Variation

Question 1

what are the three types of variation among individuals

Answer 1

• genetic variation
• environmental variation
• genotype-by-environment interaction

Question 2

types of variation - genetic variation

Answer 2

• the result of differences among individuals that are encoded in their DNA
• the instructions written in different individuals’ genes may specify different versions of particular proteins, or they may specify the manufacture of certain proteins in different quantities or different times or places

Question 3

types of variation: genetic variation - can it evolve

Question 4

types of variation - environmental variation

Answer 4

• arises when external factors influence how much protein is made from particular genes, or how the proteins work
• when individuals experience different environmental, they make different amount of proteins or show differences in protein function
• cannot evolve

Question 5

types of variation: environmental variation - can it evolve

Answer 5

• no
• DNA between individuals are different and environmental variation shapes phenotypes, not genes
• does not have I in VIST

Question 6

types of variation - genotype-by-environmental interaction

Answer 6

• result of differences among individuals that are encoded into their DNA and that make them differ in their sensitivity to environmental influences
• different individual thus react different to a changing environment

Question 7

types of variation: genotype-by-environment interaction - can it evolve

Answer 7

• yes
• differences in genes and the environment shapes the phenotypes

Question 8

define a qualitative trait

Answer 8

• discrete
• complete dominance and may be one intermediate

Question 9

define quantitative trait

Answer 9

• continuous
• multiple genes work together to create a single phenotype
• is polygenic

Question 10

define quantitative genetics

Answer 10

• the genetics of continuously vary characters
  or
• the study of the genetic basis underlying phenotypic variation among individuals

Question 11

quantitative genetics - define quantitative traits

Answer 11

• they are polygenic
• there are environmental effects that alter the phenotypic state of each individual
• value varies continuously

Question 12

environmental variation - phenotypic plasticity

Answer 12

ability of 1 genotype to produce multiple phenotypes in response to different environments

Question 13

environmental variation: phenotypic plasticity - how do we visualize it

Answer 13

• reaction norms
• the slope of the line = plasticity

Question 14

environmental variation - what causes differential gene expression

Answer 14

exposure to different environments

Question 15

environmental variation - wat is an inducible defense

Answer 15

• example of plasticity
• when organisms turn on defenses in response to chemical cues of predators

Question 16

define epigenetics

Answer 16

epigenetic markers can influence gene expression and therefore phenotypes and these can be inherited

Question 17

what is the variation of phenotypes ( Var(P) ) equal to?

Answer 17

Var(P) = Var(G) + Var(E) + Var(GxE)

Question 18

genotype-by-environment interaction - how do you read it on a reaction norm

Answer 18

the two slopes cannot be the same

Question 19

what does selection act on

Answer 19

• phenotypes
• individuals

Question 20

where do we measure genetic variation and change in allele frequencies

Answer 20

• genetic and phenotype
• population

Question 21

what can evolve

Answer 21

genetic and gene-by-environment interaction

Question 22

genotype-by-environment interaction - how may it evolve?

Answer 22

• when populations have genetic variation for environmental sensitivity, populations can evolve greater or less plasticity

Question 23

what kinds of environmental do youthink would select for high vs low plasticity

Answer 23

• high: dynamic environments that are always changing
• low: more stable environments

Question 24

within a species (or population), what does selection tend to do to a trait?

Answer 24

selection tends to erode variation

Question 25

what helps maintain variation

Answer 25

1. GxE
2. balancing selection

Question 26

what helps maintain variation - balancing selection

Answer 26

• preserves genetic variation by maintain two or more phenotypic forms in a population
• ex: negative-frequency-dependent-selection

Question 27

what helps maintain variation: balancing selection - negative-frequency-dependent-selection

Answer 27

the fitness of any genotype in a population declines if it becomes too common in the population