Evidence of Evolution

What is Natural Selection? What is evolution? = The change of a species population over generations What is Natural Selection? = organisms best suited to their environment reproduce more successfully Over generations their favorable traits increase in their population

DARWIN Survival of The Fittest Fossil Record Biogeography DARWIN EVIDENCE? Comparative Anatomy RESEARCH? Survival of The Fittest Comparative Embryology Biochemistry/ DNA

CE – Comparative Embryology FR – Fossil Record B – Biogeography “CElia and FRed Bought CAndy Before Dinner” CE – Comparative Embryology FR – Fossil Record B – Biogeography CA – Comparative Anatomy BD – Biochemistry/DNA

Fossil Evidence What does fossil evidence show about evolution? Fossils in the lower layers of the Earth are older and less complex than fossils in the upper layers How are fossils formed? Sedimentary rocks, molding and casting by wind or water

(no, scientists did not go on DATES with the fossils!) Dating of fossils (no, scientists did not go on DATES with the fossils!) How did scientists determine relative age (or approximate age) of rocks and fossils? Process called relative dating They can compare ages between fossils in different layers to determine which is older or younger

Dating of Fossils How do scientists determine absolute age of rocks and fossils? Age is determined by measuring the amount of radioactive evidence Carbon 12 Carbon 14 Half-life

Geographic Distribution (Biogeography) What is biogeography? = the study and comparison of fossils and living organisms and where they are located (geographical distribution) Animals on islands look like others on the closest land mass rather than far away distances

Biogeography cont. In other words… Two species evolve similar characteristics based on similar environments

Homologous Structures What is the definition of homologous structures? = similar features that occur in most organisms because they came (originated) from a common or shared ancestor What are some examples? Example: human and penguin arm

Homologous Structures Very similar skeletal structure

Analogous Structures What are analogous features? Similar structures found in organisms that have the same function, but have different embryological development in response to living in similar environments What are some examples? Example: bird and bee wings

Analogous Structures Both organisms can hover to feed on flowers, BUT there is NO ANATOMICAL OR EMBRYOLOGICAL SIMILARITY between the wings. Their wings evolved INDEPENDENTLY AND DIFFERENTLY

Vestigial Structures What is a vestigial structure or organ? Functionless structure that occurs in organisms in the present, but had a function in an ancient species Give an example. Example: tailbone in humans pelvic bone in whales and snakes Appendix in humans

These do not have a function

No function for these structures

Embryonic Development (Embryology) How do scientists use similarities in early development as evidence for evolution? They observe the embryos to determine similar structures. This shows that they share a common ancestor

Embryonic Development (Embryology) For example each embryo had gills and a tail in the beginning stages of development

Biochemistry and DNA In organisms, amino acid sequences are very similar, BUT not exact. An example would be Hemoglobin. How do scientists believe if organisms are closely related or not? The more-similar the homologous proteins in different species, the more closely related

Patterns of Evolution Explain coevolution and provide an example The change in two or more species in close association with each other Example: plants and animals that feed off of them (humming bird and the plant it feeds on) Butterfly and the plant

coevolution

Patterns of Evolution Explain convergent evolution and provide an example Unrelated species can develop similar characteristics Example: shark, penguin, and porpoise Share similar characteristics that suit their environment Long stream-lined body Fins that match in appearance and function

Patterns of Evolution Explain divergent evolution and provide an example Two or more related populations or species become more dissimilar over time (they adapt to their environment) Example: finches – related species but have different beaks due to different environments