2.2 Evolution Flashcards Preview

Advanced Higher Biology > 2.2 Evolution > Flashcards

Flashcards in 2.2 Evolution Deck (54)
Loading flashcards...
1
Q

what is evoluiton

A

the change, over successive generations, in the proportion of individuals in a population differing in one or more inherited traits

2
Q

what is natural selection

A

non-random process whereby certain alleles occur more frequently within a population because they confer a selective advantage

3
Q

what is sexual selection

A

the non-random process involving the selection of alleles that increase the individual’s chances of mating and producing offspring

4
Q

what is genetic drift

A

the random change in how frequent a particular allele occurs within a small population

5
Q

which evolutionary changes are random and which are non-random

A

natural selection - non-random
sexual selection - non-random
genetic drift - random

6
Q

what is a mutation

A

rare, random changes to genetic sequences which can be harmful, neutral or, in rare cases, beneficial to the fitness of an individual
mutations are the original source of new sequences of DNA
variation in traits arise as a result of mutation

7
Q

how do selection pressures arise

A

populations produce more offspring than the environment can support, resulting in selection pressures

8
Q

individuals with variations that are better suited to the environment tend to:

A

survive longer and produce more offspring, breeding to pass on those alleles that conferred an advantage to the next generation

9
Q

what does selection result in

A

the non-random increase in the frequency of advantageous alleles and the non-random decrease in the frequency of deleterious alleles

10
Q

what can sexual selection lead to

A

sexual dimorphism

11
Q

what is sexual dimorphism

A

physical difference between males and females of a species

12
Q

sexual selection can be due to:

A

male-male rivalry

female choice

13
Q

what is male-male rivalry

A

large size or weaponry increases access to females through conflict

14
Q

what is female choice

A

involves females assessing the fitness of males

15
Q

why is genetic drift more important in small populations

A

alleles are more likely to be lost from the gene pool

16
Q

genetic drift occurs because of:

A

the bottleneck effect

the founder effect

17
Q

what is the bottleneck effect

A

occurs when there is a disaster of some sort that reduced a population to a small handful, which rarely represents the actual genetic makeup of the initial population. this leaves smaller variation among the surviving individuals

18
Q

what is the founder effect

A

the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. the gene pool of the new population is not representative of that in the original gene pool

19
Q

how is a gene pool altered by genetic drift

A

certain alleles may be under-represented or over-represented and allele frequencies change

20
Q

when selection pressures are strong, the rate of evolution can be

A

rapid

21
Q

what are selection pressures

A

the environmental factors that influence which individuals in a population pass on their alleles

22
Q

selection pressures can be:

A

biotic or abiotic factors

23
Q

examples of biotic factors

A

competition
predation
disease
parasistism

24
Q

examples of abiotic factors

A
temperature 
light 
humidity
pH
salinity
25
Q

what is the Hardy-Weinberg (HW) principle

A

in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations

26
Q

conditions for maintaining the HW equilibrium are:

A
no natural selection
random mating
no mutation
large population size
no gene flow (through migration, in or out)
27
Q

what can the HW principle determine

A

whether a change in allele frequency is occurring in a population over time

28
Q

what does changes in the allele frequency suggest

A

evolution is occurring

29
Q

what is the HW principle formula

A

p² + 2pq + q² = 1

30
Q

what does p represent in the HW principle

A

frequency of dominant allele

31
Q

what does q represent in the HW principle

A

frequency of recessive allele

32
Q

what does p² represent in the HW principle

A

frequency of homozygous dominant genotype

33
Q

what does 2pq represent in the HW principle

A

frequency of heterozygous genotype

34
Q

what does q² represent in the HW principle

A

frequency of homozygous recessive genotyope

35
Q

what is fitness

A

the indication of an individual’s ability to be successful at surviving and reproducing

36
Q

what is fitness a measure of

A

tendency of some organisms to produce more surviving offspring that competing members of the same species

37
Q

what does fitness refer to

A

the contribution made to the gene pool of the next generation by individual genotypes

38
Q

what are the types of fitness

A

absolute

relative

39
Q

what is absolute fitness

A

the ratio of frequencies of a particular genotype from one generation to the next

40
Q

what is the formula for absolute fitness

A

frequency of a particular genotype after selection
/
frequency of a particular genotype before selection

41
Q

what does it mean if absolute fitness is 1

A

the frequency of that genotype is stable

42
Q

what does it mean if absolute fitness is a value greater than 1

A

an increase in the genotype

43
Q

what does it mean if absolute fitness is a value less than 1

A

a decrease in the genotype

44
Q

what is relative fitness

A

the ration of surviving offspring of one genotype compared with other genotypes
the ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype

45
Q

what is the formula for relative fitness

A
number of surviving offspring per
individual of a particular genotype 
/ 
number of surviving offspring per
individual of the most successful genotype
46
Q

what is co-evolution

A

where a change in the traits of one species acts as a selection pressure on another species with which it frequently interacts

47
Q

co-evolution is frequently seen in

A

pairs of species that have symbiotic interactions

48
Q

what is symbiosis

A

an interrelationship between members of two different species, whereby at least one species benefits

49
Q

the impact of symbiotic relationships can be … for the individuals involved

A

positive (+)
negative (-)
neutral (0)

50
Q

name the symbiotic interactions

A

mutualism
commensalism
parasitism

51
Q

what is mutualism

A

both organisms in the interaction are interdependent on each other for resources or other services as both organisms benefit from each other (+/+)

52
Q

what is commensalism

A

an interrelationship between organisms of two different species in which one species benefits and the other neither benefits nor suffers (+/0)

53
Q

what is parasitism

A

the parasite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources (+/-)

54
Q

what is the red queen hypothesis

A

in a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species
this means that species in theses relationships must adapt to avoid extinction