Exam 2 Lecs - 3 Flashcards by Gail I

1.9 million described species

- … species estimated globally, could be as many as … species

9 million;

100 million

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3 species concepts we’re focusing on:

morphospecies concept;
phylogenetic species concept;
biological

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none of the species concepts we currently have are sufficient definitions for all cases
… and … in traits can occur at the same time and place –> sometimes third stage of … doesn’t happen
the three stages of speciation aren’t necessarily followed in all cases

isolation;
divergence;
reproductive isolation

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… is the first step of speciation:

- usually happens with … influence

isolation;

geographic

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isolation is first step of speciation:

usually happens with geographic influence
for isolated populations, allele frequencies won’t be the same in both populations due to … and … –> thus, they start …

drift;
selection;
differentiating

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geographic model of speciation is …

- occurs either through … or through …

allopatric model;
dispersal;
vicariance

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geographic model of speciation is allopatric model:

occurs either through dispersal –> original population dispersing to a … (e.g. island, new region being colonized)
or through vicariance –> formation of a … that splits the distribution of the population into … such that the new species can form

new environment;
barrier;
two

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geographic model of speciation is allopatric model:
- does not necessarily require … to occur in this model. It can just rely on …, which changes frequencies such that they become …

selection;
drift;
genetically incompatible

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geographic model of speciation is allopatric model:

e.g. drosophila in Hawaii –> several species of flies and their differentiations follow the timing of the …
molokai and maui species are more closely related - … species
this is a case of …

formation of the islands;
sister;
dispersal

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geographic model of speciation is allopatric model:

- geological event in the Americas –> closure of the …, which is a connection between … and …

isthmus;
South America;
Central

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geographic model of speciation is allopatric model:

geological event in the Americas - closure of isthmus
resulted in … –> fauna that originated in South America and then migrated to … and fauna from North America also migrated to …
But some sea species became … due to the isthmus closure - this is the case of …

Great American biotic interchange; 
North America; 
South America; 
isolated; 
vicariance

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speciation with adaptation:

- gradient of … across the space –> can have species adapted to different … and different …

different climates;
regions;
climates

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speciation with adaptation:
gradient of different climates across the space –> can have species adapted to different regions and different climates

e. g. yellow monkeyflower
- coastal ecotype - … plant, keeps …
- inland ecotype - dies during … period and become … plant

perennial;
flowering;
drought;
annual

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speciation with adaptation:

e. g. yellow monkeyflower
- coastal and inland ecotypes
- scientists transplanted species and switched their environments
- if you take inland to inland field site, a lot flower and they … - expected fitness is … compared to coastal
- if you move coastal to inland site they … as much and thus have a …

thrive;
very high;
don’t flower;
lower fitness

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speciation with adaptation:

e. g. yellow monkeyflower
- if transplant inland to coastal, they … while coastal version is …
- this shows the … - adapted to different climates and it suggests that they are in a process of …

don’t flower;
fine;
adaptation;
speciation

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speciation with adaptation:

e. g. yellow monkeyflower
- could be considered … at that point depending on how you define species –> if there’s gene flow they’re not …
- this is …

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separate species;
totally reproductively isolated;
parapatric speciation

speciation with adaptation:

… within the same area
development of two different adaptations to two different …, for example, leading to speciation –> … selection regarding bill shape in seedcracking finch - ongoing process of speciation in the same geographic area

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divergence;
food sources;
disruptive

speciation with adaptation:
divergence within the same area
- disruptive selection regarding bill shape in seedcracking finch
- this is …
- this differentiation within the same region is due to …

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sympatric;

sufficient genetic polymorphism

speciation with adaptation:

in both of the above cases, the isolation is not complete (i.e. … and …)
peripatric –> difficult to tease apart in nature, edge of a population …, … forming a new species

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parapatric;
sympatric;
colonizing a new area;
periphery of distribution

3 basic models of speciation:

…, …, …

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allopatric;
parapatric;
sympatric

There can be … and … in the case of sympatric and parapatric
- what keeps sympatric species separate - two mechanisms to prevent gene flow from homogenizing the population: … and …

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gene flow; gene exchange;

prezygotic; postzygotic

There can be gene flow and gene exchange in case of sympatric and parapatric. What keeps sympatric species separate:

prezygotic: zygotes are …, usually because … doesn’t even take place (e.g. bc of a behavioral deterrent)
postzygotic: hybrids are …, … or have … (e.g. crossing tiger and lion)

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never formed; 
mating; 
inviable; 
sterile; 
reduced fitness

what keeps sympatric species separate: 
when species do interbreed, 3 possible outcomes: 
- reinforcement of ...
- formation of ... with ...
- ....

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prezygotic isolation;
new species; hybrid;
stable hybrid zones

when species do interbreed, 3 possible outcomes:

reinforcement of prezygotic isolation –> offspring doesn’t have qualities to have one extreme or the other and they can’t …
formation of new species with hybrid –> hybrid filling a … that’s not being filled by either species, …
stable hybrid zones

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attract opposite sex mate;
niche;
instantaneous

There can be gene flow and gene exchange in case of sympatric and parapatric. - if genetic incompatibility in hybrids, hybrids are ... --> this usually happens when two species are isolated ... and for some reason get into contact again (this is called ...) --> might be able to mate but never have hybrids

never born; for a long time; secondary contact;

There can be gene flow and gene exchange in case of sympatric and parapatric. - hybrid speciation is very common in ... - selection can favor hybrid just in ...

plants; | transition zone

There can be gene flow and gene exchange in case of sympatric and parapatric. - selection can favor hybrid just in transition zone --> hybrid adapted in specific transition from one climate to the other, for example. forms a stable ... - zone that only hybrids can occupy bc they're ....

hybrid zone; | better fit to the environment

There can be gene flow and gene exchange in case of sympatric and parapatric. - forms a stable hybrid zone: but they can never expand ..., can be relatively ... or ... for hybrid zones

beyond the hybrid zone; | narrow; broad

Little consensus when it comes to species concepts bc none work in all cases: - oldest and most used concept is ... concept --> relied on for ... of species, based on ... of species

morphospecies; initial naming; morphological similarities

Little consensus when it comes to species concepts bc none work in all cases: oldest and most used concept is morphospecies concept: - can use this for ... as well, except for if differences are by ... or ... - doesn't work for ...

fossils; color; soft tissue differences; cryptic species

Little consensus when it comes to species concepts bc none work in all cases: phylogenetic species concept: - based on ... - easily testable by ... --> testing and repeating process of ... - more scientifically sound, can also use ...

monophyly; building other trees; species description; statistics

Little consensus when it comes to species concepts bc none work in all cases: phylogenetic species concept: - problem: if you use morphology and genetics independently, they give you ... - other problem: could increase the ... that we have a lot - distinguishes cryptic species if using ... to build tree

different phylogenetic trees; number of species; genetics

Little consensus when it comes to species concepts bc none work in all cases: biological species concept: - widely accepted - based in ... - uses ... to describe new species - this is the concept used in the US for ... purposes

reproductive isolation; complete reproductive isolation; conservation

Little consensus when it comes to species concepts bc none work in all cases: biological species concept: - key element is ... - it's hard to apply though --> rarely can bring different species to a lab and try to ... to determine if they're ...

lack of gene flow; breed them; isolated

Little consensus when it comes to species concepts bc none work in all cases: biological species concept: - idea against this concept: keeping gene flow between species can actually be ... --> if exchanging genes with other species, can acquire ... in ...

adaptive; adaptive genetic material; changing environments

Exam 2 Lecs - 3 Flashcards

(35 cards)