1. Inbreeding typically increases:

d) the number of expressed deleterious alleles

e) juvenile mortality

2. Assuming Hardy-Weinberg equilibrium, if the frequency of allele “a” is 0.75, the frequency of genotype “Aa” would be

c) 0.375

3. If the exponential rate of population increase (i.e. r) is 0, then what is the geometric rate of increase (i.e. λ)?

d) 1

4. The world lost about 95% of all marine species and 50% of all animal families in which major mass extinction (the largest)?

c) Permian

5. Which of the following traits make a species / population especially susceptible to extinction?

b) low rates of migration

c) large body size

e) species that have no history with humans

6. In 1999 the density of collared redstarts (a bird) at the Monteverde Biological Reserve in Costa Rica was 1204. In 2000, the density was 1045. What is the exponential growth rate (i.e., r) for this population for this time period?

c) –0.14

7. You are commissioned to study the consequences of beachfront development for an endangered population of Puritan Tiger Beetles on the Connecticut River. Your study reveals a 15% probability that development will lead to the extinction of this population. Discuss this result within the context of two types of error (correctly identifying which is type I vs. type II is not essential), and consider the importance of this distinction to conservation biology. (3 points)

“Type 1 Error: Development will not lead to extinction of tiger beetle population but you conclude that it will” OR “H0 = development will not lead to the extinction of this population of tiger beetles and “Reject H0 when true” (0.75 points; 0.5 points for “Reject H0 when true” only; No points off for incorrectly identifying type I vs. type II).

“Type II Error: Development will lead to extinction of tiger beetle population but you conclude that it will not (0.75 points) OR “H0 = development will not lead to the extinction of this population of tiger beetles and “Accept H0 when false” (0.75 points; 0.5 points for “Accept H0 when false” only; No points off for incorrectly identifying type I vs. type II).

In conservation biology, we way the costs and benefits of each error. The cost of extinction is “high” and not reversible, whereas the cost of not developing is “low” and reversible, therefore, we typically accept a higher level of Type I error relative to Type II error. FYI, there is an 85% probability of type I error, and a 15% probability of type II error in this example (1.5 points).

8. What are some of the characteristics that distinguish conservation biology from many other sciences? (3 points)

It's a crisis discipline, a multidisciplinary science, an inexact science, value-laden. It has a mission (1 point each, up to 3).

10. Define heterozygosity and allelic diversity. Why are both measures significant for conservation biology? (4 points).

Definition: Heterozygosity: % heterozygous genotypes for a particular locus OR ASSUMING HW, 2pq; P = % of loci for which alternative alleles exist in the pop. (2 points).

Significance: Heterozygosity is positively related to fitness and is likely to be lost more quickly in small populations than large ones, allelic diversity is important for adaptability. (2 points).

11. What are two processes or events that decrease heterozygosity? (2 points)

Inbreeding (selfing), selection for homozygotes, random drift (1 point each, up to 2).

12. Two hypotheses have been proposed to explain the extinction of most of the world's large herbivores 11,000 years ago. What are the hypotheses?  How does the "Keystone Herbivore Hypothesis" integrate these hypotheses? (4 points)

2 Hypotheses: Global climate change(regression of glaciers converts savanna to forest) and human mediated (overkill or disease vectors) (2 point)

Keystone Herbivore Hypothesis: The keystone herbivore hypothesis (based on ecology in Africa today) suggests that the open savannas and grasslands that dominated North America 10,000 years ago were maintained as grasslands by actions of large herbivores, like elephants, mammoths, mastodonts, ground sloths, etc. Megavertebrates were able to maintain this habitat in previous glacial retreats (climate change), but the loss of these “ecosystem engineers” (by human mediated causes) resulted in a “cascade” of extinctions in the middle-sized grazers, browsers and their predators. (2 points)

13. Congratulations! Although someone else was hired to manage the Golden Bamboo Lemurs, you got your second choice: a job managing a population of endangered Muriquis in Brazil. Fortunately, the entire park (3,000 hectares) is occupied by Muriquis. They live in groups averaging 6 individuals and occupy non-overlapping territories averaging 50 hectares. These muriquis are polygamous and each group contains 4 breeding individuals (one male and three females) and two juveniles (their offspring). 50% of females survive to the next year (they live to a maximum of 4 years), and produce an average of 1.15 female infants/year, beginning in their first breeding year (i.e. age class = 1).

a) What is the carrying capacity of muriquis in this park? (1 point)

6 muriquis/group * 1 group/territory * 1 territory/50 hectares * 3000 hectares/park = 360

b) What is the effective population size for the muriquis in your park? (Use the information in part (a) to answer this.) (2 points)

N_e = 4MF/(M+F) #M = 1/6 * 360 = 60 #F = 3/6 * 360 = 180

4*60*180/(60+180) = 180

c) How much heterozygosity will remain in the population at the end of four generations? (2 points)

H_t = H₀ (1-1/(2N_e))^t 1*(1-1/(2*180))⁴ = 98.9%

d) Calculate R₀ (∑l_x*b_x) for this population. (2 points)

Age	lx	bx	lx*bx
0	1	0	0
1	.5	1.15	0.575
2	.25	1.15	0.2875
3	.125	1.15	0.14375
4	0	1.15	0
R0			1.006

e) Based on your answer to “d” above, what is the current status of this population? (1 point)

At carrying capacity

14. What are two pieces of evidence that we are in or on the verge of a mass extinction? (2 points)

Current extinction rate for birds and mammals 65-200 x higher than background OR projected rate of extinction for birds and mammals 1,700 to 5,100 x higher than background OR between 10-20 % spp. may be lost from tropics in next 30 years (assuming 50% deforestation) OR based on species-area curves we are losing 17,000-27,000 thousand spp. / year due to deforestation OR reasonable variant of these reasons

15. Using the species-area relationship (S = cA^z), calculate the expected proportion of species that will be lost from tropical forests if 50% of remaining forests are destroyed (assume z = .30) (2 points)

1-0.5^0.3 = 18.8%

16. List three ways in which humans may cause species / population extinctions and give real world examples. Are these examples of deterministic or stochastic causes of extinction and why? (6 points)

Overkill (dodo, Stellar's sea cow, passenger pigeon), exotic species (brown tree snake, “Tibbles”, carp, golden toads), habitat destruction (e.g. cutting tropical rain forest), or other reasonable example (3 points)

In most cases, these are deterministic factors – i.e. reduce mean growth rate, but some factors could be stochastic – i.e. influence variation in growth rate (3 points)

17. Draw 3 graphs with "Population Size" on the x-axis and "Growth Rate" on the y-axis to illustrate the concepts of density-independent growth, density-dependent growth, and Allee effects. Label K and threshold density, where appropriate. (4 points).