lecture 19

Question 1

what is a population

Answer 1

All the individuals of the same species that live
in a particular place at the same time - variations in traits (ex. size, color….)
- some variation due to environment, and some due to heredity

Question 2

what did Darwin’s theory and Mendel’s discovery create

Answer 2

population genetics: Science that studies the process of microevolution (how populations change genetically over time)

Question 3

what is microevolution

Answer 3

Is change in the genetic makeup of a population from generation to generation
– evolutionary change below the species level

Question 4

what can microevolution lead to

Answer 4

macroevolution (new species, new groups)

Question 5

what is a gene pool

Answer 5

all the alleles for all the loci present in the population
* Diploid organisms have 2 alleles at each genetic locus (gene location)
* each individual only has a small fraction of the alleles present in the population’s gene pool

Question 6

what is a genotype frequency

Answer 6

The proportion of a particular genotype in the population

Question 7

what is allele frequency

Answer 7

proportion of a specific allele in a population

Question 8

what is genetic equilibrium

Answer 8

Frequencies of alleles do not change from generation to generation unless influenced by outside factors
- A population whose allele and genotype freq. do not change from one generation to the next = equilibrium

Question 9

what is the Hardy Weinberg principle

Answer 9

Allele and genotype frequencies do not change from generation to generation * no evolution is occurring in a population at genetic equilibrium.

Question 10

what are the conditions for genetic equilibrium

Answer 10

• Random mating
• No mutation
• No natural selection
• Extremely large population size
• No Migration (no gene flow – transfer of alleles from another pop.)

Question 11

what does the Hardy Weingerg principle give us? why is it useful

Answer 11

tells us what to expect when a sexually reproducing population is NOT EVOLVING

Question 12

does genetic equilibrium really happen

Answer 12

no

Question 13

what does the degree of departure between observed allele frequency and those expected by HW principle indicate

Answer 13

amount of evolutionary change

Question 14

what factors cause microevolution

Answer 14

1. Mutations
2. Sexual Recombination
3. Natural Selection
4. Genetic Drift
5. Gene Flow

Question 15

in what types of cells do most mutations occur

Answer 15

somatic

Question 16

in what type of cells do mutation have to occur to be passed on

Answer 16

gametes, only small fraction of these spread through pop

Question 17

what is genetic drift, what does it explain

Answer 17

• random evolutionary changes in a population
• Describes how allele frequencies can fluctuate unpredictably from one generation to the next
• major factor altering allele frequency

Question 18

what causes genetic drift in a small population

Answer 18

• bottleneck effect
• founder effect

Question 19

what is the bottleneck effect (genetic drift)

Answer 19

occurs when number of individuels in a pop drastically reduce because of a disaster, by chance, some alleles will be overrep and some underep

Question 20

what is the founder effect (genetic drift)

Answer 20

when a few indivuduels become isolated from a larger population
small fraction establishes a new colony
bring only small fraction of genetic variability of original population

Question 21

what is gene flow

Answer 21

transfer of alleles from one pop to another potentially altering gene frequencies

Question 22

what is a consequence of gene flow

Answer 22

• mixing of indiv between pop reduces differences between pop over time
• can counter genetic drift and natural selection

Question 23

of all the factors that can change a gene pool, which can lead to adaptation of an organism to its environment

Answer 23

natural selection

Question 24

what is a consequence of naturel selection on genetype

Answer 24

can alter frequency of certain genotypes

Question 25

what are the different types of natural selection

Answer 25

• directional
• disruptive
• stabilizing

Question 26

what is direction selection

Answer 26

favors indiv at one end of the phenotypic range, one extreme

Question 27

what is disruptive selection

Answer 27

favors indev at both extremes of phenotypic range, disadvantage extreme phenotypes, favors production 2 diff species from common ancestors

Question 28

where did original differences come from

Answer 28

mutations

Question 28

what is stabilizing evolution

Answer 28

favors intermidiate variants, acts against extreme phenotypes, median of population

Question 29

what is the reproductive handicap of sexual reproduction, why has it persisted dispite this?

Answer 29

• Produces less offspring then asexual reproduction
• produces genetic variability that may aid in disease resistance

Question 30

what is sexual selection

Answer 30

natural selection from mating success

Question 31

what does sexual selection result in

Answer 31

sexual dimorphism,
* marked differences between the sexes in secondary sexual characteristics
- phenotypic difference between males and females of a species

Question 32

what is intrasexual selection

Answer 32

competiton amoung individuals of one sex for mates of the opposite sex

Question 33

what is intersexual selection

Answer 33

individuels of one sex choosy in selecting their mates