LESSON 19

Before you upload your file, ensure your name appears on the top of every page of your document. Question 1...Hare and Lynx Populations In this activity, you will graph data collected by the Hudson’s Bay Company for hare and lynx pelts collected during a period from 1845 to 1936. It is believed that the number of pelts collected directly reflects the abundance of living hares and lynx in the natural habitat they were trapped in. In constructing your graph, superimpose both sets of data on the same axes. Make sure you use an appropriate scale such that the entire page is used. You may use graphing software such as Excel, but please confirm with your teacher that the format you wish to use is acceptable. If you do not have graphing software, you may hand draw the graph, scan it, and submit it in a digital format. After you have completed your graph, complete the questions below and submit them with your graph.     Year Number of Hares (x 1 000)   Year Number of Lynx (x 1 000) 1845           48 1846           20 1850           60 1853             8 1855           80 1856           36 1860           10 1863             4 1865         130 1868           72 1870           14 1873             7 1875         105 1877           47 1880           16 1881           21 1885         115 1887           78 1890           18 1894           21 1895           83 1896           51 1900           34 1901           27 1905           72 1906           68 1908           10 1910            3 1912           40 1915           36 1919            6 1920           12 1925           80 1926           57 1930             4 1931           10 1935           92 1936           47  

1. Explain the type of growth shown on your graph. 2. Which population is dependent on which – the predator/the prey? 3. In 1865 and 1885 there were spikes in the hare population.  Give some suggestions as to why this may have occurred. 4. Does the lynx population fall below the hare population?  Is this beneficial? 5. The lynx is the carnivore and for one lynx to survive it must consume many hares.  Estimate the carrying capacity of this environment for the lynx population. 6. A controlled 6 year study was done in British Columbia on the hare population with no lynx present.  The results were interesting.  It showed an increase in the hare population, but still showed oscillations in growth. Explain how this result could be SCALE:- POPULATION OF HARES AND LYNX ----: 1:50 YEAR :- 1:5YRS

 Lack of predators: If there were fewer lynx or other predators present, the hare population would have less predation pressure, allowing them to grow in numbers.  Human influence: Human activities such as hunting, habitat destruction or introduction of non-native species may have affected the population dynamics of hares. 4. Based on the graph, it seems that the lynx population falls below the hare population at certain points in time. This is not necessarily beneficial as it can lead to a lack of food for the lynx and potentially result in a decline in their population. A stable population of prey is important for the predator population. If the prey population falls too low, the predator population will also decline due to lack of food. In the long run, the predator population will have to decrease or migrate to other regions to find food. 5. It is difficult to estimate the carrying capacity of the environment for the lynx population based on the information provided in the graph. Carrying capacity is the maximum number of individuals of a given species that an environment can sustainably support, and it is influenced by several factors such as food availability, habitat quality, and disease. To estimate the carrying capacity of the environment for the lynx population, we would need more information on factors such as the availability of hares as a food source, the size of the lynx population, and the quality of their habitat. Additionally, we would need to know the specific ecological dynamics such as the number of hares a lynx needs to survive and reproduce, the reproductive rate of hares, and the survival rate of lynx. 6. The result of a controlled 6 year study in British Columbia showing an increase in the hare population but still showing oscillations in growth could be explained by the fact that without predation from the lynx, the hare population was able to grow. However, other factors such as disease, competition for food, or changes in environmental conditions may have still affected the population and caused oscillations in growth. Some possible explanations for the observed oscillations in growth include: Density-dependent factors : As the hare population increases, competition for food and other resources may become more intense, leading to a decrease in population growth. This is known as density-dependent regulation.

Disease : An outbreak of a disease could have affected the hare population, leading to a decrease in growth. Environmental factors : Changes in weather or other environmental conditions could have affected the hare population, leading to fluctuations in growth. Human influence : Human activities such as hunting or habitat destruction could have also affected the population dynamics of hares.