Evolution

Evolution- the gradual accumulation of adaptations over time; a gradual change over time

Adaptation- evolution of a structure, behavior , or internal process that enables an organism to respond to stimuli and better survive in an environment

Fossils Age of earth- estimated 4.6 billion years old Fossil- physical evidence of an organism that lived long ago that scientist use to study the past; evidence may be in rocks, amber, or ice

Paleontologist- scientist who study ancient life Paleontologist- scientist who study ancient life. They are like detectives who use fossils to understand events that happened long ago.

Fossil record- name given to the history of life on earth as shown by fossils

Why is fossil record incomplete- not all fossils have been found, and not all organisms have been preserved

Sedimentary rock- small particles of mud, sand or clay that is compressed over time and hardened

How are fossils formed? Most fossils are formed in sedimentary rock from being buried in the mud, sand, or clay before it hardens

Relative dating- scientist determine the order of appearance and extinction of species that formed fossils in the layers. Layers at the surface must be younger than the deeper layers

Radioactive dating- AKA radiometric dating and carbon dating- utilizes radioactive isotopes in rocks or fossils.

Radioactive dating is more accurate

What is half life? b/c every radioactive isotope has a characteristic decay rate, scientist use the rate of decay as a type of clock

Extinction- when the last members of a species die

Homology Homologous structures- structures with common evolutionary origins, can be similar in arrangement, in function, or both; provides evidence of evolution of a common ancestor

Examples- 4 limbs of a crocodile Whales-flippers Birds-wings

Embryology- study of embryos which is the earliest stage of growth and development of both plants and animals; differences and similarities among embryos can provide evidence of evolution

Example. Can’t tell the embryo of a fish, bird, or mammal apart Example.. Can’t tell the embryo of a fish, bird, or mammal apart. They all have gill slits, tail, and notochord. Fish are the only ones who keep them throughout life.

Biochemical similarities (genetic)- provides evidence for evolution- All organisms have the same DNA and RNA

Vestigial structures- body structure that has no function in a present day organism but was probably useful to an ancestor long ago Appendix

Analogous structures- structures that do not have a common evolutionary origin but are similar in function

Example- a bird wing and a butterfly wing, both are used for flying; however, they are the same structure.

Natural Selection- mechanism for change in populations; occurs when organisms with certain variations survive, reproduce, and pass their variations to the next generation; can be directional , disruptive, or stabilizing

Charles Darwin- father of evolutionary theory Charles Darwin- father of evolutionary theory. Proposed the theory of natural selection.

Another name for natural selection- survival of the fittest

Peppered moth- H.B. Kettlewell studied camouflage adaptations of a population of light and dark colored peppered moths. The moths rested on the trunks of trees.

Camouflage- enables species to blend with their surroundings Ex- peppered moth , snake you do not see

Mimicry- a structural adaptation that enables one species to resemble another species Ex- butterfly that looks like a wasp

Fittest- how suitable the gene is in the environment for a particular population Niche- role and position a species has in its environment

Genetic drift-alteration of allelic frequencies in a population by chance events, result in genetic equilibrium

Speciation- process of evolution of new species that occurs when members of a similar populations no longer interbreed to produce fertile offspring

Divergent evolution- evolution in which species that once were similar to ancestral species diverge; occurs when populations adapt to different environmental conditions,

Adaptive radiation- divergent evolution in which an ancestral species evolve into an array of species to fit a number of diverse habitats

Convergent evolution- evolution in which distantly related organisms evolve similar traits, occurs when unrelated species occupy similar environments