Evolution

Question 1

Define Species

Answer 1

A species consists of members of interbreeding groups or populations that are reproductively isolated from other groups and evolve independently.

Question 2

What are Reproductive Isolating Mechanisms?

Answer 2

Any behavioural, structural, or biochemical trait that prevents individuals of different species from reproducing successfully together.

Question 3

What are the three reproductive isolating mechanisms?

Answer 3

Habitat Isolation, Temporal Isolation, Behavioural Isolation

Question 4

What is Habitat Isolation?

Answer 4

Ground hogs live in different
habitats. Woodchucks live in fields
at lower elevations while others live
in alpine meadows at higher
elevation in the same region.

Question 5

What is Temporal Isolation?

Answer 5

Similar plant species bloom at
different times of the day or in
different seasons.

Question 6

What is Behavioural Isolation?

Answer 6

Each species may use different
signals for attracting mates. The
male jumping spider jumps to attract
the female. Other similar female
spiders do not respond to the
jumping.

Question 7

What are two prezygotic mechanisms that restrict fertilization?

Answer 7

Mechanical Isolation, Gametic Isolation.

Question 8

Define Mechanical Isolation and give an example

Answer 8

The male and female reproductive parts are not anatomically compatible. Ex- Pollen sacs in a lady’s slipper orchid become attached to an insect, but they are not removed by any other.

Question 9

Define Gametic Isolation and give an example

Answer 9

The gametes (male and female) will not fuse and create a zygote. Ex- Giant clams release sperm and eggs
into open water, gametes recognize one another by molecular markers.

Question 10

What are Postzygotic Mechanisms?

Answer 10

These mechanisms prevent the hybrid organism from developing into a healthy, fertile adult.

Question 11

What are the three postzygotic isolating mechanisms?

Answer 11

Hybrid Breakdown, Hybrid Inviability, Hybrid Sterility

Question 12

What is the result of Hybrid Breakdown?

Answer 12

First-generation hybrids are viable and
fertile. Their offspring tend to be weak,
or sterile.

Question 13

What is the result of Hybrid Inviability?

Answer 13

Hybrid offspring do not live very long.

Question 14

What is the result of Hybrid Sterility?

Answer 14

Offspring of genetically dissimilar parents are likely to be strong but sterile ( mule – donkey and horse )‏.

Question 15

What are the Modes of Speciation?

Answer 15

Allopatric Speciation, Sympatric Speciation

Question 16

What is Allopatric Speciation?

Answer 16

The creation of new species due to a physical barrier
( river, ocean, canyon, highways, dams, lava flows, ocean levels rising turning peninsulas into islands). The populations begin to diverge (due to genetic drift/or gene flow).

Question 17

What is Sympatric Speciation?

Answer 17

Populations that split into two separate gene pools and remain in the same geographic area. Most common in plants. This can occur due to chromosomal changes (in plants) and non-random mating (in animals) that alter gene flow.

Question 18

What are factors that affect the Change of Allele frequency?

Answer 18

Mutations, Gene Flow (migration), Non-random mating, Genetic Drift, Natural Selection

Question 19

What are Mutations?

Answer 19

Random changes in the sequence of DNA through un-repaired changes, chromosome breakage and rejoining.

Question 20

What is Gene Flow (migration)?

Answer 20

The movement of alleles from one population to another through the movement of individuals or gametes (sex cells).

Question 21

What is Non-random Mating?

Answer 21

This occurs when mates are selected over others.

Question 22

What is Genetic Drift?

Answer 22

Changes the allele frequency as a result of chance; such changes are much more pronounced in small populations.

Question 23

What are some evidence of evolution?

Answer 23

Fossil Record, Biogeography, Anatomy, Embryology, DNA

Question 24

What are fossils and what do they do?

Answer 24

Fossils are any preserved remains or traces of an organism or it’s activity ( usually from hardened body parts such as bone )‏ They are evidence for the History of Life. Fossils discovered in sedimentary rock have provided scientists with a glimpse into the past.

Question 25

Fossil Record

Answer 25

• fossils of young rock are more similar to animals alive today.
• fossils appear in chronological order in rock layers. Older fossils are found lower in the layers.
• not all organisms are found in each layer at the same time. This tells us that they did not exist at the same time in history.

Question 26

What are transitional fossils?

Answer 26

Transitional fossils represent links between one organism to another.

Question 27

What are vestigial features?

Answer 27

Nonfunctioning structures that are homologous to fully functioning structures in closely related species. Some whales still have hind limbs that are reduced in size.

Question 28

Evidence from Biogeography

Answer 28

Geographically close environments are more likely to be populated by related species. (Ex: Cacti only found in North, South and Central America. They are not found in other deserts of the world.) Animals found on islands closely resemble animals found on the closest continent. (Ex: Finches on Galopagos resemble birds from South America.) Fossils of the same species can be found on the coasts of neighbouring continents. Closely related species are almost never found in exactly the same location or habitat.

Question 29

Evidence from Anatomy

Answer 29

When organisms have Homologous structures, or Analogous Structures

Question 30

What are Homologous structures?

Answer 30

Structures that have the same physical parts but may have different functions. Example: The fingers of a human and the fingers of a dolphin

Question 31

What are Analogous Structures?

Answer 31

Structures that perform common tasks but do not share an evolutionary ancestor. Ex: dorsal fin of both shark and dolphin (same function, different ancestors)

Question 32

Evidence from Embryology

Answer 32

Similarities between organisms in the embryo stages point to a common ancestor.

Question 33

Evidence from DNA

Answer 33

Examining the sequence of DNA in different animals can lead us to determine how closely related they are. (Dogs and bears closely related and whales and dolphins closely related to cows, moose and deer.)

Question 34

What is a Premineralized fossil?

Answer 34

A fossil that forms when minerals precipitate from a solution in the space occupied by the organisms remains.

Question 35

How was the age of the earth determined?

Answer 35

Through radioactive decay

Question 36

On Darwin’s voyage in December 1831 what did he discover?

Answer 36

He discovered fossil evidence of the giant Glyptodon ( related to present Armadillo ) and Megatherium ( the giant sloth ). When Darwin visited the Galapagos Islands he noticed that many of the species closely resembled the species in South America but they had very unique differences.

Question 37

What is Mimicry?

Answer 37

A type of structural adaption. Harmless species physically resemble a harmful species.

Question 38

How is variation created in a species?

Answer 38

By the different combinations of genetic information (alleles) that offspring inherit from their parents.

Question 39

What are selective advantages?

Answer 39

Genetic advantages that improve an organism’s chances of survival in terms of survival and reproduction

Question 40

What is Natural Selection?

Answer 40

The characteristics of a population of organisms change over time, occurs because individuals survive and pass their genetic information on to their offspring.

Question 41

What is selective pressure?

Answer 41

environmental conditions that select for certain traits of individuals