Evidence of Evolution Blue-footed booby

Part 3: Evidence of Evolution What supports the Theory of Evolution….. Five Fingers of Evolution - video Part 3: Evidence of Evolution What supports the Theory of Evolution…..

Evidence of evolution Fossil Record Anatomy Embryology Biochemistry Evidence in microevolution

Preservation (insect in amber) Fossil evidence Mold Fossil Fossils → remains of ancient life Fossils arranged according to age show a progression of changes The Law of Superposition → a layer of rock is older than the layer above Fossils can be arranged by relative age Radioactive Dating → naturally occurring radioactive substances decay at a known rate Transitional forms of fossils are evidence for evolutionary change Preservation (insect in amber) Cast Fossil

Reasons Why a Fossil Might Not Form Dead bodies may be eaten or scattered (scavengers) Decay Hard exoskeleton vs. soft-bodied organism

Anatomy evidence Evolution works primarily by modifying pre-existing structures Homologous structures: parts came from the same origins, but now may have different function e.g., forelimbs of all mammals contain the same pattern of bones, although the bones now carry out a variety of functions horse leg, bat wing, human arm, whale flipper

Anatomy evidence Analogous structures: parts came from different origin, but now have same function

Anatomy evidence Vestigial structures: parts have no current function (had a function in ancestors) Examples in humans: wisdom teeth, erector pili, coccyx, ear muscles, appendix

Embryology evidence Closely related organisms develop similarly, especially in early fetal stages This suggests that these organisms are related to other forms. Mammal embryos (including humans) have fish-like gill slits, tail

Biochemistry evidence All organisms share certain biochemistry Genetic code for building amino acids All organisms use ATP for energy Plasma membranes of all organisms consist of a phospholipid bi-layer Finding similarities in protein and DNA sequences to look for relatedness Below is a DNA sequence in several different organisms…which organisms are the most related? Human CCA   TAG   CAC   CTA Pig CCA   TGG   AAA   CGA Chimpanzee CCA   TAA   CAC   CTA Cricket CCT   AAA   GGG   ACG

# of amino acid differences between human hemoglobin and other organisms

Evidence for Microevolution Evolution Observed Evolution of pesticide resistance in response to selection.

Evolution in Action

Macroevolution Large scale changes that take place over a long period of time that create and eliminate species.

Microevolution Short time scale events (generation-to-generation) that change the genotypes and phenotypes of populations.

Part 4: Types of Natural Selection

Example of Natural Selection Nature Chooses: Individuals that survive in nature will live long enough to reproduce. This means that they are the ones that get to breed and their characteristics (being good survivors) are inherited by their offspring.

Types of Natural Selection: A) Stabilizing Selection = individuals with the average form of a trait have the highest fitness. It is favored and most common B) Directional Selection = one extreme form of trait is more successful C) Disruptive Selection = BOTH extreme forms are more successful than the average. The most extreme form of a trait is favored and becomes most common. Evolution in the Big City

Females choose mates based on certain traits D) Sexual Selection Females choose mates based on certain traits Males with these traits have higher fitness (reproductive success) Male birds show off their beauty to attract females  Sexual selection in humans Video 27

Example of Artificial Selection Humans Choose: Individuals that are allowed to breed are chosen by humans. These individuals have the characteristics that humans want. This process produces animals that express specific characteristics.

Is there “unnatural selection?” Artificial Selection = humans “select” certain characteristics in plants, dogs, etc., that they find favorable These organisms may not necessarily survive and reproduce better in nature

Artificial Selection It has led to offspring through successive generations that can be very different in appearance and behavior from their distant ancestors. Organisms with certain traits are bred repeatedly until population has only that trait Example- Dogs, Corn, Broccoli, Cows, etc. Creating the Perfect Pet - Video

Artificial Selection

These chickens cannot stand or move.

Cow selectively bred for extra meat (muscle) Cow selectively bred for extra meat (muscle). Usually cannot stand for more than a few minutes or walk more than a few steps.

Artificial Selection Selective Breeding - Video