Ch 24 The Origin of Species

Question 1

What is a species?

Answer 1

is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with other such groups; they do not breed successfully with other populations

Question 2

What is speciation?

Answer 2

Speciation is the origin of new species, is at the focal point of evolutionary theory

-evolutionary theory must explain how new species originate and how populations evolve.

Question 3

What is microevolution?

Answer 3

It consists of changes in allele frequency in a population over time

evolution on a smll scale

Question 4

What is macroevolution?

Answer 4

refers to broad patterns of evolutionary chenge above the species level

evolution on a large scale

Question 5

What is Biological species concept?

Answer 5

Emphasizes reproductive isolation

-It emphasizes that they just get it on with eachother and dont stretch out into other groups.

Question 6

How do biologists group organisms?

Answer 6

By comparing morphology, physiology, biochemistry and DNA sequeces when grouping organisms.

Question 7

Why is gene flow important if you want to keep the same species?

Answer 7

When gene flow stops then you dont see maintnce of a species

-gene flow between populations holds the phenotype of a population together.

Question 8

How do we get a new species?

Answer 8

Through isolation, if you dont get gene flow because of a barrier eventually you will get some kind of speciation event.

Question 9

What is reproductive isolation?

Answer 9

The existance of biological factors (barriers) that impede two species from producing viable, fertile offspring.

-Reproductive isolation can be classified by whether factors act before or after fertilization.

Question 10

What is the difference between prezygotic and postzygotic barriers?

Answer 10

Prezygotic barriers block fertilization from occurring

Postzygotic barriers may contribute to reproductive isolation after the hybrid zygote is formed.

Question 11

What is a habitat isolation? give an example

Answer 11

Two species that occupy different habitats within the same area

ex: snakes that live on land dont mate with snakes thta live in water because they dont coincide

Question 12

What is Temporal isolation? give an example

Answer 12

Species that tend to breed during different times of the day, seasons, etc

some skunks mate during different seasons

Question 13

What is Behavioral isolation? give an example

Answer 13

Courtship rituals that attract mates and other behaviors unique to a species help enable mate recognition

Ex: a blue footed boobie does the hey i got gum under my feet and the mate likes the behavioral courtship but if it tried it on an albatross they wouldnt like it

Question 14

What is mechanical isolation? give an example

Answer 14

Mating is attempted but the genitals dont line up.

Ex: the reproductive organs of two snails are on opposite sides so they cant line up

Question 15

Why cant an alligator mate with a dog?

Answer 15

Because the alligators genitals are inside a coeca so the dog couldnt find the part and couldnt mate

Question 16

What is gametic isolation? give an example

Answer 16

Where a sperm of one species may not be able to fertilize the egg of another species

ex: a blue sea urchin sperm does not bind well with the eggs of red sea urchins

Question 17

What is reduced hybrid viability? give an example

Answer 17

The genes of different parent species may interact in ways that impair the hybrids development or suvival in its environment

Ex: a hybrid may not develop completely or if it does, doesnt survive very long

Question 18

What is reduced Hybrid fertility? give an example

Answer 18

Even if hybrids are born they may be steril if the chromosomes of the two parent species differ in number or structure, meiosis in the hybrids fail to produce normal hybrids

Ex: a donkey and a horse produce a sterile mule

Question 19

What is a hybrid breakdown? give an example

Answer 19

some first generation hybrids are viable and fertile but somewhere down the line it becomes feeble or sterile

Question 20

Can gene flow occur between two distinct species?

Answer 20

Yes there are grolar bears which are hybrids of polar bears and grizzly bears.

Question 21

What is the morphological species concept?

Answer 21

it defines a species by how they look

-it applies to sexual and asexual species but relies on subjective criteria

The problem is that you dont know how much is enough to consider it a different species.

Question 22

What is the ecological species concept?

Answer 22

views a species in terms of its ecological niche

Ex: tree squirrels and groud squirrels wont coincide because of their different ecological niches

-it applies to sexual and asexual species ad emphasizes the role of disruptive selection.

Question 23

What is a phylogenetic species concept?

Answer 23

defines a species as the smallest group of individuals on a phylogenetic tree

Question 24

Can speciation occur with or without geographic isolation?

Answer 24

it can occur in both with allopatric and sympatric speciation.

Question 25

What is allopatric speciation?

Answer 25

It means other homeland, so gene flow is interrupted when a population is divided into geographically isolated subpopulations. ex:the grand canyon not allowing two species of squirrels to interbreed because of a geographic barrier.

Question 26

Whats is sympatric speciation?

Answer 26

Means together homeland, speciation occurs in populations that live in the same geographic area. ex: two species of fish living in the same lake, some prefer the open waters and some prefer to live in the plant area and for some reason they dont mate with eachother

Question 27

What is polyploidy? Is this more common in plants or animals?

Answer 27

The presence of extra sets of chromosomes due to accidents during cell division -polyploidy is more common in plants than in animals Ex: down syndrome on chromosome 21 where they have one extra chromosome

Question 28

What is an autopolyploid?

Answer 28

an individual with more than two chromosome sets, derived from one species ex:

Question 29

What is an allopolyploid?

Answer 29

a species with multiple sets of chromosomes derived from different species? ex: a mustard seed can be used to make cabbage and broccoli etc, so you get species with multiple sets of chromosomes derived from different species

Question 30

What is sexual selection?

Answer 30

sexual selection can drive sympatric speciation -sexual selection for mates of different colors has likely contributed to the speciation in cichlid fish in lake victoria

Question 31

What is a hybrid zone?

Answer 31

a hybrid zone is a region in which members of different species mate and produce hybrids -hybrids are a result of mating between species with incomplete reproductive barriers. a hybrid zone can occur in a single band where adjacent species meet

Question 32

What are the three possible outcomes when closely related species meet in a hybrid zone?

Answer 32

- reinforcent - fusion - stability

Question 33

What is reinforcement? give example

Answer 33

Strengthening of reproductive barriers occurs when hybrids are less fit than the parent species -overtime the rate of hybridization decreases

Question 34

Should reproductive barriers in reinforcement be stronger for sympatric or allopatric species? give example

Answer 34

Reinforcement should be stronger for sympatric than allopatric in order to have reinforcement you need to have more reproductive baarriers more so in sympatic than in allopatric, usually because of behavioral of physiological ex: in populations of flycatchers, males are more similar in allopatric populations thn sympatric populations

Question 35

What is fusion?

Answer 35

weaskening of reproductive barriers, if the hybrids are as fit as parents, there can be substantial gene flow between species If gene flow is great enough the parent species can fuse into a single species everyone is mating with everyone so you end up with one species at the end

Question 36

What is stability?

Answer 36

continued formation of hybrid individuals -extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone Equal amount of hybids and parent species and it just continues to happen

Question 37

What is habitat differentiation? give an example

Answer 37

sympatric speciation can also result from the appearance of new ecological niches Ex: the north american maggot fly can live on native hawthorn trees as well s more recently introduced apple trees so they start hanging out separatelt and create a separate species.

Question 38

Why is interbreeding prevented?

Answer 38

because of speciation, whether it is mechanical isolation, behavioral isolation etc

Question 39

What is punctuated equilibria?

Answer 39

it is described as periods of apparent stasis punctuated by sudden change

Question 40

How many genes change when a new species forms?

Answer 40

Depending on the change of only a single allele or many alleles -ex: in japanese snails the direction of shell spiralaffects mating and is controlled by a single gene, however if we wanted to change human it would take a lot more change to occur