Evolution

Question 1

population genetics

Answer 1

the frequency at which
different alleles occur in a population affects
the overall characteristics of the population

Question 2

allele frequencies

Answer 2

how common
the alleles for a gene are in a population

Question 3

hardy-weinberg principle

Answer 3

hardy-weinberg principle states that allele
and genotype frequencies of populations do
not change when assumptions are satisfied.
- no mutation
- random mating
- no trait advantages
- large population
- no migration

Question 4

hardy-weinberg equation

Answer 4

equations are limited
to a specific situation:
- sexual population
- autosomal gene
- clear generations
- two alleles for gene
- diploid organism

Question 5

evolution

Answer 5

evolution is formally defined as a change in
allele frequencies of a population over time
- processes that drive evolution correspond to
assumptions of the Hardy-Weinberg model.
- no mutation -> mutation
- random mating -> nonrandom mating
- no trait advantages -> selection
- large population -> genetic drift
- no migration -> gene flow

Question 6

mutation

Answer 6

mutation is the original source of all genetic
variation and essential for evolution
- produce new alleles but generally have a small impact on allele frequencies

Question 7

gene flow

Answer 7

gene flow is the movement of alleles into or
out of a population, which can change allele
frequencies if the movement is large enough
and could bring new alleles to a population
- can increase or decrease alleles

Question 8

genetic drift

Answer 8

genetic drift includes any changes in allele
frequencies of a population due to random
events, which could be just about anything
from gamete sampling to natural disasters
- small numbers are more at risk
- larger the sample size, the smaller the chance of gamete sampling
- can only decrease alleles

Question 9

founder effect

Answer 9

changes in allele
frequencies when new populations arise
- new population is likely to have different allele frequencies than the source population, by chance

Question 10

bottleneck effect

Answer 10

changes in allele
frequencies due to severe population losses
- high mortality strikes individuals at random
- bottlenecked populations likely to have different allele frequencies than original population, by chance

Question 11

fitness

Answer 11

the ability of an individual to have
fertile offspring relative to other individuals

Question 12

selection

Answer 12

selection occurs when individuals that have
certain heritable traits produce more fertile
offspring than individuals without the traits.
- natural selection
- artificial selection
- sexual selection
- favors individuals

Question 13

artificial selection

Answer 13

the process of modifying living things (as plants and animals) by selective breeding controlled by human beings

Question 14

gamete sampling

Answer 14

when genes are passed on to the next generation in frequencies unlike those of the parental population

Question 15

natural selection

Answer 15

Trait variation exists in populations, and
at least some of the variation is heritable.
- Resources are limited in the environment,
which will inevitably lead to competition.
- Individuals with traits that are beneficial
in a specific environment are more likely
to survive and reproduce (higher fitness)

Question 16

directional selection

Answer 16

a pattern in which one
extreme trait provides
greater fitness

Question 17

stabilizing selection

Answer 17

a pattern in which a trait
that is intermediate will
provide greater fitness

Question 18

disruptive selection

Answer 18

a pattern in which the
extreme traits provide
greater fitness

Question 19

sexual selection

Answer 19

a form of selection that
favors individuals with traits that increase
the ability to obtain mates (and sometimes
significantly reduce the ability to survive)

Question 20

asymmetry of sex

Answer 20

the idea that females
will invest more energy in offspring (eggs
or parenting) than males in many species.
- Females produce limited offspring and
should select the most attractive males.
- Males produce unlimited offspring and
should mate with any available female.
- Result will be competition between males.

Question 21

non random mating

Answer 21

In addition to sexual selection, other forms
of nonrandom mating can occur that affect
the genetic characteristics of a population
- inbreeding is an example, and it only causes genotype frequencies not allele frequencies

Question 22

inbreeding depression

Answer 22

loss of viability or function resulting from excess inbreeding

Question 23

morphological species concept

Answer 23

determining species based on observable traits is called the morphological species concept, and although subjective and unreliable, this method is used in certain situations

Question 24

biological species concept

Answer 24

species is a group of organisms that
interbreed and produce fertile offspring under natural conditions
- two populations that cannot or
will not interbreed are said to be reproductively isolated from each other, and the populations are
considered separate species by the biological species concept
- can’t be applied to asexual reproduction

Question 25

reproductive barriers

Answer 25

mechanisms that result in reproductive isolation

Question 26

prezygotic

Answer 26

barriers that prevent mating or fertilization from occurring
- geographic
- temporal
- ecological
- behavioral
- mechanical
- gametic

Question 27

postzygotic

Answer 27

barriers that act after fertilization
- hybrid inviability
- hybird sterility

Question 28

geographic isolation

Answer 28

occurs when organisms from different populations are separated from
each other by distance or a physical barrier. For example, finches on the Galapagos Islands
are separated by too much water to fly over. Populations of insects could be separated by a
large river, while populations of fish could be isolated from each other in different lakes

Question 29

temporal isolation

Answer 29

occurs when different populations are unable to interbreed because they
reproduce at different times. For example, some species of cicada emerge to mate every 17
years, while other populations emerge every 13 years. Their reproductive seasons will only
overlap every 221 years! Some populations of plants reproduce in the spring, while others
reproduce in the fall. Certain fruit flies mate in the morning, and others only mate at night

Question 30

ecological isolation

Answer 30

occurs when organisms are isolated due to the environments in which
they prefer to live. For example, lions prefer to live in open grasslands, while tigers prefer
wooded areas. Some frogs prefer fast streams, and others only live in stagnant ponds

Question 31

behavioral isolation

Answer 31

happens when the presence or absence of a specific behavior prevents
reproduction. For example, male fireflies use light patterns to attract females, and different
firefly species display different patterns. Many bird species recognize certain songs or use
elaborate mating rituals to attract mates that are not recognized by other species

Question 32

mechanical isolation

Answer 32

occurs when different populations are physically unable to interbreed
with each other. Incompatible reproductive organs are the most common cause for animals,
while in plants, some populations could use a different pollinator to transfer pollen

Question 33

hybrid inviability

Answer 33

occurs when different populations can mate with successful fertilization,
but the resulting embryos are unable to develop or are unhealthy and do not survive

Question 34

hybrid sterility

Answer 34

occurs when interbreeding between different populations produces healthy
embryos, but the resulting offspring are unable to reproduce. For example, horses have 64
chromosomes, donkeys have 62 chromosomes, and their offspring (mules or hinnies) have
63 chromosomes that cannot be divided evenly during meiosis, which results in sterility

Question 35

ecological

Answer 35

group of organisms adapted to certain environmental resources

Question 36

phylogenetic

Answer 36

group of organisms that share a history due to descent from a common ancestor

Question 37

speciation

Answer 37

two or more distinct species forming from a single ancestral species during an extended period
of reproductive isolation and divergence

Question 38

phylogenetic trees

Answer 38

hypothesized evolutionary
relationships between species are displayed in diagrams

Question 39

gametic isolation

Answer 39

happens when gametes from different populations are incompatible. For
example, many marine organisms release their gametes into the water for fertilization, and
the eggs and sperm recognize each other through surface proteins. Gamete proteins from a
species will not recognize those from another species, which causes incompatibility

Question 40

phylogeny

Answer 40

a long evolutionary history

Question 41

taxa

Answer 41

the inferred evolutionary relationshops between select groups of organisms

Question 42

systematics

Answer 42

investigating evolutionary relationships and classifying groups of organisms
based on those relationship

Question 43

nodes

Answer 43

branching points on phylogenetic trees

Question 44

branches

Answer 44

lines on a phylogenetic tree that represent evolving lineages

Question 45

synapomorphies

Answer 45

traits that are present in lineages that descend from a node or branch
- defining traits of monophyletic groups

Question 46

monophyletic groups

Answer 46

consist of a common ancestor and all of the lineages that descend from that ancestor

Question 47

non-monophyletic groups

Answer 47

groups that do not include all of the lineages descended from a common ancestor

Question 48

relatedness

Answer 48

the most important information found on any phylogenetic tree
- others are genetic divergence & time
- evolutionary
relatedness of various species is similar to relatedness in human families and is based exclusively
on most recent common ancestry

Question 49

parsimony

Answer 49

the concept that the simplest explanation is most likely to be true
- this means evolutionary relationships are determined by producing a huge
number of possible phylogenetic trees based on data and choosing the one with the least number
of evolutionary changes

Question 50

convergent evolution

Answer 50

different organisms independently evolve similar traits that have the same function rather than inherit the traits from a recent common ancestor
- organisms might display many similar traits but do not share a recent common ancestor
- analogous

Question 51

analogous

Answer 51

corresponding in function, but not evolved from corresponding organs, such as the wings of a bee or a hummingbird