chapter 10 - natural selection Flashcards
can evolution by natural selection be observed over time?
yes
what can happen to the direction and magnitude of natural selection over time?
it can vary
how do adaptations to similar selective pressures come up ?
via similar or different pathways in different populations
what aspects of natural selection can vary over space?
the direction and magnitude
do different agents of selection work simultaneously or one at a time in opposite directions?
simultaneously
what did beak size in medium ground finches show?
variation in beak size influences efficiency at eating different types of seeds
what change in diet did birds with big beaks have when there were plenty of seeds for the species?
no change in diet- ate the same seeds
what change in diet did birds with different beak sizes have when there was a drought in food.
drought led to change in diet based on beak sizes- big beaks could eat seeds hat were hards to crack
what evolutionary components do beak size have?
variable, heritable, and linked to performance on different seed types
is direction and magnitude of natural selection variable over time?
yes
why did sticklebacks evolve armor?
the minimize injury due to predation
what causes variation in phenotype in sticklebacks?
ectodysplasin (Eda) gene
what is the problem with producing armor ?
energetically costly
do places with high predation select for high or low Eda?
high Eda
is low Eda more commonly found in freshwater or marine environments?
freshwater
light coat colors evolving independently in different populations is an example of what type of evolution?
convergent
allopatry
when populations of the same species are geographically separated, preventing gene flow between them.
sympatry
when populations live in the same geographic area but do not interbreed due to other isolating mechanisms.
what type of phenotype is gall diameter in the gall fly?
an extended phenotype
is gall size heritable?
yes, it is variable and heritable with a strong genetic component
examples of artificial selection with how humans have affected evolution in wild populations
-agriculture and domestication
-creating selection for the evolution of pesticide and herbicide resistance
-changing environment- new selective pressures and invasive species
-selection for undesirable traits through hunting and fishing
how have humans driven artificial selection in crop production?
one plant has turned into several different plants.
Brassica oleacea turns into broccoli, collard greens, brussel sprouts, cabbage, etc.
how many genes have a major effect on the maize morphological evolution?
3 genes
what aspect of agriculture acts as agents of selection and drives rapid evolution?
pesticides and herbicides
