Evolution To see where we might be going, we must understand where we have been Robert Tamarkin, 1993

Definition? Theory supported by evidence Biological evolution concerns changes in living things during the history of life on earth. Sharing of common ancestors Darwin term: descent with modification

Formation of the Earth 4.6 billion years old Universe 13.7 billion years old Complex: but woven out of 30ish main molecules – oxygen, hydrogen, carbon, nitrogen, Sulphur and phosphorus. (evidence #1)- present in early Earth- amino acids, RNA, DNA, Phosphorus (ATP????) Collision Theory and gravity.

Evidence of Evolution

Earth is Old Fossils: the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock. record shows changes in organism over the past 3.6 billion years. Transitional species – show the link between an ancestral form and that of the descendants (many examples)

Generally older fossils are lower in the strata Changes begin from simple to more complex First Life Form – simple cells – fossil evidence 3.4 billion years ago Generally older fossils are lower in the strata

Fossil Record Supports Evolution Millions of fossils have been discovered Fossil record shows changes of organisms through time Early earth shows simple life forms. As time passes life-forms become more complex Documents the order of appearance of groups and types of organisms The discovery of thousands of transtitionals species show transtions from fish to tetrapods (fish to salamanders, salamanders to reptiles), dinosaurs to birds, proto-horses to hores , apes to human, synapsid to mammals. Document major crises in Earth’s history and the recovery from events.

Example of transitional species- Whales Meet the transitional species

Horse Evolution - Transitions- changes from 4 toes to 1 toe Changes in skull size and changes in height

From Land to Water Tiktaalik 375 million years ago One intermediate fossil between fish and the first animals Tiktaalik 375 million years ago

Oxygen Environment What type of organisms increased in numbers to pump oxygen into the air? Photosynthetic Red beds Luckily- happened slowly 2.7 to 2.0

Descent with Modification A shared character is one that two lineages have in common, and a derived character  is one that is in the lineage leading up to a clade (group) and sets members of that clade apart from other individuals. Amniotic egg, lungs, vertebral Columns, etc.

Radiometric Dating

Radiometric Dating *Fossils show relative dating by comparing data in the rock strata *Radiometric Dating ability to use absolute dating - done by comparing proportions of radioactive isotopes in the sample. * Radiometric Elements are unstable (called parents) and they decay into different elements (daughter elements). Uranium to lead. http://science.howstuffworks.com/29145-100-greatest-discoveries-radiometric-dating- video.htm

Earth’s oldest crustal rocks – 4.03 billion years old. Oldest metamophised sediment – zircon crystals found in Canada- 4.4 billion years old.

Radiometric Dating Supports Evolution many naturally-occurring elements are radioactive and they break down, or decay, at known predictable rates. Many isotope pairs are useful in dating the Earth such as rubidium/strontium, thorium/lead, potassium/argon, argon/argon, or uranium/lead, all of which have very long half-lives, ranging from 0.7 to 48.6 billion years. Subtle differences in the relative proportions of the two isotopes can give good dates for rocks of any age. Geologists have made many radiometric age determinations, and continue to refine earlier estimates with new data. Dates are often cross-tested using different isotope pairs. Results from different techniques, often measured in rival labs, continually confirm each other. Repeatable results Comparisons to other methods of absolute dating.

Charles Darwin Not exactly a star student, but he revolutionized the scientific view of the natural world with his Theory of Natural Selection Traveled on the Beagle where his journey began in 1831 for a 5 year voyage The Beagle traveled from Europe to the Galapagos Islands then to Australia around the Cape of Good Hope and back to Europe

Observations aboard the Beagle Species vary globally a. Two similar species live in different areas of the world Species vary locally a. Differences among tortoises in the Galapagos islands Species vary overtime Fossils of extinct animals looked similar to living animals

Putting the pieces together ! Some of the species Darwin noted had never been identified before There were similarities between the finches on the Islands when compared to the ones in South America. What could it be????

Natural Selection Natural Selection: Organisms best suited to their environment survive and are able to produce offspring Fitness-How well an organism can survive Adaptation- Any heritable characteristic that increases an organisms ability to survive

Conditions Necessary for Natural Selection Variation among offspring (must be genetic) More organisms born than can survive (surplus) – creates competition for limited resources…Struggle for existence Individuals with the adaptations with the highest fitness for the environment live and pass along their traits.

Artificial Selection Artificial selection is when nature provides the variation amongst a species and human select the traits that they find most useful.

Comparing anatomy Homologous Structure: structures that are shared by related species and that have been inherited from a common ancestor Analogous Structures: When the structure is common but the function is different and example of this is the wing of a bird and a horses hoof

Comparing Anatomy Vestigial structures: inherited from ancestors but have lost much or all of their original function due to different selection pressures acting on the descendent