﻿ Genetics ClimateCycle

# Changing Environments

Typical genetics deals with constant (or consistent) conditions

• if there is selection,
. . . -multiply the Hardy-Weinburg values by fitness, w = survival probability
. . . . {AA, Aa, aa} = {wAA*p2, wAa*2pq, waa*q2}
• since w is constant
. . . -the same percentage survives every generation and
. . . . with sufficient time, if wAA or waa is smallest of the w-values,
. . . . that genotype will disappear from the population!

Imagine a mutation that gives a tropical plant species the ability to withstand up to one hour exposure to minimum temperatures, and which occurs 10% of the time:

 n = 1 expF-1 .81 .18 .01 geno-type AA Aa aa minTemp 32 oF 30 oF 28 oF w32 1.00 0.80 0.60 w30 0.80 1.00 0.80 w28 0.60 0.80 1.00

In the 'normal' environment,
where winter nighttime temperatures do not drop below 32 oF:
 n = 1 geno-type AA Aa aa q w 1.00 0.80 0.60 minTemp 32 oF 30 oF 28 oF expP-1 810 180 10 0.100 expF-1 810 144 6 0.081 expF-2 844 119 3 0.065 expF-3 874 96 2 0.051 expF-4 899 78 1 0.041 expF-5 919 62 1 0.033 expF-6 935 50 0 0.025 expF-7 949 39 0 0.020 expF-8 960 30 0 0.015 expF-9 969 23 0 0.012 expF-10 976 18 0 0.009

Starting with the P-1 generation {AA, Aa, aa} = {810, 180, 10}

• if environment changed to winter nighttime temperatures drop to 28oF
. . . q would rise as . . . . . . p declines
. . . q approaches 1.00; . . . p approaches 0.00