Evidences Of Evolution

Evidences of Evolution

What are the evidences for evolution?

• Fossils

• Anatomic evidence

• Molecular evidence

Evolution II

2

Evidence of Evolution 1.

Biogeography: Geographical distribution of species.

Eastern Long Necked Turtle

Evidence of Evolution 2. Taxonomy: Classification of life forms. 3. Homologous structures: Structures that are similar because of common ancestry (comparative anatomy)

Anatomical evidence What type of evidence does anatomy reveal? Derived traits have similar anatomy “homologous structures”

Traits can evolve independently Will have very different anatomy “analogous structures”

Called “Convergent evolution’ What causes convergent evolution? Distinguishing homologous and analogous traits is not always easy A platypus has fur, a bill, webbed feet, and lays eggs

Evolution II

6

Anatomical Evidence, con’t. What does this mean: “Ontogeny reciprocates Phylogeny”? Ernst Haekel’s original data is somewhat flawed

See Fig 41.2 in text

What are vestigial structures? See Wikipedia for other cool examples http://en.wikipedia.org/wiki/Vestigial

Human coccyx

Evolution II

7

Evidence of Evolution 4. Comparative embryology: Study of structures that appear during embryonic development.

Evidence of Evolution 5. Molecular biology: DNA and proteins (amino acids)Slide 10

Molecular evidence Comparing protein -- amino acid sequence Comparing DNA -- base (ATGC) sequence

‘Molecular Clocks’ -- if you know the rate of mutation -- can be used to calculate when two species diverged

Evolution II

10

Evidence of Evolution 6. Fossil Record: Fossils and the order in which they appear in layers of sedimentary rock (strongest evidence).

Paleontology

What does the fossil record show? Extinct life forms Structural relationships with existing species Sequential appearance of derived characteristics Transitional forms

What are some limitations of the fossil record?

Preservation depends upon habitat Geologic disruption of record Soft-bodied organisms

What is ‘Biogeography’?

Evolution II

12

Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. • considered as the most direct evidences of evolution •

stromatolites

Ammonites

gastropod

bivalve

Araucaria sp.

Microfossil

Priscacara

Trilobites

amber

Earth’s oldest fossils are the stromatolites consisting of rock built from layer upon layer of sediment and other precipitants.

Ammonites are extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda, phylum Mollusca. Ammonites' closest living relative is probably not the modern Nautilus (which they outwardly resemble), but rather the subclass Coleoidea (octopus, squid, and cuttlefish).

Priscacara is an extinct genus of perch from the Eocene. It is commonly found in the Green River Formation in Wyoming.

Trilobites ("three-lobes") are a well-known fossil group of extinct marine arthropods that form the class Trilobita. Trilobites first appear in the fossil record during the Early Cambrian period (540 million years ago) and flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders, with the sole exception of Proetida, died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about 250 million years ago.

External mold of a bivalve from the Logan Formation, Lower Carboniferous, Ohio.

A fossil gastropod from the Pliocene of Cyprus where a serpulid worm is attached

Petrified cone of Araucaria sp. from Patagonia, Argentina dating from the Jurassic Period (approx. 210 Ma)

'Microfossil'

is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked eye. Microfossils may either be complete (or near-complete) organisms in themselves (such as the marine plankters foraminifera and coccolithophores) or component parts (such as small teeth or spores) of larger animals or plants.

A mosquito and a fly in Baltic amber that is between 40 and 60 million years old