Name __________________________________ Hour 1 2 3 4 5 6

Biology B Guided NotesUnit 8: Evolution

Introduction and Scientists

What is Evolution anyway?

Evolution: __________________________________________________________________________________

____________________________________________________________________________________________

Carolus Linnaeus

Swedish botanist in the 1700’s

______________________________________________________

Developed a classification system for all known organisms at the time

Categorized them by their ________________________; showing evolutionary

___________________________________________

Proposed that some organisms may have arisen through

_____________________________________

o What is “hybridization”?

_____________________________________________________________________________________

_____________________________________________________________________________________

Georges-Louis Leclerc de Buffon

French naturalist in the 1700s

o What does it mean to be a “naturalist”?

___________________________________________________

___________________________________________________

Proposed that species ______________________________________

instead of ________________________________________________.

Rejected that the Earth was only ___________ years old, saying it was

__________________________.

Erasmus Darwin

_________________________________________________

Born in 1731

Respected English doctor and poet

Proposed that all living things were ____________________ from a ____________________________.

Proposed that ___________________________ organisms (Eukaryotes) arose from

_________________________forms (Prokaryotes).

Jean-Baptiste Lamarck

French Naturalist in 1809

Proposed that all organism evolved toward _____________________

and _____________________

Believed that species did not _________________________, but simply

evolved into different forms

Came up with the idea of “Inheritance of acquired characteristics”

o Lamarck proposed that

____________________________________________ led to

changes in an organism’s ____________________, leading to

greater use or disuse of a structure or organ.

o i.e.: Giraffes’ long necks

Lamarck's ideas were flawed, and he did not provide explanations for his theories, however, his ideas did

influence ___________________________ later on.

Charles Darwin

Born in 1809

Sailed on the H.M.S Beagle as the ship’s ______________________

_______________________________________________________

_______________________________________________________

Biogeography: The study of the distribution of organisms around the world

Evidences behind Evolution• Fossils

• DNA Sequence Analysis

• Developmental Similarities

• Anatomical Structures

Fossils

• Fossils can tell us a lot about an organism

• Using fossils, scientists can think about an organism’s ________, _____________________, and what the

environment was like when the organism was alive

• Fossils provide a _________________________________________________

o The Fossil Record is not complete

o No fossil evidence that contradicts evolution has ever been found

DNA Sequence Analysis

• Because all living organisms share the same ________________________________ and use the same 20 amino

acids, it has been possible to determine that organisms share a remarkable number of

______________________ that are similar to one another.

• Due to __________________________, the sequences of nucleotides change over time

• Vestigial DNA: DNA that is _____________________________________ but is in the genome

Developmental Similarities

• _____________________________: The process of animals being formed from an egg to an infant

• Some organisms have similar structures in early stages of development

o _____________________________________

o _____________________________________

o _____________________________________

Anatomical Structures

• Homologous Structures

o Homo = same

o Structures that suggest a _________________________________________________________

o i.e. Forelimbs of _________________________ vertebrates (four legged animals)

• Analogous Structures

o Body parts of organisms that do not have a common evolutionary origin but are

_____________________________________________

o Wings of birds vs. flies

• Vestigial Structures

o A body structure in a present day organism that is ____________________________________, or is

used for a different function.

o __________________ on an ostrich or _________________________________ in whales

Natural SelectionWhat is Natural Selection?

• The choosing of _____________________________________ in a population which allows the population to

better _____________________ or reproduce. More successful individuals are “naturally selected” to live longer

and to __________________________________________________ that share those adaptations for their

environment.

• Natural selection acts on ____________________________________, or physical traits, rather than on genetic

material itself. New alleles are not made by natural selection —they occur by genetic mutations.

__________________________________________ can act only on traits that already exist.

• Population: is all of the individuals of a _____________________ that live in an area.

Variation

• The __________________________________________________________ of an individual from those of other

individuals in the group to which it belongs. It can occur either among members of different species

(_____________________________ variation) or among individuals of the same species

(______________________________ variation).

• Comes from two different sources:

o ________________________________

o ________________________________

Mutations

• Changes in the DNA sequence of a gene.

• ________________________: The ability of a trait to be passed down from one generation to the next.

• Mutations must be heritable to ________________________________________ in populations

• Can cause ___________________________ in a population

• Occur frequently

• The Pakicetus’s that had flatter tails were able to pass on the mutation

Recombination

• When gametes are made, each parent’s alleles are __________________________________________. This

shuffling of alleles results in many different genetic ____________________________________.

• Happens during _____________________

Adaptation

• A feature that allows an organism to better ________________________________________________ in its

environment. Adaptations can lead to genetic change in a population over time.

• Panda’s “thumb”

Different types of Natural Selection

• Stabilizing Selection: This selection favors the _________________________ individual in a population

o Example: Human baby size; too small and too large are both problems

• Directional Selection: This selection favors _________________________________________ of a trait.

o Tall sunflowers will get more sunlight

• Disruptive Selection: This selection favors __________________________________________of a trait.

o Rabbits with black, grey, and white fur

Alleles and Genetic Equilibrium

• Random mating: is the mating of a species randomly _______________________ any selection preference. This

allows populations to be in genetic equilibrium.

• Genetic Equilibrium: The frequency of the alleles in the population remaining the _________________ over

generations. If the frequencies remain the same, _______________________________________ can take place.

• Allelic Frequency: The ______________________ of the gene pool with any specific __________________

(trait).

Other terms you need to know

• ________________________________: While having many offspring raises the chance that some will survive, it

also results in competition between offspring for resources.

• ________________________________: The observable change in the allele frequencies of a population over

time. Microevolution occurs on a small scale—within a single population.

• ___________________________________________________: occurs when a barrier separates populations of a

species, each evolves independently because they can no longer mate.

Changes and How They Affect EvolutionBehavioral Changes

• Behavioral Isolation: Isolation caused by differences in _____________________________________ or

________________________ behaviors.

• Sexual Selection: The choosing of a mate due to specific _________________________________.

o Female birds choosing mates due to ______________, songs, or __________________ patterns

o Patterns of flashes for ________________________

o Cow elk breeding with the bull who wins the fight

• Temporal Isolation: When ___________________ prevents reproduction between populations. Some members

of a population may show signs of courtship at different times if there is a lot of competition for mates.

Reproductive periods may change to a different time of the year or a different part of the day. These differences

in timing can lead to _________________________.

o Trout

• Some behavior changes can lead to increased ____________________________ for limited resources.

Morphological and Physiological Changes

• Morphology: The _____________ and _______________________ of animals and plants.

• Physical changes that result from organism’s __________________________ over long periods of time.

• Sexual Selection: The choosing of a mate due to specific physical traits.

• Males changing over time to ____________ more successfully with females. (Birds of paradise changing over

time)

• Reproductive isolation: When two populations _________________________________________ and create

viable offspring. It can be behavior, geographic, or genetic. Reproductive isolation occurs when formerly

___________________________ organisms can no longer mate and produce fertile offspring.

Competition

• Competition: When species must compete for a ____________________________________. If there is less

food/resources, competition __________________________.

o Brook trout vs cutthroat trout

o Darwin’s finches competing for food

• Competition between viable mates can lead to ___________________________________ changes

o Peacock’s feathers being used to attract the peahen

ExtinctionHow Does the Environment Affect Evolution?

___________________________________________________, flooding, hurricanes, ______________________,

earthquakes, meteor strikes, and climate change can all change an organism’s ____________________________

When the environment changes species will be required to adapt or die. These adaptations to new

environmental influences can drive a species to evolve into a new species.

What Happens When Species Adapt?

Divergent Evolution: The pattern of evolution in which species that once were similar to an ancestral species

diverge or become increasingly ______________________.

o Example: Darwin’s finches, Honeycreepers in Hawaii.

Adaptive radiation: Occurs when an ancestral species evolves into an ___________________________________

to fit a number of _______________________ habitats.

Convergent Evolution: Distantly related organisms evolve _____________________________________ due to

environmental pressures.

o Example: The ___________________________ of whales and sharks. They each evolved to be similar

due to similar environmental conditions.

What If A Species Doesn’t Adapt?

A species can become ________________________

Extinction: ___________________________________________________________________________

Extinction often occurs when a species as a whole is unable to ___________________ to a change in its

environment.

Two types:

o ___________________________________________

Extinctions that occur continuously but at a very ___________ rate

Part of the cycle of life

Usually affects only ___________ or a few species in a relatively _________________________,

such as a rainforest or a mountain range

Can be caused by a change in the environment such as:

New predators

Decrease in food supply

o ___________________________________________

Much ____________________________ than background extinction, but also much more

__________________________

Often occurs on a ___________________ (worldwide) level

Thought to occur _____________________________, usually because of a catastrophic event

such as an ice age or asteroid impact

Fossil record confirms that there have been at least _______ mass extinctions over the past 600

million years