Exam 2 Lecs - 3 Flashcards
- 1.9 million described species
- … species estimated globally, could be as many as … species
9 million;
100 million
3 species concepts we’re focusing on:
- …
- …
- …
morphospecies concept;
phylogenetic species concept;
biological
- 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
… is the first step of speciation:
- usually happens with … influence
isolation;
geographic
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
geographic model of speciation is …
- occurs either through … or through …
allopatric model;
dispersal;
vicariance
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
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
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
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
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
speciation with adaptation:
- gradient of … across the space –> can have species adapted to different … and different …
different climates;
regions;
climates
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
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
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
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 …
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
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 …
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
parapatric;
sympatric;
colonizing a new area;
periphery of distribution
3 basic models of speciation:
…, …, …
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 …
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)
never formed; mating; inviable; sterile; reduced fitness
what keeps sympatric species separate: when species do interbreed, 3 possible outcomes: - reinforcement of ... - formation of ... with ... - ....
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
attract opposite sex mate;
niche;
instantaneous
