3.1 Biodiversity and evolutionIB Environmental Systems and Societies SL: Flashcards
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Define biodiversity.
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- Define biodiversity.
- The total diversity of living systems, existing at several levels: genetic, species and habitat or ecosystem.
- What is genetic diversity?
- The variety of alleles within a species or population.
- What is species diversity?
- The number of species in a community and the relative abundance of each, a product of richness and evenness.
- What is habitat diversity?
- The variety of habitats or ecosystems within an area.
- Why does high genetic diversity increase resilience?
- Some individuals are likely to carry resistance alleles, survive a disease or change in conditions, and reproduce.
- Why are Cavendish banana plantations vulnerable to Panama disease?
- The plants are genetically identical clones, so a pathogen that infects one can infect all.
- List the four features of evolution by natural selection.
- Variation, overproduction of offspring, competition for limited resources, and differences in adaptation affecting survival and reproduction.
- Define speciation.
- The generation of new species through evolution.
- Give an example of natural selection in a wild population.
- Medium ground finches on Daphne Major: after the 1977 drought deep-beaked birds survived better, so average beak depth rose in the next generation.
- Define species richness and evenness.
- Richness is the number of species. Evenness is how equal the numbers of individuals of each species are.
- Write Simpson's reciprocal index.
- D = N(N − 1) / Σn(n − 1), where N is the total number of individuals and n is the number of each species.
- What does a higher Simpson's reciprocal index mean?
- Higher species diversity: more species and/or more even abundance.
- Why can two communities with equal richness have different indices?
- The index also reflects evenness: a community dominated by one species has a low index.
- Why is knowledge of biodiversity needed for conservation?
- It shows which species and areas to prioritise and allows change to be monitored so managers can judge whether strategies work.
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).