Chapter 3

Question 1

species

Answer 1

is defined as a group of organisms that are able to breed with one another and produce fertile offspring
a species will not be able to produce fertile offspring with members of other groups

Question 2

speciation

Answer 2

is the emergence of a new species

Question 3

mircoevolution

Answer 3

gradual changes within a population over a umber of generations
-gradual adaptation of a population to its enviornement

Question 4

macroevolution

Answer 4

broad patterns of evolutionnary change over long time periods
-largest scale changes that include the introduction of new groups

Question 5

species

Answer 5

speciation acts to increase the diversity of life
usually a new species closely resembles its parent species (mircroevolution) but occasionally a new species will have enough change to define a new branch on the tree of life (macroevolution)
ex) the legs of land animals
the definition of species can take on many forms:
charles linnaues a swedish botanist developed the taxonomix system of naming and classifying in the 18th century and it is still used today
a binomial system assigning a genus and a species name to each organism
organisms were grouped as species based on physical similarities
ex) first and last name
rahel = specific, species -must be lower case
muster = lots of these, genus - must be capital letter and underlined

Question 6

how to define a species

Answer 6

sometimes two organisms are of a different species but their apperance are very similar
-eastern spotted skunk and the western spotted skunk
they breed at different times of the year and even though they live close to one another they do not interbreed (temporal seperation)
humans appear very different from one another but still belong to the same species

Question 7

the biological species concept

Answer 7

developed in 1942
defines a species as a group of populations whose members are bale to interbreed and produce fertile offspring
members of different species do not usually mate with one another but if they do their offspring are usually infertile
reproductive isolation occurs when the inability to produce fertile offspring assist in maintaining the gap in between different species
prevents gene flow between populations of different species
there are some problems with biological species concept
-prokaryokes do not reproduce sexually
we are unable to determine weather fossils were capable of interbreeding

Question 8

other ways to define a species

Answer 8

1. morphological species concept
2. ecological species concept
3. phyogenetic species concept

Question 9

morphological species concept

Answer 9

classification of a species based on measureable and observable physical traits

• shape, size, and other morphological features
• can be used for fossils and asexual organisms
• doesnt require info on interbreeding
• disavantage: relies on subjective criteria, some may disagree with what other people consider similar

Question 10

ecological species concept

Answer 10

indentities species on the basis of ecological niche

• how they have adapted to a particular environment
• ex) two fish may be visibly similar to one another but distingishable based on diet or depth of water in which they live

Question 11

phylogentic species concept

Answer 11

defined as the smallest group of individuals that share a common ansestor and form one branch on the tree of life

• determined based on comparisons of morphology and DNA sequences
• problem: agreeing on the amount of difference necessary to constitute a separate species

Question 12

reproductive barriers and speciation

Answer 12

reproductive barriers: features a particular organism that makes it incapable of breeding with closely related species which live in the same geographical area
there are two types of reproductive barriers:
1. pre-zygotic reproductive barriers: prevent mating or fertilization between species
2. post-zygotic reproductive barriers: operate after hybrid zones are formed

Question 13

pre-zygotic reporductive barriers (before zygote)

Answer 13

1. temporal isolation
2. habitat isolation
3. behvaioural isolation
4. mechanical isolation
5. gametic isolation

Question 14

post- zygotic reproductive barriers (after zygote)

Answer 14

1. reduced hybrid viability
2. reduced hybrid fertility
3. hybrid breakdown

Question 15

temporal isolation

Answer 15

occurs because two species mate at different times
can be different seasons, years, or time of the day
ex) a flowering plant have flowers which open at different times of the day

Question 16

habitat isolation

Answer 16

two species living in the same general location
ex) two snakes living in westerm north america but one lives on land and the other in water
affects paarasites that are animal host species

Question 17

behavioural isolation

Answer 17

little or no sexual attraction in between males and females of different species
special signals that work to attract mates of the same species do not work with other species
ex) courtship rituals are elaborate displays that must be preformed before mating can occur

Question 18

mechanical isolation

Answer 18

female and male sex organs are not compatible

ex) spiraling of snail shells in different directions prevents mating

Question 19

gametic isolation

Answer 19

the sexual act of mating may occur but the male and female gametes will not unite to form a zygote
ex) sea urchins release eggs and sperm into the sea but ferilization will occur only if species specific receptors are present on the egg and the sperm allowing them to attach to one another

Question 20

hybrids

Answer 20

union of gametes from two different species

Question 21

reduced hybrid viability

Answer 21

most hybrid offspring do not survive

ex) salamander may hybribize but most ybrids do not complete development and those that do are very frail

Question 22

reduced hybrid fertility

Answer 22

hybrid offspring of two different species reach maturity and are healthy but sterile
they are unable to facilitate gene flow between the two parent species
ex) a horse and a donkey can mate and produce a mule, the mule is sterile
-gene pool of the horse and the donkey remain seperate

Question 23

hybrid breakdown

Answer 23

fist generation hybrid offspring are viable and fertile
when these hybrid mate with one another or with a memeber of one of the parent species the offspring are feeble or sterile

Question 24

mechanisms of speciation

Answer 24

1. allopatric speciation
2. sympatric speciation
   a) polyploidy
   b) habitat differentiation
   c) sexual selection

Question 25

allopatric speciation

Answer 25

speciation that occurs as the result of introducing a geographical barrier leads to the separation of a population with its gene pool from other populations of the same species this can occur as the result of: -the introduction of a mountain range which gradually splits two populations of organisms -the formation of a land bridge diving marine populations in two the size of the barrier required to create speciation depends on the species -birds are not affected by the introduction of moutains or rivers this likeihood of this occuring is higher when the population is small and isolated

Question 26

sympatric speciation

Answer 26

a new species arises within the same geographical area as the parent species how can this lead to reproductive isolation if the populations are not seperated from one another three main ways: a) polyploidy b) habitat differentation c) sexual selection

Question 27

polyploidy

Answer 27

accidents during cell division result in extra sets of chromosomes polyploidy: a cell that has greater than two complete chromosome sets ex) a tetraploid plant arises from a diploid plant teraploids cannot produce fertile offspring by mating with the parent plants this would produce triploid offspring which are sterile since there are only three chromosome sets they would not be able to form homologous pairs and seperate properly during meiosis this means that the production of a tetraploid organism is instaneous speciation, produce in just one generation most polyploid species result from mating of two different species

Question 28

habitat differentiation

Answer 28

more likely to be the mechanism of speciation in animals adaptations to different habitats in the same geographical area can lead to speciation because mating in between the two groups would become rare rare mating- isolated gene pools = speciation

Question 29

sexual selection

Answer 29

choosing mates based on some physical characteristics | leads to reporductive isolation via seperated gene pools

Question 30

hybrid

Answer 30

when two sperated but closely related populations come back into contract with one another do reproductive barriers remain or will the two species be able to interbreed and become one? hybrid zones: are regions in which members of different species meet and mate producing some hybrid offspring these zones are studied by scientists in order to answer the above question there are three possible outcomes for the hybrid zone over time: 1. reinforcement 2. fusion 3. stability

Question 31

reinforcement

Answer 31

when hybrids are less fit than both parents species expect that natural selection would strengthen/reinforce reproductive barriers prevents the formation of unfit hybrids (two species go in different directions)

Question 32

fusion

Answer 32

reproductive barriers between two species are not strong gene flow may occur in the hybrid zone reversing speciation two hybridizing species fuse into one (fuse and then come out as one)

Question 33

stability

Answer 33

hybrid zones are stable- best thrive hybrids continue to be reproduced some genes flow may occur between populations each species maintains its own integrity (species stay parallel to one another)

Question 34

adaptive radiation

Answer 34

is the evolution of many diverse species from one common ancestor -the adaptations of these species allow them to fill new habitats or roles in their community -this occurs when a few organisms colonize new, unexploited areas or when environemental changes cause a number of extinctions opening up a number of habitats for new species adaptive radiation is linked to new opportunity: no competitors new habitats and food sources sometimes new structures evolve

Question 35

rate of speciation

Answer 35

punctuated equilibrium | gradualism model

Question 36

punctuated equilibrium

Answer 36

long periods occuring with little or no change, equilibrium, punctuated by abrupt episodes of speciation

Question 37

gradualism model

Answer 37

species that have diverged gradually over long periods of time - differences gradually evolve in a population as they become better adapted to their new environment - new species evolve gradually from the ancestral population

Question 38

marcoevolution

Answer 38

major changes recorded in the history of life over large periods of time ex) the evolution of flight in vertebrate lineages

Question 39

earth is estimated to be

Answer 39

4.6 billion years old all matter of the universe was initially present as one big mass -the occurrence of a big bang 10-20 billion years ago blew this mass of matter apart

Question 40

conditions on early earth

Answer 40

earth probably began as a molten mass the atmosphere was likely thick with water vapor and contained other compounds released b volcanic eruptions: -nitrogen, oxides, carbon dioxide, methane, ammonia, hygroden, hydrogen sulfide -as the earth gradually cooled the water vapor condensed into oceans and the hydrogen gas escaped into space -very intense ultraviolet light, lightening, and volcanic activity occurred on early earth -the early earth also lacked oxygen: the primary necessity for life - no molecular oxygen present

Question 41

early earth

Answer 41

the earliest evidence of life on earth is from fossils such as stromatolite which are 3.5 billion years old it is thought that life in an even simpler form may have arose as early as 3.9 billion years ago how did life arise if it has been shown that life cannot arise from non- living matter

Question 42

how did life arise

Answer 42

scientists have collected evidence and conducted experiments that led to the hypothesis that the conditions of early earth could have allowed the production of simple cells these simple cells could have formed via the following four stages 1. abiotic synthesis of small organic molecules such as amino acids and nucelotides 2. joining of these small molecules into macromolcules ex) protiens and DNA 3. packaging of these marcomolecules into "protobionts" which are droplets surrounded by membranes that maintain an internal chemistry different than that of the external surrounds 4. the orgin of self-replicating molecules which eventually made inheritance possible

Question 43

stanley millers experiments

Answer 43

miller was the first to show that amino acids and other organic molecules could e formed under conditions of early earth organic molecules cannot be synthesized spontaneously because of the presence of atmospheric oxygen which oxidizes chemical bonds the energy for this abiotic synthesis is thought to have come from lighting and intense UV radiation the early oceans were thought to have been "primative soup" or a solution of organic molecules

Question 44

stanley millers experiments- what he did

Answer 44

a flask of warm water represented the early sea the water was heated so that some evaporated and moved into a second flask to simulate the early atmosphere this atmosphere consisted of hydrogen, water vapor, methane, and ammonia-all gases thought in the 1950s to have made up the ancient atmosphere electrodes discharged shocks into the flasks to simulate lightening a condenser cooled the atmosphere, raining water and any dissolved particles back into the initial flask-the miniature sea after one week miller found a variety of organic compounds in the solution including some amino acids