5 1 Evidence for evolution Understanding Evolution occurs

5. 1 Evidence for evolution Understanding: - Evolution occurs when heritable characteristics of a species change - The fossil record provides evidence for evolution - Selective breeding of domesticated animals shows that artificial selection cause evolution - Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function - Populations of a species can gradually diverge into separate species by evolution - Continuous variation across the geographical range of related populations matches the concept of gradual divergence. Applications - Comparison of the pentadactyl limb of mammals, birds, amphibians and reptiles with different methods of locomotion - Development of melanistic insects in polluted areas Nature of science: - Looking for patterns, trends and discrepancies: there are common features in the bone structure of vertebrate limbs despite their varied use

Match up the key words Variation Sections of DNA that code for certain characteristics Genes Characteristics animals have that make them better suited to their environment Adaptations Members of the same species have different characteristics Competition The ability to remain alive Survive Reproduce The ability to produce offspring Animals and plants try to get more food, space, light, mates or water to survive

Match up the key words Variation Sections of DNA that code for certain characteristics Genes Characteristics animals have that make them better suited to their environment Adaptations Members of the same species have different characteristics Competition The ability to remain alive Survive Reproduce The ability to produce offspring Animals and plants try to get more food, space, light, mates or water to survive

Evolution Changes in species over time Characteristics passed down through generations Evolution only concerns HERITABLE characteristics Things like tattoos don’t count! Understanding: - Evolution occurs when heritable characteristics of a species change

Evidence Many oppositions to theory of evolution Must take into account all evidence Understanding: - The fossil record provides evidence for evolution

Fossils Evidence for Evolution Homologous Structures Selective Breeding Vestigial Organs Pentadactyl Limbs

Evidence: Fossils Use fossil record as evidence for evolution Geological eras named using rock layers Older at bottom, younger at the top Understanding: - The fossil record provides evidence for evolution

Evidence: Fossils Inside the rock layers there were different fossils Fossil records show strong evidence for evolution Understanding: - The fossil record provides evidence for evolution

Evidence: Fossils 1. Fossils follow the sequence they would be expected to evolve (becoming more complex) 2. Fits in with ecology – plants evolved first which provide for animals Understanding: - The fossil record provides evidence for evolution

Evidence: Selective Breeding Huge differences between domestic animals and the wild species they descended from: Change after repeatedly selecting the same characteristic over and over Understanding: - Selective breeding of domesticated animals shows that artificial selection cause evolution

Think how each of these animals have been selectively bred

What do they have in common?

Evidence: Homologous structures Pentadactyl Limbs Crocodile Penguin Echidna Frogs How are their forelimbs similar? How did they move? Nature of science: Looking for patterns, trends and discrepancies: there are common features in the bone structure of vertebrate limbs despite their varied use Applications Comparison of the pentadactyl limb of mammals, birds, amphibians and reptiles with different methods of locomotion

Evidence: Homologous structure Used in many different ways Joints moves in different ways Common bone structures in all vertebrate limbs Possible explanation: common ancestor Difficult to explain without evolution Understanding: - Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function

Analogous Structures Example: tails may look very similar Different structures or functions Convergent evolution – different structure performs a similar function Understanding: Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function

Evidence: Vestigial Organs Structures that no longer have a function and are gradually lost Human appendix Small pelvis bone in whales Understanding: Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function

Galapagos Islands Lava Lizards One species present on all large main islands Each smaller island there are closely related but different species Formed by migration and speciation Understanding: Populations of a species can gradually diverge into separate species by evolution

Speciation over time Not a sudden change (happens over time) Problem for scientists classifying species More on variation later! Red Grouse: sometimes classified as separate species, sometimes same species Understanding: Continuous variation across the geographical range of related populations matches the concept of gradual divergence

Melanism What is melanism? Find out what it is! With a focus on peppered moth describe industrial melanism Applications - Development of melanistic insects in polluted areas