9.3 and 18.3 Genetic diversity and adaptation Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is the main cause of variation

A

DNA
It determines many proteins that make up each organism
So similarities and differences between organisms are defined in terms of variation in DNA

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

What is a gene

A

A section of DNA that codes for a specific polypeptide

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

What do all members of the same species have in common

A

They have the same genes

Eg a gene for blood group, petal colour etc

It is the alleles of a gene that cause variation, so humans may have different alleles of blood group.

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

What is genetic diversity

A

The total number of different alleles in a population

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

What is a population

What is the difference between a species and a population

A

A group of individuals of the same species that live in the same place and can interbreed

A species consists of multiple populations

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

What increases genetic diversity

A

The more alleles that all members of the species possess, the greater the genetic diversity of that species

So genetic diversity is reduced when a species have fewer different alleles

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

Why is increased genetic diversity good

A

. More genetic diversity leads to more variation
. So it is more likely that the species will survive an environmental change (selection pressure)
. Because a wider range of alleles leads to a wider range of phenotypes/ characteristics
. So there is a greater probability that an individual will possess a characteristic that suits it to the new environmental conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the process of evolution by means of natural selection depend on

A

. Depends on variety of phenotypes that selection operates against

. Genetic variety within the populations of all species

. Organisms producing more offspring than they can support with food etc so only the most well adapted ones survive and reproduce

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

What are selection pressures

A

The environmental factors that limit a population of a species

Eg predation, disease, and competition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How many alleles are there per gene

A

There are 2 alleles per gene
One from each parent

So both alleles together form the genotype for that specific gene

As they is an alternative forms of it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is natural selection

A

Not all alleles are passed down to the next generation, as not all the individuals that carry those alleles will reproduce successfully to pass the allele down.

So natural selection is a mechanism of evolution, where organisms more adapted to the environment are more likely to survive and reproduce to pass their alleles down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe process of natural selection

A

. Within any species there is a gene pool which contains a wide variety of alleles

. Random mutation of alleles within this gene pool result in a new allele of a gene which is usually harmful

. But in certain environments, this new allele of a gene may give the individual that possesses it a selective advantage over others in the population

. These individuals have characteristics that are more adapted to the environment
so they will survive more due to obtaining all available resources etc

. They have a better chance of reproducing successfully to give this allele to the offspring, than other individuals who don’t have it

. As these new offspring have the advantageous allele they will survive and reproduce more successfully

. Over many generations, the number of individuals with this allele will increase at the expense of those without it

. So allele frequency of that advantageous one increases, whilst that of other non-advantageous one decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a gene pool

A

The total number of alleles in a specific population at the same time

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

What is allele frequency

A

How many of a specific allele there is in a gene pool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What shape graph would there be if a species reproduced exponentially, so if there were no environmental selection pressures stopping it

A

It would be shaped like an exponential graph, so e^x in maths
Going through (0,1)

However in reality this isn’t the case as death rate must be extremely high for the populations to not grow by that much

This is why there are high reproductive rates in most species, so there are enough offspring to be the next generation, and this compensates for high death rates from predation, water, food, territory etc

However some species produce less offspring, but have lots of parental care and attention now so lower death rates help maintain their population size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is intraspecific competition

A

There are too many offspring for the available resources, so there is competition between the individuals for these limited resources

The greater the numbers, the greater this competition so more individuals die as they struggle to survive
So those who are better suited to conditions eg thick fur in the cold will be more likely to survive and breed, passing on their favourable alleles to next generation

17
Q

Why does allele frequency change between generations

A

Because selection pressures change between generations, so those with alleles that are more adapted to the environment will survive more and pass down these alleles

So the new generation contains alleles more adapted to the current conditions

18
Q

Why is variation important in natural selection

A

Variation provides the potential for a population to evolve and adapt to new circumstances

If there are any environment changes and selective pressures, if there are many genetically different individuals in the species…

There will always be a combination of genes (so phenotypes) to survive in a new set of circumstances

The larger a population, and more genetically varied it is , there is a higher chance of an individual who will have a combination of alleles that lead to a phenotype which is advantageous.

Populations with less variation are more vulnerable to new disease and climate changes.