quantitiave traits Flashcards
define a discrete trait
countable
define continuous variation
things you need to measure rather than count
weight
what causes variation in height
genes and envrionment changes in lifestyle hormones protein eaten in childhood exercise
what is heritability
the proportion of variation in a trait that can be attributed to the genetic variation
speicfic to a population in an environment
if the heritability is zero waht does this mean
the only influences on the trait is envrionment
what is the breeders equation
shows how much of a trait is down to heritability and thus if its useful for breeding and selection
how is parent-offspring regression used to measure heritability
compare relatives and measure the siblings and parents
look for correltions
what does the parent offpsring regression conclude
if your parents have a trait, you are also likely to have that trait and thus its heritabl
correlation is used as a measure of the heritability
how are twin studies used to measure heritability
look at the two types of twins
if heritability is higher, MZ twins more similar than DS
assumed they share environment
what is QTL
quantitative trait loci: a section of DNA (the locus) that correlates with variation in a phenotype (the quantitative trait). Usually the QTL is linked to, or contains, the genes that control that phenotype.
GWAS
genome wise assosication studyes
take huge numbers of people and look at gentic variants
often can be used to identify genes responsible for a part of heritability
define broad sense heritability
proportion of total phenotypic variation of traits due to genetics
useful to measure importance of genetic and environmel effects on expression
directional selection
shapes populations by favouring indidivuals with trait valves at an end of the distrubution virve
stabilising selection
favours the middle of the curve
disruptive selection
favours those at both ends
