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Unity and diversity - Conservation of biodiversity

Grade 11IBBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Biodiversity is the variety of life on Earth and can be measured at three levels: Genetic diversity (variation within a gene pool), Species diversity (richness and evenness), and Ecosystem diversity (variety of habitats and communities).

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Species Richness refers to the total number of different species present in a community, while Species Evenness refers to the relative abundance of each species.

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Causes of biodiversity loss are often summarized by the acronym HIPPCO: Habitat destruction, Invasive species, Pollution, Population growth (human), Climate change, and Overexploitation.

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In-situ conservation involves protecting species in their natural habitats (e.g., National Parks, Nature Reserves). This allows for the continuation of natural evolutionary processes and the maintenance of complex ecological interactions.

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Ex-situ conservation involves the preservation of species outside their natural habitats (e.g., Botanic gardens, Seed banks, Zoos, and Captive breeding programs). This is often a last resort for species nearing extinction in the wild.

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The Theory of Island Biogeography suggests that biodiversity on an 'island' (which can include isolated forest fragments) is determined by two factors: proximity to the mainland and the size of the island. Larger islands closer to the mainland typically support higher biodiversity.

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Edge Effects occur at the boundary of ecosystems. When a habitat is fragmented, the ratio of 'edge' to 'interior' increases. Some species thrive in edge habitats, while interior species may decline due to increased exposure to predators or environmental changes.

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Indicator species are organisms whose presence, absence, or abundance reflects a specific environmental condition (e.g., Lichens are indicators of air quality/sulfur dioxide levels).

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Biotic Indices, such as the Trent Biotic Index, use the presence and abundance of indicator species to provide a numerical score representing the health of an ecosystem (often used for water quality in rivers).

📐Formulae

D=N(N−1)∑n(n−1)D = \frac{N(N - 1)}{\sum n(n - 1)}

N=n1×n2n3N = \frac{n_1 \times n_2}{n_3}

💡Examples

Problem 1:

In a forest survey, three species of trees were counted. Species A had 50 individuals, Species B had 30 individuals, and Species C had 20 individuals. Calculate the Simpson's Reciprocal Index of Diversity (DD) for this community.

Solution:

  1. Calculate the total number of individuals (NN): N=50+30+20=100N = 50 + 30 + 20 = 100
  2. Calculate N(N−1)N(N - 1): 100(99)=9900100(99) = 9900
  3. Calculate n(n−1)n(n - 1) for each species: Species A: 50(49)=245050(49) = 2450 Species B: 30(29)=87030(29) = 870 Species C: 20(19)=38020(19) = 380
  4. Sum the results: ∑n(n−1)=2450+870+380=3700\sum n(n - 1) = 2450 + 870 + 380 = 3700
  5. Apply the formula: D=99003700≈2.68D = \frac{9900}{3700} \approx 2.68

Explanation:

Simpson's Reciprocal Index (DD) measures biodiversity. A higher value indicates greater diversity. The minimum value is 1 (representing a monoculture).

Problem 2:

A biologist captures and marks 40 turtles in a pond (n1n_1). One week later, the biologist captures 50 turtles (n2n_2), of which 10 are already marked (n3n_3). Estimate the total population size (NN) using the Lincoln Index.

Solution:

Using the Lincoln Index formula: N=n1×n2n3N = \frac{n_1 \times n_2}{n_3} N=40×5010N = \frac{40 \times 50}{10} N=200010N = \frac{2000}{10} N=200N = 200

Explanation:

The Lincoln Index (capture-mark-release-recapture) provides an estimate of the population size of mobile organisms. It assumes the population is closed and the marks do not affect survival or catchability.