Joe Felsenstein GENOME 453, Winter 2004

Evolution of chromosomes and genomes

Joe Felsenstein

GENOME 453, Winter 2004

Evolution of chromosomes and genomes – p.1/28

Chromosome rearrangements

Inversion Translocation Transposition Tetraploidy

Additional question: when these occur they are

rare in a population: how do they spread?Evolution of chromosomes and genomes – p.2/28

Chironomus banded chromosomes

Evolution of chromosomes and genomes – p.3/28

Banding pattern changes

in two species of Chironomus midgesEvolution of chromosomes and genomes – p.4/28

Polytene Drosophila chromosomes

Evolution of chromosomes and genomes – p.5/28

Chromosome phylogeny of Drosophila pseudoobscura etc.

Evolution of chromosomes and genomes – p.6/28

Chromosome phylogeny of Hawaiian Drosophila

Evolution of chromosomes and genomes – p.7/28

Formation of the Hawaiian islands

plate

hot spot

Evolution of chromosomes and genomes – p.8/28

Geology of the Hawaiian islands

Evolution of chromosomes and genomes – p.9/28

Inferred migration events on the Hawaiian islands

Evolution of chromosomes and genomes – p.10/28

Paracentric and pericentric inversions

A B C E F G H I JD

A Paracentric Inversion

A Pericentric Inversion

A B C E F G H I JD

A B C E F G H I JD

A B G H I JCEF D

A B G H I JCEF D

A B C E F G H I JD

A B C I JEFGH D

A B C I JEFGH DEvolution of chromosomes and genomes – p.11/28

Pairing in a paracentric inversion heterozygote

A B

C

D

E

F

G H I

A B

C

D E

F

G H I

J

J

Evolution of chromosomes and genomes – p.12/28

Crossing-over in a paracentric inversion heterozygote

A B

C

D

E

F

G H I

A B

C

D E

F

G H I

J

J

Evolution of chromosomes and genomes – p.13/28

Pairing in a pericentric inversion heterozygote

A B C

D

E

F

G

H

I

A B C

D

E F G

H

I

J

J

Evolution of chromosomes and genomes – p.14/28

Crossing-over in a pericentric inversion heterozygote

A B C

D

E

F

G

H

I

A B C

D

E F G

H

I

J

J

Evolution of chromosomes and genomes – p.15/28

A translocation

A B C D E F G H I J K L M N O P Q

A B C D E F G H I J N O P QK L M

E F G H I J N O PQ K L M

ABCDE F G H I J N O PQ K L M

ABCD

Before

After

Breaks

Rearrangement

Evolution of chromosomes and genomes – p.16/28

Segregation of translocation heterozygote

at first division of meiosis metaphase

EFGHIJ

Q

AB

CD

NOP KLM

QNOP KLM

EFGHIJ

AB

CD

pairs with a pair of untranslocated chromosomes

A pair of translocated chromosomes

Evolution of chromosomes and genomes – p.17/28

Adjacent segregation in translocations

AB

CD

NOP KLMEFGHIJ

AB

CD

EFGHIJ

Q QNOP KLM

... Leads to deletions and duplications.

Evolution of chromosomes and genomes – p.18/28

Alternate segregation in translocations

EFGHIJ

Q

AB

CD

NOP KLM

Q

NOP KLM

EFGHIJ

AB

CD

... Leads to euploid (normal gene complement) gametes

Evolution of chromosomes and genomes – p.19/28

The fern Ophioglossum, high number champion

Evolution of chromosomes and genomes – p.20/28

The ant Myrmecia, low chromosome number champion

Evolution of chromosomes and genomes – p.21/28

Distribution of chromosome numbers in mammals

Evolution of chromosomes and genomes – p.22/28

Karyotypes of Drosophila species

Evolution of chromosomes and genomes – p.23/28

Karyotypes of gymnosperms

Evolution of chromosomes and genomes – p.24/28

Mouse and human maps compared

(this shows only the larger homologies)Evolution of chromosomes and genomes – p.25/28

Polyploid species

Barriers between mating of polyploids and euploids

gametes

triploid offspring

a tetraploid an ordinary diploid

gametes

the resulting aneuploid offspring

Evolution of chromosomes and genomes – p.26/28

Polyploid evolution in Clarkia

Evolution of chromosomes and genomes – p.27/28

How it was done

This projection produced

using the prosper style in LaTeX,

using Latex to make a .dvi file,

using dvips to turn this into a Postscript file,

using ps2pdf to mill a PDF file, and

displaying the slides in Adobe Acrobat Reader.

Result: nice slides using freeware.

Evolution of chromosomes and genomes – p.28/28