Lecture 2: Species Reality and Concepts pt.1

Question 1

What ways do most biologists act as if species are real?

Answer 1

1. naturalists label specimens with scientific names
2. systematists reconstruct relationships among species and publish phylogenies
3. population geneticists measure DNA variation within species
4. ecologists calculate species diversity and document whether species are going extinct or not

Question 2

Why do botanists claim species are subjective divisions of nature for human convenience?

Answer 2

plant mating systems have made it difficult to identify species boundaries

Question 3

Why is it important to study if species are realities of nature or theoretical constructs made by humans in groups that live in sympatry?

Answer 3

geographic variation within species can lead to morphological or genetic aps between individuals

Question 4

true or false: Darwin believed species are real

Answer 4

false

Question 4

What did Coyne and Orr believe

Answer 4

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

Question 4

What 3 methods determine whether species are real in sexually reproducing groups?

Answer 4

1. arguments from common sense
2. comparing between indigenous and scientific species classifications
3. statistical identification of clusters

Question 5

What are the arguments from common sense?

Answer 5

1. species are real because everyone recognizes
2. clusters are often discrete even to casual observers
3. the usefulness of field guides is proportional to the discreteness of taxa

Question 6

What is the counterargument to the common sense argument?

Answer 6

humans have a propensity to divide a continuous array of organisms into discrete units

Question 7

What evidence disproves that humans have a propensity to divide a continuous array of organisms into discrete units?

Answer 7

remarkable coincidence between indigenous species and Linnaean species

Question 8

What is the main criticism to indigenous and scientific species evidence?

Answer 8

this is just how human brains are wired

Question 9

What is statistical identification of clusters?

Answer 9

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

Question 10

What evidence supports statistical identification of clusters?

Answer 10

Neff and Smith’s discriminant analysis of morphology in sunfish and shiners, found sympatric species are well differentiated and hybrids have intermediate morphology

Question 11

Why does the presence of hybrids not refute the distinctness of species?

Answer 11

1. hybrids can be rare or sterile
2. fuzziness of plant species boundaries caused by hybridizations may be overstated
3. surveys suggest the frequency of hybridizing plant species is less than 6%

Question 12

Are higher taxa real?

Answer 12

no

Question 13

What are some uniparentally reproducing eukaryotic taxa?

Answer 13

vegetative reproduction, self-fertilization, apomixis, agamospermy

Question 14

true or false: asexual reproduction is more common in plants

Answer 14

true

Question 15

true or false: complete uniparental reproduction is common in eukaryotes

Answer 15

false

Question 16

What are some ways plants form taxonomically confusing agamic complexes?

Answer 16

1. core diploid species with obligate sexual reproduction
2. sexual species hybridize to form polyploids that may reproduce sexually but more often by agamospermy
3. can produce a continuum if variation between sexual forms

Question 17

What is the best way to establish whether groups are distinct?

Answer 17

perform cluster analysis on many sympatric individuals (to avoid microspecies)

Question 18

How do prokaryotes (bacteria) reproduce?

Answer 18

asexually but transduction, transformation ad conjugation can cause rare gene transfer and recombination or horizontal transfer

Question 19

What is expected in prokaryotes?

Answer 19

something similar to agamic plant complexes but clusters are actually distinct