EVOLUTION

Question 1

What is Darwin’s theory of natural selection?

Answer 1

Charles Darwin (1809 – 1882)
* HMS beagle
* developed the theory of evolution by natural selection
* Did not use term of evolution
* Natural Selection: gradual change in a population’s traits over time as individuals with favorable traits are more likely to survive and pass on their genes to the next generation.

Question 2

Homologous structures

Answer 2

similar in structure, different in purpose.
Ex. The bones in a horse’s leg are larger and heavier than the bones in a bat’s wing.

Question 3

Analogous structures

Answer 3

different in structure, similar in purpose.
Ex. Birds and bats have bones to support their wings, whereas butterflies have a chitin.

Question 4

Vestigial structures

Answer 4

leftovers from an organism’s ancestors that are now reduced or non-functional.

Question 5

Mimicry

Answer 5

harmless species resemble (mimic) a harmful species so predators will avoid them
Ex.Viceroys mimic monarchs because monarch are not palatable

Question 6

Camouflage

Answer 6

adaptations that prevent detection and/or recognition –

Question 7

Genetic Fitness

Answer 7

the contribution an individual makes to the gene pool of the next generation by producing
offspring that can survive long enough to reproduce

Question 8

Pre-zygotic Isolating Mechanisms

Answer 8

a barrier that either impedes mating between species or prevents fertilization of the eggs

Question 9

Behavioural Isolating Mechanisms

Answer 9

behaviours that prevent other spp. from recognizing or selecting them for mating.
Ex: the songs of birds, the courtship of elks, and chemical signals (pheromones) of insects.

Question 10

Temporal Isolating Mechanisms

Answer 10

• Two species in the same habitat, different mating seasons, reproductive isolation due to timing mismatches.
• Ex. two species might live in the same habitat but mate at different times of the day/in different seasons/different years.

Question 11

Ecological Isolating Mechanisms

Answer 11

• two species that live in same general area but in different habitats
• due to different habitats they do not encounter one another to reproduce
• ex: common garter snake is often found near water but northwest garter snake prefers open meadows

Question 12

Mechanical Isolating Mechanisms

Answer 12

• structural differences in reproductive organs that prevent fertilization.
• Ex. genital anatomy allows organisms to mate due to their “lock and key” type system of the females and males.

Question 13

Gametic Isolating Mechanisms

Answer 13

• the sperm and eggs of different species can’t mix or connect properly, stopping fertilization from happening
• gametes are incompatible in some way
• ex: sperm from one species is unable to survive in female reproductive tract
  *

Question 14

Directional

Answer 14

natural selection that favours the phenotypes at one extreme over another, resulting in the distribution curve of phenotypes shifting in the direction of that extreme.

Question 15

Stabilizing

Answer 15

natural selection that favours intermediate phenotypes and acts against extreme variants.

Question 16

Disruptive

Answer 16

natural selection that favours the extremes of a range of phenotypes rather than intermediate phenotypes; this type of selection can result in the elimination of intermediate phenotypes.