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Biology II (115) > Exam 2 Part 3 Origin of Species > Flashcards

Exam 2 Part 3 Origin of Species Flashcards

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0
Q

MACROEVOLUTION

A

Evolutionary change above the species level. Examples of macroevolutionary change include the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery.

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1
Q

MICROEVOLUTION

A

Evolutionary change below the species level; change in the allele frequencies in a population over generations.

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2
Q

The unit of speciation is

A

The population

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3
Q

SPECIATION

A

(spē’-sē-ā’-shun) An evolutionary process in which one species splits into two or more species.

When 2 populations of the same species diverge phenotypically and genetically.
This process has to begin with variation among populations

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4
Q

How does speciation begin

A

With variation among populations

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5
Q

What are some PATTERNS IN VARIATION tat lead to speciation

A
  1. Cline
    b. Ecogeographic rules
    i) Bergman’s rule
    ii) Allen’s rule
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6
Q

CLINE

A

A gradual phenotypic change along a geographic axis.Gradual geographical variation correlated with ecological gradient.

Eg mumuchog fish
Cold tolerant. LDL alleles are more common in colder temperature and high latitudes , but there is a gradual shift in the amount of LDL alleles going to warmer temperatures where there is a gradual shift to LDL that are more heat tolerant. This is caused by Geneflow ( this graduation)

Eg. Vegetation height gradually shift with altitude / elevation
Yarrow plant

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7
Q

Ecogeographic rules are

A

Clines found consistently across species
Eg. Clutch( number of eggs) size increases with latitude ( birds of the same species have the same size in the north but are different from those in the south.

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8
Q

BERGMANNS RULE as a pattern of variation

A

A type of ecogeographic rule where animals further away from the equator the body size is larger

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9
Q

ALLENS RULE,

A

Closer to the equator there are higher surface are volume ratios. Closer to the poles there are lower surface area volume ratio.

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10
Q

what are the mechanism of why populations differ across species.

A
  1. GENETIC DIFFERENTIATION

2. Phenotypic plasticity

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11
Q

GENETIC DIFFERENTIATION

A

The accumulation of differences in allelic frequencies between completely or partially isolated populations due to evolutionary forces such as selection or genetic drift.

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12
Q

2 CAUSES OF GENETIC DIFFERENTIATION why are species different

A
  1. GENETIC DRIFT : ( non adaptive) accumulation of random genetic differences that lead to divergence

Eg. Salamander( isolation due to distance from other populations leading to divergence and no longer can mate, however can mate with adjacent populations.

    .Six finger dwarfism ( due to founder' s effect) lead to difference between the original ancestral home and the new population. The frequency of the disease is much higher in the new population
  1. LOCAL ADAPTATION: ( selection has favored different traits in different habitats- a result of natural selection) accumulation of adaptive genetic differences
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13
Q

PHENOTYPIC PLASTICITY

A

Phenotypic response to the environment

Eg. Yarrow plants differ in stature due to difference in elevation along a gradient.

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14
Q

RECIPROCAL TRANSPLANT EXPERIMENT

A

Designed to disentangle genetic effects from phenotypic plasticity when organisms with different phenotypes but of the same species are found in different environment. ( drift vs local adaptation )

Eg. Yarrow plant : the difference that exist between high elevation and low elevation plants maybe due to 1. Genetic differences or 2. Phenotypic plasticity.
high elevation plants were replanted in low and the opposite along with a control to see if they would have the same phenotype. If genetic differences should have no change

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15
Q

2 ways to define species

A
  1. MORPHological/typological species concept

2. BIOLOGICAL SPECIES CONCEPT

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16
Q

Why are species hard to define

A

Because a the classification of organisms are on a continuum ( alike in some ways and different in others ) - continuum of variation in species.
Eg ensatina salamanders
The golden rod

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17
Q

MORPHOLOGICAL SPECIES CONCEPT

A

Species are defined in terms of observable phenotype

. Species are distant up changing entities defined by unique morphological features

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18
Q

Limitations to the morphological species concept

A
  1. Sexual dimorphism ( mistake differences in the gender as evidence of different species )
  2. Metamorphism - distinct life stages ( tadpoles to frog)
  3. Alternative morphs - different physical morphology within the same species eg. Polymorphism in horn beetles some at a development stage will detect a poor food environment as choosen not to develop horns looking different from other males in the population
  4. Phenotypic plasticity- phenotypic response to the environment
  5. Cryptic species - although physically similar have other mechanical subtleties for example song in crickets that look a like but are unable to breed because in the difference in the song each type produces.
  6. Evolution- phenotypes change over time.. MSC assumes that organisms are fixed and not evolving. Type species maybe different evolutionarily
    Eg. Artificial selection of oil content in oil.
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19
Q

BIOLOGICAL SPECIES CONCEPT

A

Species are defined by reproductive isolation

. It is a population or group of populations that can potentially interbreed and produce viable offspring, but that is reproductively isolated from other populations.
. If there is Geneflow between populations then they are the same species.
. There must be some time of reproductive barrier

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20
Q

What are the problems with BOLOGICAL SPECIES CONCEPT

A
  1. We are unable breed/ test large animals like the whale with another species
  2. ASEXUAL SPECIES
    eg. Dandelions
    . Prokaryotes by budding
    . Triploid lizard
  3. SOME SPECIES ARE ONLY KNOWN FROM FOSSILS
  4. GRADUAL GEOGRAPHICAL VARIATION
    Eg. Ring species ( ensatina salamander)
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21
Q

2 groups of REPRODUCTIVE ISOLATION

A

I. PREZYGOTIC

II. POSTZYGOTIC

22
Q

Types of PREZYGOTIC ISOLATION

A
  1. HABITAT ISOLATION
  2. TEMPORAL ISOLATION
  3. BEHAVIORAL ISOLATION
  4. MECHANICAL ISOLATION
  5. GAMETIC ISOLATION
23
Q

HABITAT ISOLATION

A

Populations live in different habitats and do not meet

Eg. Anolis in the West Indies inhabit different suites of a tree ( trunk, twig, crown, bushes, grass) which are all different habitats.

ENSATINA are separated by physical barrier ( mountain ranges )

24
Q

TEMPORAL ISOLATION

A

Mating or flowering occurs at different seasons

Eg. Western spotted skunk breeds in the summer and eastern spotted skunk winter

25
Q

BEHAVIORAL ISOLATION

A

Little are or no sexual attraction between males and females.
Eg. DifferentFlashing patterns of different species to attract different mates in fireflies.

26
Q

MECHANICAL ISOLATION

A

Structural differences in genitalia or flowers prevent copulation or pollination.
Eg. Genital morphology in waterfowl: female genital has pouches and spirals where cooperation is needed for the male phallus maybe spiraled the opposite way.

27
Q

GAMETIC ISOLATION

A

SPerms of one species are not able to fertilize the species of another species by physical or biochemical reasons.
Eg. Pollen grains only germinate the stigma of the correct species.
. Eggs do not recognize the sperm of other urchins

28
Q

POST ZYGOTIC ISOLATION

A
  1. HYBRID INVIABILITY
  2. HYBRID STERILITY
    3.
29
Q

HYBRID INVIABILITY

A

Embryos die early in development

Eg.

30
Q

HYBRID STERILITY

A

Hybrid may be vigorous but are infertile

Eg. Horses x donkey = sterile mule ( meiosis does not work well - CHROMOSOME DYSFUNCTION.

31
Q

Closely related species

A

Share amino acid sequences- recent divergences.. The more divergence the more post zygotic isolation
Eg. Isolation of drosophila species: the greater the genetic distance the greater the post zygotic isolation, and the lesser survivorship
/ fertility of hybrids.

32
Q

What type of reproductive isolation is more efficient

A

PREZYGOTIC

33
Q

SPECIATION

A

. The result of reproductive isolation

. Formation of two species from one ( not from evolution but from divergence)

34
Q

The 2 types of SPECIATION ( result of reproductive isolation)

A
  1. ALLOPATRIC SPECIATION

2. SYMPATRIC SPECIATION

35
Q

IDEAL SPECIATION

A

The concept that if 2 divergent population come back together they can’t breed

36
Q

ALLOPATRIC SPECIATION

A

It begins with a physical barrier that causes physical isolation, and leads to a divergence that results in 2 species. If the the groups have diverged enough if the are rejoined there is no Geneflow.

37
Q

VACARIANCE

A

When a physical body causes speciation, the formation of the barrier is called a vicariance event.

Eg.
The Harris ground squirrel and the white tail squirrel are physically separated by a water way and have diverge to 2 different species

. desert pupfish ( drying has resulted in divergence in aquatic population.
.ADAPTIVE RADIATION in galopogus isololated islands which are specialized for food for specific islands and so is selected against hybridization.

38
Q

geographic isolation alone does not equal speciation

A

Mechanisms that prevent hybridization, must evolve according to the BIOLOGICAL SPECIES CONCEPT.

39
Q

SYMPATRIC SPECIATION

A

Occurs when a group diverges from the population without a physical/ geographical barrier

40
Q

Ways to SYMPATRIC SPECIATION

A

NONDISJUNCTION ( causes polyploidy)

  1. Auto polyploidy
  2. Allopolyploidy
41
Q

NONDISJUNCTION

( INSTANT REPRODUCTIVE ISOLATION– IMMEDIATE SPECIATION)

A

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other. Where 1 gamete gets all the copies of the chromosomes, have twice of the parents making it a different species from the parent.

. NONDISJUNCTION separate individuals from a single parent species
. A polyploid with a normal parent will not produce viable offspring.
Resulting in immediate speciation/ instant reproductive isolation

42
Q

What is INSTANT REPRODUCTIVE ISOLATION

A

Mutant polyploidy can only make fertile offspring with other polyploids

43
Q

AUTOPOLYPLOIDY

A

Separates individuals from a single parent species

44
Q

ALLOPOLYPLOIDY

A

Hybridization followed by NONDISJUNCTION separate individual from 2 parent species.. 50% of plants are polyploidy

45
Q

Habitat differentiation + ASSORTATIVE mating

A

Eg. Apple maggots specialize on HARTHORNE or pallets and because hybridization produce lower fitness the flies have evolved a mechanism that prevents them from mating with the opposite speciation.

. Seperate races reinforced by ASSORTATIVE mating

46
Q

Sexual selection by SYMPATRIC speciation can occur

A

Eg. Cichlids diversity lake Malawi. SYMPATRIC speciation occurred because of different groups have developed food specialization along with different mouth morphology. Through ASSORTATIVE mating individivuals are prefer to mate with others that looked like them. (BEHAVIOURAL ISOLATION)

47
Q

Most speciation is gradual

A
  1. Polyploidy can evolve fast, but
  2. Reproduction isolation mechanism evolve slowly
  3. Forces that create reproductive isolation are evolutionary forces
    Eg.
    Natural selection
    Genetic drift
    Mutation
    ASSORTATIVE mating

.Mechanisms for speciation are the same as for evolution in a population

48
Q

Gametic isolation results in

A

SYMPATRIC speciation ( most common in plants)

49
Q

Causes of Hydridization

A
  1. Breakdown of reproductive isolation mechanisms
    Eg. turbid water interferes with ASSORTATIVE mating
  2. New and secondary contact( when the physical barrier moves and the 2 groups are joined)
50
Q

What can occur when HYBRIDS HAVE HIFGER FITNESS THAN THE PARENTS

A
  1. Fusion

2. Introgression

51
Q

INTEOGRESSION

A

.A takeover or a spread of one species gene into a population of another species
. One genome of one species takes over the genome of another species through hybridization ( hybrids can mate with parent)
Eg through hybridization it has become difficult to find pupfish ( pure)

52
Q

When hybrids have lower fitness in the case of the apple maggots and the cichlids what can this lead to

A

Individuals will evolve mechanism to avoid hybrization and lead to
. Reinforcement of species recognition mechanisms
. Reinforcement reproductive character displacement ( phenotype tat are used to distinguish one species from another ( including phenotypes that are used in mate choice) CONSPICUOUS ADVERTISEMENT
EG. PEACOCKS
KNOLLS
CRICKET

Biology II (115) (13 decks)

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