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BIOLOGY APES > EVOLUTION 1 > Flashcards

EVOLUTION 1 Flashcards

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1
Q

DEFINE EVOLUTION

A

Evolution can also be defined as = a change in genetic composition of a population from
generation to generation
• Evolution can be viewed as either a pattern or a process:
o Pattern (of evolutionary change) = revealed by data from many scientific disciplines
(biology, chemistry, physics and geology), data as facts i.e. observations about the natural
world
o Process (of evolution) = consists of mechanisms that produce the observed pattern of
change, these represent natural causes of the phenomena we observe

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2
Q

HOW DID ARISTOLE VIEW SPECIES?

A

Aristotle (384-322 BCE) = viewed species as fixed (unchanging)

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3
Q

WHAT DID Carolus Linnaeus do?

A

Carolus Linnaeus (1707-1778) = developed the binomial format for naming species (e.g.
homo sapiens)
o Contrasting to linear hierarchy of scala naturae, he grouped similar species into
increasingly general categories
o Did not ascribe the resemblance to evolution but rather to the pattern of their
creation

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4
Q

define Paleontology

,and statewho developed it?

A

Palaeontology= study of fossils (developed by Cuvier)
o He noted that the older the stratum, the more dissimilar its fossils were to current
life-forms
o Observed from strata to strata that some new species appeared while others
disappeared
o Inferred that extinctions must have been a common occurrence but staunchly
opposed the idea of evolution

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5
Q

What did James Hutton propose about the Earth’s geological features?

A 
James Hutton (1726-1797) = proposed the Earth’s geological features could be explained by
gradual mechanisms such as valleys being formed by rivers
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6
Q

What did Charles Lyell say about Geological processes?

A 
Charles Lyell (1797-1875) = same geological processes are occurring today as in the past and
at the same rate
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7
Q

Describe Lamarck’s hypothesis of Evolution

what is he remembered for?

How did he explain his findings(using 2 principles)?

A

Lamarck’s Hypothesis of Evolution
• Proposed a mechanism for how life changes over time
• Remembered for incorrect mechanism
• By comparing living species with fossil forms, he found several lines of descent
o Explained his findings using 2 principles
o 1) use and disuse = parts of the body that are used extensively become larger and
stronger while those not used deteriorate
o Used giraffe example = stretching their necks to reach higher leaves
o 2) inheritance of acquired characteristics = an organism can pass these modifications
to its offspring
o Genetic research refutes this: traits acquired by use during one’s life are not
inherited by offspring
• He thought evolution happens because organisms have an innate drive to become more
complex

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8
Q

What is Artificial selection?

A

Artificial selection = selective breeding (usually of domesticated plants and animals) by
selecting and breeding individuals that possess desired traits
o As a result, crops, livestock and pets often bear little resemblance to their wild
ancestors

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9
Q

An organism’s heritable traits can not only influence its own performance but also its
offspring’s chances at surviving environmental challenges

Describe NATURAL SELECTION.

A

o An organism might have a trait that gives its offspring an advantage in:
§ Escaping predators, obtaining food, or tolerating physical conditions
o Such advantages increase the no. of offspring that survive and reproduce = traits are
favoured and will appear at a greater frequency in the next generation
o Over time natural selection can lead to an increase in the proportion of favourable
traits in a population

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10
Q

Does natural selection act on an organism’s genotype of phenotype?
Explain your Answer.

EVERYTHING IS EASY, AS LONG AS YOU PUT YOUR WHOLE MIND INTO IT. IT MAY SEEM DIFFICULT AT FIRST, BUT TRUST HEAVEN’S, IT IS NOT.

A

Natural selection acts on an organism’s phenotype – only traits that are expressed can
improve the survival and reproductivity of the organism.n

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11
Q

describe the Evolution of drug-resistant bacteria.

A

A particular problem because resistant strains of pathogens can proliferate very quickly
• Consider evolution of the drug resistance in the bacterium Staphylococcus aureus

A drug does not create resistant pathogens but rather allows for resistant individuals to be
selected for

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12
Q

Define HOMOLOGY

give an example of homology

A

Similarity resulting from common ancestry = homology
• Closely related species share the features used to determine their relationship
• They also have many other shared features which can only be explained in the context of
evolution

E.g. forelimbs of all mammals
show the same arrangement of
bones even though they each
have special adaptations to suit
their functioning for that
mammal
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13
Q

what are vestigial structures?

A

Vestigial structures = remnants of features that served a function in an organisms
ancestors

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14
Q

WHAT IS MICROEVOLUTION???

A

Microevolution
• A change in allele frequencies in a population over generations
o Evolution on its smallest scale= evolutionary changes in populations

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15
Q

Natural selection is not the only cause of microevolution

What are the 3 mechanisms that cause allele frequency change?

A

o Natural selection
o Genetic drift = chance events that alter allele freq.
o Gene flow = transfer of alleles between populations
• Only natural selection consistently improves the match between organisms and their
environment (adaptation)

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16
Q

Define genotypic variation

A

o Genotypic variation = differences among individuals in their composition of genes

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17
Q

WHERE CAN PHENOTYPIC VARIATIONS OCCUR ON???

NKANYISO THE WARRIOR

A

Phenotypic variations can occur on:
o An “either-or” basis = typically determined by a single gene locus, different alleles
produce distinct phenotypes
o Or along a continuum = results from influence of two or more genes on a single
phenotypic character

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18
Q

What is gene variability?

A

Gene variability = genetic variation at the whole-gene level
o Can be quantified as the average percentage of loci that are heterozygous
o E.g. average fruit fly is heterozygous for about 1 920 of its 13 700 loci (=14%) and
homozygous for the rest

19
Q

What is Nucleotide variability?

first semester’s work becomes useful…I’M PROUD OF YOU NKANYISO.

A 
Nucleotide variability = genetic variation at the molecular level of DNA
o Little of this variation results in phenotypic variation
o Many of the differences occur within introns (= noncoding segments of DNA) lying
between exons (= coding segments retained in mRNA after RNA processing)
o Of the variation within exons, most do not cause a change the amino acid sequence
of the protein expressed for that gene
20
Q 
Genetic variants can be produced more rapidly in organisms with short generation
times (i.e. that reproduce quickly)
o In multicellular organisms, only mutations that occur in cell lines that produce
gametes can be passed to offspring
o In plants and fungi = many different cell lines produce gametes
o In animals = far fewer cell lines produce gametes, and majority of mutations occur in
somatic cells (therefore not passed on)
o Sexual reproduction can also result in variation as genes with different alleles can be
put together (doesn’t occur in asexual reproduction

WHAT IS MUTATION?(REVISION BROOO)

A

Mutation causes for new alleles to be formed
o Mutation = change in nucleotide sequence

o ) FLIP THE CARD. IT IS NOT HARD TO KNOW TRUST ME

KANCANE KANCANE-KUTLWANONG PROVERB

21
Q

WHO ARE YOU?
THE GREAT THAT YOU ARE?
WHAT DOES YOUR EXISTENCE MEAN TO YOUR FAMILY?

A

A change of one base in a gene (point mutation) can significantly affect the
phenotype
§ E.g. sickle-cell disease

22
Q

WHAT IS Heterozygous protection?

A

“heterozygous protection” maintains a huge pool of alleles that may not be
favoured in present conditions, but could be beneficial if environment changes

23
Q

what is neutral variation?

A

Neutral variation = no advantage or disadvantage

24
Q

Sexual reproduction shuffles existing alleles and deals them at random to produce individual
genotypes

what are the 3 mechanisms that contribute to this shuffling?

A

3 mechanisms contribute to this shuffling:
o Crossing-over
o Independent assortment of chromosomes
o Fertilization

25
Q

YOU CAN DO IT BRO

NKANYISO ZULU

ZULU NKANYISO

NELSON NKNAYISO ZULU

ZULU NKANYISO NELSON

A

AND THE LORD SAID ‘IT IS DONE’’

YOUR COMPLAINTS ARE ZERO

sometimes you can be your own enemy, so remember to fire the negative voice in your head and employ the positive one all the time.

be optimistic(but not naive)

26
Q

Hardy-Weinberg equation

A

• Presence of variation does not guarantee evolving of population
• Factors enabling evolution must be at play, affecting survival and reproduction of the
population

27
Q

define population?

A

• Population = group of individuals of same species living in same area, that interbreed and
produce fertile offspring

28
Q

what is gene pool?

A

Gene pool = consists of all copies of every type of allele at every locus in all members of
population

29
Q

what do we do to assess whether natural selection or other factors are affecting a particular locus??

it always seems impossible until it is done.

A

To assess whether natural selection or other factors are affecting a particular locus:
o Calculate genetic makeup without evolution at the locus
o Compare this to the data actually observed
o If no differences = population is not evolving
o If difference = populations is evolving

30
Q

equilibrium= in a pop. not evolving, allele and genotype frequencies will
remain constant from generation to generation

what does this equation consider?

A

o Considers the combination of alleles in all of the crosses in a population
o Assuming that mating occurs at random
o p = dominant allele
o q = recessive allele

31
Q

what are the conditions for the Hardy-Weinberg Equation?

A

Conditions for equation:

  1. No mutations - this would modify gene pool
  2. Random mating – random mixing ensures average proportions to stay same
  3. No natural selection – would alter gene pool
  4. Extremely large population size – ensures accurate probability
  5. No gene flow – would change number of alleles in population
32
Q

define natural selection in terms of genetics

A

Natural Selection in genetic terms
• Selection results in alleles being passed down in different proportions to that found in the
present generation
• By consistently favouring some alleles over others = adaptive evolution
• Adaptive evolution = results in a better match between organisms and their environment

33
Q

what is genetic drift?

A

Genetic drift = process by which chance events cause allele frequencies to fluctuate
unpredictably from one generation to the next
o Especially in small populations

34
Q

DESCRIBE THE FOUNDER EFFECT

A

Founder Effect
• When a few individuals become isolated from a larger population, this smaller group may
establish a new population
o Gene pool differs from source population
• Might occur if members are blown by storm to a new island (e.g. Galapagos)
o Genetic drift will occur in such a case if storm randomly transports some indiv. and
not others
• Accounts for the relatively high freq. of inherited disorders among isolated human pop.
o E.g. during colonialist times

35
Q

DESCRIBE THE BOTTLENECK EFFECT

IT IS POSSIBLE NKANYISO NELSON ZULU

YOU WERE BORN FOR THIS

MEDICINE IS MY FATE.

A

Bottleneck Effect
• A sudden change in environment such as a fire or flood = drastically reduces the size of the
population
o Drop in population size causes bottleneck effect
o Population has passed through a “bottleneck” which reduces its size
o By chance alone, certain alleles may be overrepresented among survivors and others
may be underrepresented and some may be absent altogether
• Ongoing genetic drift is likely to have substantial effects on the gene pool until pop.
becomes large enough that chance has less of an impact directly on the gene pool
• Even if a pop. recovers in size after a bottleneck, it may have low variation for a long period
of time

36
Q

define phenotypic variation.

A

o Phenotypic variation = differences among individuals in their expressed traits
(visibly seen or on a molecular scale

Phenotypic variations often reflect genotypic variation

37
Q

NKANYISO NELSON ZULU

THE GREAT THAT I AM

A

it is only in your mind

believe in the great that you are if not yourself. Your life was pre-planned, it is not yours to live but yours to enjoy.

38
Q

SUMMARISE THE GENETIC DRIFT

A

Genetic drift summary:

  1. Genetic drift is significant is small populations
  2. Genetic drift can cause allele frequencies to change at random
  3. Genetic drift can lead to a loss of genetic variation within populations
  4. Genetic drift can cause harmful alleles to become fixed
39
Q

what is the Gene flow?

A

Gene Flow
• Allele frequency can also change by gene flow
• Gene flow = the transfer of alleles into or out of a population due to the movement of fertile
individuals or their gametes
• Because alleles are transferred between populations, gene flow tends to reduce the genetic
differences between populations

40
Q

What is the directional selection and when does it occur?

A

Directional selection
• Occurs when conditions favour individuals exhibiting one extreme of a phenotypic range
o Shifts the population’s frequency curve for the phenotypic character, in one
direction or the other
• Common when a population’s environment changes or when members of a population
migrate to a new (different) habitat

41
Q

what is Disruptive selection and when does it occur?

A

Disruptive selection
• Occurs when conditions favour individuals at both extremes of a phenotypic range over
individuals with intermediate phenotypes
o E.g. big beaks and small beaks for cracking one of two types of seeds
o Intermediate beak sizes are inefficient at cracking open either

42
Q

what is stabilizing selection?

A

Stabilizing selection
• Acts against both extreme phenotypes and favors intermediate variants
• Reduces variation and tends to maintain status quo for a particular phenotypic character
o E.g. birthweight of babies

43
Q

how did Aristotle view Species?

A

viewed species as unchanging

BIOLOGY APES (17 decks)

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