1. 1 Evolution of Genomes and Developmental Mechanisms Chapter 24

2. 2 Comparative Genomics Chimpanzee – Humans and chimps diverged from a common ancestor about 5 mya.  share about 98.7% of genes

3. 3 Origins of Genomic Differences Genome changes arise in at least six ways. – mutation of a single gene – regions of DNA duplicate – large chunks of chromosomes rearrange – individual chromosomes duplicate – whole genomes duplicate or combine to create polyploids – integration of foreign DNA

4. 4 Polyploidization There is growing evidence that duplication of fewer genes in organisms has been a major contributor to morphological diversity. – Polyploidy can result from either genome duplication in one species or from hybridization of two different species.

5. 5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. HaploidDiploidPolyploid

6. 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diploid: 2 x 7 Triticum monococcum (2n = 14) AA Sterile hybrid (1n = 14) AB Triticum searsii (2n = 14) BB Chromosome doubling Diploid: 2 x 7

7. 7 Lateral Gene Transfer Phylogenies are built on the assumption that genes are passed from generation to generation (vertical gene transfer). – Hitchhiking genes from other species lead to phylogenetic complexity referred to as lateral gene transfer.

8. 8 Evolution of Development Genes with similar sequences in two different species may work in different ways. – regulatory gene may turn on different sets of genes in different organisms – changing time of gene expression can also result in dramatic changes in shape – Convergent function  recruitment of existing regulatory programs for new functions

9. 9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Egg and sperm released Pluteus larva (plankton) Metamorphosis and settlement to sea-floor Direct development into adult Eggs brooded by female Adult (Benthic) Development of free-swimming larva