Evolutionary Biology Define Evolution Change through time Darwin & Natural Selection History of Darwin Naturalist (old-school biologist) collected specimens of various animals locally 1831 employed as a officer on the HMS Beagle for a 5 year mapping expedition. Like most biologists, as he collected specimens from other continents; noticed differences of anatomy By the time he got to the Galapagos islands started to notice the similarities between different species History of Darwin Observed that among similar species on different islands: their differences were of body parts that were used differently Anatomical differences were based on different environments. Darwins Idea Natural selection Suggested that there was a struggle for existence among individuals within a population ( for what?, type?) Process of Natural Selection 1)Overproduction of offspring 2)Individuals w/in a popn will have genetic variation.(caused by?) 3)Individuals with more favorable variations FOR THAT ENVIRONMENT are more likely to survive and pass those alleles on to offspring. 4)Gradually, over many generations, the individuals w/in popn will have more of that variation (adaptation) Depends on environment, and when environment changes so will the pops w/in it by this process. Evolution by Natural Selection The struggle for existence: Intraspecific competition for resources This struggle leads to the survival of the fittest. Fitness: How many viable offspring an organism produces in their reproductive years The fitness of an organism depends on their adaptations Adaptation Any inheritable trait or variation that aids in the reproductive success of organism w/in a population. Develop through natural selection. Three Types 1.Structural: a physical characteristic (ex) Camouflage, mimicry, defense 2.Behavioral: (ex) hunting in groups, Herding, bird songs, dancing 3.Physiological: biochemical characteristics (ex) resistance to pesticides, antibiotics, pheromones Structural Behavioral Physiological Evolution by Artificial Selection Humans select variations that were found to be useful or beneficial to us. Produced diverse domestic plants and animals that are vital to our survival.