EVOLUTIONARY EVIDENCES

JRMGBio1 2009

Evidences Fossil Record and Geology Morphology Embryology Biochemistry Biogeography/ Geographical

Distribution

Fossil Record Fossils

relics or impressions preserved

because the material that surrounds the organism prevents it from decaying

Mostly in sedimentary rocks

Proposed: Earth- hundreds of millions in age rather than thousand years old

Fossil Record Fossils in layers

of rocks gradual change

over time Succession is

compatible with other evidences of the major branches of descent in the tree of life

Fossil formation Cold places: animals might fell

into crevasses in ice or trapped in snow fields

Trapped in sticky sap of trees: amber

When trapped in peat bogs (certain kind of quicksand)

Otzi the Iceman is a well-preserved natural mummy of a man from about 3300 BC, found as shown in the above astonishing photographs by two German tourists, Helmut and Erika Simonby in 1991 in a glacier of the Otztal Alps in Italy, near its border with Austria. Otzi rivals the Egyptian "Ginger" as the oldest known human mummy, and has offered an unprecedented view on the habits of Chalcolithic (Copper Age) Europeans.

Mummy Juanita is a frozen Inca mummy of a teenage girl who died more than 500 years ago and was discovered in Peru in 1995 by anthropologist Johan Reinhard and his Peruvian climbing partner Miguel Zarate. Also known as Momia Juanita (original Spanish), the Ice Maiden, the Lady of Ampato and the Frozen Lady, this mummy is unfortunately going through quite a difficult modern life and not doing so well. In 2006 daily newspaper El Comercio published that an expert from the U.S. Smithsonian Institution who was vacationing in the southern Andean city of Arequipa detected dampness inside the mummy's glass-enclosed refrigeration compartment. Shown above: Mummy Juanita when found on Mount Ampato in Peru in 1995.

peat bog is a type of wetland whose soft, spongy ground is composed largely of living and decaying Sphagnum moss. Decayed, compacted moss is known as peat, which can be harvested to use for fuel or as a soil additive

PROCESS OF FOSSIL FORMATIONSedimentary Rocks

Rain, Heat, Cold

Sand, Silt, Clay

StreamsRiversSeas

Settles down at the bottom

Of these bodies of water

Dead animals/plant

s

Are embedded into these

Sediment layers

PROBLEMS IN ASSEMBLING THE PUZZLE

Many organism die and vanish without leaving a trace

SR: only in certain bodies of water Organisms that live on mountains and

deserts* When exposed to weathering reveals fossils Fossil reconstruction

Radioactive dating Potassium 40- old fossils Carbon 14- new fossils

WHAT FOSSIL RECORDS TELL US

Represents the preserved collective history of the earth’s organisms

Shows the change followed change on earth

Morphology Similarities in Body Structure Homologous structures

meet differential needs but developed from the same body parts

different mature forms but developed from the same embryonic tissue

Vestigial Organs Reduced in size or traces of homologous organs in

other species No or little function Doesn’t affect an organism’s ability to survive and

reproduce

TRANSFORMATION TO VESTIGIAL ORGANS

new adaptations that make some organs unnecessary Serves as a clue to

an animal’s evolutionary ancestry

EMBRYOLOGYStudy of organisms at an early stages of development

SIMILARITIES IN EARLY DEVELOPMENT

Shows similar genes at work Hox genes*

Occur because of the same basic control mechanism

Although organisms are different and evolved through mutations, similarities are retained**

Same groups of embryonic cells develop in the same order and in similar patterns***

“Ontogeny recapitulates phylogeny”

Ontogeny (development of an individual organism) is a replay of the evolutionary history of species (phylogeny)

Ontogeny provides clues to phylogeny

BIOCHEMISTRY Use of DNA and proteins to reflect the

relationships among speciesDNA sequences

divergencehuman vs. chimpanzee 1.2%human vs. gorilla 1.6%human vs. baboon 6.6%

DNA of all eukaryotic organism Always has the same basic structures and replicates in the

same way RNA of various species

may act little differently but are similar in structure from one species to the next

Geographic Distribution of Living Species

Species differ through their distribution

Islands have many species of plants and animals that are endemic but closely related to the nearest mainland.

• Islands with similar environmental conditions but in different parts of the world are not populated by closely related species.

GEOGRAPHIC DISTRIBUTION OF LIVING SPECIES

Examples: Darwin’s Finches Armadillos in South America Australia’s pouched mammals