Name_________________________Per_____

Evolution NotesPart 1: Principles of Evolution—Evolution by Natural Selection

(Ch. 10 Sec. 1-5, Ch. 12 Sec. 1 & 2) Look at the star-nosed mole. (p. 285)

1. What sorts of modifications are obvious?

2. How might these traits arise in the first place?

These _______________will then be passed on to future generations.

What is Evolution? (Ch. 10.1-10.2)Evolution • Evolution is _____________________________________________________________.• Process of biological change by which descendants come to differ from their

ancestors (p.286)• Change happens in characteristics of a population from one generation to the

next• _______________________ evolve, _______________________ do not!

Vocabulary • __________________-all of the individuals of a species that live in an area (p. 294)• ___________________- the differences in the physical traits of an individual from

those traits of other individuals in the population p. 290• ______________- group of organisms that are closely related and can mate to

produce fertile offspring– Dogs (Canis familiaris) are all the same species; just like all modern

humans are all Homo sapiens– We have different dog breeds based on their genetic variations but they

are all the SAME species. No two people look exactly alike due to genetic variation within the human population.

• _______________________- process in which new species are formed over time • _______________________-a feature that allows an organism to better survive and

reproduce in its environment; this can lead to genetic change in a population over time

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Charles Darwin- the father of evolution p. 290-291• born in 1809, in England• was asked to sail on the _________________ to chart stretches of the South

American coast• voyage of H.M.S. Beagle

– 5 year unpaid voyage– Darwin studied plants, animals, collected fossils (ship’s naturalist)– found fossils of extinct animals that were similar to modern

species – during his voyage, he made observations that led him to his theory of

evolution– on the __________________ in the Pacific Ocean he noticed variations among

plants and animals of the same general type as those in South America – Darwin noticed there were several types of _____________on these islands,

and that they all looked like a bird he had seen on the South American continent

the most distinct difference among finch species is their beaks Why would beaks be different in different locations on an island?

______________________________________________________________ Darwin hypothesized that some of the birds from South America

migrated to the Galapagos Islands once on the islands, the birds must have ________________ over the

years, explaining the numerous species of birds present• After returning from the Galapagos and studying all the different types of

plants & animals he collected during the voyage, Darwin concluded that organisms change over time….– He called this __________________ which means change in species over

time.– Darwin called the mechanism for evolution natural selection (a.k.a.

______________________________________________________).

How Does Evolution Happen? • natural

selection• mutations

• artificial selection

• geographic separation/ isolation

• genetic drift• gene flow

(migration)

Natural Selection— the main mechanism of evolution (Ch. 10.3 & 11.2)Natural selection explains how evolution can occur.

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• _________________________ a mechanism by which individuals that are better fit for their environment have a greater chance to survive and mate/reproduce p. 293– aka- survival of the fittest– What does it mean to be “fit”?

• fit means they have inherited beneficial _______________ which allow them to be more likely to survive and reproduce more offspring.

– The genetic traits of “fit” individuals become ________ common or frequent over time.

– the genetic traits of less fit individuals become ________ common or frequent over time.

• There are four main principles to the theory of natural selection1. Variation—heritable ______________ that exist in populations2. Overproduction— _______ all offspring will _______________ due to

competition3. Adaptation—certain variations can allow an individual to survive better

than others (the environment can present challenges for survival)4. Descent with Modification—the number of individuals with the

advantageous adaptations will ___________________ over each generation

A well studied example of natural selection in jaguars is shown in Figure 3.2 p.295

o View animated biology—10.3 Principles of Natural Selection (jaguar)

Example: Natural Selection and beetles – beetles have genetic variation

• some are brown, others are green– there is a struggle for survival

• predation – more fit individuals leave more ______________– characteristics of fit individuals increase in a

population over time

Natural Selection acts on existing variation. Natural selection can only act on _______________ that already exist. Natural selection acts on _______________; new alleles occur by genetic

____________.o Read p. 296-297 about the 2 examples supporting this concept.o View Animated Biology 10.3 Natural Selection (fish)

Artificial Selection p. 292

What would happen if the environment switched from brown stones to green grass?

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Artificial selection- the process by which _______________ change a species by breeding it for certain traits

Humans determine which traits are ________________ and breed individuals that show those traits.

Ex. Race horses, show dogs

Part 2: Evidence of Evolution (Ch. 10.4-10.5, Ch. 12.1)Evidence to Support Evolution

fossil record p. 298, 306, 348 biogeography p. 298-9 homologies : anatomy, development & molecular p. 299-304

Fossil Record (Ch. 10.4 & 12.1)

What is a fossil? Fossil—trace of a ________________________________. Scientists consider three things about fossils: age,

location, and what the environment was like when that organism was alive.

Fossils are dated through _________________ dating and ________________ dating.

Radiometric dating uses the known time of natural decay of unstable isotopes to calculate the ___________ of the material.

Relative dating estimates the age of fossils by comparing the fossils found in certain rock layers to those in other layers. The _________fossils are found on the _____________, further from the surface. The ____________ fossils are closest to the __________________.

Fossils can form in several ways (p. 298, 306, & 348). The most common fossils result from permineralization.

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What may happen if the organism doesn’t die in ____________________? Fossil doesn’t form; ______________________ takes place

Why is the fossil record not complete? Most living things do not form into fossils when they die since the

________________ are not conducive to fossil formation Many fossils may _________ have been discovered yet

Biogeography p. 299• biogeography - is the study of the ___________________ distribution of plants,

animals and fossils. – it is used to test predictions about the nature, age, and location of certain

fossils– species tend to be more _______________ related to other species from the

same area than to other species with the same way of life but living in different areas

Anatomy and Development p. 299-304homologous structures p. 302• homologous structures:

– common ancestor– similar structure– different function

• example: the bones of a cat, human, whale and bat are __________________ in structure (made of bones) but have ________________ functions.

analogous structures p. 303• analogous structures:

– not related– _____________ structures– ______________ function

• examples:– bird wing and insect wing– quills on a sea urchin, hedgehog and cactus

vestigial structures p. 304• vestigial structures- serve _____ useful purpose.• examples:

– pelvic bone in a whale– human appendix

– pelvic bone & hind limb bones in some snakes

– human canine teeth & wisdom teeth

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Embryology p. 299-301• Embryology--similarities in embryological development among organisms is

further evidence of shared ________________________• Ex. Embryos of vertebrates• Ex. Crab and barnacle—

adults look very different but the larva can look very similar Fig. 4.4

Molecular Evidence p. 307 Very different species

have similar molecular (DNA, genes, amino acids) and genetic mechanisms. Because all living things have DNA (bacteria, plants, animals, etc.), they share the same ___________ ________ and make most of the same proteins from the same _____ amino acids.

More similarities in ______ (which translates into proteins) between two organisms, the more ___________ related they are; the more differences, the more ________________ related.

Comparing Amino Acids

1. Which organism is most closely related to the human? Why?

2. Which organism is least closely related to the human? Why?

Remember, the _______ sequence dictates the ______________________ sequence through the processes of transcription and translation; therefore, ALL 4 levels (DNA, RNA, amino acids, and proteins) can show evidence of evolution

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Watch Hox genes video clip (2:44)Section 10.5 “Evolutionary Biology 1”

Part 3: The Evolution of Populations (Ch. 11)Genetic Variation Within Populations p. 316-321Vocabulary

_________ ________ combined alleles of all the individuals in a population

________________ different forms of a gene o flower color gene may be “P” (purple) or “p”

(white) __________________ how often something occurs over

timeo Allele frequency- measure of how common a certain allele is in the

population; decimal value similar to a percent. Ex. if 25 rabbits are white out of a population of 100 rabbits, the frequency of white rabbits is 0.25

Genetic variation in a population increases the chance that some individuals will survive.

Genetic variation comes from two main sources. _______________- random change in the DNA of a gene; if the change occurs in

the DNA of a reproductive cell (gamete=egg or sperm), then the mutation will be passed on to offspring.

_____________________- new allele combinations in an offspring that occurred during meiosis through crossing over and independent assortment.

Other Mechanisms of Evolution p. 323-327Natural selection isn’t the only mechanism through which populations evolve. Other mechanisms include: genetic flow, genetic drift, mutation and sexual selection. Gene Flow gene flow – movement of alleles from one population to another• another word for gene flow is (immigration & emigration)• gene flow ____________ the genetic ______________ of the receiving population 7

• lack of gene flow between two populations may lead to the formation of different species

Genetic Drift • genetic drift - change in allele (gene) frequency due to chance; results in loss of

diversity• Two types of genetic drift

1. Bottleneck Effect2. Founder Effect

o bottleneck effect - when a population is drastically decreased due to a natural disaster (hurricane, disease)

some genes are completely lost; others are over-represented

some genes are reduced so much they can’t “make a comeback” in their new population

o founder effect – when a small group ________________ from a larger population and starts their own population isolated from the original population

Amish in America – original population was 14 individuals that immigrated from Europe

Mutations • a random mutation can happen to one individual in a population and can be

beneficial, harmful, or ______________• random mutations can increase chances of survival and reproduction

• random mutations can ____________ chances of survival – if an individual ______ before it can reproduce that

mutation is not passed down to the another generation

• random mutations might ______ affect an individual’s ability to survive and reproduce and will become a __________________________ instead of a mutation Ex. dark spots on pigs

Sexual Selection p. 326 Sexual selection occurs when certain traits _____________ mating success. Ex. Males compete for females such as the head-butting of bighorn sheep; Male

peacocks fan out their tails to attract the female.

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Hardy - Weinberg p. 328• 1908 - two scientists created an ____________ to test these ideas of probability

and chance• Hardy-Weinberg principle - the frequency of alleles in a population does _______

change unless evolutionary forces act on the population• Characteristics of a Hardy-Weinberg (non-evolving) population:

– very large population– no migration (no immigration or emigration)– no mutations– random mating (no individuals are “more fit”, they all seem the same) – no natural selection

• A population with all of these criteria is _______ evolving. This doesn’t happen in nature; therefore _______ populations in nature are evolving.

Isolation of a population can lead to speciation p. 332Reproductive Isolation

Reproductive isolation – when members of _______________ populations of the same _______________ can no longer ______________ successfully.

Reproductive isolation can lead to ___________________________. Three barriers that can cause reproductive isolation to occur:

1. Behavioral barriers—courtship or mating behaviors are now different in the populations

2. Geographical barriers—physical __________________ of the populations; Ex. Mountains, roads, rivers

3. Temporal barriers—the two populations aren’t ready to mate at the _______ time of day (ex. Flowers that bloom in morning vs. evening) or in the same season

Patterns of Evolution p. 335-341Convergent evolution- (word part: co-together) individuals share

similarities because they are related but because they need certain adaptations to survive in their environment; therefore, they have____________________ structures

Example:• sharks, dolphins, tuna, & penguins have streamlined

bodies, and fins• HOWEVER sharks are cartilaginous fish, dolphins are

mammals, tuna are bony fish, and penguins are birds• they share similarities because they all ____________ to the

same marine environment and predatory lifestyle Convergent evolution is sometimes called ____________________ ____________________. 9

Divergent evolution - (word part di – two); the process by which one species begins to split into ______ distinct groups with different traits; therefore, they have ___________________ structures

Example: • all canines have long legs, walk on their

toes, non-retractable claws, and dew claws because they all come from a common ancestor.

• different populations diverged at different points and created all these species (domestic dogs, wolves, coyotes, foxes, etc)

Divergent evolution is sometimes called _________________ _____________________ and may lead to speciation.

Phylogenetic (or Phylogenic) Tree• a ____________ showing the

___________________ _______________ of a species

• Is this convergent or divergent evolution?

_______________

Coevolution – process in which ______ ____ _______ species evolve in response to changes in each other. Ex. Ant & acacia tree, crabs & snails, flower structure & bird beak shape p. 337

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Extinction – ____________________ of a species, usually as a result of its inability to ________________ to a change in the environment; Ex. Dinosaurs p. 338

Patterns of Speciation p. 339• gradualism - slow changes happen ______________

over a long period of time

• punctuated equilibrium - bursts of _________________ _______________ in species are separated by periods of little to no ______________________– “spurts in evolution”– traits “appear suddenly” in the fossil record usually due to climate changes

or catastrophic events

Ex. of gradualism—evolution of the horse

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