ch 13- evolution Flashcards

Question

phyletic graduation

Answer 1

Evolution happened gradually via accumulation of small intermediary changes. Not likely to be true (not supported by fossil evidence).

Answer 2

Short spurts of evolutionary changes during periods of stasis (supported by fossil evidence).

Answer 3

is how species form, starting with reproductive isolation, which leads to interruption of gene flow between populations that gradually develop into two species.

Answer 4

refers to barriers to organism success after zygote has formed. hybrid motality (inviability) hybrid sterility hybrid F2 breakdown: Hybrid F2 generation have reduced fitness compared to their parental generation.

Answer 5

habitat isolation temporal isolation behavioural isolation mechanical isolation gamete isolation (incompatibility)

Answer 6

is long-term and occurs at a level at or higher than species. Species are reproductively isolated (via prezygotic and postzygotic isolating mechanisms) resulting in a lack of gene flow between species.

Answer 7

is the process when gene frequencies change within a population over generations (favorable genes increase, unfavorable decrease).

Answer 8

genetic drift non random mating mutations natural selection gene flow: migration- non random moving alleles between populations leading to variation through mixing

Answer 9

Allele frequencies change by chance. Larger effects on small populations. ● Bottleneck effect: Smaller gene pool, some alleles may be lost (eg. disaster killing majority of population). ● Founder effect: Some individuals migrate away from the population.

Answer 10

mutation sexual reproduction balanced polymorphism polyploidy

Answer 11

Maintains a variety of phenotypes within a population. ● Heterozygote advantage (e.g., sickle cell anemia): Two parents produce an offspring that is more fit than either parent. ● Minority advantage: Rare phenotypes offer higher fitness. Cycle between high and low frequency (e.g., advantageous against hunters’ search images). ● Neutral variations: May become beneficial if the environment changes.

Answer 12

Plants have multiple copies of alleles introducing more variety and preserving different alleles. Can also mask effects of a harmful recessive allele.

Answer 13

is the study of fossils through actual remains of the animal or their traces (ichnofossils). Petrification is the process by which living organisms turn into fossils. These fossils allow us to see the development of species through time by comparing deepest (oldest) fossils to shallowest (youngest).

Answer 14

gill slits

Answer 15

may or may not perform the same function but have a common ancestor. eg. forearm of bird and forearm of human.

Answer 16

same function, do not have a common ancestor, e.g. bird wings and bat wings.

Answer 17

serve no purpose but are homologous to functional structures in other organisms, e.g. human appendix and cow cecum.

Answer 18

proposed catastrophism. Catastrophes lead to mass extinctions of species in those areas. The different populations in different areas were shaped by what catastrophes had occurred, and what random organisms

Answer 19

● Use and disuse: used body parts will develop and unused ones are weakened, leading to evolution. ● Inheritance of acquired traits: traits acquired through use and disuse are passed onto offspring (eg. giraffe stretching neck will cause its neck to develop, and produce long necked offspring). This is incorrect - acquired characteristics are generally not heritable.

Answer 20

theory of natural selection Natural selection is the gradual, non-random process where allele frequencies change as a result of environmental interaction. Survival of the fittest occurs as individuals with greatest fitness (ability to survive and produce viable and fertile offspring) have greatest success, and pass on more DNA to future generations compared to less fit parents. Leads to the evolution of the population (not individuals).

Answer 21

1. Demand for resources exceeds supply: results in competition for survival (fittest survive to pass on genes). 2. Difference in levels of fitness due to variation in traits: differentiate ability to compete and survive (e.g., black peppered moths favored over white moths during Industrial Revolution). 3. Variation in traits must be genetically- influenced (heritable) to be passed onto offspring. 4. Variation in traits must be significant for reproduction and/or survival: genes improving reproductive success/survival are favored and increase over generations and vice versa. .

Answer 22

1. Stabilizing selection: Mainstream (average) is favored (e.g., birth weight). Diagram follows a standard bell curve. 2. Directional selection: One extreme favored (e.g., longest giraffe neck allows access to the most leaves). 3. Disruptive selection: Rare traits favored, mainstream is not (e.g., snails living in low and high vegetation areas).

Answer 23

Carried out by humans to selectively breed for specific traits (e.g., dog breeding).

Answer 24

calculates genetic frequency during genetic equilibrium (no change in gene frequencies). If both equations hold true, the population is under Hardy-Weinberg equilibrium. p+1=1 p^2+ 2pq + q^2= 1