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76 Cards in this Set

  • Front
  • Back
What is evolution?

Evolution is the change in inherited traits (genetic makeup) of a population of organisms over time.

What did George Cuvier contribute?

-Theory of Catastrophism

-Studied fossils

-Believed earth was very young

- Changes in earth are due to big, violent events a long time ago (nothing in present day)

What did James Hutton contribute?

- Theory of actualism

- No catastrophism

- Believed earth was very old

- "Present is the key to the past" - geological processes occurring in present, are the same as those in the past

- Basis for uniformitarianism

What did Charles Lyell contribute?

- Uniformitarianism

- Built on Hutton's ideas-present is the key to the past

- Believed earth was very old

- Earth's features are due to small, slow, gradual changes over many years...not catastrophic

Importance of Hutton and Lyell ?

- Laid the foundation about the history of the earth

- If big changes in landscape can occur due to small, slow changes, then the same can occur for lifeforms on earth

What did Buffon contribute?

- Similar organisms have similar history

- Proposed that species could change over time and changes could result in new organisms

What did Erasmus Darwin contribute?

- All life comes from a single source of life

- Wrote first detailed treatise on evolution asserting evidence that all life comes from one place

- Believed humans were closely related to primates

What did Linnaeus contribute?

- Developed biological nomenclature and taxonomy ( naming and classifying) based on shared characteristics of species

- Proposed that relatively few species formed many new species through hybridization and interbreeding

What did Lamark contribute?

- Environment key to evolution of traits

- "Acquired characteristics"...changes acquired by organism due to adaptation could be passed down

-Reasoned that for species to survive, they must adapt

- Did not believe single species could result in additional species...argued that species become more complex and new simple species are created by spontaneous generation

What did Charles Darwin contribute?

1) Members of the same species compete for survival

2) Survival is not random -those better suited to environment will win

3) A "fit" individuals survive and reproduce more, the favourable traits will become more common


What's the difference between natural selection and evolution?

Evolution is the change in inherited traits (genetic make-up) of a population of organisms over time

Natural selection is the process by with organisms best adapted to their environment tend to survive and reproduce. One mechanism by which evolution occurs.

What is fitness?
Fitness is the ability of an individual to survive, find a mate, and reproduce; ultimately passing down its genes to the next generation of offspring.
What is survival of the fittest?
Refers to those individuals who have more favourable variations as being more likely to survive.
Describe a possible evolutionary pathway of an organism (format)

Original population

- Describe original, random mutation causing...,variation within po.

How does it affect individuals?

-Benefits of mutated individual, gives selective advantage, more fit to survive and reproduce to pass down the favourable trait variation.

Evolutionary impact on species?

-Over many generations, mutation causing trait is selected for by nature and others would be selected against. Pop. evolves to have trait.

What is a DNA mutation?

An error occurring that modifies DNA code when DNA is copied.

DNA mutations occurer RANDOMLY and can produce variation in living things.

What are the three things needed for evolution?
Variation, time and selection
What two processes are important to introduce variation into living things?
Mutation and recombination.... constantly at work generating RANDOM diversity in all forms of life
What is natural selection responsible for? What processes are involved in controlling population numbers?

- Controlling which variations are kept and which variations are eliminated

- Predators, competition and changing environments control population numbers

- Those with most favourable combination of genes survive and pass down DNA to next gen.

What happen to unfavourable variations over time? Favourable variations?

- Unfavourable variations drop out of population

- Favourable variations become more widespread

What leads to diversity in living things?
Small changes adding up to significantly change population
What is an example of artificial selection?

- Evolution of gray wolf into domesticated dog is the first example of artificial selection

- Natural variation in stress hormones caused some wolves to be less afraid of humans and grew closer; passing on to future offspring

- Selection for "tameness" reinforced in generations by humans

- Those who could not be trained were killed, those would could be survived to pass them on

- Bred dogs to please humans and selected for by cuteness

What is an example of natural selection?

- Evolution of the bear, one mutation in genes affected the dark colour of fur and cubs were born with white coat instead of brown

- These cubs were able to prosper (hide in snow) and pass on these genes

- Gene for dark fur loses in comp. for survival

- Over many generations two bears evolved into different species

What is the significance of the trunk and branches in the tree of life?

- The trunk represents the common ancestors of all life on earth beginning 3.5 billion years ago.

- The branches represent how close relative occupy the same branch, distant relatives being farther away. Each living species is a twig on the tree.

What is the significance of Darwin's finches to the theory of natural selection?

- Solidified that the favourable adaptations of Darwin's Finches' beaks were selected for over generations until they all branched out to make new species.

- Beaks had adapted to the type of food and isolation on islands made them undergo speciation.

How might have the PTC tasting ability evolved?

- Random mutation occurred allowing living things to taste bitter which allowed them to detect likely poisons

How is sickle cell anemia and malaria demonstrate evolution?

- Demonstrates natural selection in humans

- Those with one sickle cell allele were protected against malaria in malarial regions

- Protects the individual from being vulnerable to malaria

- Puts individuals at selective advantage; better adapted to fight parasite, survive and reproduce

How are sickle cell anemia and malaria related? In what populations? How was this proven?

- In areas where Dr. Allison found high levels of sickle cell is where there were also high levels of malaria (in the coast and in/near lake Victoria).. Africa

- Proven by taking blood samples from children in various regions and looked at malaria parasite load in each sample, then tested for sickle cell

What is the evolutionary scenario for the sickle cell allele in African-Americans?

Original Pop...many people died from malaria. Random mutation introduced HbS allele (altering hemoglobin protein shape), now variation

How does it affect?...carriers of HbS allele protected against malaria. selective advantage. carriers pass down trait to future generations.

Impact on species?...carriers of sickle cell are selected for. those carrying 2 alleles or none are selected against. Eventually population would consist of mainly those with sickle cell.

What is stabilizing selection?

- Most common form of selection

- Selection against individuals exhibiting variation in a trait that deviates from the current population average

- Once a species becomes adapted to its environment their evolved traits "want" to be maintained and extremes are selected against.

What is directional selection?

- Selection that now favours one extreme phenotype in a population and selects against the average and other extreme.

- When habitat changes, an organism will encounter new forces of natural selection

- Ex. hummingbirds. as food supply changes (larger flowers), beaks changes (longer beaks)

What is disruptive selection?

- Selection that favours individuals at opposite extremes of a trait, therefore population changes in 2 different directions.

- The environment will be favourable for more than one phenotype.

- Distinct groups may eventually become isolated breeding populations.

- Ex. Darwin's finches.

What is sexual selection?

Selection that favours any trait which increases the mating success of the individual such as:

- Sexual Dimorphism -striking differences between physical appearances of males and females

- Behavioural differences -between males and females...courtship displays and songs

- Physical features -assist them in establishing territorial control

What is cumulative selection?

- The evolution of complex features

- The accumulation of many small evolutionary changes over long periods of time and many generations

- Results in a significant new adaptation relative to the ancestral species

- Example: evolution of the eye

How are evolutionary changes in a population measured?
By looking for changes in genes (allele frequencies) from generation to generation.
Define gene pool.
The total of all the alleles within a population.
Define alleles.
The different versions (traits) of a gene that are available within a population.

Define allele frequency.
In a population, the proportion of gene copies of a gene allele.

Define fixed allele frequency.
The term to indicate the frequency of an allele within a population when only a single allele is present for a particular gene (alleles frequency is 100%).
Define genotype frequency.
In a population, the proportion of various allele combinations.
What does the Hardy-Weinberg principle state?
That if a population is not undergoing evolutionary changes, its genetic makeup should remain in equilibrium from generation to generation.

What conditions must be met for the Hardy Weinberg principle to be true?

Assuming all conditions are met (factors limiting chance for evolution), the allele frequencies within a population will remain the same IF...

- The population is very large

- Mating opps. are equal (random mating)

- No mutation, migration, or natural selection

THEN the population remains in H-W equalibrium

What do results of Hardy-Weinberg determine?

- Predict what the genetic make-up of population should be from one generation to the next if the population is in equilibrium.

- If it's different than expected, then the population is evolving.

How are alleles of a gene with only two different alleles (A and b) expressed?

If 'p' = frequency of dominant allele (A)

If 'q' = frequency of recessive allele (a)

Then in a population the following equation applies... p + q = 1 (equation from allele frequencies)

What is the Hardy-Weinberg equation? What is it useful in finding?

Allows to find frequency of each genotype:

p^2 + 2pq + q^2 = 1

'p^2' = frequency of AA genotype

'2pq' = frequency of Aa genotype

'q^2' = frequency of aa genotype

What causes a change to the gene pool in a population of a species (factors affecting allele frequency)?

Not in Hardy-Weinberg Equalibrium

- Populations are small

- Mating opportunities are non-random

- Individuals migrate

- Mutations occur

- Natural selection occurs

What is genetic drift?

- Refers to change in allele frequency as a result of chance

- More pronounced in smaller populations since any change can have a dramatic affect on a small population

- Can lead to FIXATION of alleles (having only one allele within a population), thereby reducing genetic diversity.

What is the founder effect?

- Type of genetic drift that results when a small number of individuals leave their original population and start a new one of their own.

- The allele frequencies of the new population won't be the same as the original

- Ex. Amish in Pennsylvania (short limbs)

What is the bottleneck effect?

- Refers to a dramatic, usually temporary, reduction in population size

- Tends to remove traits (alleles) from a population, resulting in a genetic drift

- Often due to a large catastrophic event

- Ex. Northern Elephant Seals (overhunting)

What is gene flow?


- Refers to the movement of alleles from one population to another due to movement of individuals

- Occurs commonly in many wild populations

- Tends to reduce differences between populations (makes them more similar)

- Ex. Male prairie dogs (genes shared)

What is mutation?

- The only source of new/unique alleles into a population

- Mutations in body (somatic) cells are not inherited...wont affect evolution

- Mutations in gametes have potential to be passed though generations...groundwork for natural selection

What are the kinds of mutations?

Neutral: changes in DNA that are neither beneficial or harmful. Mutations in which natural selection does not affect the spread of the mutation in a species.

Harmful: changes in DNA that kill or cause infertility to individual. Puts them at a selective advantage in population.

Beneficial: changes in DNA that aid individual in survival and increase their chances of producing offspring

What are all the factors affecting allele frequency?

1) Genetic Drift... Founder Effect and Bottleneck

2) Gene Flow

3) Mutation

4) Natural Selection

What is a species?
A species is a group of organisms that look alike and can interbreed (gene flow) with each other under natural conditions.

What is non-speciation (microevolution)?

One species...

Beneficial mutations...

Survival of the fittest...

Adaptations within pops. of 1 species

Ex. some crabs have evolved larger claws than others BUT they are not different species than original.

What is speciation?

One species...

Geographical isolation...

Reproductive isolation...

Mutations/Natural Selection continues

in isolated populations

Eventually new population can no

longer breed with original pop.

What are the reproductive isolating mechanisms?

Preventing mating: Ecological isolation, temporal isolation, behavioural isolation

Prevention of fertilization: mechanical isolation, gametic isolation

Prevention of healthy offspring: zygotic mortality, hybrid inviability, hybrid infertility

What is ecological isolation?

Species occupy different habitats, therefore can't physically meet to reproduce

What is temporal isolation?

- Live in the same area/habitat

- Reproductive cycles for mating occur at different times

What is behavioural isolation?
- Distinct mating rituals of one species prevent other species from recognizing it
What is mechanical isolation?
- Structural differences in the reproductive organs therefore cannot copulate
What is gametic isolation?
- Male/female gamate don't recognize each other or cannot reproduce
What is zygotic mortality?
- No fertilized zygotes survive
What is hybrid inviability?
- Offspring are born but don't live long
What is hybrid infertility?
- Offspring are strong and live BUT are infertile
What comparative anatomy evidence is there for evolution?

Although whales live in water and seem to resemble fish, they have similar anatomical features to land mammals. Similarities:

- Feed milk to young

- Warm blooded

- Hair like land mammals

- Hand, wrist, finger bones

- Live birth

What embryology and development evidence is there for evolution?

Similarities between dolphin and human embryos:

- Both have are and leg buds

- Nostril groves on face of dolphin

What fossil record evidence is there for evolution?

Fossil records involving the Basilosaurid show nasal openings in the middle (intermediate evolutionary step) and small fully developed hip, toe, leg bone, etc.

The fossil records of the maiacetus innus show to be a walking whale.

What DNA comparisons act as evidence for evolution?

Whale DNA is closely matched to hippo DNA. Both have walking bones, give birth and raise young under water, have internal testicles and multichamber stomach.

What is evolutionary developmental biology (EVO DEVO)?

- A discipline that focuses on understanding how development is tweaked over evolutionary time

- The same genes are involved in making animals as different as a worm and a human (distal-less gene is responsible for limb formation in organisms from marine worms to mice to humans)

- Discovery of toolkit gene such as these, shared across animal kingdom

How does the study of evolution allow us to try to overcome antibiotic-resistant bacteria?
- To overcome antibiotic resistant bacteria, patients are often given two different antibiotics at the same time

- Chances of developing resistance is lower with multiple antibiotics given rather than only 1.

- Because chances of 2 resistant mutations occurring at same time in a bacteria are low compared to just a 1 mutation in billions of bacteria

What are antibiotics used for?

To kill bacteria NOT viruses

What is antibiotic resistance? How does it arise?

- Bacteria change so they are resistant to antibiotics; bacteria is no longer sensitive to the antibiotic originally given

- Mutation occurs in the DNA sequencing of bacteria in gene so that bacteria become resistant to the administrated antibiotic

- Bacteria in patient subjected to new environmental selective agent giving mutant strain a selective advantage

Compare wild-type bacteria to antibiotic resistant bacteria with respect to how they will compete in different environments?

- When an antibiotic is not present, natural selection favours those bacteria that do not carry antibiotic resistant alleles (wild type).

- When in an environment where antibiotic is present, natural selection favours those bacteria with antibiotic resistant alleles.

What factors have contributed to antibiotic resistance problems in society today? Be specific and describe how it contributes to the problems?

- Repeated and improper uses of antibiotics are primary causes of the increase in drug-resistant bacteria. (not effective against viral infections)

- Use of antibacterial soaps and hand sanitizer

- Not using full course of medication (so all pathogenic bacteria die)

- Risk of transferring resistance bw animals and humans, judicious use in food plant & humans

Why do all embryos look so similar?

All embryos look similar due to the fact that they always start off with the same cells that make up all living things. All embryos use the same "tool kit" (tells the embryo how and where to develop organs and limbs).

What's a primitive trait? Derived?

- An inherited trait from distant ancestors.

- A trait that just appeared (by mutation) in the most recent ancestor.