Evidence for Evolution

Evidence Available to DarwinEvidence Available to Darwin FossilsFossils TaxonomyTaxonomy Comparative AnatomyComparative Anatomy Comparative EmbryologyComparative Embryology BiogeographyBiogeography

Fossils

Fossils areFossils are remains or imprints of past liferemains or imprints of past life preserved in sedimentspreserved in sediments occur in layers (strata)occur in layers (strata) many no longer occurmany no longer occur others resemble modern speciesothers resemble modern species

Strata layers in Rocks

Fossilized remains of a bird like dinosaur Archeopteryx

Fossil trilobite

Fossils in Amber

Fossil Jellyfish

Fossil Evidence for Evolution

Fossils distributed consistently throughout Fossils distributed consistently throughout strata of same agestrata of same age

Order of fossil appearance shows more Order of fossil appearance shows more complex forms appearing after simpler complex forms appearing after simpler formsforms

Recent fossils (new strata) most closely Recent fossils (new strata) most closely resemble modern organismsresemble modern organisms

Evidence for Evolution

Evidence Available to DarwinEvidence Available to Darwin FossilsFossils TaxonomyTaxonomy Comparative AnatomyComparative Anatomy Comparative EmbryologyComparative Embryology BiogeographyBiogeography

Taxonomy

Hierarchical classification structure Hierarchical classification structure developed by Linnaeusdeveloped by Linnaeus

Implies that species can be grouped Implies that species can be grouped together based on their relatednesstogether based on their relatedness

Bears with bears, bees with other beesBears with bears, bees with other bees A family tree can be made implying descentA family tree can be made implying descent

Related species of Ursus

Family Tree of Bears

Evidence for Evolution

Evidence Available to DarwinEvidence Available to Darwin FossilsFossils TaxonomyTaxonomy Comparative AnatomyComparative Anatomy Comparative EmbryologyComparative Embryology BiogeographyBiogeography

Comparative Anatomy

Compares anatomical structures from Compares anatomical structures from different organismsdifferent organisms

Similar structures in two or more species Similar structures in two or more species are called are called homologous structureshomologous structures

Homologous structures may perform Homologous structures may perform different tasks in different organismsdifferent tasks in different organisms

Homologous forelimbs

Family Tree of the Horse (Equus)

Evidence for Evolution

Evidence Available to DarwinEvidence Available to Darwin FossilsFossils TaxonomyTaxonomy Comparative AnatomyComparative Anatomy Comparative EmbryologyComparative Embryology BiogeographyBiogeography

Comparative Embryology

Embryos (young stage of organisms are Embryos (young stage of organisms are compared)compared)

Show similar features due to shared Show similar features due to shared ancestryancestry

All vertebrates haveAll vertebrates have tailstails gill-like branchial archesgill-like branchial arches

Evidence for Evolution

Evidence Available to DarwinEvidence Available to Darwin FossilsFossils TaxonomyTaxonomy Comparative AnatomyComparative Anatomy Comparative EmbryologyComparative Embryology BiogeographyBiogeography

Biogeography

Distribution of speciesDistribution of species Many related species occur across the earthMany related species occur across the earth Isolated areas (islands, Australia) often Isolated areas (islands, Australia) often

have unique specieshave unique species Biogeography explained by continental drift Biogeography explained by continental drift

of plates and speciationof plates and speciation

Map of Oceanic Crust Ages in the Atlantic

Map of Earthquake Epicenters, 1980-1990

Molecular Biology

Not available to Darwin in 1800’sNot available to Darwin in 1800’s Includes comparisons ofIncludes comparisons of

protein sequencesprotein sequences DNA sequencesDNA sequences cytochrome ccytochrome c chloroplast genomes (plants only)chloroplast genomes (plants only)

Used to developed phylogenetic trees Used to developed phylogenetic trees (hypothesized relationships)(hypothesized relationships)