Transcript Chapter 21: Evolutionary genetics Fig. 21-1

Chapter 21:
Evolutionary genetics
Fig. 21-1
Variation can be driven differently
within or between populations
Genetic change is directed by a combination of evolutionary forces
which tend to increase (blue) or decrease (red) variation
Fig. 21-5
Origins of new genes:
Polyploidy (provides additional gene copies to be
“molded” by mutation and selection)
Dicotyledonous plants vary widely in their chromosome number
Polyploidization is a common feature of their evolution
Fig. 21-9
Origins of new genes:
Polyploidy (provides additional gene copies to be
“molded” by mutation and selection)
Duplications (example: globin gene evolution)
Globin family:
myoglobin and predecessors
erythrocyte hemoglobins
Expression of α-globins and β-globins during human development
Fig. 21-10
Human globin sequence divergence reflects their ancestry
α and ζ are most closely related
β, γ and ε are most closely related
Human globin sequence divergence reflects their ancestry
α and ζ are most closely related
β, γ and ε are most closely related
Fig. 21-11
ζ → α “switch” in the embryo (α maintained throughout remaining life)
ε → γ “switch” in embryo
γ → β “switch” at birth
Fig. 21-10
Diversification of
β-globin genes during
vertebrate evolution
Similar structures of apparently disparate genes & proteins
can reflect common ancestral origins
Fig. 21-
Nuclear and mitochondrial codon usages
reflect distinct origins
Multiple prokaryotic “invasions” of eukaryotes?
Rate of molecular evolution
can be studied in neutral mutations
rate of neutral replacement of alleles by genetic drift
approximates
rate of mutation yielding neutral mutation
Can directly measure nucleotide substitution (divergence)
(“molecular clock”)
β-globin nucleotide substitutions over time (molecular clock)
Fig. 21-13
Rate of molecular evolution
can be studied in neutral mutations
rate of neutral replacement of alleles by genetic drift
approximates
rate of mutation yielding neutral mutation
Can directly measure nucleotide substitution (divergence)
(“molecular clock”)
Substitution rates in proteins is a function of the
sensitivity of their function to substitutions
Variation in protein structure reflects constraints on its function
Fig. 21-14
Distinguishing neutral and adaptive nucleotide substitutions
Nonsynonymous substitutions are apparently enriched
(appear to derive from selective adaptation)
Evolutionary homologies
among forelimb skeletal
elements in vertebrates
Fig. 21-15
Evolutionary homologies among signal transduction pathways
that direct cell-specific transcription in development
of insects and mammals
Fig. 21-16
Comparative genomics: proportions of genomes dedicated to
diverse functions in various organisms
Fig. 21-17
Comparative genomics: homologies of human proteins
with proteins of other organisms
Fig. 21-18
Comparative genomics: synteny of the human and mouse genomes
reflects ancestral rearrangement histories
Fig. 21-19
Recommended problems in Chapter 21: 4, 10, 11, 12, 14
Fig. 21-