Basic concepts evolution etc.

Question 1

What’s the difference between the scientific and colloquial use of the word theory?

Answer 1

Colloquial theory is a possible explanation unsupported by evidence

Scientific theory is an idea supported by evidence that has not been previously disproven

Question 2

Define evolution

Answer 2

Descent with modification; a change in the genetic composition of a population from generation to generation

Question 3

Define microevolution, provide an example

Answer 3

Small, subtle changes within a population within a short amount of time
Ex;
Medium ground finches

Question 4

Define macroevolution, provide an example

Answer 4

A large, dynamic change at or above the species level over a long time.
This results in speciation and a change in a line of descent
Ex;
Initial galapagos finches speciation into 13 different species

Question 5

What is the difference between natural, artificial, and sexual selection?

Answer 5

a variation in heritable traits that ….
Natural selection: promote survival and reproduction due to environmental selection pressures
Sexual selection: A variation in traits determined by intra and inter sexual selection to increase reproductive success
Artificial selection: determined by human selection pressures
Dog breeders

Question 6

What are the two types of sexual selection, provide examples

Answer 6

ntrasexual selection: pressures of the same gender
Males competing w/ males for the right to reproduce with females.
Ex; bigger claws, bigger body sizes, lions mane (intimidation), aggression
Intersexual selection: pressures of the other gender
Males proving to females that they are healthy, have good genes, and have surplus energy. If too exaggerated may lead to death.
Ex; peacock feathers, strong male calls (frogs), elephant spider’s butt & dancing. Female generally involves having more oovum

Question 7

Define reproductive success

Answer 7

Total sum of offsprings an individual organism has within its lifespan

Question 8

Define adaptation

Answer 8

Any trait or characteristic (mutated or inherited) that promotes or favors survival and/or reproduction

Question 9

What is the difference between homologous, analogous, and vestigial structures?

Answer 9

Homologous: similar traits due to a common ancestor with the same trait, derived from the same anatomical structures or tissues
Ex; tetrapod forearms
Analogous: convergent evolution, similarity in form and structure of two structures not due to a common ancestor but due to similar selection pressures
Ex; moths, bats, and birds both have wings
Vestigial: leftover structures due to … reduced selection pressures and/or reduced function
Ex; coccyx in humans, phalanges in most birds

Question 10

What is heterozygosity and homozygosity, and how do they relate to genetic variation?

Answer 10

The number of individuals with … traits on their loci
Heterozygosity: heterozygous traits, increase genetic variation
Homozygosity: homozygous traits, decrease genetic variation

Question 11

Difference between convergent and divergent evolution

Answer 11

Convergent evolution: aka analogous evolution / characteristics, is different species adapting similar traits due to similar selection pressures

Divergent evolution: species adapting dissimilar traits and undergoing speciation, the development of new species over time due to selection pressures

Question 12

Can you provide evidence to support the theory of evolution?

Answer 12

microevolution: Darwins finches, antibiotic resistant bacteria.
Homologous proteins: RuBisCo
Fossils, biogeography, & continental drift

Question 13

Define population

Answer 13

A group of individual organisms in the same species in a given area that interbreed

Question 14

Define gene pool

Answer 14

All the genes, including all the different alleles for each gene, that are present in a population at any one time

Question 15

Define population genetics

Answer 15

The study of gene frequencies in a population (microevolution)

Question 16

Define relative fitness

Answer 16

How well an individual organism survives and reproduces RELATIVE to others in the population

Question 17

What are Hardy Weinberg’s
5 assumptions?

Answer 17

Very large population
No new mutations
No migration (emigration or immigration)
No natural selection
No sexual selection

Question 18

Define, draw, and give an example of directional selection

Answer 18

Selection pressures favor one extreme phenotypic trait, thereby shifting the frequency distribution of one phenotypic range either higher or lower. Commonly occurs due to environmental changes.
Medium Galapagos finches

Question 19

Define, draw, and give an example of stabilizing selection

Answer 19

Negative selection pressures exist at both phenotypic extremes, favoring intermediate phenotypes. Reduces variation.
Human baby body weight

Question 20

Define, draw, and give an example of disruptive/divergent selection

Answer 20

Selection pressures favor both extreme phenotypes, and negatively select for intermediate traits. Aka dimorphism.
Peppered moths & cameroon finches

Question 21

Define, draw, and give an example of frequency-dependent selection

Answer 21

Selection pressures favor the rare phenotype in a population, which will switch between the dimorphic phenotypes
P. microlepis, parasitic fish (left fish and right fish)

Question 22

Which one of the four selection pressures most often results in speciation?

Answer 22

1. Directional: most likely due to its relation to microevolution
2. Disruptive: usually it just results in dimorphic species that still mate with each other, unless the phenotypic range is great enough for the longest time or an environmental change
3. Stabilizing: reduces genetic variation, so very unlikely
4. Frequency-dependent: traits and adaptation is inherently circular, therefore evolving in one way is nearly impossible

Question 23

Define canalize

Answer 23

Driving the average frequency of a trait down, otherwise known as a negative selection pressure

Question 24

Define polymorphism and what causes it

Answer 24

The movement of alleles into and out of a population due to immigration or emigration
Insect pollination
Contributes to balancing out species wide genetic diversity and heterozygosity

Question 25

Define gene-flow

Answer 25

The movement of alleles into and out of a population due to immigration or emigration
Insect pollination
Contributes to balancing out species wide genetic diversity and heterozygosity

Question 26

Define genetic drift
and its consequences

Answer 26

Change in allele frequencies, a loss or gain, due to a random chance event. Usually negatively affects and constrains evolution by damaging genetic variability by destroying beneficial alleles. Occurs in small pop’ns.
Sometimes, by chance, future evolution is compromised
Ex;
Typhoon hits an island, and a bunch of lizards die. The genes that were lost were random and didn’t represent the selection pressures, and the remaining lizards had a lesser frequency of adaptive traits … go extinct

Question 27

Define bottleneck effect
and its consequences

Answer 27

A sudden, indiscriminate change in the environment (not a chance event) that may drastically reduce the size of a population - and the remaining genes weren’t adaptive.
Occurs over a generation in relatively large pop’ns
Ex;
Illinois prairie chicken pop’n was reduced over 100 years and the remaining chickens had high frequencies of recessive diseases

Question 28

Define founder effect
and its consequences

Answer 28

When a few individual organisms get isolated and gene flow between the isolated and the rest of the population, the consequences are an evolutionary limitation due to the genes first introduced, homozygosity, and inbreeding.
Anolis segrei (bahamas lizard)