Notes : 5.17 + 5.19 - Natural selection, Evolution and speciation Flashcards

1
Q

Define the term evolution

A

The frequency of an allele in a population changes over time due to natural selction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain the process of evolution by natural selection

A
  • M : Random mutation causes alternative version of a gene whihc leads to differnt allels.
  • V : This creates genetic variation between individuals of the same species (intraspecific variation)
  • A : A selection pressure occurs which means that organisms on the most adapted to their environment survive and reproduce. ( Bacteria don’t reproduce the multiply or instead say that they reproduce asexually in an exam)
  • A : Passing on the advantageous allele.
  • T : Over time the frequency of the beneficial allele increases from generation to generation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name all the evidence you know for evolution

A
  • Genomics (required to know)
  • Proteomics (required to know)
  • DNA hybridisation
  • DNA profiling/fingerprinting
  • Protein sequencing
  • Fossils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does genomics provide evidence for evolution ?

A
  • DNA technology is used to determine the base sequence of an organism genome.
  • This allows scientist to make comparisons between organisms DNA.
  • If the bases sequences are similar of two species they are closely related and share a common ancestor,
  • If the base sequences are less similar for two species they are not closely related.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is proteomics

A

The study of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does proteomics provide evidence for evolution

A
  • The sequence of amino acids in a protein is coded for by the DNA sequence in a gene
  • Related organisms have a similar DNA sequences and so similar amino sequences in their protein
  • The amino acid sequences of some proteins are very similar across many different species;this indicates common ancestry.

The level of similarity between amino acid sequences of equivalent proteins can give a
measure how long ago two species diverged from each other Knowing how long ago a species diverged from a common ancestor enables scientists to establish the relationships between organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does DNA hybridisation provide evidence for evolution

A
  • If we mix a 2 single strand of DNA from two different species together their DNA stands will nybrisies together forming hydrogen bonds with complementary bases creating a double helix
  • Species that are similar will form more hydrogen bonds as they have similar base sequencing.
  • A Lot of energy will be required to break these bonds
  • We know that if the temperature required to break these bonds are higher then the species are closely related as there bases sequeung is similar causing them to have more hydrogen bonds.
  • Conversely, if it separates easily at lower temperatures, it suggests that the species are more distantly related.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does fossils provide evidence for evolution ?

A

Fossils provide a record of how creatures evolved and how this process can be represented by a ‘tree of life’, showing that all species are related to each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The role of the scientific community in validating new evidence

A
  • Scientific journals
  • Peer review process
  • Scientific conferences
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Blurt everything you know about Scientific journals

A
  • Scientist publish their new discoveries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Blurt everything you know about Peer Review

A
  • Scientist check that studies are carried out in
    such a way that results will be valid, and that results have been analysed
    appropriately e.g.by the use of the correct statistical tests.
  • Check that it supports conclusions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Blurt everything you know about conferences

A
  • A scientific conference is a gathering of scientists in a particular field of study from all over the world
  • Scientists can present their findings for questions and discussion
    Conference Members have the opportunity to speak with each other about their work and to share ideas and concerns
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is speciation

A

The development of a new species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does speciation occur ?

A
  • When populations of the same species become reproductively isolated, reducing gene flows (transfers between genes) between two populations.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What causes variation

A
  • Mutations
  • Independent assortment
  • Crossing over
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define the term allele frequency

A

The relative frequency of a particular allele in a population

17
Q

Define the term gene pool

A

All of the genetic information, including all variations, contained within a population of a particular species at a particular time

18
Q

How does reproductive isolation

A

Due to :
- Geographical isolation (allopatric speciation)
- Random mutations produce changes in a phenotype that prevents populations from mating (sympatric speciation)

19
Q

Blurt everything you know about allopatric speciation

A
  • It occurs when populations are geographically isolated. (e.g due to physical barriers) - Thebarriercouldbenatural e.g.a bodyofwateror a mountain range
    It Can also be man-made.g.a motorway
  • This prevent groups from mating. Causing reproductive isolation. So there is no gene flow between them
  • Natural selection occurs(explain this process in an exam) as if they are geographically isolated they will experience different conditions so will experience different selection pressures acting on them so there will be changes in the allele frequency.
20
Q

What is sympatric speciation and how can it occur ?

A
  • Its when species become reproductively isolated even though there is no geographical isolation.
  • This can happen through a number of ways :
  • Seasonal changes
  • Mechanical changes
  • Behavioural changes
21
Q

Explain how seasonal changes lead to reproductive isolation reducing gene flow causing sympatric speciation

A

Seasonal changes can cause individuals from the same population to develop different flowering or mating seasons, or become sexually active at different times of the year.
- This will reduce the interberreding causing them to become reproductively isolated and so sympatric speciation occurs

22
Q

Explain how mechanical changes reduces gene flow, leading to reproductive isolation causing sympatric speciation

A
  • This refers to physical alteration in the organism
  • changes in genitalia prevent successful mating. Which reduces gene flow, leading to reproductive isolation causing sympatric speciation
23
Q

Explain how behavioral changes reduces gene flow, leading to reproductive isolation causing sympatric speciation

A
  • When a group of individuals develop courtship rituals that aren’t
    attractive to the opposite sex they won’t mate with the opposite sex. This reduces the gene flow between them and the main population, leading to reproductive isolation causing sympatric speciation
24
Q

The fruit fly example of sympatric speciation

A
25
Q

Exam tip

A