Evolution and Adaptation Flashcards
who was before Darwin?
Lamarck
what was Lamarck’s contributions to evolutionary thought?
species change over time
changes pass on from one generation to another
organisms respond to environmental conditions
hypothesized mechanism, how species evolve over time
what is Darwin’s first observation and interference?
observation: populations have great capacity to grow, but are ultimately limited by resource availability
Interference: competition between individuals in a population for resources
what is a Darwin’s 2nd observation and interference?
observation: individuals vary within population in heritable traits related to competitive success (ultimately survival)
Interference: some individuals more likely to survive and reproduce that others
what is Darwin’s third observation and interference?
observation: individual may also vary within populations in heritable traits related to reproductive competitive success (reproductive success)
inference: some individuals more likely to reproduce than others (traits with competitive success will mate more)
what is adaptive evolution?
a population’s characteristics change over time, as advantageous traits become more common
competition for seed among finches
resources were noy limited, there would be no consequences for phenotypic variations
what is the Phenotypic variation in beak length among finches?
of there was no phenotypic variation there can be no differential performance between individuals
what is the beak length influences an individual’s ability to consume seeds
the functional relationship between phenotype and performance
what is the Beak length variation has an genetic component
evolution is change in allele frequencies over time, so variation in trait must be heritable to have an effect
what is the beak length has an environmental component?
not necessary for evolution to occur
what is natural selection?
alleles increase likelihood of survival and the reproductive output of the individuals that carry them become more common in subsequent generations
what is artificial selection
selective breeding of animals or plants to ensure that certain desirable traits appear appear at higher frequencies in successive generations
what are the changes on allele frequencies over time?
evolution encompasses all types of changes brought about by selection processes and chance events
Darwin suggested mechanism of natural selection (adaptive evolution) used by domesticated species
illustrated by artificial selection
what is artificial selection?
selective breeding of animals or plants to ensure that certain desirable traits appear at higher frequencies in successive generations
what happens with domesticated species and adaptation?
depending on environment, different phenotypes are adaptive or deleterious
traits that put individuals at a disadvantage may be desirable to humans and become favoured by selective breeding
what is an endemic species?
a species that is found in a single, limited, geographic region on earth
what is an adaptation?
characteristics that help an organism survive longer or reproduce more under a particular set of environmental conditions
what is fitness?
an individuals reproductive success
what is the misconception about environmental challenges?
misconception: environmental challenge is what brings about new genetic variation
reality: selection often acts on pre existing variation
what is convergent evolution?
the evolution of similar adaptations in distantly related organisms that occupy similar environments
what is anagenesis?
accumulation of changes in lineages, with no change in number of species
what is cladogenesis?
accumulation of changes in 2 or more descendent species (splitting of lineages)
what is the rate of speciation?
thought changes were slow and gradual
puncture equilibrium: a fast change followed by a period of no change
what is generation time?
the average time between the birth of an organism and the birth of its offspring
what are the three changes in chromosome numbers?
euploids
aneuploids
polyploids
what is euploids?
normal number of chromosomes
what is aneuploids?
extra or missing chromosomes
what is polyploids?
extra set of chromosomes
spindle fails during mitosis
what is autopolyploid?
2 different species that mate and make a genetic hybrid
2 diploids from 2 parents
what is a misconception about evolution?
that it is linear
there is a lot of different branches that didn’t survive due to selection
reality: evolutionary radiations
what is population genetics?
the branch of science that studies the prevalence and variation in genes among populations of populations of individuals
what is microevolution?
small scale changes in the genetic makeup within populations over time, often in response to shifting environmental circumstances or chance events
what is macroevolution?
large scale evolutionary patterns in the history of life, producing major changes in species and higher taxonomic groups
what can maladaptation arise
mutation, genetic drift, variation in selection, heterozygote advantage, gene flow, lack of sufficient genotypic variation, trade offs between traits
what is evolutionary developmental biology?
study effects of variation in genetic sequence, timing and location of gene expression during growth and development
what is homeotic genes?
control transcription of development genes
small changes in homeotic genes can produce large changes in morphology
what is developmental switches?
regulatory sites of transcription factors switch on or off downstream genes
determined by natural selection
small changes in regulation produced large changes in morphology
