lecture 2 Flashcards
what is evolution?
change over time in the proportions of individual organisms that differ genetically
what are the two types of evolution?
- microevolution
- macroevolution
what is microevolution?
change over time in gene frequency within a population (within a species)
what is macroevolution?
change over time in the proportions of species that determines the diversity of a taxonomic group (new or different species)
what is the micro evolutionary process that creates a new type of organism?
mutation
what is the macro evolutionary process that creates new types of organisms?
speciation
what is the micro evolution process that alters the proportions of different types of organism?
genetic drift, natural selection
what is the macroevolution process that alters the proportions of different types of organisms?
adaptive radiation
what is genetic drift?
random changes in allele frequencies that occur by chance alone and lead to changes in allelic ratio (microevolution)
when is genetic drift particularily impactful?
in small populations
what is adaptive radiation?
the process by which one species (common ancestor) gives rise to great diversity (mutiple species)
what is natural selection?
differential genetic contributions by particular phenotypes to the next generation
what are the differeces between mutation and genetic drift?
- natural selection causes non-random changes
- natural selection depends on both genotype and phenotype
- natural selection involves ecological interactions
- natural selection results in adaptation
what is the 1st key aspect of natural selection?
the environment can’t support the offspring produced each generation
what is the 2nd key aspect of natural selection?
individuals in a population have variable physical, physiological and behavioral traits, some of which are heritable.
what is the 3rd key aspect of natural selection?
some individuals posses traits that give an advantage over other members of the population. those who have those traits have a higher survival and reproductive chance
what is the 4th key aspect of natural selection?
traits that increase fitness become more common within a population
what is fitness?
the average contribution of genes to the next generation by a particular phenotype in a particular environment
what are outcomes that characterizes an individuals life history?
- survival to reproduce
- number and timing of reproductive events
- number of offspring per reproductive event
what are the conditions for natural selection?
- phenotypic variation
- fitness differences associated with different phenotypes
- inheritance ( genetic response)
what is adaptation?
the process by which populations evolve to become better suited to their environment
what are important characteristics of a species?
- a collective –> a group of individuals
- common ancestry –> shared geneology
- interbreeding –> common gene pool
- genetic integrity –> gene pool doesn’t regularily mix with gene pools of other species
why is there no universal definition of a species?
because species are products of continuous dynamic processes
