Activities

Activity 1: Calculating Vital Rates

Aim: To practice calculating birth and death rates from population data.

Procedure:

1. Scenario A: In a pond, there are 25 lotus plants. After one year, 5 new plants are added through reproduction. Calculate the birth rate.
   • Calculation: 5 / 25 = 0.2 offspring per lotus per year.
2. Scenario B: In a laboratory, there are 50 fruitflies. During a week, 10 fruitflies die. Calculate the death rate.
   • Calculation: 10 / 50 = 0.2 individuals per fruitfly per week.
3. Discuss why these rates are more meaningful than total counts for comparing populations.

Conclusion: Per capita rates allow for standardized comparison of population dynamics across different sizes and timeframes.

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Activity 2: Analysing Age Pyramids

Aim: To interpret population growth status from age distribution diagrams.

Procedure:

1. Refer to Figure 11.1 in the textbook.
2. Identify the three types of pyramids:
   • Triangular: Growing population (e.g., India in late 20th century).
   • Bell-shaped: Stable population.
   • Urn-shaped: Declining population.
3. Discuss the social and economic implications of an urn-shaped pyramid (e.g., high proportion of elderly).

Conclusion: Age pyramids provide a visual snapshot of a population's future growth or decline.

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Activity 3: Case Study – The Prickly Pear Cactus

Aim: To understand the impact of invasive species and the success of biological control.

Procedure:

1. Research the introduction of the Prickly Pear Cactus (Opuntia) into Australia in 1920.
2. Note the extent of its spread (millions of hectares).
3. Identify the biological agent used to control it (the Cactoblastis moth).
4. Discuss why the cactus spread so rapidly in the first place (lack of natural predators).

Conclusion: Invasive species can destabilize ecosystems, and biological control is an effective, natural way to restore balance.

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Activity 4: Mapping Plant-Animal Mutualism

Aim: To visualize the co-evolution of fig trees and wasps.

Procedure:

1. Study Figure 11.4 in the textbook.
2. Describe the "one-to-one" relationship:
   • The fig provides a site for egg-laying and food for wasp larvae.
   • The wasp ensures pollination of the fig flowers.
3. Explain why this system must be protected against "cheaters" (animals that take nectar without pollinating).
4. Briefly research the Mediterranean Orchid (Ophrys) and its use of sexual deceit to attract pollinators.

Conclusion: Mutualism often involves highly specialized, interdependent relationships that drive co-evolution between species.