EVOLUTIONCH. 15

Ch. 15.1 – DARWIN’S THEORY OF EVOLUTION BY NATURAL SELECTION

MAIN IDEA – Charles Darwin developed a theory of evolution based on natural selection.

QUESTION: What do you think you can look at to see how species change over time?

Where did Charles Darwin do most of his studies in regard to figuring out evolution?

Developing the Theory of Evolution In 1831 when Charles ______________ began his

voyage most people believed that the world was _______ yrs. old & animal & plants did _____ change.

During Charles Darwin voyage on the HMS ________, which lasted 5 years, he collected biological (plants & animals) and geological specimens (fossils).

Darwin read a book by Charles Lyell, which proposed that the Earth was __________________ of years old. This book influenced Darwin’s thinking as he observed

fossils of marine life at __________ elevations, giant fossils looking similar to smaller living mammals, and saw how earthquakes could lift rocks great distances very quickly.

Darwin in the Galapagos Islands ______________________________________ are

located off the west coast of S. America. Darwin studied the mockingbirds,

_________________ & __________________ from the _______________ islands Discovered that he could recognize what

island the tortoises came from by their ____________________.

After returning to England Darwin discovered that the finches of the Galapagos were found ____ where else, but they closely resembled the species from mainland S. America. Should ____________ have resembled each

other because of _____________________ environments.

Began to suspect the populations changed _______ reaching the islands

Tortoises and Finches of the Galapagos Islands

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DARWIN CONTINUED HIS STUDIES Darwin hypothesized that ________ species could

appear gradually through small changes in ancestral species.

Darwin looked to breeders of pigeons to help understand these changes. __________________________ or selective breeding is

the process of directed breeding to produce offspring with the _____________________________________.

Learned that breeders do select and breed the pigeons for the __________ exaggerated certain traits. EX: larger tails

Concluded that if humans can do artificial selection then the same process could work in nature. Given enough _____________ could produce a new species.

NATURAL SELECTION Natural selection says that some

_____________________ in the struggle for existence would be _____________________ equipped for survival than others. The competitors ___________ equipped ______. Thomas ___________ influenced Darwin’s thinking on natural selection. Malthus’ essay suggested that the human population if left unchecked would outgrow its food supply, leading to a _________________ struggle for existence.

Natural Selection – Cont. Darwin’s theory of evolution by natural selection

has 4 principles: 1. Individuals in a population show differences or

________________________________________. 2. Variations can be __________________________. 3. Organisms have _____________ offspring than

can _________________________ on available resources.

4. Variations that ___________________ reproductive success will have a ____________________ chance of being passed on than those that do not increase reproductive success.

Given enough time, natural selection could ___________ a population enough to produce a ____________ species.

The Origin of Species About 1840 Darwin formulated his theory of

evolution and he began writing his book that explained natural selection.

Darwin compiled evidence to support his theory of evolution for years.

In 1858 Alfred _________________________ proposed a theory almost identical to Darwin’s theory.

Both men presented their ideas on evolution and a year later Darwin published his book, “On the _____________ ____________________ by Means of Natural Selection.”

Evolution is defined as the cumulative _______________ in groups of organisms through ____________________. _________________________________________ is

the mechanism by which evolution occurs.

QUICK QUIZ 1. Darwin referred to the process of promoting certain traits by breeding

members with those traits as___________. A. Natural selection B. Artificial selection C. Evolution D. Ancestral breeding

2. What theory accounts for why populations can be modified over time? A. Natural selection B. Artificial selection C. Ancestral modification D. Fossil theory

3. Which statement is true regarding evolution? A. It describes changes over many generations. B. It is the same as natural selection. C. It only involves artificial selection. D. It occurs within a single generation.

4. What are 2 main components of natural selection? A. Vestigial structures and camouflage B. Artificial Selection and selective breeding C. Variation and inheritance D. Mimicry and artificial selection

Section 15.2 – EVIDENCE OF EVOLUTION

MAIN IDEA – Multiple lines of evidence support the theory of evolution.

QUESTION: What evidence supports the theory of evolution by natural selection?

What are the 4 principles of natural selection?

SUPPORT FOR EVOLUTION A ___________________ provides an explanation for a

natural phenomenon based on ________________. Theories explains available data and suggest further areas for experimentation.

Theory of evolution states that all organisms on Earth have ____________________ from a _________________ ancestor.

The _______________________________ provides a record of species that lived long ago and supply some of the most significant ______________________ of evolutionary change. Shows how ancient species are _____________________

to current species. Shows that __________________ species have remained

__________________________ for _________________ of years.

Fossil record is an important source of information for determining the ________________________ of organisms and patterns of ______________________________________.

The fossil record has intermediate species

EXAMPLE OF FOSSIL RECORD

SUPPORT FOR EVOLUTION – CONT. Two major classes of traits when looking at

transitional fossils are: _____________________ traits – newly evolved

features, like feathers, which do ____________ appear in the fossils of common ancestors

_________________ traits – are more primitive features, like teeth and tails, which _________ appear in the ancestral form.

____________________ fossils provide detailed patterns of evolutionary ___________________ for the ancestors of many __________________ animals, like horses, whales and humans.

COMPARATIVE ANATOMY _____________________________________ are

anatomically ______________ structures that are _______________ from a ____________ ancestor. Evolution predicts that an organism’s

body parts are more likely to be _________________ of ancestral body parts than to be entirely _____________ features.

VESTIGIAL STRUCTURES _________________ structures are structures

that are ______________________ forms of functional structure in other organisms.

Evolutional theory predicts that features of ancestors that __________ longer have a function for that species will become __________________ over time until they are _________________. Ex: snake pelvis – pelvis but no legs

attached Ex: human appendix – important for

digestion in many mammals but only limited use in humans and apes

ANALOGOUS STRUCTURES ________________ structures can be used for the

_____________ purpose and can be superficially _______________ in construction but are ______ inherited from a common ancestor. Ex: wings of an eagle and wings of a beetle

have same function, but are constructed in different ways and from different materials

Analogous structures do ________ indicate ______________ evolutionary relationships, they do show that functionally similar features can evolve ____________________________ in _____________________________ environments.

COMPARATIVE EMBRYOLOGY _______________________ embryos provide

more glimpses into evolutionary relationships.

____________________ is an early prebirth stage of an organism’s development.

Vertebrate embryos exhibit __________________ ______________________________ during certain phases of development but become ___________ __________________ structures in the adult form. Demonstrates that the embryos of

vertebrates evolved from a ___________________ ancestor.

COMPARATIVE EMBRYOLOGY

ADAPTATION _____________________ is a trait shaped by natural

selection that ______________________________ an organism’s ___________________________ success. Ex: either physical or behavioral

______________________ is a measure of the relative contribution that an individual ______________________ makes to the _________________________ generation. Measured as the number of reproductively viable

_______________________________ that an organism produces in the next generation.

Better an organism is adapted to its environment, the ______________________ its chances of ___________ and ________________________________ success.

EX: environments _________________ on the different ________________________________ so the different beak characteristics were selected for.

___________________________ is the ability of an organism to _____________________ in with their ________________________________________. Allows organisms to become almost

____________________ to _________________. ____________ survival & ability to reproduce

____________________ is where one species has evolved to __________________ another species. Mimicry increases _______________ because it

helps ______________ them against predators. Ex: a harmless organism mimics a harmful organism so predators leave them alone.

QUICK QUIZ – SECTION 15.2 1. Recently evolved traits that do not appear in ancestral

fossils are called ________. A. Homologous traits B. Ancestral traits C. Primitive traits D. Derived traits

2. A morphological adaptation in which one species resembles another is called _____.

A. Mimicry B. Camouflage C. Vestigial adaptation D. Fitness

QUICK QUIZ CONTINUED 3. Which of these is an example of analogous structures? A. Hawk wings and fish fins B. Hawk and insect wings C. Horse legs and insect wings D. Horse legs and elephant trunks.

Section 15.3 – SHAPING EVOLUTIONARY THEORY

MAIN IDEA – The theory of evolution continues to be refined as scientists learn new information.

QUESTION: How would an albino of a species that is normally green and lives among leaves be less fit?

Mechanisms of Evolution Scientists Hardy & Weinberg showed mathematically

that evolution will ______________ occur in a population unless allelic frequencies are acted upon by _____________________ that cause _____________________________.

___________________________________________ is when allelic frequencies remain _________________________ in a population.

For a population to stay in genetic equilibrium 5 conditions must be meet: 1. there must be ___________________________ genetic

drift 2. no _______________________________________________ 3. no _______________________________________________ 4. mating must be

____________________________________ 5. there must be _______________________ natural

selection. Hardly any population in nature will meet these

requirements for a long time so populations are ____________ in genetic equilibrium.

_____________________________________ is any change in the allelic frequency in a population that results from _____________. In _________________ populations allelic frequency remains relatively ___________ from one generation to the next.

In _____________ populations the effects of genetic drift becomes more pronounced and the chance of losing an allele becomes __________________________.

___________________________ can occur when a ______________________ sample of a population settles in a location ________________________ from the rest of the population. EX: Amish or Mennonite populations in the US

___________________ occurs when a population ___________________ to a very __________ number and then __________________________________. ____________________ of the rebound population

often is genetically ___________________ to the population at its ____________________________ level and has reduced diversity.

______________________ has random movement of individuals between populations, migration, which increases genetic variation within a population and reduces differences between populations.

Nonrandom mating – _______________________ is mating completely random in a population, usually will mate with an individual in __________ proximity. EX: Promotes __________________________

_______________________________ is a random change in genetic material. Mutations may cause a ______________________

in allele frequency, which violates genetic equilibrium.

Mutations can be harmful, helpful, or no affect When a mutation gives an organism an

_____________________________, the mutation will be selected _______________ and become ___________ common in subsequent generations.

Natural selection acts on an organism’s _____________________________ and changes allele frequencies.

3 ways that natural selection alters phenotypes: _______________________ selection ________________________ selection ________________________ selection

Stabilizing selection Stabilizing selection is the ____________ common form of natural selection Will _____________________________ extreme expressions of a trait when the average expression leads to __________ __________________________. Ex: babies born of average weight have best chance of survival

Directional selection Directional selection occurs when

the _______________________ version of a trait is _______________ fit for survival. EX: Galapagos Island finch beak size.

Disruptive Selection Disruptive selection is a process

that ______________ a population into ____ groups. It will ____________________ individuals with the ________________ traits and retain individuals that express the extreme traits at _______________ ends of a bell curve.

Sexual Selection Sexual Selection is another type of

natural selection based on the frequency of a trait that enables an organism to _____________ a ______________. Occurs in populations where male and female organism ____________________ in appearances.

Usually males are ___________________ than females and more _______________. EX: peacock – males have the brightly colored tails.

Reproductive Isolation 2 types of

______________________________________: Prezygotic isolating mechanism

Operate ___________________ fertilization occurs which prevents ________________________ from entering the population’s _____________________

Ex: birds mating songs or dances are different or the time when mating occurs is different

Postzygotic isolating mechanisms The _________________ offspring are

___________ Ex: tiger & lion produce liger, which is

sterile

______________________________ is the process where members of a sexually reproducing population change so much that they can ______ longer produce ___________ offspring with members of the original population.

2 types of speciation: Allopatric speciation (geographic

isolation)– where a physical ______________ divides one population into 2 or more populations. Eventually after enough time has passed the populations will _______ longer be able to ____________________ successfully with one another Most common form of speciation.

Sympatric speciation – where a species evolves into a _______ species ________________ a physical barrier. Ex: polyploidy plants

Temporal Isolation – Members of that species will ______ mate together because the _________ that they mate has ______________. Ex: Used to mate in the morning, now mates in evening

Behavioral Isolation – Members of that species will no longer mate together because the _____________________________ has changed EX: Birds song has changed

Patterns of Evolution _____________________________, also called divergent

evolution, can occur in a relatively ______________ time when one species gives rise to many species in response to the creation of a _______________________________ or another ecological opportunity. Adaptive radiation often follows large scale

________________________________________. Ex: mammals increased drastically after the

extinction of dinosaurs. _____________________ occurs where 2 species living

in close relationship with another species affects the evolution of ________________ species. Another form of coevolution is where one species can evolve a parasitic dependency on another species. EX: Mutualism

Convergent Evolution _______________________________ occurs when

___________________ species evolve _________________ traits even though they live in ________________ parts of the world but with similar ecology and ____________.

______________________ is a theory which states that evolution proceeds in ________, gradual steps.

_____________________ equilibrium is a theory which states that _______________ transitions in the _____________ record occurs due to rapid spurts of genetic change causing species to diverge _____________________.

CONVERGENT EVOLUTION

QUICK QUIZ: 1. What occurs when average traits

benefit a population rather than extreme traits?

A. Unnatural selection B. Directional selection

C. Disruptive selection D. Stabilizing selection

2. What has occurred when fertilization produces a hybrid offspring that cannot develop or reproduce?

A. prezygotic isolation B. Postzygotic isolation

C. Non-reproductive isolation D. Speciation