new material evolution final

• natural selection is a theroy that explains the observation in evolution
• natural selection is the main mechanism for evolution of adaptive characteristics or traits of an organism and is one of the many ways one type of evolution occurs.
• evolution is pluralistic with respect to mechanisms
• evolution includes variation and differential survival/ reproductive success and inheritance
• natural selection acts on standing inheritable variation in a population
• standing: traits are present
• inheritable: traits are passed down to descendents
• variation: traits must vary with enough respect to fitness to result in differential reproductive success
• natural selection acts on phenotypes
• genotypes get passed down
• the norm of reaction is a relationship between geneotype and phenotype that depends on the environment. The environment is not a filter but a promotor
• multiple pathways: a phenotype may have different genetic basis in different individuals
• epistasis: given phenotypic traits is often determined by complex interactions among multiple genes
• pleiotropy: a single gene can have effects on multiple aspects of a phenotype
• positive selection if for a trait
• negative selection is against a trait
• directional selection favors one extreme of the phenotype
• stabilizing selection favors the intermediate phenotype
• disruptive selection favors both extremes
• adaptation: feature developed as a result of natural selection for its primary function
• exaptation: a feature that performs a function that did not arise through natural selection for its current use
• swim bladders evolved from lungs because ancient seas had low amounts of oxygen
• tetrapod limbs evolved originally for aquatic locomotion
• half a wing breaks up the body outline, camouflage, arresting a fall, and stabilize running on unstable surfaces
• sexual reproduction favors anisogamy
• anisogamy is a "split strategy" with each sex. primary and secondary traits corresponding to specializations to support one gamete strategy vs the other
• different strategies mean different evolutionary pressures
• sexual selection: evolutionary dynamics arising from the interaction of these different and counter aligned evolutionary pressures that vary by sex
• sexual dimorphism- males and females of the same species look and behave differently. reflects the intensity of the sexual selection on males
• handicap principle: the very maladaptiveness that leads to these traits being selected in one form of sexual selection
• direct benefits: selection favors who choose males that provide them with resources that increase their own survival and fecundity
• female eats food and male copulation can occur is an example of direct benefits
• good genes: selection favors females who choose males that result in favorable traits
• good genes require honest indicators which are external sign of fitness
• runaway selection: favors both the male ornamentation and female preference for the ornamentation
• runaway selection is known as the fisher process
• runaway selection leads to genetic correlation which leads to self-reinforcing process
• male is selected for viability in good genes
• in runaway selection the male is selected for ornamentation
• sensory bias: female preference for a male trait evolves in a non mating context; males exploit a preexisting sensory bias by female