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Level 3 Biology > Speciation Definitions > Flashcards

Speciation Definitions Flashcards

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1
Q

Species

A

A group of similar organisms who can reproduce in nature to form fertile offspring.

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2
Q

Gene pool

A

All the alleles in a population.

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3
Q

Mutation

A

A change in the order of bases in DNA. This may lead to a new phenotype.

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4
Q

Natural selection

A

Where some phenotypes have the advantage in a certain environment, so individuals with that phenotype are more likely to survive, reproduce and pass on their alleles the next generation.

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5
Q

Disruptive natural selection

A

Favours two phenotypic extremes at the expense of intermediate form.

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6
Q

Stabilising natural selection

A
  • Decreased variation for the phenotypic character
    involved.
  • Acts to prevent divergence from adaptive phenotype
  • Happens when environments are stable.
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7
Q

Directional natural selection

A

The adaptive phenotype is shifted in one direction and is favoured over others . Directional when there is a trend in environmental conditions.

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8
Q

Gene flow (migration)

A

The ability of alleles to enter or leave a population.

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9
Q

Speciation

A

The formation of a new species.

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10
Q

Allopatric speciation

A

Speciation that begins with a geographic barrier.

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11
Q

Sympatric speciation

A

Speciation that does not begin with a geographic barrier.

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12
Q

Living sympatrically

A

Living in the same area - niche differentiation.

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13
Q

Evolution

A

Change in the allele frequencies in a population over time.

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14
Q

Genetic biodiversity

A

Refers to the number of different alleles of all genes and the frequency with which the alleles appear within a population.

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15
Q

Geographic Barrier

A

Physical thing that stops gene flow.

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16
Q

Reproductive isolating mechanism

A
  • Individuals in the population who can no longer fulfil the
    species definition.
  • They can no longer reproduce to produce fertile
    offspring.
  • They don’t need to mate, they don’t recognise each
    other as someone to mate with, they CAN’T mate or their
    offspring are not fertile.
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17
Q

Pre-zygotic RIM

A

Occur before fertilisation. Prevents the fertilisation of eggs.

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18
Q

Ecological RIM

Pre-zygotic RIM

A

The existence of a prezygotic barrier between two species as a result of them occupying or breeding in different habitats within the same general geographical area.

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19
Q

Behavioural RIM

Pre-zygotic RIM

A
  • Courtship behaviours are a necessary for successful
    mating.
  • Dances, calls, displays, or the presentation of gifts. The
    displays are specific and unique to each species. -
  • Members of other species do not recognise or pay
    attention to these behaviours.
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20
Q

Temporal RIM

Pre-zygotic RIM

A

Temporal isolation means isolated in time and prevents species interbreeding because they mate or they are active at different times. Different times of the day or seasons.

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21
Q

Mechanical RIM

Pre-zygotic RIM

A

Structural differences in the anatomy of reproductive organs prevents sperm transfer between individuals of different species.

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22
Q

Post-zygotic RIM

A

Operate after fertilisation has occurred. Important for maintaining the integrity of closely related species.

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23
Q

Hybrid inviability

Post-zygotic RIM

A

Mating between individuals of two species may produce a zygote, but genetic incompatibility may stop development of the zygote. Fertilised eggs often fail to divide because of mis-matched chromosome numbers from each gamete.

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24
Q

Hybrid sterility

Post-zygotic RIM

A

When two species mate to produce a hybrid offspring, but the hybrid is not fertile. The species are still reproductively isolated and genes cannot flow from one species gene pool to the other.

25
Q

Hybrid breakdown

Post-zygotic RIM

A

The first generation may be fertile but the second generation are infertile.

26
Q

Hybrid

A

The offspring of two plants or animals of different species.

27
Q

Polyploidy

A

Having more than 2 haploid sets of chromosomes (being more than diploid.

28
Q

Diploid

A

2 sets of haploid gametes.

29
Q

Autopolyploid

A

Made from only one species.

30
Q

Allopolyploidy

A

Come from more than one species.

31
Q

Non-disjunction

A

When chromatids fail to seperate and go to either pole.

32
Q

When non-disjunction occurs in mitosis…

A

The rest of the plant made from that cell is a polyploid.

33
Q

When non-disjunction occurs in meiosis…

A

The resulting 2n gamete may either fuse with another 2n gamete to create a 4n polyploidy plant. Or it could fuse with a normal haploid gamete to make a 3n plant. A 3n plant would usually be sterile, however sometimes it can have a chromosome doubling event to make a fertile 6n plant.

34
Q

Divergent evolution

A

Where a common ancestor diverges into two or more species.

Homologus features.

35
Q

Adaptive Radiation

A

Rapid evolution of a number of different species from a single common ancestor.

Adaptive radiation is divergent evolution.

36
Q

Convergent evolution

A

Species that have a similar way of life often evolve similar features even though they have quite different ancestors.

Analogus structures.

37
Q

Co-evolution

A

Evolutionary changes in one species act as a selection pressure for another.

Each acts as one of the others most important selection pressures. Changes in one species brings about changes in the other.

38
Q

Gradualism

A

Evolution occurs at a slow steady rate.

39
Q

Punctuated Equilibrium

A

Short periods of rapid change interspersed with longer periods of relatively slow change called stasis.

40
Q

Stasis

A

longer periods of relatively slow change.

41
Q

Phylogeny

A

The evolutionary history of a species.

42
Q

Homologus structures (features)

A

Features which are similar in structure and origin but have different functions.

43
Q

Analogus structures (features)

A

Features which have different evolutionary origins but have similar functions and may have similar appearances.

44
Q

Vestigial structures

A

A structure in an organism that has lost all or most of its original function in the course of evolution.

45
Q

Glacial period

A

A period in the earths history when polar and mountain ice sheets were extensive across the earths surface.

46
Q

Interglacial period

A

A geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods with an ice age.

47
Q

Gondwana

A

An ancient supercontinent that broke up about 180 million years ago.

48
Q

Fossil

A

Any non-living object which shows the presence of a once living organism.

49
Q

Transitional fossil

A

Any fossilised remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group.

50
Q

Nuclear DNA

A

Encodes the primary structure of proteins, consisting of the amino acid structure.

51
Q

Mitochondrial DNA

A

The small circular chromosome found inside mitochondria.

52
Q

Biogeography

A

Is a branch of geography that studies the past and present distribution of the worlds many animal and plant species.

53
Q

Mutations create…..and therefore…..

A

Mutations create new alleles and therefore new phenotypes.

54
Q

Mutations may become common in a population if……

A

Mutations may become common in a population if they provide a survival or reproductive advantage in the current environment.

55
Q

Different environments have…

A

Different environments have different selection pressures.

56
Q

For 2 populations to become different overtime there needs to be….

A

For 2 populations to become different overtime there needs to be an interruption of gene flow.

57
Q

The more similar 2 organisms DNA…..

A

The more similar 2 organisms DNA the more closely related they are, the more recently they shared a common ancestor.

58
Q

Molecular clock

A

Mutations occur at a relatively constant rate for any gene, so genetic differences can indicate how long ago they shared a common ancestor.

Level 3 Biology (4 decks)

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