SBI3U1 Evolution Unit Test//FINAL

What is evolution?

How populations & species change over time

What are the 4 major mechanics that promote evolution?

Natural selection, mutation, Gene flow, Genetic Drift

What is variation?

Differences between traits in individuals of the same specie

What are the two kinds of variation?

Continuous and discontinuous (discrete)

What is continuous variation?

Continuous variation is where a characteristic can have any value over a range, from minimum to maximum

What is discontinuous variation?

When there are two or more distinct categories, each individual falls into only one of these categories

What causes variation?

Due to a relationship between an organism's genotype and their phenotype

What does phenotypic display (variations) depend on?

Phenotypic display depends on genetic makeup or their environments when the phenotype is "plastic"

What is the source of genetic variation?

Mutations which cause changes in the DNA of an organism's germ cells creating new alleles that can be passed to offspring

When do these mutations occur?

These mutations occur spontaneously or through mutagens

How are more variants made?

Because of sexual reproduction which "mixes and matches" gene variants to make more variation

What can variations be?

Variations can be neutral, detrimental, or beneficial

What does adaptation require?

All adaptation requires genetic variation, but not all variation becomes adaptation

What may beneficial mutations confer?

Selective advantage

What is selective advantage?

The traits that are "selected for" which become the adaptations (species do not "choose" to adapt)

What is natural selection?

The process whereby organisms better adapted to their environment tend to survive and produce more offspring

What is fitness?

Describes an organism's reproductive successfulness and how well it is adapted to its environment for survival & reproduction

What is adaptation?

A characteristic or feature of a species that makes it well suited for survival and reproductive success in its environment

What can adaptations be?

Can be structural, behavioral, or physiological

What is structural adaptation?

Physical characteristics or traits of an organism that enhance its ability to survive in its environment

What are examples of structural adaptation?

Mimicry, camouflauge, quills, long snots, posion

What is behavioural adaptation?

Is the response an animal gives to environmental stimulus and a change in that behaviour for protection

What are examples of behavioural adaptation?

Migration, school of fish, playing dead

What is physiological adaptation?

Chemical changes within the body, and hormones for protection

What are examples of physiological adaptations?

Hibernation and venom production

What does natural selection depend on?

The environment, which creates selective pressures based on abiotic factors or biotic factors

What are abiotic factors?

Non-living factors of the environment that affect organisms

What are biotic factors?

Living factors of the environment that affect organisms

What does natural selection favour?

Favors traits that are beneficial and help an organism survive and reproduce more effectively in a specific environment

Is one trait favourable in all environments?

No. Traits that are helpful in one environment might actually be harmful in another environment

What does natural selection act on?

Existing heritable variation

For natural selection to act on a feature, what does there need to be?

There must already be differences among individuals for that feature and the differences have to be heritable (have the ability to be passed on)

Why is variation important?

As variation is essential to the long-term survival of a population—variation that is not advantageous now might become important in the future due to environmental changes

What is normal distribution?

A function that represents the distribution of many random variables as a symmetrical bell-shaped graph

What is stabilizing selection?

A selection against individuals exhibiting traits that deviate from the current population average

When does stabilizing selection occur?

Occurs when the average phenotype within a population is favoured by the environment

What is directional selection?

A selection that favours individuals with a more extreme variation of a trait

What does directional selection result in?

This selection results in a shift away from the average phenotype

When does direction selection occur?

Usually during artificial breeding/selection

What is disruptive selection?

A selection that favours two or more variations of a trait

that differ from the current population average

What does disruptive selection result in?

Favouring individuals with variations at opposite extremes of a trait over the intermediate phenotypes

What is sexual selection?

Differential reproductive success caused by variation in the ability to obtain mates

What is sexual selection the favouring of?

Is the favouring of any trait that specifically enhances the mating success of an individual

What might sexual selection confer?

May confer a selective disadvantage to other selective pressures

What is direct competition?

Large body size or features that provide males with tools to compete and establish control over a territory where they can mate

What is female mating choice?

When females select mates based on physical traits such as bright colours or specific behavior

What is artificial selection?

Selective pressure exerted by humans on populations in order to improve or modify particular desirable traits (in animals/agriculture)

What is the difference between natural and artificial selection?

Artificial selection is a controlled process caused by humans, whereas natural selection occurs due to natural cause

Why is artificial selection used?

Because artificial selection is a comparatively faster process where the effects are seen over a few generations

What are monocultures?

Are extensive plantings of the same varieties of a species over large expanses of land for the purpose of easing the maintenance of a crop

What does the lack of variation in monocultures lead to?

The inability to adapt in the event of an environmental change

What are gene banks?

Banks that contain populations of early ancestors of modern plants -provide a means to reintroduce genetic diversity

What is an example of a gene bank?

The Svalbard Global Seed Vault which was developed to maintain current seed varieties in the event of a global crisis

What did Carl Linnaeus create?

Created classification systems for plants and animals based on anatomy and physiology

What did Carl Linnaeus hypothesize?

Hypothesized that species came from hybridization and interbreeding of a handful of original species

What did George-Louis Leclerc suggest?

Suggested species change over time to make new organisms

What similarities did George-Louis Leclerc notice?

Noticed similarities between humans and apes and proposed a common ancestor

What did Mary Anning contribute to?

Contributed to the field of paleontology (study of fossils)

What did Mary Anning discover?

Discovered the first plesiosaur (aquatic reptile fossil)

What are the steps of fossil formation?

1. Organism dies and sinks to the bottom of a body of water

2. Organism rots, leaving only bones that get covered by mud

3. Millions of years pass and the mud turns to rock

4. The organism's bone matter completely changes into mineral matter and is now a fossil

What two principles contribute to rock layer formation?

Principle of original horizontality and the law of superposition

What does the principle of original horizontality state?

States that layers of sediment are generally deposited in a horizontal position

What does the law of superposition state?

States that in an undeformed sequence of rocks, the rock layers (strata) are progressively younger upward

What did Cuvier propose the idea of?

Catastrophism

What is the idea of catastrophism?

The idea that suggests that drastic environmental events caused large population extinction events

What did Cuvier suggest would happen to affected areas?

That the affected areas would be repopulated by species from nearby unaffected areas

What did Sir Charles Lyell propose the idea of?

Proposed the idea of uniformitarianism

What does the idea of uniformitarianism suggest?

Suggests that geological events in the past are no different than in the present

What did this idea imply?

That geological events are slow and continuous, meaning the Earth is very old

What did Jean-Baptiste Lamarck propose?

Propose the idea of inheritance of acquired characteristics

How did Lamarck depict the inheritance of acquired characteristics?

Lamarck chronologically ordered fossils to interpret a "line of descent"

What were Lamarck's hypotheses?

1. Species became more complex over time to achieve "perfection"

2. Organisms become progressively better adapted to their environment during their lifetime

What are the errors within Lamarck's first hypothesis?

-There is no "end goal" to evolution

-Species don't "choose" to adapt

-"Complex" is not necessarily better

What is the error within Lamarck's second hypothesis?

That "Acquired" characteristics cannot be inherited through genes

What was Darwin's first observation?

Different regions had structurally similar but distinctly different organisms (Why are these organisms clustered geographically)

What was Darwin's second observation?

That fossils in a region shared characteristics ofliving organisms in that region

What was Darwin's third observation?

Organisms in proximal regions share greater organism characteristics

What was Darwin's fourth observation?

Galapagos species demonstrated variation between islands

What was Darwin's fifth observation?

Artificial selection (breeding) selected for heritable traits (Was it possible for this idea to occur in nature)

What did Thomas Malthus propose?

That populations produced far more offspring than their environments could support (populations were eventually reduced by starvation or disease)

What did Wallace propose?

Proposed idea of evolution through natural selection

What was Wallace's first observation?

He noticed a sharp boundary between nearby islands that

separates distinct ecosystems of Asia and Australia

What was Wallace's second observation?

That to the west of the line, placental mammals are prevalent

What is the Wallace Line?

A line that separates species with Asian and Australian affinities

What was Wallace's third observation?

That to the east of the line, marsupials are prevalent

What are plate tectonics?

A theory explaining how the pieces of Earth's surface move

What are the differences between Wallace's and Darwin's theories?

Wallace's theory of evolution by natural selection emphasized environmental pressures, while Darwin's theory of evolution by natural selection emphasized competition between organisms

What are the big ideas of evolution?

-All living organisms descended from a universal common ancestor

-Evolution of living things is powered by natural processes/ natural selection

What is the fossil record?

The remains and traces of past life that are found in sedimentary rock and reveal the history of life on Earth

What are 3 key points fossil records provide for the evidence of evolution?

-Fossils found in young layers of rock are more

similar to species alive today

-Fossils can be used to trace the evolution of

modern species through time

-Not all organisms appear in the fossil record at the same time

What is biogeography?

The study of geographic distribution of organisms based on both living species & fossil

Where are animals most similar found?

Animals that are the most similar are typically found in the same region

How can similar species in different regions be explained?

Similar species in very different regions can be explained by shifting landmasses

Where are closely related species never found?

Closely related species are almost never found inexactly the same location or habitat

What is a homologous feature?

A structure with a common evolutionary origin that may serve difference functions in modern species

What is divergent evolution?

Species that were once similar to an ancestral species become

increasingly distinct

What are analogous features?

Structures of different species having similar functions but not from the same ancestor

What is convergent evolution?

Similar traits that arise because different species have independently adapted to similar environmental conditions

What are vestigial structures?

Anatomical remnants that were important in the organism's ancestors, but are no longer used in the same way

What are examples of vestigial structures in humans?

Wisdom teeth, appendix, muscles for moving the ear, body hair, little toe, tailbone