midterm 2 Flashcards
Phenotypic traits have a discontinuous distribution because?
they are polygenetic
whats the difference between polyphenic and polygenic traits?
polyphenic traits are the multiple discrete phenotypes that can arise from different alleles within a population. Polygenic traits are traits influenced by many genes leading to a continuous distribution of phenotypic variation over a given range
what were two important facts of charles darwin theory n evolution by natural selection?
- no two individuals are exactly the same, rather, every population expresses variability
- much of the variation among individuals within a population is heritable
can genes that pass though environmental stimuli be passed to offspring?
yes individuals can inherit mechansims that respond to the environment
how does broad sense heritibility differ from narrow sense?
broad–> the proportion of the total phenotypic variance of a trait that is attributable to genetic variance, genetic variance is a single value
narrow–> total phenotypic variance that is attributable tot he additive effects of alleles
what source does variation arise?
genetic recombination, mutation, independent assortment
what is the selection differential?
the difference between the trait mean of reproducing individuals and the trait mean of the general population
what mechanism is most sensitive to variation among individuals?
natural selection because variation among individuals is the foundation for relative success of individuals and that relative success affects frequencies
aposematism ?
an antipredator strategy used by a potential prey item to signal danger or lack of patability.
ecological character displacement?
evolution driven by competition between species for a shared resource, traits evolve in apposing directions, minimizing overlap.
selective sweep?
situation in which strong selection can sweep an allele to fixation so fast that there is little opportunity for recombination.
extended phenotypes?
structures constructed by organisms that can influence there performance or success.
are homologous traits ancestral or dervived?
they can be both ancestral or derived, depends on the clade of interest
are synapomorphies important when developing phylogenies?
yes because they are shared derived traits, that can distinguish groups of species
what is purifying selection?
selection that removes deleterious alleles from a population, common form of stabilizing selection