Evolutionary genetics 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-