4.2 biodiversity

• Biodiversity is the variety of living organisms
• Over time, the variety of life on Earth has become more extensive
• Biodiversity is threatened by human activities such as deforestation, agriculture, and climate change
• Species richness is the number of different species in a community
• Species richness can be measured by counting the number of species present using methods like random sampling
• Other sampling methods include systematic sampling, opportunistic sampling, and stratified sampling
• Species evenness is a comparison of the abundance of different species in a habitat
• Genetic diversity is the measure of genetic variation found in a particular species
• Genetic diversity can be determined by calculating the heterozygosity index (H)
• Index of diversity (D) can be calculated as D = Diversity index / N = total number of organisms / n = total number of organisms of each species
• Maintaining biodiversity is important for ecological, economic, and aesthetic reasons
• Methods of conserving biodiversity include in situ methods like marine conservation zones and wildlife reserves
• Ex situ conservation methods include zoos, seed banks, and botanic gardens
• Zoos use scientific research, captive breeding programs, reintroduction programs, and education programs to conserve endangered species
• Seed banks store seeds in cool, dry conditions to conserve genetic diversity and prevent plant species from going extinct
• Biodiversity conservation requires international cooperation
• Historic and current agreements include CITES, the Rio Convention on Biological Diversity (CBD), and the Countryside Stewardship Scheme (CSS)
• Classification is the process of naming and organizing organisms into groups based on their characteristics
• Organisms can be grouped into animals, plants, fungi, prokaryotes, and protoctists
• Organisms can be further grouped into phylum, class, order, family, genus, and species
• Molecular phylogeny analyzes molecular differences in organisms to determine their evolutionary relatedness
• All organisms can be separated into three domains: Bacteria, Archaea, and Eukaryota
• Evolution
• The niche of a species is its role within the environment
• Natural selection is the process where fitter individuals survive and pass on advantageous genes to future generations
• Evolution occurs as the frequency of alleles in a gene pool changes over time due to natural selection
• If two populations become reproductively isolated, new species will be formed
• Evidence for Evolution
• Observations by scientists like Charles Darwin and Alfred Wallace provide evidence for evolution
• Evidence includes fossils, molecular biology, and comparative anatomy
• Variation
• Each population shows natural variation in characteristics
• Characteristics can vary in a continuous or discontinuous fashion
• Discontinuous variation has no intermediates and is controlled by a single gene
• Continuous variation can take any value within a range and is influenced by multiple genes and environmental factors