Evidence of EVOLUTION

Evidence Supporting Evolutionary Theory

Fossil Record Biogeography Homologies

Anatomical- Homologous structures Anatomical- Vestigial structures Molecular- DNA Similarities in the genetic

code Developmental- Embryology

Fossils

Remains, impression, tracks or other evidence of an organism that lived long agoMost fossils are found in layered sedimentary rock.

Newest fossils are at the top.

Oldest fossils are at the bottom.

Ancient shrimp fossil A shrimp today

Biogeography Scientists can study the distribution of species to help

them determine evolutionary relationships. Species that evolved from a common ancestor are usually

found geographically near each other. Just because two ecosystems are very similar, it doesn’t

mean you will find the same species inhabiting it.

Patterns in the diversity and distribution of species.

The continental drift theory, first proposed by Alfred Wegener in 1912, has been supported by oceanographic evidence. Continental drift has also influenced the distribution of species.

What is it?

Arctic AntarcticWhy aren’t they found in both places?

Why are there penguins found in Australia, Chile, and South Africa?

Homologous structures

Structures that share a common ancestor may have the same anatomical structure but

may have adapted in ways that enable the organism to survive in different

environments.

Anatomical Homologies

Anatomical similarities

TurtleAlligator

Bird

Mammal

Some organisms may not look alike, but they’re built alike

Homologous structures show evidence of:

-similar genes

-common ancestor

Homologous Structures

Turtle AlligatorBird Horse

common ancestor

Vestigial Structures Body parts and organs that

are reduced (smaller) in size and have no benefit, but are still present in the body.

Ostrich with wings

Blind cave salamander and blind cave fish

Pelvis in Snakes without legs

DNA•The genetic material of some organisms is very similar.•DNA sequences that are very similar tell us the organisms originate from a common ancestor.•When they are very different, we know the organisms are not related. •Amino acids are coded by DNA.

Amino Acid Difference in Hemoglobin Compared with

HumanSpecies DifferenceGorilla 1Rhesus Monkey 8Mouse 27Chicken 45Frog 67Lamprey 125

Animal Amino Acid Sequences in Cytochrome-C

Horse gln pro phe thr thr ala lys asn lys thr lys glu glu thr leu met glu lys ala thr

Shark gln gln phe ser thr asp lys ser lys thr gln gln glu thr leu arg ile lys thr ala

Human gln pro tyr ser thr ala lys asn lys ile gly glu asp thr leu met glu lys ala thr

Turtle gln glu phe ser thr glu lys asn lys thr gly glu asp thr leu met glu asp ala thr

Monkey gln pro tyr ser thr ala lys asn lys thr gly glu asp thr leu met glu lys ala thr

The chart below shows the amino acid sequence for cytochrome-c of five vertebrates.

1. Compare the amino acid sequence of human cytochrome-c with that of the other four vertebrates.

DNAHemoglobin Comparison

Amino acid differences from HUMAN hemoglobin proteinSpecies

Lamprey eel 125

Frog

Chicken

Gorilla

Mouse

Rhesus monkey

67

45

27

8

1

DNA directs the assembly of amino acids into specific

proteins; therefore, species that shared a common

ancestor more recently have fewer amino acid

differences.

EmbryologyThe similarities between the development and growth of a fertilized egg cell.

Embryos of different species may appear similar in early stages of development

Bird embryo Human embryo

Embryo Development

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