Lecture 4 origin of species

Question 1

What two phenomenas does the concept of a species must account for?

Answer 1

The distinctiveness of species that occur together at a single locality and the connection that exists among different populations belonging to the same species.

Question 2

What is the morphological species concept?

Answer 2

1. All individuals of a species share measurable anatomical traits that distinguish them from individuals of other species.

Question 3

When can relying exclusively on morphology present problems?

Answer 3

when there is much variability within a single species or when two species are nearly identical in appearance.

Question 4

What is the biological species concept?

Answer 4

species are composed of populations whose members mater with each other and produce fertile offspring.

Question 5

What is reproductive isolation?

Answer 5

they do not mate with each other or do not produce fertile offspring.

Question 6

What are prezygotic isolating mechanisms?

Answer 6

mechanisms that prevent formation of a zygote

Question 7

What are postzygotic isolating mechanisms?

Answer 7

mechanisms that prevent proper functioning of zygote after they form

Question 8

What does the biological species concept focus on?

Answer 8

the ability to exchange genes

Question 9

What are some prezygotic isolating mechanisms?

Answer 9

ecological isolation, behavioral isolation, temporal isolation, mechanical isolation, and prevention of gamete fusion

Question 10

What are some postzygotic isolating mechanisms?

Answer 10

hybrid inviability or infertility

Question 11

What is ecological isolation (PIS)

Answer 11

species occur in the same area, but occupy different habitats and rarely encounter each other

Question 12

What is behavioral isolation (PIS)

Answer 12

species differ in their mating rituals

Question 13

what is temporal isolation? (PIS)

Answer 13

species reproduce in different seasons ar at different times of the day

Question 14

what is mechanical isolation?

Answer 14

Structural differences between species prevent mating

Question 15

what is prevention of gamete fusion (PIS)?

Answer 15

gametes of one species function poorly with the gametes of another species or within the reproductive tract of another species.

Question 16

What is hybrid or infertility (PIS)?

Answer 16

hybrid embryos do not develop properly, or do not survive in nature, or are sterile

Question 17

With behavioral isolation what are some differences that keep sympatric species from mating with each other?

Answer 17

visual signals, sound protection, chemical signals (pheromones), and electrical signals (electroreception)

Question 18

With hybrids what are some defects?

Answer 18

They may have abnormal sex organs, or fail to form gametes and chromosomes may not be able to pair properly in meiosis

Question 19

What can lead to speciation?

Answer 19

Adaptation

Question 20

How does adaption lead to speciation?

Answer 20

as populations of species adapt to different circumstances, they likely accumulate many differences that may lead to reproductive isolation

Question 21

What are some criticisms of the biological species concept?

Answer 21

1. reproductive isolation may not be the only force maintain species integrity
2. interspecific hybridization
3. difficult to apply the concept to populations that geographically separated
4. many organisms are asexual
5. many species that do not hybridize in the wild do in captivity
6. it is possible that different processes maintain species identity in different organisms

Question 22

What are some benefits of the ecological species concept?

Answer 22

1.Each species adapted to its environment
2.distinctions among species are maintained by natural selection
3.stabilizing selection maintains the species’ adaptions
4. hybrids are quickly eliminated from gene pool

Question 23

What is the phylogenetic species concept?

Answer 23

A species is defined as a cluster of populations that share a recent evolutionary history as shown on the evolutionary tree

Question 24

What is to used to reconstruct an organism’s evolutionary tree?

Answer 24

morphological and genetic sequence data

Question 25

Why can't the phylogenetic species concept not be applied to all forms of life?

Answer 25

Because evolutionary histories have been described for relatively few groups

Question 26

What is the two step process of speciation?

Answer 26

1. initially identical populations must diverge 2. reproductive isolation must evolve to maintain these differences

Question 27

What effect of gene flow erases differences?

Answer 27

Homogenizing effect

Question 28

Where is speciation more likely to occur?

Answer 28

in geographically isolated populations

Question 29

What is allopatric speciation?

Answer 29

It takes place when a physical barrier subdivides a large population, or when a small population becomes separated from a species' main geographical distribution

Question 30

What are the two stages of allopatric speciation?

Answer 30

1. two populations become geographically separated (preventing gene flow) 2. accumulated genetic differences isolate them reproductively

Question 31

What is sympatric speciation?

Answer 31

one species splits into two at a single locality, without the new species ever having been geographically separated

Question 32

how does sympatric speciation occur as a result of polyploidy?

Answer 32

Because individuals have more than two sets of chromosomes

Question 32

What is autoploidy?

Answer 32

all chromosomes arise from a single species and an error occurs in cell division which produces tetraploids which cannnot produce fertile offspring

Question 32

How can sympatric speciation occur by disruptive selection?

Answer 32

It can cause a population to contain individuals exhibiting two different phenotypes

Question 33

what is allopolyploidy?

Answer 33

two species hybridize, resulting in offspring having one copy of chromosomes of each species,

Question 34

What is polymorphism?

Answer 34

a discontinuous genetic variation which results in one species having several different phenotypes

Question 35

What is adaptive radiation?

Answer 35

closely related species that have recently evolved from a common ancestor by adapting to different parts of the environment (the bats and pollen)

Question 36

What is key innovation?

Answer 36

New traits evolves within a species allowing it to use resources that were previously inaccessible

Question 37

What is character displacement?

Answer 37

Two reproductively isolated but ecologically similar species come into contact, and natural selection in each species favors those individuals that use resources not used by the other species

Question 38

What is are some results of character displacement?

Answer 38

greater fitness 2. trait differences in resources use will increase in frequency over time 3. species will diverge

Question 39

With pace of evolution, what is gradualism?

Answer 39

accumulation of small changes over time

Question 40

What is punctuated equilibrium?

Answer 40

Long periods of stasis followed by rapid changes

Question 41

What has greatly increased over the last 600 million years?

Answer 41

Biological diversity

Question 42

Define mass extinction

Answer 42

sharp decline of species divirsity

Question 43

How many mass extinctions have occured?

Answer 43

5 mass extinctions

Question 44

What is the cause of the 6th ongoing mass extinction?

Answer 44

human activity

Question 45

What are the names of the five mass extinctions?

Answer 45

1. ordovician 2. devonian 3. permian 4. triassic 5. cretaceous

Question 46

What is another word for the cretaceous extinction?

Answer 46

K-T extinction

Question 47

What is the K-T or cretaceous extinction, and when did it happen?

Answer 47

It is the extinction of nonavian dinosaurs and it happed 66 MYA because of a meteor impact