BIO 3122 M2 Questions With Complete Solutions
2 reasons why gene trees may not match species trees Correct
Answers 1) Introgression and hgt: hybridization events
introduce different genes.
2) Incomplete lineage sorting: gene trees don't match species
trees. Coalescent events in gene trees may be deeper than in
species tree.
2 types of homologous characters Correct Answers 1) Shared
derived characters (synapomorhphies): traits that differentiate
members of a clade from other clades
2) Shared ancestral characters: characters common to a larger
group that stems from a common ancestor (less exclusive)
2 types of homplasy Correct Answers 1) Analogous traits
2) Evolutionary reversals
3 methods of phylogenetic inference Correct Answers 1)
Maximum parsimony
2) Maximum likelihood
3) Bayesian methods
3 reasons why two segments of DNA can have shared ancestry
(not for the reason of being homologous). Correct Answers 1)
Gene duplication creates paralogs (identical sequences but then
diverge due to speciation) (i.e. human histone H1.1 and H1.2)
2) Introgression and hgt: species "grab" chromosomal chunk
from another to gain some advantage that comes with having
that gene (i.e. to be able to mimic). Gene flow at the genetic
level.
, 3) A speciation event in which case genes are considered
orthologous (i.e. chimpanzee H1.1 and human H1.1)
4 issues with the biological species concept. Correct Answers
1) What constitutes "reproductively isolated"?
2) Reproductive isolation doesn't make sense for asexual
species.
3) How is it applicable to species only known from fossils?
4) How to measure reproductive isolation? (many barriers)
- But if you can demonstrate total reproductive isolation, best
model. Difficult when there is less than total isolation.
a clade Correct Answers a monophyletic group that includes all
species descended from a common ancestor
a cladogram Correct Answers A phylogenetic tree that only
shows the evolutionary relationships.
a genetic synapomorphy Correct Answers Change in base pair.
a phylogram Correct Answers A phylogenetic tree with branch
lengths proportional to the amount of genetic change.
allopatric speciation Correct Answers - Reproductive isolation
due to geographical isolation.
- No gene flow.
- Allele frequencies diverge due to the accumulation of
mutations, drift and selection in each population.
an isolating barrier Correct Answers Specific mechanism that
acts to reduce or prevent gene flow.
2 reasons why gene trees may not match species trees Correct
Answers 1) Introgression and hgt: hybridization events
introduce different genes.
2) Incomplete lineage sorting: gene trees don't match species
trees. Coalescent events in gene trees may be deeper than in
species tree.
2 types of homologous characters Correct Answers 1) Shared
derived characters (synapomorhphies): traits that differentiate
members of a clade from other clades
2) Shared ancestral characters: characters common to a larger
group that stems from a common ancestor (less exclusive)
2 types of homplasy Correct Answers 1) Analogous traits
2) Evolutionary reversals
3 methods of phylogenetic inference Correct Answers 1)
Maximum parsimony
2) Maximum likelihood
3) Bayesian methods
3 reasons why two segments of DNA can have shared ancestry
(not for the reason of being homologous). Correct Answers 1)
Gene duplication creates paralogs (identical sequences but then
diverge due to speciation) (i.e. human histone H1.1 and H1.2)
2) Introgression and hgt: species "grab" chromosomal chunk
from another to gain some advantage that comes with having
that gene (i.e. to be able to mimic). Gene flow at the genetic
level.
, 3) A speciation event in which case genes are considered
orthologous (i.e. chimpanzee H1.1 and human H1.1)
4 issues with the biological species concept. Correct Answers
1) What constitutes "reproductively isolated"?
2) Reproductive isolation doesn't make sense for asexual
species.
3) How is it applicable to species only known from fossils?
4) How to measure reproductive isolation? (many barriers)
- But if you can demonstrate total reproductive isolation, best
model. Difficult when there is less than total isolation.
a clade Correct Answers a monophyletic group that includes all
species descended from a common ancestor
a cladogram Correct Answers A phylogenetic tree that only
shows the evolutionary relationships.
a genetic synapomorphy Correct Answers Change in base pair.
a phylogram Correct Answers A phylogenetic tree with branch
lengths proportional to the amount of genetic change.
allopatric speciation Correct Answers - Reproductive isolation
due to geographical isolation.
- No gene flow.
- Allele frequencies diverge due to the accumulation of
mutations, drift and selection in each population.
an isolating barrier Correct Answers Specific mechanism that
acts to reduce or prevent gene flow.
