Lecture 9 - Species, Species Concepts, and Speciation Flashcards
What are 5 examples of species concepts?
- biological
- morphological
- evolutionary
- recognition
- phylogentetic
Which 2 species concepts are most commonly used today?
biological (BSC) and phylogenetic (PSC)
Who discovered the BSC?
Ernst Mayr
What is the BSC?
species are groups of interbreeding natural pops that are reproductively isolated from other such groups
Among what profession is the BSC widely accepted among?
zoologists, not botanists or palentologist
Is BSC applicable to asexual organisms?
no doesn’t apply to them; so doesn’t apply to parthenogenetic lizard
Is BSC testable with sympatric or allopatric populations?
sympatric
Can you know BSC for fossils?
unknowable for fossils; doesn’t have time element
What does it mean if ability to interbreed for BSC is plesiomorphic?
meaning its and ancestral trait is lost
Is testing for reproductive isolation always feasible?
no; some species may mate in lab but not nature; individuals viable in lab might not be in nature
What is most speciation?
allopatric
Who discovered the morphological species concept?
Eldredge and Cracraft (1980)
What is the morphological species concept?
diagnosable cluster of individuals within which there is a pattern of ancestry and descent and beyond which there isn’t; similarity in morphological characters w consistent differences from other species
Can siblings or cryptic species be told apart by morphology?
no
Who came up with the evolutionary species concept?
G.G Simpson and Wiley (mainly the former)
What is the evolutionary species concept?
a species is a single lineage of ancestral descendant pops of organisms that maintain its identity from other such lineages and which has its on evolutionary tendencies and historical fate
What are recognition species?
sets of organisms that recognize each other as potential mates; crickets sing diff songs
Is the ability to discriminate individuals of one group from another a static property of species?
no itself is a phenotype that evolves
What is the phylogenetic species concept?
a species is the smallest diagnosable cluster of individuals orgs within which there is a parental pattern of ancestry and descent; grouped bc of evidence of monophyly
Who is associated with the phylogenetic species concept?
Joel Cracraft (1983)
What are 3 steps in delimiting species common to all species concepts?
- survey morphological or molecular variation within and among populations
- group individuals into groups called taxa
- rank taxa in taxonomic hierarchy (subspecies, species)
Where do BSC and PSC diverge?
with ranking taxa in taxonomic hierarchy
How does BSC rank taxa?
ranking based on reproductive compatibility
How does PSC rank taxa?
ranking based on diagnosability
What happens with species diverge from each other?
become evolutionary species
What happens when evolutionary species are diagnosable?
become phylogenetic
What happens when species are absolutely reproductively isolated?
become biological species
Rank order of evolutionary, biological and phylogenetic species forming?
evo, phylo, bio
What does pattern vs process based mean?
how bio vs phylo differ in ranking taxa
What does BSC do based on morphological differences?
group individuals into 2 taxa and if they hybridize, rank as subspecies
What is the association btw morphology and PSC?
morphology reveals 2 groups w independent evo histories, ranks as species whether hybridizing or not
Why doesn’t PSC use info on reproductive isolation to decide species limits?
- hybridization is an ancestral condition and only derived conditions unite taxa
- species limits should be based on what has evolved (pattern) and not what might happen (process) in the future
- hybridization has a potential future role but outcome is unknowable
How long for hybridization to erase evidence of independent evolution?
can use cline theory to answer question
What is the difference btw allopatry and sympatry?
allopatry = not overlapping in distribution
sympatry = overlapping in distribution
How many taxa of brown towhee?
4 as confirmed with MtDNA studies
What type of populations are hard to assess under BSC?
allopatric; what can seem as sisters bc the are neighbors aren’t
How could wrong classification come to be with the BSC?
guessing if allopatric populations could hybridize as w PSC there is no guessing
Are sister species thought to hybridize with PSC?
species thought to be able to hybridize not sister species
With evidence, how do PSC and BSC differ?
PSC: 4 species w independent evo history = 4 species
BSC: need to know abt hybridization
Under BSC, what are hybridizing groups classified as?
same species which misinterprets evo history
What do most biological species equal?
one single phylogenetic species
What do ecological factors fuel?
process of evolution producing characteristic differences btw species
What is allopatric speciation?
geographic isolation; prerequisite for speciation; vicariance
Do isolation by vicariance and dispersal have diff consequences?
yes
What is parapatric speciation?
geographic barrier isn’t necessary, pops touching but no random mating; hybrid zone along common border initially
What is sympatric speciation?
long thought rare; new populations forming without geographic isolation
What is main example of sympatric speciation?
polyploidy in plants; aka instant speciation - polyploids originate when entire genome is doubled via fertilization w unreduced gametes; fertile but cannot mate w parentals
What is assortative mating?
tendency to choose similar or dissimilar mates in phenotypes than would be expected by chance
