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Biology I > 5-Evolution > Flashcards

5-Evolution Flashcards

1
Q

Who invented the first theory on evolution of life?

A

Jean-Baptiste Lamarck

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2
Q

What book did Jean-Baptiste Lamarck publish?

A

‘’Philosophie zoologique’’

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3
Q

What is Lamarck’s hypothesis of acquired characteristics?

A

Physical changes in organisms during their lifetime— such as greater development of an organ or a part through increased use — could be transmitted to their offspring

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4
Q

What is an example of that can explain Larmarck’s hypothesis?

A

The giraffe wants to eat leaves that are higher and higher in trees, therefore it stretches its neck, elongating it over time. As a result, all the individuals of the species will gradually grow a longer neck and pass this characteristic to their offspring

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5
Q

Was Lamarck’s hypothesis rejected or accepted?

A

Rejected

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6
Q

What is the modern definition of evolution?

A

It’s the change in the heritable characteristics of biological populations over successive generations to be better adapted to their environment

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7
Q

What are 3 parts to Darwin’s hypothesis?

A

1) Variation must exist in the population

2) Among individuals this variation must lead to differences in reproductive success

3) Among individuals variation must be genetically transmitted to the next generation

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8
Q

What is an example of variation having to exist in a population?

A

Mice litter varies in their fur colours

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9
Q

Explain the 2nd part of Darwin’s hypothesis (Among individuals this variation must lead to differences in reproductive success)?

A

Because of their phenotype or behaviour, some individuals are more successful than others in producing offspring

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10
Q

What is an example of ‘’among individuals this variation must lead to differences in reproductive success’’?

A

Mice with fur matching their background will better evade predators

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11
Q

What is ‘’among individuals variation must be genetically transmitted to the next generation’’

A

A trait that is favourable and permits the organism to survive and thus reproduce will have a better chance to be transmitted to the next generation (the info must be coded in their sex cells)

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12
Q

What is an example of ‘’among individuals variation must be genetically transmitted to the next generation’’?

A

Mice that did not get eaten, because the camouflage coloured fur will pass this trait to their offspring

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13
Q

What is an example of Darwin’s hypothesis?

A

-Finches birds on the Daphne Major island in the Galapagos feed preferentially on small, tender seeds, produced in abundance by plants in wet years.

-During droughts, plants produced few seeds, and all available small seeds were eaten quickly, leaving only large seeds.

-There is a natural variation of beak shape in the population.

-Birds with powerful short and de beaks will survive better, because they can open large seeds. This will make them more likely to reproduce

-Birds with powerful short and deep beaks will be transmitted to the next generation

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14
Q

What were Darwin’s postulates (observations/evidences)? (8)

A

1) Adaption
2) Fossils
3) Homologous structures
4) Convergent evolution
5) Some structures are imperfectly suited to their use
6) Vestigial structures
7) Age of earth
8) Competition

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15
Q

What did Darwin postulate about the birds at the Galapagos?

A

That they were most likely blown away by a storm from main continent to the numerous Galápagos Islands

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16
Q

What is an example of Darwin’s first postulate (adaption)?

A

Each Finch differed from each other and their physiology seemed to be specific to the island they lived on.

Different species evolved from a common ancestor by adapting to the local environment on different islands in the Galapagos

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17
Q

What are fossils?

A

-Fossils are the preserved remains of once-living organisms

-Fossils include specimens preserved in: amber, permafrost, dry cave and rocks

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18
Q

Rock fossils are created when which events occur?

A

1) Organism buried in sediment

2) Calcium in bone or other hard tissue mineralizes

3) Surrounding sediment hardens to form rock

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19
Q

True or false? The process of fossilization is a common event

A

False

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20
Q

What is the oldest known bird fossil?

A

The Archaeopteryx

(Intermediate between the bird and a dinosaur)

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21
Q

The discoveries of Ambulocetus, Rodhocetus, and Pakicetus have filled in the gaps between whales and their _____ ______ ________.

A

Hoofed mammal ancestors

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22
Q

What are homologous structures (evolution)?

A

-Anatomical evidence for evolution

-Structures with different appearances and functions that all derived from the same body part in a common ancestor

-The bones in the forelimb of mammals are homologous structures

23
Q

True or false? At an early stage, human embryo have gill slits and a tail

A

True

24
Q

What is convergent evolution?

A

-Similar forms having evolved in different, isolated areas because of similar selective pressures in similar environments.

25
Q

What is an example/application of convergent evolution

A

Hydrodynamics of moving through water requires a streamlined body shape to minimize friction

26
Q

Why are some structures imperfectly suited to their use (evolution)?

A

-Because natural selection can only work on the variation present in a population, some organisms do not appear perfectly adapted to their environment

27
Q

What is an example of some structures being imperfectly suited to their use (evolution)?

A

Most animals with long necks have many neck vertebrae for enhanced flexibility

However, giraffes have only 7 very long neck vertebrae, because mammal species have no variation in vertebra number among individuals in a population, natural selection has nothing to work with

28
Q

What is an example of some structures being imperfectly suited to their use (evolution) for eyes

A

-Eye of vertebrate animals have an inverted retina where the photoreceptors face backward, so that light has to pass through layers of neurons and capillaries before it reaches the rods and cones

-As a result, the nerve fibres extend forward into the eye chamber, where they slightly obstruct light

-The axons from the optic nerve are at the front of the retina; therefore the optic nerve must cross through the retina en route to the brain. In this region there are no photoreceptors, giving rise to the blind spot

29
Q

Why don’t mollusks have blind spots?

A

Their retina, which evolved independently, is not inverted, therefore they have no obstructions or blind spots

30
Q

What are vestigial structures?

A

-have no apparent function but resemble structures ancestors possessed

-Humans have muscles for wiggling their arms (no purpose)

-Manatee is a descendent of a terrestrial mammal and retained nails even though they never leave water

31
Q

How were humans able to deduce that the Earth formed 4.3 billion years ago?

A

Using the rates of radioactive decay

32
Q

Why did Darwin conclude that individuals must compete for food, water and space?

A

-Those who win the struggle to live reproduce to pass on their genes to their offspring which will have a better chance to reproduce (survival of the fittest)

33
Q

What are the types of selection?

A

1) Natural selection

2) Artificial selection

3) Sexual selection

34
Q

What is natural selection?

A

The organism best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations. Any characteristic of an individual that allows it to survive to produce more offspring will eventually appear in every individual of the species, simply because those members will have more offspring

35
Q

What is the distinction between natural selection and evolution?

A

Evolution: historical record, or outcome, of change through time

Natural selection: a process, which is one of several processes that can result in evolution

36
Q

What are examples of selection to avoid predators?

A

-Pocket mice come in different colours

-Population living on rocks favour dark colours

-Populations living on sand favour light colours

37
Q

What is artificial selection?

A

-Change initiated by humans

-Operates by favouring individuals with certain phenotypic traits, allowing them to reproduce and pass their genes on to the next generation

-This directional selection should result in evolutionary change

38
Q

What is domestication?

A

Human-imposed selection that produces a variety of cats, dogs, pigeons, cows, chickens and others

39
Q

What is an example of artificial selection for chickens

A

-Program of artificial breeding created chickens 4x more massive than the same chicken in the 1950s

40
Q

What is sexual selection?

A

-Males and females usually differ in how they attempt to maximize fitness

-Females evaluate a male’s quality and then decide whether to mate

41
Q

An example of sexual selection with peacocks and peahens

A

-Peahens prefer to mate with peacocks with more eyespots on their tall feathers

-Male peacocks with more impressive tall feathers show that they are able to invest energy in their tall feathers, in addition to not being eaten by predators

42
Q

Does natural selection act on individuals?

A

Yes

43
Q

True or false? Natural selection can only act on variation with a genetic component

A

True

44
Q

What are the three modes of selection called?

A

1) Directional selection
2) Disruptive selection
3) Stabilizing selection

45
Q

What are some characteristics of directional selection?

A

-Favours individuals possessing extreme values of a trait (like fur colour in a mouse, long necks in giraffes), which causes the population to move in a particular direction

-Is most common during periods of environmental change or when members of a population migrate to a new habitat with different environmental conditions

46
Q

What are characteristics of disruptive selection?

A

-Occurs when environmental conditions favour individuals at both extremes of the phenotypic range over those with intermediate phenotypes

-Disruptive selection many occur in an area that provides different resources or danger (predation)

47
Q

What are characteristics of stabilizing selection?

A

-Favours intermediate variants and acts against extreme phenotypes

-Acts against individuals who deviate too far from the average, favours the average

48
Q

What are the 5 agents of evolution (mechanisms that change gene pools)?

A

1) Mutation
2) Gene Flow
3) Nonrandom Mating
4) Genetic Drift
5) Selection

49
Q

What are characteristics of mutation?

A

-Rates generally low (1/100,000 cell division)
-Mutation must occur in the gametes to be transmitted to their offspring
-Most mutation are neutral
-Other evolutionary processes usually more important in changing allele frequency
-The ultimate source of genetic variation, since it creates new alleles.

50
Q

Characteristics of gene flow:

A

-Movement of alleles from one population to another
-Alleles can be transferred through the movement of fertile individuals or gametes (for example, pollen)
- The movement of alleles from one population to another will reduce the genetic differences between these populations

51
Q

Characteristics of nonrandom mating?

A

Assortative mating (phenotypically similar individuals mate, increases proportion of homozygous individuals and can cause inbreeding)

Disassortative mating (phenotypically different individuals mate and produces excess o heterozygotes)

52
Q

What is genetic drift?

A

-In small populations, allele frequency may change by chance alone
-Thus, magnitude of genetic drift is inversely related to population size
-Can lead to loss of alleles in isolated populations and uncommon alleles are more vulnerable
-Affects the genetic makeup of the population but, unlike natural selection, through an entirely random process

53
Q

What is founder effect?

A

-A few individuals disperse and become the founders of a new, isolated population

-Some alleles are lost, and other change in frequency.

54
Q

What is the bottleneck effect?

A

-Drastic reduction in population size due to drought, disease, or other natural forces

-Survivors may constitute a random genetic sample of the original population

-By chance, some alleles may be overrepresented and others underrepresented.

-Results in loss of genetic variability

Biology I (7 decks)

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