Speciation

Question 1

What is the “species problem”? Are species fundamentally different from other taxonomic ranks?

Answer 1

The “species problem” refers to the question of whether species are an actual reality of nature or simply human construct. Parameters for a species are not as objective as other taxonomic ranks

Question 2

Morphospecies concept

Answer 2

Species are groups that are morphologically distinguishable. Only potentially useful in long extinct organisms for which no information apart from size and shape is known

Question 3

Phylogenetic species concept

Answer 3

Species are the smallest recognizable monophyletic groups in a phylogeny. Only used by taxonomists for issuing scientific names. Problems include that it is based on a fixed difference, heavily dependent on whatever gene is being looked at, may be arbitrary, not effective for showing how speciation happens

Question 4

Ecological species concept

Answer 4

Species are co-occuring organisms that occupy different niches. Based on niche exclusion. Problems are that it is impossible to extrinsically define a niche. Useful in asexual populations

Question 5

Biological species concept

Answer 5

Species are groups of interbreeding populations that are reproductively isolated from other populations. Closest to a unified species concept. However problems include the fact that complete reproductive isolation is required, and this is not always realistic

Question 6

Genotypic Clustering Species concept

Answer 6

Species are genetically distinguishable groups of individuals maintained in contact with other groups, and this pattern is driven by the evolution of reproductive isolation. Migration and recombination work against this by homogenizing the gene pool. Species can interbreed but offspring will have low fitness

Question 7

Which concept(s) did I find say were the most useful and why?

Answer 7

BSC and GCS

Question 8

What do I mean by “evolutionary independence” and what does this have to do with species?

Answer 8

Evolutionary forces that act on one population have no impact on the evolutionary outcome of another population, the idea being that species are made up of populations of evolutionary independent organisms

Question 9

Why do we not expect any one species concept to work well across all organisms?

Answer 9

They can not all account for asexual reproduction, high/low frequencies of reproduction

Question 10

Allopatry

Answer 10

Complete geographic separation of populations during divergence

Question 11

Vicariance

Answer 11

Separation of a large population into two parts

Question 12

Peripatric divergence

Answer 12

Allopatry caused by the colonization of a distant habitat from a larger population. Drift may play an important role in this situation

Question 13

Parapatry

Answer 13

Geographic separation without complete isolation, often occurring in adjoining habitats

Question 14

Sympatry

Answer 14

No geographic separation among diverging populations. Divergence begins as polymorphism

Question 15

Premating isolation

Answer 15

Behavioral- organisms fail to attract mates, Mechanical- reproductive structures are incompatible, Ecological- divergent adaptations lead to decreased mating events across pops

Question 16

Postmating/Prezygotic isolation

Answer 16

Gametic- gametes transfer but fail to form a zygote,

Question 17

Postzygotic isolation

Answer 17

Sterility or inviability

Question 18

How does extrinsic postzygotic isolation result in reproductive isolation if fertile offspring are still produced between species?

Answer 18

The offspring can reproduce and survive in theory but are bad at doing so

Question 19

How do Dobzhanksy-Muller incompatibilities work, and in what way are they nearly inevitable?

Answer 19

Epistatic incompatibilities build up over time as new mutations in separate populations move to fixation. In allopatric scenarios this is nearly inevitable

Question 20

How does geographic mode influence how these incompatibilities evolve?

Answer 20

Greater separation will lead to decreased homogenization via migration and incompatibilities will increase at a higher rate

Question 21

What is an adaptive radiation?

Answer 21

The divergence of a clade into populations adaptive to many ecological niches