Lecture 9: Species, Species Concept, and Speciation Flashcards
Who collected birds in New Guinea?
Ernst Mayr
How many species did Ernst Mayr recognize?
137
Why are species important?
They are the currency with which we do our studies as biologists
What are the two most commonly used species concepts?
Biological Species Concept
Phylogenetic Species Concept
Who defined the biological species concept?
Ernst Mayr
What is the biological species concept?
species are groups of interbreeding natural populations that are reproductively isolated from other such groups
What are 2 cons of of the BSC?
1) doesn’t apply to asexual organisms and fossils
2) testable with sympatric populations, not allopatric ones
Why is testing for reproductive isolation in lab not feasible for some species? (2 reasons)
1) Species might mate in lab but not in nature
2) Individuals viable in the lab may not survive in nature
Who defined the morphological species concept?
Eldredge and Cracraft
What is the morphological species concept?
Species are recognized by similarity in morphological characters. There are consistent differences from other species (morphological gaps), particularly in sympatry
Which types of species can’t be told apart by morphology?
Sibling or cryptic species
What is the evolutionary species concept?
Distinct lineages
Who made the evolutionary species concept?
G. G. Simpson
What is the recognition species concept?
A set of organisms that recognize each other as potential mates
How do moths display the recognition species concept?
Pheromonal recognition
What did Joel Cracraft believe?
Organisms are grouped because of evidence for monophyly
What is monophyly?
A group of species that have a common ancestor
What are the three steps to delimiting species common to all species concepts?
1) Survey morphological variation within/among populations
2) Group individuals into taxa
3) Rank taxa in taxonomic hierarchy
What is the phylogenetic species concept?
A species is the smallest diagnosable cluster of individual organisms within which there is a PARENTAL pattern of ancestry and descent
Where do BSC and PSC diverge? How?
When ranking taxa in taxonomic hierarchy
BSC: ranking based on reproductive compatibility
PSC: ranking based on diagnosability
What is the taxonomic hierarchy?
Kingdom, Phylum, Class, Order, Family, Genus, Species
Which species concept is pattern based?
PSC
Which species concept is process based?
BSC
How does grouping work for the BSC?
BSC groups individuals based on morphological differences into two taxa, and if they hybridize, rank as subspecies
How does grouping work for the PSC?
Morphology reveals two groups with independent evolutionary histories, ranks as species whether hybridizing or not
What is hybridization?
When two evolutionary species (distinct lineages) come together and interbreed
How do you determine how long it takes for hybridization to “erase” evidence of independent evolution?
Cline theory
PSC considers hybridization to be an ____ trait
ancestral
What do brown towhees show the problems with?
The problems with BSC in allopatry
Hybridization in allopatric populations BSC vs PSC
BSC: guessing if allopatric populations could hybridize led to wrong classification
PSC: no guessing if allopatric populations could hybridize
Under BSC, hybridizing groups are considered to be the ____ species
same species
What is one criticism of PSC?
Results in too many species and every individual might end up being a species
What is adaptive radiation?
a single ancestor radiated (speciated) into many current species
What is allopatric speciation?
speciation by geographic isolation
What are the two kinds of isolation in allopatric speciation?
Vicariance: physical barrier
Peripatric (peripheral isolate): migration/dispersal
Which of the two kinds of isolation in allopatric speciation occurs quicker?
Peripatric (peripheral isolate)
What is parapatric speciation?
when you have a main geographic distribution with nearby habitats/niches that are different…and species go to these new niches and eventually become a distinct species
What is sympatric speciation?
polymorphism (such as mutation) occurs in original population…polymorphism spreads within population and new species forms
What is assortative mating?
Mating with individuals of similar characteristics
What is the effect of assortative mating on gene flow?
Gene flow is reduced
Which type of speciation happens most?
Allopatric speciation
Which type(s) of speciation doesn’t require a barrier?
Parapatric and sympatric
What is polyploidy?
Instant speciation…entire genome is doubled
What is a hybrid zone, what are the two types of hybrid zones, and when do they occur?
regions where genetically distinct groups of individuals meet and mate
Primary hybrid zone: in parapatric speciation
Secondary hybrid zone: with allopatric speciation and subsequent secondary contact
What can hybrid zones result in? What does that concept mean?
Introgression, when alleles are spread from one species into another
What are the two main reasons why monkeyflowers aren’t very successful at reproduction?
Elevational separation
Pollinator isolation
What are the two categories of prezygotic isolating mechanisms?
Pre-mating and post-mating
What are two types of pre-mating isolation?
Ecological isolation, meet but don’t mate
What are the two types of ecological isolation? What do they mean?
Temporal isolation: reproduce at different times
Habitat isolation: occupy different habitats
What are the two types of “meet but don’t mate” isolation?
Sexual isolation: reproductively isolated
Pollinator isolation: don’t get pollinated by the same species
What are the three types of post-mating isolation?
Mechanical isolation: genitals not compatible
Copulatory isolation: issues during/after copulation
Gametic isolation: gametes incompatible
