Friday 3/7

1. Pop Quiz #72. Turtles and Snakes ID Quiz3. Notes on population math from Chs 9 and 104. Lab 4B5. Lab 4A - 15 SP only (for homework)

30 (lab 7) + 20 (PQ 7) + 15 (S&T ID) + (10 wk8Eng)= 75!

Pop Quiz #7

Snakes begins on next slide

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• We’ve talked about (at least) one way to determine if a population is growing

• ?

Rate?

Rate?

• Variable per time

Rate?

• Variable per time• N, t

N/t = rate• Individuals added per unit time = rate of

growth

BUT,

• The growth rate will change in response to other variables

• Like what?

So, Change in Rate

dN/dt

So, Change in Rate

dN/dt

=rN

This is compounding

dN/dt = rN

Because as N gets larger, the constant r multiples by a larger and larger number.

As population size (N) increases, the rate of increase gets larger.

The result of this compounding is an exponential growth curve. (p 243, 244, 245 Molles; p 67 Kingsolver for examples)

PS - Stretch it out

• By plotting this same data on a logarithmic scale (10X at each increase), the line straightens out (p 68 Kingsolver)

In exponential growth

• We can determine the population size at any time (t), by:

Nt = N0ert

P 244 Molles

Can exponential growth continue forever?

Can exponential growth continue forever?

• Stay tuned for logarithmic (more realistic) growth models (11.2 – 11.3)

Lab 4B

For Monday

• Read Molles 11.2 and 11.3• Finish AA sheep

• Monday is last day to withdraw from full semester courses

• Exam 2 is M 3/31 – Ch 9-12• Five labs left – all field