Download Name: ANSWER KEY SN: 1 - Department of Zoology, UBC

Name: ANSWER KEY
SN:
Biology 413 (Zoogeography) Mid-term Exam
Winter Term 2 - 2014
Directions:
1. Write your name and student number on each page of the exam.
2. All answers should be written in the space provided. If you need extra space, write on the back
of the last page and clearly label your answers.
3. The exam is designed to be completed in 50 minutes. Plan accordingly.
4. The exam questions are organized into two parts and consist of 6 pages.
5. PART I consists of 5 short-answer questions.
6. PART II consists of one two-part question and one long-answer (essay-form) question.
Marks
PART I: 14 points
PART II: 22 points
TOTAL: 36 points
PART I
Answer the following questions 1 – 5, using 1-2 sentences or less (point-form is OK) in the space
provided. These questions should take no more than 5 minutes each.
Question 1 [2 points]:
Describe one contribution made by the following individuals to the development of Biogeography:
a) Carl von Linnaeus: Father of binomial nomenclature and taxonomy. Believed in immutability of species.
Suggested that world's biodiversity originated by dispersal from Mt. Ararat, Turkey where Noah’s Ark was
thought to have landed after biblical flood (first incidence of idea that taxa have centres of origin).
b) Alexander von Humboldt: Extended Buffon's Law to plants and terrestrial animals. Promoted idea that plant
distribution is determined by climate. Coined the term “floristic belts”. Noted complementarity of South
American and west African coastlines.
c) Phillip Sclater: Made connection between low dispersal ability and ability to reconstruct origin of a region's
biota from current composition. Developed first major classification scheme for earth’s biota based on
distribution and composition of birds (described over 1,000 species – mostly passerines). Proposed six
biogeographic regions, each with distinct centres of origin for regional faunas (still used today).
d) Alfred R. Wallace: Compiled observations on distributions, diversity, extinction, disjunctions, and climate
effects on distribution into: “The Malay Archipelago”, “The Geographical Distribution of Animals”, “Island
Life”. Refined Sclater's regions so concordance in distributions of taxa reflects reality of divisions and processes
generating them. Recognized Wallace’s Line separating fauna of SE Asian origin from those of Australian origin.
Independently developed ideas on natural selection and the origin of species.
Question 2 [2 points]: Answer the following questions based on Figure 2.1:
a) What is the name of the latitudinal belt receiving the most direct sunlight?
Tropic of Capricorn, 23.5° S Latitude
b) What day of the year is it? (in words, or give the approx. date)?
December 21 (Winter Solstice)_________________
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Figure 2.1. Earth tilted on its axis with the
angle of incoming sunlight shown. Latitudes
indicated with dotted lines (Equator 1labeled).
Name: ANSWER KEY
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Question 3 [2 points]:
Explain why we often see the driest deserts on the western side of continents at the Horse Latitudes.
Over land, Horse Latitude belts (30° N and S latitude) represent the world’s deserts and Mediterranean
climates. In summer, land is warmer than ocean water, and cool westerly winds over oceans absorb
water as the air warms and expands while passing over warmer land. In winter, land is cooler than the
ocean and moisture-laden westerly winds can bring precipitation to these regions, but this is minimal.
The world’s driest deserts occur where very cold currents/winds encounter warm land (e.g., Atacama
desert in South America, western Australia, Namib Desert in Africa).
Question 4 [4 points]:
We discussed in class that community assemblage depends, in part, on energetics and productivity.
a) What are the two basic characteristics that affect energy use in organisms? [1 point]
Tropic level and body size (or metabolic rate)___________________________________________
b) Which organisms tend to be numerically rare in communities and why? [3 points]
Tertiary consumers (top predators). These organisms tend to be large bodied, with high metabolic rates
and thus high energetic demands, but at the highest trophic level, they have the least amount of energy
available to them, as 90% of energy is lost as heat with energy transfer to higher trophic levels
Question 5 [4 points]:
Species distributions are dynamic in space and time, but in all cases, ranges can be described by five
basic parameters: r, b, d, i, e.
a) Use an equation to show how these five parameters are related to one another, and define each
parameter using a few words. [2 points]
r = b + i – d – e where r is the per capita rate of population growth, b is per capita birth rate, d is per
capita death rate, i is per capita immigration rate and e is per capita emigration rate
b) Figure 5.1 shows “source” and “sink” habitats that are linked by dispersal. If r > 0 in the sink habitat,
what can we infer about parameters b, d and i in the sink habitat? [2 points]
In a sink habitat, b < d; however, because r > 0, i must be large to
sink
compensate for low birth rates/high death rates, or the combined rates
of i + b > d
source
r>0
Figure 5.1. Source and sink habitats.
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Name: ANSWER KEY
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PART II
Answer the following Questions 6-7. Use sentences for Questions 6-b and 7 in the space provided.
Question 6 [10 points]:
Figure 6.1 and 6.2 show the relationship proposed by Santiago Claramunt and colleagues to support
their hypothesis for an “intermediate dispersal model”.
Figure 6.1 Relationship between wing-aspect ratio and dispersal ability
A
geographic barrier:
strong
B
C
intermediate
weak
distribution:
Figure 6.2 Relationship between dispersal ability (x-axis) and speciation rates (y-axis).
In Figure 6.2 above, using the lines under A, B and C, use one word to describe the relative strength of a
geographic barrier. [2 points]
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Name: ANSWER KEY
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a) Provide an explanation for the proposed “intermediate dispersal model”, based on what you have
learned about mechanisms of speciation and dispersal. Use Figures 6.1 and 6.2 to support your
answer. [8 points]
Figure 6.1 shows a positive relationship between a bird’s dispersal ability and its wing-aspect ratio.
Thus, birds with higher wing-aspect ratios should be better at colonizing areas beyond geographic
barriers compared to birds with low wing-aspect ratios. In Figure 6.2, we see a hump-shaped
relationship between dispersal ability and speciation rate. For birds with low dispersal capacity (A), the
strength of a given geographic barrier should be large. As such, the geographic range of this species
should be spatially restricted. Because the species is a poor disperser, the likelihood of establishing
populations outside the range is low, offering little or no opportunity for allopatry and consequently, low
speciation rates (we assume sympatric speciation is unlikely). For birds with high dispersal capacity (C),
a given geographic barrier will not be effective in preventing dispersal. Species with high dispersal
capacity would be expected to exhibit a larger geographic distribution with high gene flow, preventing
any divergence of populations in allopatry. In contrast, an intermediate dispersal ability (B) allows some
individuals to overcome geographic barriers, resulting in the establishment of allopatric (isolated)
populations (as depicted in the figure). However, dispersal (gene flow) is not high enough to prevent
divergence in allopatry, resulting in relatively high speciation rates. Once allopatric populations are
established, they will likely diverge as the result of either differing ecological selection pressures or
genetic drift until reproductive isolation is attained.
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Name: ANSWER KEY
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Question 7 [12 points]:
In class, we discussed numerous potential determinants of species distributions in the context of the
fundamental and realized niche. In the space provided, describe the fundamental and realized niche
[4 points] and provide four possible determinants of species distributions as they relate to the
fundamental/realized niche concept, using an example to support your answers [8 points].
The fundamental niche is the total range of abiotic environmental conditions in which a taxon can
survive and reproduce. From Hutchinson, the n-dimensional hypervolume (or multidimensional space)
that describes the range of abiotic environmental conditions in which a taxon can survive and reproduce
(each abiotic factor is a single dimension). The realized niche is a subset of the fundamental niche
comprising the actual environmental conditions in which a taxon survives and reproduces in nature,
including biotic factors (e.g., competition, predation, mutualism, parasitism). (4 points)
There are many possible determinants of distributions, including abiotic interactions (e.g., climate/soil
related factors), biotic interactions (i.e., direct/diffuse competition, predation, parasitism, mutualism),
metapopulation dynamics, disturbance and historical factors/dispersal barriers. Full credit given for
describing four different factors supported by a logical example (2 points per example for 8 points total).
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