Ch. 15 Notes Outline

Ch. 15 Notes Outline

Evolutionchange over time. The process by which modern organisms have descended from ancient organisms. OWL PELLETS What can skeletal remains reveal?

Vocab pg 392 and 401 Kahoot: Owl pellet dissection How Do We Know? How do we know anything about the past

if humans were not around? By studying other planets and rocks on earth we know that earth was molten rock 4.6 billion years ago. Gravity pulled the densest to the center and the crust was formed 500 million ya

Then. The atmosphere formed because of gravity and life would not have existed like we know it because volcano gasses were in the atmosphere and it was too hot.

Clues in the Rocks Clues in the Rocks Eventually the earth cooled and oceans formed 500 milya

1st life clues came from 3.5 bill ya How do we know?????? FOSSILS FOSSILS

Most organisms decompose when dead. 99% of species that lived on earth are extinct only a tiny amount of those fossilized. Fossils ONLY form when buried in sediment soon after death.

Most common in aquatics environments because sediment is always moving Law of Supposition Types of Fossils

Trace fossils- any indirect evidence left by an organism- example footprints, burrows, feces Types of Fossils Molds and Casts

Mold is an impression of an organism Cast is a mold filled with sediment Types of Fossils Replacement- original material is replaced with mineral crystals leaving a replication

of the organism. Types of Fossils Petrified- empty pores fill with minerals Types of Fossils

Amber- preserved tree sap traps and then hardens preserves organism Types of Fossils Original- mummies or freezing

Why are they not everywhere? Why dont we see fossils everywhere? What type of rock must they be in? Why are there sea shells on top of mountains? What type of fossil would the bones of

your owl pellet likely form? Why? How do we know??? How old a fossil is? Dating fossils 1. Relative dating- compare to the layer of

earth they were found in 2. Radiometric dating uses half life of isotopes of the rock fossil was found in. 3.Carbon dating- for mummies or unaltered living organisms

life- dating Geological Time Line Foldable 4.6 meter long where each meter represents 1 billion years and each mm= 1

million years Earth formed at one end humans the other Geological Time Line

High lights! Origin of Life Oldest ideas of life was spontaneous generation. Redis meat experiment

Replace with Biogensis Louis Pasteur- used flasks to grow organisms Premordial Soup Hypothesis

Simple organic molecules could be made from inorganic compounds- Miller Uray experiment THEN Protein synthesis gave rise to genetic

code and RNA gives life its first genetic code. Molecules go to cells and metabolisms evolve ENDOSYMBIOTIC THEORY

ENDOSYMBIOTIC THEORY How Does Evolution Occur? We have all heard of .

But is that what it really means? History Before Darwin Jean Baptiste Lamarckfirst evolution

theory in 1809 Nature moves toward perfection Thought that it happened by Use and disuse Inheritance of acquired traits

LamarckUse and disuse Ex. fiddler crabs claws gets larger with use during lifetime Ex. blacksmiths biceps get larger over time

LamarckInheritance of Acquired Traits Modification acquired during lifetime is passed on to offspring

Not true! Ideas Darwin considered James Hutton: (gradualism) geologic change is continuous & slow Sir Charles Lyell: (uniformitarianism) forces that

shape Earth are still occurring (volcanoes, earthquakes, etc) ResultEarth must be more than a few thousand yrs. old Malthus

Believed that species have the capacity to overproduce offspring (only the fittest survive) This could lead to a

lack of food, space, etc for human population. Charles Darwin- Born 1809 Credited with the Theory of Evolution

based on Natural Selection. H.M.S. Beagle- ships naturalist Did not believe that species change at the start of the voyage. Darwin married his first cousin

Emma Wedgwood Down House, Darwins home Voyage of the HMS Beagle 1831-1836

Galapagos Islands-located off coast of South America At first he believed that the Earth was 6000 years old; species were designed for specific habitats and appeared on Earth in

present forms On the Galapagos Islands, he realized that the species were like those of South America, but not exactly. He specifically noted the different finches, tortoises, and iguanas

Galapagos Islands A Galapagos Tortoise Darwins finches (13 different species)

Could all have come from a single species in South America? Iguanas- Marine and Land Significant findings

Fossils resembled living organisms in same areawhy had they died and others lived? Galapagos Islands: Animals resembled mainlands, but different Characteristics of animals and plants differed from island to island.

Darwin thought and thought He hypothesized that new species were a result of natural selection. Natural Selection: Nature (environment) selects survival traits (variations)

Darwins book, On the Origin of Species (1859) Theory of Natural Selection Variations occur in nature There is a struggle for existencecompetition

Survival of the Fittest- organisms best suited for their environment will survive, reproduce and pass their traits to offspring. Overproduction of offspring

Artificial Selection Plant and animal breeders who selected traits causing variations so why would nature be different? Evidence for Evolution

1. Fossil Records Older fossil records are in lower rock layers Derived Traits: new traits not found in similar fossils Ancestrial traits: primitive features that

appear in ancestors teeth, tails Transitional fossils- show changes in traits Evidence for Evolution Comparative anatomy- what do you see?

Evidence for Evolution Embryos of related ancestors are similar in early stages. Gill slits and post anal tail?

Evidence for Evolution Vestigial structures: reduced form of a structure in other organisms. Ex birds wings, appendix and snake pelvis

Vestigial Organs Organs that have no function now but did have a function in ancestors. Ex: appendix, tailbone Evidence for Evolution

Analogous structures: not all similar features mean a common ancestor. Ex the wing of a beetle and bird evolve for different reasons. Homologous Body Structures

Wing of a bat resembles forelimb of a mammal, not a bird. Wing of bird resembles forelimb of reptile. Evidence for Evolution Biochemical Evidence

Comparing DNA nucleotide sequences. Evidence for Evolution Geographic Distribution-Due to different climate changes adaptations resulted in differences among organisms.

How does this happen? Adaptation A trait shaped by natural selection which makes a living thing better able to survive

in its surroundings Three Types: Structural Behavioral Physiological

Survival of the Fittest Fitness = reproductive success or the number of offspring you produce that contribute to the next environment. Better adapted = more fit (not strongest)

Structural Adaptations Traits that involve the physical structure (anatomy) of an organism. Ex: Camoflague, mimicry, beak of a bird, claws, etc.

Mimicryedible comes to look like poisonous Camouflagewalking stick & toad

Behavioral Adaptations Inherited traits or actions that help an organism survive and reproduce in a given environment. Examples: birds migrating, opossum faking death

Physiological Adaptations Traits that involve the internal functions or chemistry of an organism. Examples: Chemicals to digest food

Antarctic fish with anti-freeze in their body. Venom of a snake Anitbiotic resistance Mechanisms of Evolution Natural Selection is not the only

mechanism for evolution Population genetics how do any recessive genes ever show up? Shouldnt dominant always take over? Evolution wont occur unless allelic frequencies ( how many Aa vs AA) are

acted upon by forces that cause change Hardy-Weinberg Principle Allele frequency remains constant in a population (no evolution) if these factors are present in the population:

Random mating Population size very large No movement in or out of population No mutation No natural selection

Can determine frequencies by using the Hardy-Weinberg equation 2 allelesA & a 3 combinationsAA, Aa, & aa Let p = A and q = a A + a = 100 percent of alleles

Sop + q = 1 Square both sides p2 + 2pq + q2 = 1 homozygous dominant + heterozygous + homozygous recessive = all possible combinations

Practice Problem Having long tongues is dominant in frogs. 64% of the frog population is homozygous dominant. What percentage of the population is heterozygous? Practice problems

Equilibrium If Hardy Weinberg = 1 then equilibrium exists This hardly happens in nature over the extended period because of

No Genetic drift No gene shuffling No gene flow No Founder effect No mutations No Bottle neck

No random mating No natural selection Evolution of Populations Gene Pool: the combined genetic information of a population.

Two main types of Genetic Variation: Mutation: a change in the DNA strand Gene Shuffling: during sexual rep., chromosomes move independently producing millions of combinations of genes.

What is all that stuff? Genetic Drift- change in alleles due to chance. Some individuals by chance leave more genes in the pool! What is all that stuff?

Gene flow-also called migration- moves genes from one population to another- like pollen. What is all that stuff? Mutations- random mutation mostly cause

death but some are beneficial Pepperd moth lab What is all that stuff? Random mating- mating is not random. Mates choose carefully example

peacock What is all that stuff? Bottle neck- example of genetic drift where population declines to extremely low numbers then rebounds

Example of Bottle neck An example of a bottleneck Northern elephant seals have reduced genetic variation probably because of a population bottleneck humans inflicted on them in the

1890s. Hunting reduced their population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000 but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern

elephant seals that was not so intensely hunted. Northern Elephant Seals What is all that stuff? Founder effect- Small sample settles in a

location completely separate from others the random alleles now become the norm. For example, the Afrikaner population of Dutch settlers in South Africa is descended mainly from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene that causes Huntington's disease, because those original Dutch

colonists just happened to carry that gene with unusually high frequency. This effect is easy to recognize in genetic diseases, but of course, the frequencies of all sorts of genes are affected by founder events .

Afrikaner What is all that stuff? Gene shuffling-crossing over! Genes are shuffled to create variation

Three Types of Natural Selection 1. Stabilizing Selection 2. Disruptive Selection 3. Directional Selection

Stabilizing Selection Genetic diversity decreases as the population becomes stable. Disruptive Selection

Directional Selection Natural selection favors one phenotype and the allele frequency shifts in one direction. Speciation

Forming a new species This can happen because of species isolation: Reproductive: organisms cant interbreed and have separate gene pools Behavioral: different courtship rituals. Geographic: separated by barrier (river,

canyon) Temporal: reproduce at different times (seasons) Allopatric speciationgeographical Physical barrier divides 2 populations long

enough that they will not be able to reproduce. Allopatric Example Sympatric Speciation

Species evolve into new species with NO physical barrier- side by side 200 years ago, the ancestors of apple maggot flies laid their eggs only on hawthorns but today, these flies lay eggs on hawthorns (which are native to America) and domestic apples (which were introduced to America by immigrants and bred). Females generally

choose to lay their eggs on the type of fruit they grew up in, and males tend to look for mates on the type of fruit they grew up in. So hawthorn flies generally end up mating with other hawthorn flies and apple flies generally end up mating with other apple flies. This means that gene flow between parts of the population that mate on different types of fruit is reduced.

Sympatric example Patterns of Evolution Divergent evolution aka Adaptive radiation

Co evolution- ex mutualism Co evolution arms race Convergent evoution Divergent Evolution The process of two or more related species

becoming more and more dissimilar. Ex: Red fox and the kit fox. Red fox lives in mixed farmlands and forests, where its red color helps it blend in with surrounding trees. The kit fox lives on the plains and in the deserts, where its sandy color helps conceal it from prey and predators. Kit fox has

large ears as an adaptation to its desert environment. Similarities in structure indicate that the red fox and the kit fox had a common ancestor. As they adapted to different environments, the appearance of the two species diverged.

Kit Fox vs Red Fox Co - evolution Mutualism- as one species evolves another does as well Some Central AmericanAcacia species

have hollow thorns and pores at the bases of their leaves that secrete nectar.These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant they also defend their

acacia plant against herbivores. Co evolution arms race Predator / prey systems- a predator has an adaptation that prey have to overcome. They do and then the predator has to

evolve a new trait to fight back. Molluscs, such as Murex snails, have evolved thick shells /spines to avoid being eaten by animals like crabs and fish. These predators have evolved powerful claws and jaws -compensate for the snails

thick shells and spines. Can you relate? How does antibiotic resistance relate to this?

Convergent Evolution Two different species with different ancestors evolve to display similar physical features. Ex: Different anteaters found in Australia, Africa, and America. Though not closely

related, they all evolved the "tools" necessary to live on an ant diet: a long, sticky tongue, few teeth, and large salivary glands. Micro and Macro Evolution Micro-evolution- changes in allele

frequency within a species Macro-evolution- new species, new forms replacing old as revealed in the fossil record

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