1.7 - Evolution Flashcards

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1
Q

Evolution Definition

A

Evolution is the changes in organisms over generations as a result of variations in the genome.

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2
Q

Natural Selection Definition

A

Natural selection is the non-random increase in frequency of DNA sequences that increase survival and the non-random decrease in frequency of deleterious sequences.

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3
Q

Gene Transfer

A

Natural Selection is more rapid in prokaryotes.

Prokaryotes can transfer genetic information horizontally. This results in faster evolutionary change compared to other organisms.

Non-prokaryotes transfer genetic material vertically which is a slower process.

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4
Q

Horizontal Gene Transfer

A

Horizontal gene transfer is where genes are transferred between individuals in the same generation. This does not occur due to reproduction.

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5
Q

Vertical Gene Transfer

A

Vertical gene transfer is where genes are transferred down generations, from parent to offspring.

This can happen through sexual and asexual reproduction.

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6
Q

Sexual Reproduction

A

Sexual reproduction involves two genetically different parents.

Offspring inherit different combinations of genes from each parent causing variation.

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7
Q

Asexual Reproduction

A

Asexual reproduction involves one single parent.

Offspring produced are genetically identical to the parent.

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8
Q

Selection:
Stabilising

A

An average phenotype is selected for and extremes of the phenotype rage are selected against.
E.g human birth mass

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9
Q

Selection:
Directional

A

One extreme of the phenotype range is selected for.
E.g bear mass during an ice age

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10
Q

Selection:
Disruptive

A

Two or more extreme phenotypes are selected for.
E.g dark and light mussels

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11
Q

Speciation Definition

A

Speciation is the generation of a new biological species by evolution.

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12
Q

Stages of Speciation

A
  1. Isolation
  2. Mutations occur randomly across the sub-populations
  3. Different selection pressures act on both sub-populations
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13
Q

Isolation Barriers

A

A population is split into sub-populations by an isolation barrier

Isolation barriers prevent gene flow between the sub-populations.

Isolation barries can be:
* Geographical: This leads to allopatric speciation
* Ecological: This leads to sympatric speciations
* Behavioural: This leads to sympatric speciation

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14
Q

Species Definition

A

A species is a group of organisms that are capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.

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