Evolution. Chapters 22 - 26. Evolution. Processes by which living organisms originated on Earth and have been diversified and modified through sustained changes in form and function. The earliest known fossil organisms are single-celled forms resembling modern bacteria (3.4 bya)
Chapters 22 - 26
Walking with the Dinosaurs: Genetics Video
What is considered to be an “advantageous” gene?
Are all acquired traits good, bad, or somewhere in-between?
Speciation- microevolution is changes to a single gene pool; macroevolution is changes above the species level (feather appearance)
Anagenesis-phyletic evolution- accumulation of changes that gradually transform a given species into a species with different characteristics
Cladogenesis-branching evolution- is the splitting of a gene pool into two or more separate pools, which give rise to one or more new species
Allopatric- gene flow is interupted when a population is divided into geographically isolated subpopulations (ex., squirrels in Grand Canyon); “Other country”
Sympatric- a small population becomes a new species without geographic isolation; polyploidy or autoploidy (more than 2 sets of chromosomes due to failure to complete cell division); “Same country”
Hybridization- mating or crossing of 2 true-breeding varieties
Adaptive radiation- evolution of many diversely adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges