanation of phenomena that have occurred in the natural world, like the

theory of __________________, ________, and _____________.

well-supported testable

gravitational attraction cell theory atomic theory

Isn’t evolution just a theory?

http://www.avgoe.de/StarChild/DOCS/STARCH00/questions/apple_falling.gif http://sixthsense.osfc.ac.uk/chemistry/atomic_structure2/atom.gif

Regents Biology

Evidence supporting evolution

Fossil recordAnatomical recordMolecular record

Regents Biology

1. Fossil record

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 organisms descended from ancestral species

Today’s organisms descended from ancestral species

Evolution of birds

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Land Mammal

?

???

Where are the

intermediate

fossils?Where are the

intermediate

fossils?

Ocean Mammal

Someone’s idea of a joke!

But the joke’s on them!!

Complete seriesof transitional

fossils

We found the fossil!

Regents Biology

2. Anatomical record

Animals 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 different functions

on the outside evidence of common ancestor

Regents Biology

Vestigial organs Hind leg bones on whale fossils

Why 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

Vestigial organs Structures on modern animals that have no

function remains of structures that were functional

in ancestors evidence of change over time

some snakes & whales have pelvis bones & leg bones of walking ancestors

eyes on blind cave fish

human tail bone

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

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

Rate Yourself 4 Apply concepts of natural

selection and evolution by creating a scenario that demonstrates the ideas

3 Explain how natural selection leads to evolution.

2 Describe how the evidence supports evolution.

1 Identify evidence for evolution.