BISC 204 - Worksheet 1 - Climate, Biogeographic regions and Biomes

  1. a) what is the albedo effect?

  • the measure of how much sunlight (solar radiation) a surface reflects back into space rather than absorbing it as heat

Studies report that cities usually have lower albedo values than rural surface (commonly 2-5 % lower than crop-lands at the same latitude) but the fraction of Earth's land surface covered by built-up areas is only 0.7 %.

b) Will urbanization that leads to an increase in buildings/roads/parking lots have a greater effect on local or global temperatures. Explain.

  • urbanization and the increase in development of buildings/roads/parking lots will have a greater effect on local temperatures rather than global temperatures. Since the fraction of the Earth’s land being covered up by built-up areas is not as significant the increase of development will likely not impact the global temperatures as much as it would for local temperatures

  1. a) The position of the solar equator changes throughout the year. Explain why.

  • the position of the solar equator changes throughout the year due to the tilt in the Earth’s axis of rotation relative to its orbital plane

b) how will the location of the solar equator influence the location of the inter-tropical convergence zone at different times of the year

  • the location of the solar equator will most likely determine the location of the intertropical convergence zone as the ITCZ typically moves to areas where the sun is at its highest intensity

c) why does the ITCZ in the June solstice extend further north over Africa than over the pacific ocean

  • The ITCZ extends further north over Africa than over the pacific ocean due to the intense heating of landmasses in comparison of the oceans → will prioritize the landmass over the pacific ocean due to the solar equator

  1. a) explain how the Hadley’s cells and the rotation of the Earth contribute to the creation of the northeast and southeast trade winds

  • trade winds are created by the combination of Hadley cell circulation - moves the air vertically and meridionally (direction along the meridian) + Coriolis effect resulting from the rotation of the Earth

Coriolis effect - the perceived curving of the path of objects (i.e. wind, water, or planes) moving over a large distance across the earth’s surface

  1. The temperate rainforest on the west coast of British Columbia is found at a latitude of 50-60 degree North and has as a climate characterized by abundant rain (up to 4000mm/year) and mild but very seasonal temperatures (average monthly temperatures range from -10 to +20oC)

a) What creates the westerly winds at mid latitudes (30-60oN), and why do the westerly winds result in the high precipitation (rainfall) in BC’s temperate rainforest.

Hint: the western cordillera mountain range runs from N to S along the west coast of Canada

  • The Ferrel cell creates the westerly winds at mid latitudes. Due to the westerly winds, it brings in high moisture from the pacific ocean. It then rises towards BC’s coastal mountains → cools → then releases as heavy precipitation

b) use three sentences to explain how solar radiation, the tilt and radiation of the Earth combine to create the highly seasonal climate of the BC temperate rainforest

  • the tilt of the Earth’s axis causes the Northern hemisphere to tilt toward the sun in the summer and away in the winter - creating drastic seasonal variations

  • pacific ocean absorbs solar radiation and remains relatively warm - westerly winds pick up the air and circulates to the Coastal mountain ranges - air rises + cools → forces water vapor to condense and fall as heavy precipitation

c) The Great Bear Rainforest of BC and Tasmanian Rainforest of Australia (latitude 40 oSouth) are both in the same biome (Temperate Rainforest). Would you expect to find similar plants in the two locations? Explain why AND why not?

  • I wouldn’t expect to find similar plants in the two locations since both geographical regions are isolated from one another especially Australia.

  • What I would expect to find are plants that have the same or similar characteristics or physical traits. Since they live in similar biomes, I would expect them to adapt (through evolution) traits that serve similar purposes

  1. a) Explain how variation in the El Nino Southern Oscillation influences sea surface temperature and productivity on the west coast of South America.

  • during the El Nino phase - it leads to weakened trade winds in which leads to warm water to pool eastward

  • therefore raises sea surface temperatures and reduces nutrient rich upwelling → reduction of marine productivity

b) why does the impact of El Nino and La Nina for organisms in the Galapagos Islands depend on whether they live and feed on land or in the ocean

  • climate events directly change the upwelling of nutrient rich cold water + amount of rainfall → creates polar opposite conditions for marine and terrestrial food sources

  • during El Nino weak trade winds stop cold nutrient rich current from surfacing → marine species suffer as there is a lack of nutrients

    • during El Nino warmer waters lead to more rainfall and warmer temperatures → vegetation on land thrives

  • during El Nina strong winds circulate cold nutrient rich currents from surfacing → more nutrients = more population - marine species thrive

    • during El Nino there is less rain + more dry, therefore plants do not thrive as much - land species suffer

  1. a) what is the difference between a biogeographic region and a biome

biogeographic region - large, continental-scale area defined by the evolutionary history, ancestry, geography, and distribution of its species

biome - worldwide habitat type defined by climate and vegetation structure

b) What environmental features drive differences in the terrestrial biomes

  • primarily driven by climate - and the interaction between temperature and precipitation

Climate change predictions for British Columbia include both an increase in average annual temperature and increased precipitation across all seasons.

c) How would this be predicted to change the southern and northern boundaries of the boreal forest biome in Canada.

  • boreal forest is expected to expand Northward and the southern boundaries are expected to shrink

  • general shift up northwards

d) What could limit the predicted changes in the biome boundaries in the north and south?

  • migration speed, soil quality southern competition, fire frequency

    • migration speed - plant species migrate slowly, if climate change outpaces the dispersal rate → cannot establish newly suitable areas fast enough

    • soil quality - northern soils are typically nutrient poor and frozen → not ideal in supporting plant species

    • southern competition - more animals migration = more competition for the same amount of resources

    • fire frequencies - change in fire regimes could change the successional patterns - impact how quickly boundaries shifts

e) Do the data provide support for the idea that biomes and thus species distributions will change in response to climate change. Why and why not?

  • the data does provide support for the idea that a biome and species distribution will change in response to climate change as higher values are found in the northern range of the biome

f) Pose a follow-up research question driven by the results below that might inform conservation strategies for butterflies.

  • what are the habitat requirements for the butterflies species and are there limitations to their dispersal limitations in regarding to the species that stayed southwards

Worksheet 2 - Study Design & Behavioral Ecology

  1. For their honors project a BSc student is studying the effects of captively breeding tadpoles on their ability to detect predators while foraging. Below is the main result of their research.

a) What is the likely study design that would give this result? Which treatment would you consider to be the control?

  • It is likely to be an experimental study design as varying treatments are displayed and would give the results provided

  • I would consider the treatment with wild tadpoles with the absence of predators to be the control → no change in variables

b) Propose a hypothesis or explanation for why the researchers got this result.

Wild tadpoles that were exposed to predators initiated a anti-predator response meanwhile those who are captive-bred did not respond to the presence of a predator at all. Likely do to their lack of exposure to predators and the wild they did not learn the behavioral trait

c) Does this study answer a proximate or ultimate question about tadpole behavior? Why?

this study answers a proximate question about tadpole behavior as it studies the immediate response of the tadpoles with or without the presence of a predator and both in captivity or in the wild

  1. Fish that inhabit deep lakes are known to exhibit diel vertical migration (DVM, movement up and down the water column between night and day).

a) Researchers found that the brighter the light above the water, the deeper the fish are (e.g. Figure 3). Is this a proximate or ultimate explanation for DVM in fishes? Why?

  • this is a proximate explanation for DVM in fishes as it studies the fishes immediate response to the stimulus

b) provide an ultimate explanation for the diel vertical migration of these deep lake fish

  • an ultimate explanation can be that deep lake fishes who typically stay in the lower depths had a higher likelihood of surviving compared to those dwelling in the shallow parts of the water. By increasing their chances of survival they increased their success for reproduction

  1. Chickadees (the small black and white bird you see around campus) produce two types of alarm calls in response to predators, a high frequency seet alarm call in response to flying predators, like a hawk and a low frequency chick-a-dee alarm call in response to stationary predators, like cats.

a) Propose a functional (= adaptive/ultimate) explanation for why chickadees use two specific alarm calls and not one general alarm call to warn their young about the presence of a predator

  • a possible explanation for two specific alarm calls instead of one general alarm call is to assign an appropriate response to each distinct alarm to determine the best course of actions depending if the threat is ground based or sky based

b) I would design an experiment with varying treatments and use a general call as a control treatment - measure the varying responses to each treatment → measure the frequency by Hz and categorize the varying responses

The Atlantic cod fishery in harvested 100,000-200,000 tonnes of cod per year for over two centuries. The Atlantic cod harvest for the Northwest Atlantic peaked in 1968 at 810,000 tonnes. Overharvesting is thought to have caused the cod population to crash and Canada closed the commercial fishery in 1992.

Based on life history theory predict how overharvesting would be expected to alter the life history of Atlantic cod. Name the life history trait, and explain how and why it would be expected to change

  • overharvesting is predicted to change the age/size at maturity as overharvesting will create a selective pressure that will favor individuals who reproduce earlier in their lifespan compared to those who reproduce later in their lifespan → will most likely get caught before they’re able to reproduce

Worksheet 3 - Population ecology

  1. Oregon spotted frogs in the Fraser Valley breed once per year in March. Using mark-recapture Kissel estimated the number of females in a critically endangered population (Morris Valley) in spring 2021 to be 159. In 2022, she estimated the number of females to be 137

a) Which of the four simple population models introduced in lecture would it be most appropriate to use to estimate population size after 5 years, if no conservation actions are taken? State why?

  • geometric growth model

    • breeding frequency occurs in annual pulses instead of continuously throughout the year

    • population is endangered → not at stable carrying capacity

b) Calculate λ and plot the population abundance for the next 5 years. Be sure to label your axes and include units if needed

N0 = 159

N(t) = 137

t = 1 year

\lambda=\left(\frac{Nt}{N0}\right)^{\frac{1}{t}}

\lambda=\left(\frac{137}{159}\right)^1

\lambda = 0.862

\lambda < 1 → population is declining

c) Using a captive breeding program, the Vancouver Aquarium released young Oregon-spotted frogs into the Fraser Valley population and increased lambda to 1.1. How many years would it take for the population to double if captive breeding and release started in 2025?

N0 = 159

N(t) = 318

\lambda= 1.1

\lambda=\left(\frac{Nt}{N0}\right)^{\frac{1}{t}}

\log_{\left(\frac{318}{159}\right)}\left(1.1\right)=\frac{1}{t}

t=7.27years

  1. Ground squirrels reproduce seasonally (once per year). A small population in the Rocky mountains is estimated to have an annual growth rate of l = 1.011. If the population continues to grow unchecked (resources are not limiting) calculate the doubling time for this population.

Doubling time for the exponential growth model is given by t = loge2 / r

Doubling tine for the geometric growth model is given by t = loge2 / loge lamda

\lambda=1.011

t=\frac{\log_{e}\left(2\right)}{\log_{e}\left(1.011\right)}

t=63.36 years

  1. Researchers studied the population dynamics of an Elk herd in Northern California after the removal of grazing cattle

a) The researchers estimated r = 0.242 for this herd. Calculate lambda and use the discrete geometric growth model to predict the population size for 2008 (N=245 in 2003) assuming that the growth rate remains unchanged.

N_{t}=N_{o}e^{rt}

N_{t}=\left(245\right)e^{0.242\cdot5}

N_{t}=821.603

N_{t}=822

N_{t}=\lambda^{t}N

\frac{821}{245}=\lambda^5

1.27 =\lambda

b) Using Figure 1b. above, what is the approximate average carrying capacity for this herd? Hint – the figure shows the confidence interval around the predicted intrinsic rate of growth.

  • approx 340

d) Propose 2 reasons why the populations of Elk in Figure 2 appear to reach a carrying capacity, decline, and then increase again

Carrying capacity may vary rather than being fixed with K lower in period 2003-2013

Chance (stochastic) events may have depressed population growth for a short period

Worksheet 4 - Population ecology 3 & 4