18 - Populations and Evolution Flashcards Preview

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Flashcards in 18 - Populations and Evolution Deck (15)
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1
Q

gene pool

A

all the alleles of all the genes of all the individuals in a population at a given time

2
Q

allelic frequency

A

number of times an allele occurs within the gene pool

3
Q

use of Hardy-Weinberg principle

A

used to predict the proportion of dominant and recessive alleles of any gene in the population, provided the population remains the same from one generation to the next

4
Q

conditions required for Hardy-Weinberg

A
no gene mutations
no immigration
no emigration
large population
random mating between individuals
all genotypes have the same reproductive success
5
Q

effect of population size on the impact genetic drift on a population’s genetic diversity and evolution

A

greater population size, smaller impact of genetic drift on a population’s genetic diversity

6
Q

genetic variation arises as a result of

A

mutation
meiosis
random fertilisation of gametes

7
Q

selection pressures that limit the population of a species

A

predation, disease, competition, food, light, space

8
Q

evolution by natural selection depends on

A
  1. over production of offspring
  2. genetic variation within populations of all species
  3. phenotypic variation
9
Q

over production of offspring

A

death rates must be high as populations rarely increase exponentially
some species have lower reproductive rates but increased parental care in order to maintain population
intraspecific competition for aailable resources
death isn’t random

10
Q

disruptive selection

A

selection pressure towards the extreme values creates two modal values

11
Q

stabilising selection

A

selection pressure towards the central value increases the number of individuals at the modal value

12
Q

directional selection

A

selection pressure towards one xtreme value moves the mode in this direction

13
Q

speciation

A

the evolution of new sppecies fro existing ones, often caused by geographical isolation and different selection pressures acting over many generations

14
Q

allopatric speciation

A

speciation caused by geographical separation

  1. environmental conditions on either side of the geographical barrier vary
  2. natural selection influences the two populations differently
  3. each evolves in different ways leading to adaptations to their local conditions
15
Q

sympatric speciation

A

speciation caused by reproductive separation within the same population

  1. different individuals of the same species start utilising a new resource or area
  2. mate with other individuals in this area
  3. over time mutations arise which lead to genetic differences
  4. results in unsuccessful breeding between the different groups of individuals