SBI3U Evolution Test #1

Question 1

Define fitness

Answer 1

The sustainability of an organism to its environmental conditions.

Question 2

Define selective pressure

Answer 2

Environmental condition(s) that select for certain characteristics of individuals and select against others.

Question 3

Define natural selection

Answer 3

The process whereby the characteristics of a population of organisms change because individuals with certain heritable traits survive specific local environmental conditions.

Question 4

Define Evolution

Answer 4

The relative change in the characteristics of populations that occurs over successive generations.

Question 5

What are some modern examples of evolution?

Answer 5

Bacteria, mosquitoes (those resistant to DDT grow and thrive in the population - pesticides no longer work), coral reefs (adapting to heat stress/global warming over time), super weeds (over-use of pesticides), and varolla mites on bees (have developed resistance to chemical pesticides that were used to control them).

Question 6

What are the 3 requirements for evolution to happen?

Answer 6

1. Time - lots of time (or at least many, many generations). 2. Genetic variation - a variety of alleles in the genetic make up of the population 3. Pressure from the environment - something that causes some to survive and some to not.

Question 7

What is micro-evolution?

Answer 7

This is the evolutionary change within a species.

Question 8

What is macro-evolution?

Answer 8

These are changes that take place over long periods of time, changes in kinds of plants and animals on earth.

Question 9

What is genetic variation?

Answer 9

Genetic variation is a variety of alleles in the genetic make up of the population.

Question 10

Define homologous structures.

Answer 10

Body parts in different species that have the same evolutionarly origin but have different structures and functions.

Question 11

Define analogous structures

Answer 11

Analogous structures are body parts in different species that have a similar function, but evolved differently.

Question 12

Define convergent evolution

Answer 12

This is the evolutionary process in which similar traits arise in 2 or more species because each species has independently adapted to similar environmental conditions, not because they share a common ancestor. The organisms are unrelated, but occupy the same niche in very different geographical regions and have similar structures/functions.

Question 13

Define divergent evolution

Answer 13

This is the process by which species that were once similar to an ancestral species become increasingly different. They become different through adapting to different habitats and food sources and eventually become their own new species.

Question 14

Define vestigial structures

Answer 14

These are body parts that were functional in a species’ ancestors, yet appear to have no current function, e.g. pelvic bones in baleen whales.

Question 15

Define embryology

Answer 15

This is the study of embryos.

Question 16

Define co-evolution

Answer 16

This is the evolutionary process in which two species of an organism are tightly linked and evolve together, each population responding to the changes in the other population, e.g. plants and their pollinators.

Question 17

Define speciation

Answer 17

This is the formation of a new species.

Question 18

Define prezygotic barrier

Answer 18

A prezygotic barrier is a factor that prevents mating between two species, or that prevents fertilization if individuals from different species do attempt to mate. Pre-zygotic barriers include behavioural isolation, temporal isolation, mechanical isolation, and gametic isolation.

Question 19

Define sympatric speciation

Answer 19

This is the differentiation of populations within the same geographic area into species.

Question 20

Define post-zygotic barriers

Answer 20

A factor that prevents hybrid zygotes from developing into normal fertile individuals. Includes hybrid inviability, hybrid sterility, and hybrid breakdown.

Question 21

Define allopatric speciation

Answer 21

This is the formation of a new species that occurs when a population is split into two or more isolated groups by a geographical barrier.

Question 22

Define gene flow

Answer 22

This is the movement of new genes into a gene pool. This movement can reduce differences between populations that were caused by isolation and genetic drift.

Question 23

Define the bottleneck effect

Answer 23

This is the effect that occurs when a population is greatly reduced by events such as natural disaster or overhunting, resulting in certain alleles being overrepresented and other alleles being underrepresented or absent in the population, due to chance. The effect leads to a genetic drift and decreased genetic variation in the population.

Question 24

Define the founder effect

Answer 24

This is the cause of genetic drift due to small group of individuals colonizing a new area; the small group probably will not contain all the genes represented in the parent population.

Question 25

Define non-random mating

Answer 25

Any situation in which individuals do not choose mates on a random basis, such as mating based on proximity, relatedness, or similarity of phenotype.

Question 26

Define assortive mating

Answer 26

A type of non-random mating in which individuals choose partners that have similar phenotypes.

Question 27

Define stabilizing selection

Answer 27

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

Question 28

Define directional selection

Answer 28

This is 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 29

Define disruptive selection

Answer 29

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.

Question 30

Define sexual selection

Answer 30

Selection for mating based, in general, on competition between males and choices made by females.

Question 31

Name the 5 types of pre-mating isolation and briefly explain the meaning of each

Answer 31

• Geographic (individuals are geographically separated from each other)
• Ecological (individuals have different habitats from each other, e.g. in a tree vs. on the ground)
• Temporal (the species are not compatible, e.g. have different mating seasons)
• Behavioural (they have different mating rituals from each other)
• Mechanical incompatibiliy (sexual reproduction organs do not “fit” together

Question 32

Name and briefly explain the 3 types of post-mating/post-zygotic isolation.

Answer 32

• gamete incompatibility (the sperm cannot fertilize the egg)
• hybrid inviable (egg can be fertilized, but no offspring can be produced)
• hybrid infertile (offspring can be produced, but is infertile)

Question 33

Define species

Answer 33

A group of individuals that actually or potentially interbreed in nature (the biggest gene pool possible under natural conditions).

Question 34

Name what evolutionary process causes new species to form

Answer 34

Two populations reach the point where they are no longer able to mate, resulting in reproductive isolation.

Question 35

What must be true in order for species to remain distinct?

Question 36

What is the cause of speciation?

Answer 36

Gene flow reduction

Question 37

Define sympatric speciation

Answer 37

Two populations live in the same area but are reproductively isolated (usually happens) in plants, occasionally happens with animals (because of specialization of range/food supply)

Question 38

Define allopatric speciation

Answer 38

Two populations are physically separated, then the species become diverse due to natural selection (i.e. salamanders)

Question 39

Define instantaneous speciation

Answer 39

Occurs in one generation due to major changes in the chromosome numbers (polyploids, chromosome fusion or fission) - most happen in plants

Question 40

What is the only source of new genetic material in a population?

Answer 40

Mutations

Question 41

What quality of mutation increases reproductive success?

Answer 41

Only beneficial mutations

Question 42

Define genetic drift

Answer 42

This is the change of frequencies of particular alleles in a small population, caused by chance alone. Changes can be drastic.

Question 43

Name 4 mechanisms for genetic variation

Answer 43

Gene flow, mutations, natural selection, genetic drift (bottleneck effect and founder effect).

Question 44

Define sexual dimorphism

Answer 44

This is the difference between the phenotypes of males and females of the same species.

Question 45

Define structural adaptations

Answer 45

Physical features like anatomy, colouring, and appearance that allow for an organism to be better suited and more fit for its environment.

Question 46

Define physiological adaptations

Answer 46

Alterations in functions that allow for increased success in the environment they live in, e.g. humans produce hormones to help them react in stressful situations - increasing heart rate, respiratory rate and improve vision.

Question 47

Define behavioural adaptations

Answer 47

• actions taken by the organisms that allow for greater success
• actions are taken all for different reasons
• migration courtship, foraging, defense
• movement in large groups

Question 48

Define anatomical clues

Answer 48

Comparison between anatomical features in related or unrelated species are explained as homologous or analogous features.

Question 49

State two evidences in DNA for evolution.

Answer 49

• the relationship between closely related species is clearly evident when DNA comes to light
• the more similar the DNA sequence between species the more closely related they are in evolutionary history