The Process of Change Over Time EVOLUTION The Process of Change Over Time

Evidence of Evolution Geologic Record Fossils Comparative Anatomy Comparative Embryology Comparative Cytology Comparative Biochemistry

Geologic Record Man, that record ROCKS! Geologists estimate the Earth is 4.5-5 billion years old based on radioactive dating of rocks Fossils: The oldest fossils date back to about 3.5 billion years ago and are similar to bacteria Can be Imprints, Casts, Molds Can be petrified, preserved in amber, or even frozen The oldest fossils are below more modern ones, and we can compare structures, see similarities/differences in body form, and see where/when certain species went extinct.

Rock Record

Trilobite Fossils

Other Evidence

Look a Mammothsicle!

Amber

Fossils Man, I’d like to see the dog that buried this one!

Petrified Wood What are they so afraid of?

Imprints... Definitely left an impression on this kid

Descent With Modification: Evidence from the Fossil Record

Comparative Anatomy Observations of basic structural or anatomical similarities between organisms Homologous Structures: anatomical parts found in different organisms that are similar in origin and structure. This indicates they shared a common ancestor. The arm/hand of a human, the wing of a bird Analogous Structures: Can be misleading, have similar function, may even look similar, but have a different structure. E.g. the wing of a bird, the wing of a bee

Comparative Anatomy

Comparative Cytology Study of cell parts to find similarities/differences

Comparative Embryology We compare the early stages of embryological development of different organisms and find similarities that suggest a common ancestry. Humans, reptiles, birds, fish all share remarkable similarities. You had gill slits, webbed feet/hands and a tail in early development!

Comparative Biochemistry We compare the DNA and Protein makeup of different organisms to see evolutionary relationships. DNA of an organism/species: Genome Protein of an organism/species: Proteome Hey, YOU did this! Scientists are turning to this more often

Comparative Biochemistry

Speciation

Taxonomy/Evolutionary Relationships

Cladogram

Evolution Theories: Jean Baptiste Lamarck Principles of Use and Disuse: Use it or lose it. New structures appeared in a single organism because they were NEEDED Used structures became bigger, better developed, unused structures shrunk in size. Inheritance of Acquired Characteristics: traits acquired through the life of an animal are passed to its offspring. The species becomes better adapted based on the changes made during the lives of individual organisms

Weismann Disproved Lamarck Chopped the tails off of many generations of mice, all offspring had tails

Darwin OVERPOPULATION: within a population, more organisms are born in each generation than can survive COMPETITION: There are limited natural resources for a species so there is a struggle for survival . examples? SURVIVAL of the FITTEST: Not necessarily the strongest. Natural variations among individuals makes them better able to compete. The best adapted survive.

Darwin, part 2 NATURAL SELECTION: Environmental conditions select for which adaptations are beneficial or detrimental (adaptive value). This is called SELECTION PRESSURE REPRODUCTION: Individuals BORN WITH helpful variations reproduce more, leaving more offspring, influencing the gene pool SPECIATION: Over many generations, adaptations accumulate, the “new” species no longer mates with the old. Reproductive Isolation reinforces speciation

Modern Evolutionary Theory Combines Darwin’s views of variation and natural selection and our knowledge of the genetic basis of variation Genetic sources of variation? In meiosis/fertilization: crossing over random segregation recombination Random mutations in genes/chromosomes

Diversity Within a Species

The Results of Genetic Variation Structural Change: A physical anatomical change in an individual. Ex. : long necks of giraffes, elephants’ trunks, webbed feet of ducks, large size of human brain. Functional Change: Molecular/biochemical changes affect how an organism works. Ex.: electric eel, enzymes in bacteria in hot springs, chameleon’s ability to change colors, snakes’ ability to make venom. Behavioral Change: Ex.: fireflies’ blinking, mating dance/song of birds, fighting between males in deer, sheep.

Insecticide Resistance

Adaptation

Extinction Out with the old, in with the new The disappearance of an entire species Generally extinction is more likely when environmental conditions happen faster than natural selection The fossil record shows that the majority of species that have ever lived on Earth are now extinct. Now that makes you feel special, doesn’t it?

The Real Reason Dinosaurs Went Extinct

Punctualism/Gradualism

Rate of Evolution Gradualism: Relatively stable environmental conditions often lead to continuous, slow, and gradual evolutionary rates Punctuated Equilibrium: Long periods of relative stability are interrupted by short explosions of evolutionary change The fossil record shows examples of each

Primitive Earth Hot, had inorganic substances in all three states, much radioactivity, lightning, UV,X-rays,volcanic activity Atmosphere: H2, NH3 (ammonia), CH4 (methane), H20 vapor Seas: dissolved atmospheric gases, minerals. “Hot, thin soup”

Early Earth?

Organics/aggregates Inorganics chemically bonded to become organics. Definition? Who is Stanley Miller? What did he prove? Aggregates: large, complex molecules clump up and a membrane will spontaneously form around them Reproduction: When the aggregates got big/complex enough, they split. Poof!

Heterotroph to Autotroph The first organism on the planet were heterotrophs. They’d bump into eachother and assimilate eachother (early eating). They did anaerobic fermentation and pumped Carbon Dioxide into the air which set the stage for…. Autotrophs: began to do primitive photosynthesis, pumped oxygen into the air

Anaerobes to Aerobes With the advent of free oxygen, the capacity of organisms to use it in respiration increased. Why did natural selection ultimately “favor” aerobic respiration in most organisms?