Monday 2/24

1. Pop Quiz #62. Review Prickly Pear math questions3. See Salamanders and Lizards – Quiz M 3/34. Chapter 9 – L-P population estimates

5. Due today: all of Prickly Pear Case Study

6. Exam postmortem due Wednesday!!

Class Amphibia• Order Anura – frogs and toads• Order Caudata – salamanders and newts• Order Apoda – caecilians

Class Reptilia• Order Testudines - turtles, terrapins, and

tortoises• Order Squamata - lizards and snakes• Order Crocodilia - crocodiles and alligators

Missouri Lizards and Salamanders

All images are from Wikimedia Commons, unless otherwise

identified

Common mudpuppyNecturus maculosus

HellbenderCryptobranchus alleganiensis

Ringed salamanderAmbystoma annulatum

Tiger salamanderAmbystoma tigrinum

Spotted SalamanderAmbystoma maculatum

Eastern newt, red-spotted newtNotophthalmus viridescens

Broad-headed skinkPlestiodon laticeps

American five-lined skinkPlestiodon fasciatus

Little brown skinkScincella lateralis

Prairie lizard, eastern fence lizardSceloporus undulatus

Not on quizAxolotl

Ambystoma mexicanum

Chapter 9 – Population Distribution and Abundance

• What are some methods of counting populations?

Chapter 9 – Population Distribution and Abundance

• What are some methods of counting populations?– What if the individuals are mobile?– Hidden/“cryptic”?– What if we only have a sample?

Required variables

• N = n1n2/m2

• N = estimated population size• n1 = number of individuals marked in first

sample.• n2 = number of individuals marked in second

sample.• m2 = number of individuals captured in second

sample, that were marked in the first.

This method only works IF:

• Probability of survival is equal• Births and deaths are insignificant between

release and recapture• Immigration and emigration are nonexistent or

insignificant• Marked individuals re-mix randomly• The mark makes it no easier or more difficult to

recapture• Marks are permanent

Practice

A biologist nets 45 largemouth bass from a farm pond, tags their fins, and releases them unharmed. A week later, she nets 58 bass from the pond, including 26 tagged. Based on the L-I index, estimate the size of the population.

Mark-Recapture

• m2 / n1 = probability that an animal will be captured.

• So, how large is the population?• n2 is really the portion of N that we expect to

capture. • This is N*p = n2 where p is m2/n1.

Population Density

• So, N*p = n2

• N = n2 / p

• N = n2 / (m2 / n1) = n1n2 / m2

• But, this is only part of the problem. We also need some estimate of area since Density, D = N / A.

Population Density

• Imagine we study rodents using a trapping grid w/ 15m trap spacing.

• We trap the animals over a series of nights, always noting the identity and location of each animal.

• Then, we can estimate how far each individual moved between captures.

Population Density

• Now, if an organism can travel from one station to the next, we can assume that it could travel half the distance to the next station as well.

• Thus, the ‘effective area’ of our sample is the area of our grid, plus a border region around the grid, with a width of half the distance between stations.

Population Density

Area?

• What is the area of the grid?• Ag = W2

• How about the 4 rectangles?• Ab = 4 * W * (0.5 * D)

• How about the 4 corners?• This is essentially the area of a circle.• Ac = (0.5D)2

Population Density

• Finally, density can be estimated as

D

n nm

W WD D

1 2

22 22 05 ( . )