Lecture 2: Species Reality and Concepts pt.1 Flashcards
(21 cards)
What ways do most biologists act as if species are real?
- naturalists label specimens with scientific names
- systematists reconstruct relationships among species and publish phylogenies
- population geneticists measure DNA variation within species
- ecologists calculate species diversity and document whether species are going extinct or not
Why do botanists claim species are subjective divisions of nature for human convenience?
plant mating systems have made it difficult to identify species boundaries
Why is it important to study if species are realities of nature or theoretical constructs made by humans in groups that live in sympatry?
geographic variation within species can lead to morphological or genetic aps between individuals
true or false: Darwin believed species are real
false
What did Coyne and Orr believe
thought it was contradictory that many evolutionists who doubt the validity of species act as if species are real in their own research by using Linnaean names and treating members of one species as equal
What 3 methods determine whether species are real in sexually reproducing groups?
- arguments from common sense
- comparing between indigenous and scientific species classifications
- statistical identification of clusters
What are the arguments from common sense?
- species are real because everyone recognizes
- clusters are often discrete even to casual observers
- the usefulness of field guides is proportional to the discreteness of taxa
What is the counterargument to the common sense argument?
humans have a propensity to divide a continuous array of organisms into discrete units
What evidence disproves that humans have a propensity to divide a continuous array of organisms into discrete units?
remarkable coincidence between indigenous species and Linnaean species
What is the main criticism to indigenous and scientific species evidence?
this is just how human brains are wired
What is statistical identification of clusters?
Measuring multiple traits of an individual in one species and comparing those traits to different individuals of another species and seeing if they cluster together the way they’re predicted to
What evidence supports statistical identification of clusters?
Neff and Smith’s discriminant analysis of morphology in sunfish and shiners, found sympatric species are well differentiated and hybrids have intermediate morphology
Why does the presence of hybrids not refute the distinctness of species?
- hybrids can be rare or sterile
- fuzziness of plant species boundaries caused by hybridizations may be overstated
- surveys suggest the frequency of hybridizing plant species is less than 6%
Are higher taxa real?
no
What are some uniparentally reproducing eukaryotic taxa?
vegetative reproduction, self-fertilization, apomixis, agamospermy
true or false: asexual reproduction is more common in plants
true
true or false: complete uniparental reproduction is common in eukaryotes
false
What are some ways plants form taxonomically confusing agamic complexes?
- core diploid species with obligate sexual reproduction
- sexual species hybridize to form polyploids that may reproduce sexually but more often by agamospermy
- can produce a continuum if variation between sexual forms
What is the best way to establish whether groups are distinct?
perform cluster analysis on many sympatric individuals (to avoid microspecies)
How do prokaryotes (bacteria) reproduce?
asexually but transduction, transformation ad conjugation can cause rare gene transfer and recombination or horizontal transfer
What is expected in prokaryotes?
something similar to agamic plant complexes but clusters are actually distinct
