Question

The Arctic hare (Lepus arcticus) changes its coat color every spring from white to brown to maintain camouflage as the snow melts (in order to avoid predation); however, the precise timing of this color transition varies slightly among individuals. You find a best fit linear least squares regression of

y = 0.25 x + 0.023

between average parent and offspring times of color transition. On average hares start to change color on the 15th of April. Following a particularly warm year with unusually early snow-melt you find a shift in the surviving hares who now start the color transition on the 10th of April.

A) What is narrow sense heritability in color transition timing?
B) What is the response to selection (R ) following the warm year?
C) What is the strength of selection (S) during the warm year (in units of days)?

Answer 1

In this regression equation h2 can be estimated as the slope of the linear regression of mid parent value on offspring value so it is given by

Offspring value = h2 * mid parent value + c

y = h2 x + c

So h2 = 0.25 ans A

Strength of selection is given by

S = difference between days of start of change colour for surviving hair and average hair

Arctic hair found in southern labrador where snow appear from late october to mid april. If average hare start to change colour from 15 april means total 165 days after snow fall hair start to change colour where as 160 days for surviving hair

So, S = 160-165

C) S= -5 days

B) R = h2 S

R = 0.25 * -5

R= -1.25

Means offspring are not as extreme as their parent.