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 can 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. 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 Development of melanistic insects in polluted areas

What is evolution? Species changes over time Characteristics passed down through generations Evolution only concerns HERITABLE characteristics

Theory A coherent group of propositions formulated to explain a group of facts or phenomena in the natural world and repeatedly confirmed through experiment or observation

Evidence Many oppositions to the theory of evolution Who is proposing these oppositions? What are their arguments? Fossils Selective breeding Antibiotic resistance Vestigial organs DNA/proteins

Selective breeding Selective breeding

Selective breeding Huge differences between domestic animals and the wild species they descended from: Change after repeatedly selecting the same characteristic over and over How would a farmer use selective breeding?

Big Lad

Fossils Use fossil record as evidence for evolution Geological eras named using rock layers Older at bottom, younger at the top Main evidence is fossils

Radioactive dating techniques used Clear patterns to be found including ‘intermediate’ species Many logical patterns simple to complex Plants before animals video

What do they have in common?

Make a colour key and identify

Vertebrate limbs (Homologous structures) The study of comparative anatomy Structures that are similar in shape in different species Used in many different ways - Joints moves in different ways for locomotion Common bone structures in all vertebrate limbs

Homologous structures Possible explanation: common ancestor Adaptive radiation: Same origin but have adapted for different purposes More similar in structure = more closely related Difficult to explain without evolution

Vestigial organs/structures Structures that no longer have a function and are being gradually lost Human appendix Small pelvis bone and hind limbs in whales Laryngeal nerve in a giraffe Giraffe

Analogous Structures- Convergent Evolution Example: tails may look very similar Different structures and functions Convergent evolution – different structure performs a similar function because they have evolved in the same environment

Also in this section in the book but we will look at these after natural selection. Speciation Patterns of variation Industrial melanism Qs

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