Ch 6 Exam 2

Question 1

Genetic drift occurs when..

Answer 1

Random or chance events determine which alleles are passed to the next generation

Question 2

What is a problem of small sample size?

Answer 2

Genetic drift

Question 3

Genetic drift has four effects on small populations:

Answer 3

• causes allele frequencies to fluctuate at random
• reduces genetic variation
• frequency of harmful alleles can increase
• differences between separate populations can increase -> genetically “drift” apart

All by chance

Question 4

Fixation

Answer 4

When an allele reaches 100% frequency or disappears completely

Question 5

Loss of ___ ___ reduces ability of population to respond to changing environmental conditions.

Answer 5

Genetic variation

Question 6

Increase of ___ ___ can reduce survival and reproduction.

Answer 6

Harmful alleles

Question 7

Genetic or population bottleneck -

Answer 7

Population may experience sharp reduction in population size

Question 8

___ may also decrease genetic diversity and spread deleterious alleles.

Answer 8

Inbreeding

Question 9

Founder effect -

Answer 9

When only a small number of individuals migrate or are otherwise isolated from parent population

Question 10

Gene flow -

Answer 10

Occurs when alleles are transferred from one population to another via migration or gamete dispersal

Question 11

Migration -

Answer 11

Movement of individuals

Question 12

Gamete dispersal -

Answer 12

Movement of gametes

Question 13

Gene flow has two effects:

Answer 13

• separate populations become more similar

- new alleles can be introduced into population from outside

Question 14

___ ___ is the only evolutionary mechanism that consistently causes adaptive evolution.

Answer 14

Natural selection

Question 15

___ are features of organisms that improve their ability to survive and reproduce in their environments.

Answer 15

Adaptations

Question 16

Micro evolution -

Answer 16

Evolution on small scale on relatively short timeframe

Question 17

Is natural selection a random process?

Answer 17

No

Question 18

By consistently favoring individuals with certain alleles, natural selection causes ___ ___.

Answer 18

Adaptive evolution

Question 19

Clines -

Answer 19

Gradual changes in a characteristic over a geographic region

Question 20

Phenotypic plasticity -

Answer 20

One genotype produces different phenotypes in different environments

Question 21

___ ___ can limit how well populations adapt to their environment.

Answer 21

Gene flow

Question 22

Gene dilution -

Answer 22

Introduce alleles that are not adapted to local conditions

Question 23

Natural selection does not result in..

Answer 23

A perfect match between organisms and their environment

Question 24

Constraints on evolution:

Answer 24

• lack of genetic variation
• evolutionary history
• ecological trade-offs

Question 25

___ does not drive mutation.

Answer 25

Need

Question 26

Example of constraint from lacking the right genetic variation

Answer 26

Initially, mosquito population lacked alleles that provided resistance to pesticides, so the pesticides were effective

Question 27

Example of constraint from evolutionary history

Answer 27

Dolphins evolved from terrestrial animals They have lungs and cannot breathe underwater

Question 28

What are the creative processes in evolution?

Answer 28

Brings about great chances by modifying traits that are already present, not by creating advantageous traits Selection is more of an "editing" process than a "creative" process

Question 29

Adaptations represent ___ in abilities of organisms to perform different and sometimes conflicting functions.

Answer 29

Compromises

Question 30

Example of constraint from ecological trade-offs

Answer 30

Trade-off between survival and reproduction in female red deer

Question 31

Adaptive evolution highlights connection between ___ and ___.

Answer 31

Ecology and evolution

Question 32

Long-term patterns of evolution are shaped by large-scale processes such as..

Answer 32

- speciation - mass extinction - adaptive radiation

Question 33

Species -

Answer 33

Groups of organisms whose members have similar characteristics and can interbreed

Question 34

Speciation -

Answer 34

Process by which one species diverges into two or more species

Question 35

Speciation most commonly occurs when a ___ prevents gene flow between two or more populations of a species.

Answer 35

Barrier

Question 36

Key step in speciation is evolution of ___ ___ that prevent breeding with parental species.

Answer 36

Reproductive barriers

Question 37

Pre-zygotic -

Answer 37

Prevents mating or fertilization

Question 38

Post-zygotic -

Answer 38

occurs when population accumulates so many genetic differences that they cannot produce viable, fertile offspring if they mate with parental species

Question 39

Examples of pre-zygotic reproductive barriers -

Answer 39

- geographic isolation - ecological isolation - behavioral isolation - temporal isolation - mechanical isolation - prevention of gamete fusion

Question 40

Examples of post-zygotic reproductive barriers -

Answer 40

- hybrid embryos do not develop properly - hybrid adults do not survive in nature - hybrid adults are sterile or have reduced fertility

Question 41

Geographic isolation -

Answer 41

Species occur in different places

Question 42

Ecological isolation -

Answer 42

Species utilize different resources in the habitat Fruit flies grown on different food sources

Question 43

Behavioral isolation -

Answer 43

Species have different mating rituals Fruit flies get separated by lava, each evolve their own mating beats -> wings, stomping feet, rubbing of legs Females will recognize beats of their species

Question 44

Temporal isolation -

Answer 44

Mating or flowering occur during different seasons or at different times of the day Coral

Question 45

Mechanical isolation -

Answer 45

Structural differences prevent mating or pollen transfer Duck penis is twirled so only fits in certain duck vaginas

Question 46

Evolutionary tree -

Answer 46

Branching diagram that represents the evolutionary history of a group

Question 47

The closest living relatives of pinnepeds are the ___ family.

Answer 47

Weasel

Question 48

Macroevolution -

Answer 48

Change over a large scale

Question 49

The first organisms were ___

Answer 49

Prokaryotes

Question 50

The oldest multicellular fossils are ___ years old.

Answer 50

2.1 billion Red algae

Question 51

Animals first appeared how long ago?

Answer 51

600 million years

Question 52

A variety of fossils illustrate ___ ___ in the origin of tetrapods from fishes.

Answer 52

Transitional steps

Question 53

Fossil record documents ___ mass extinction events.

Answer 53

Five

Question 54

Increases in diversity over a relatively short time period are called __ __.

Answer 54

Adaptive radiations Finches of the Galápagos Islands

Question 55

Soft-bodied animals predominant in the ___.

Answer 55

Precambrian

Question 56

Hard-bodied animals appeared during the ___ ___.

Answer 56

Cambrian explosion

Question 57

"Arms race" between predators and prey

Answer 57

- early predators equipped with adaptations for capturing large prey provided powerful selection pressure that favored heavily armored prey species - that armor, in turn, promoted further increases in the effectiveness of the predators

Question 58

Coevolution -

Answer 58

reciprocal evolutionary change in interacting species

Question 59

Rise of a new species in one group can lead to increased diversity of other groups Example :

Answer 59

When apples were introduced into North America Some apple maggot fly populations switched from eating Hawthorn to apple Probably forming a new species

Question 60

___ ___ leaves spatially isolated patches that can affect evolutionary processes.

Answer 60

Habitat fragmentation

Question 61

Human actions that affect environment can alter the three main mechanisms of evolution:

Answer 61

Natural selection Genetic drift Gene flow

Question 62

Speciation reversal -

Answer 62

Fusing two previously isolated species, and thus reducing biodiversity