Lecture 20 Vocab and Prereading Flashcards
adaptation
a trait that enhances the fitness of an organism to its environment;
artificial selection
a form of directional selection similar to natural selection (breeding dogs to get specific physical trait
allele frequency
proportion of a specified allele among all the alleles of a gene in a population
allele fixation
when over generations, one allele of a gene becomes the only ones present in a population
allele loss
when a particular allele becomes less common in a population over time
balancing natural selection
natural selection that acts to maintain two or more alleles of a given gene in a population
eg: *a bunny with long ears can hear predator better
*bunny w short ears can move through bushes quicker to get away from predators
continuous (polygenic) traits
characteristic that varies across a tangle and is controlled by multiple genes
eg: height(it varies and many genes come together to influence how tall someone is
discrete trait
characteristics that have distinct separate options
*traits controlled by just one or a few genes
eg: that doll has blonde hair, that doll has red
directional natural selection
“nature pushing things in a certain direction based on what works better in the environment
eg: birds in forest have huge beaks and small ones. change in environment occurs causing bigger seeds and it’s easier for bigger beaks to eat the seeds
disruptive natural selection
when nature favors both extreme traits
eg: brown rabbit and white rabbit
white rabbit can hide in snow brown rabbit can hide in brown bushes
evolution
theory of how all living things are related in some way
fitness
how well living this so in terms of survival and reproduction
eg: very fast cheetah, can find food quickly, naturally stronger than others,
(how these traits will pass down to their offspring)
gene interaction
how different genes team up and work together to create the traits we see in living things
environment interaction
how surroundings of environment can influence and shape the traits or characteristics of living things
heterozygote advantage
where individuals with two different versions (alleles) of a particular gene have a better chance of survival or reproductive success compared to individuals with two identical alleles (homozygotes)
natural selection
polygenic(quantitative) inheritance
polymorphism
positive selection
relative fitness
negative selection
stabilizing natural selection is
nature favoring the average or middle traits because they seem to work well and help the organisms survive and have babies
example of heterozygote advantage
sickle cell anemia-
if you have two copies of the normal allele (AA) you’re at risk for malaria. But if you have two copies of the sickle cell(aa) your might have sickle cell. Being heterozygote and having Aa gives you a better advantage if surviving malaria without getting sickle cell anemia
natural selection changes
allele frequencies
positive selection increases the frequency of
beneficial alleles
negative selection decreases the frequency of
deleterious alleles
natural selection increases the frequency of
advantageous mutations
natural selection decreases the frequency
of deleterious mutations
when a allele is fixed what’s the frequency?
1
when an allele is lost or eliminated the frequency is
0
directional selection can be applied to
discrete or polygenic traits l
stabilizing and disruptive selection only applies to
polygenic traits
(show a continuous distribution within a population)
