🐆Biology Unit 5 Biodiversity

• Classification system hierarchy

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• DNA sequencing, gel electrophoresis and bioinformatics

  • Can be used to distinguish between species and determine evolutionary relationships
• Natural selection

  A random mutation occurs that is favourable. This allows individual with it to survive and reproduce, passing the allele on, increasing its frequency in the population.
• Niche

  Organisms role within an ecosystem
• Pathogens and the development of medicines

  There is an evolutionary race between them
• Five Kingdoms

  • Prokaryotae (or Monera), Protoctista (or Protista), Fungi, Plantae, Animalia
• The Archaea

  • They share some features with bacteria and some features with the Eukarya, but some features are unique to the Archaea domain
  • have a different rRNA gene
  • have a unique phospholipid in the membrane
  • Many of the Archaea are extremophiles
• Types of Archaea extremophiles

  • Thermophiles
  • Psychrophiles
  • Halophiles
  • Acidophiles and Alkaliphiles
  • Barophiles
  • Xerophiles
• Darwin's Theory of Evolution by Natural Selection

  1. There is genetic variation in characteristics within a population

  2. Individuals with characteristics that make them less well adapted to their environment will die young

  3. Individuals with characteristics that make them well adapted to their environment will live longer and reproduce, passing on their alleles to their offspring

  4. The allele frequency will change in each generation
• Natural Selection and Adaptation

  • The result of Natural Selection is that organisms who survive are well-adapted to their ecological niche
  • Successful organisms have features (called adaptations or adaptive traits) that make them good at surviving in their niche
  • Adaptations can be anatomical, physiological, or behavioural
  • Adaptive traits give the appearance of design, but this is misleading and in fact close examination often reveal design flaws
• Bacterial resistance to antibiotics

  1. Random mutation occurs

  2. Mutation makes bacterium resistant to antibiotic

  3. Resistant strain reproduces and spreads

  4. Resistant strain colonises environment
• Species

  Members of the same species can breed together to produce fertile offspring but cannot breed with members of other species
• Speciation - The Origin of New Species

  1. An existing species splits into two separate groups

  2. The two groups become reproductively isolated, so there is no mixing of genes between them

  3. The two groups evolve differently due to different environments or genetic drift

  4. Eventually the two populations are unable to interbreed, so they become different species
• Allopatric speciation

  Happens when two populations of the same species become geographically separated

  1. Start with an interbreeding population

  2. Population becomes divided by a physical barrier

  3. Isolated populations evolve differently

  4. If barrier is removed, populations are now different species
• Sympatric speciation

  • Happens when two populations of the same species become reproductively isolated even though they share the same geographical location
  • Ecological isolation
  • Behavioural isolation
  • Temporal isolation
  • Mechanical isolation
  • Genetic isolation
  • Hybrid sterility
• Populations of the same species that are currently isolated are called subspecies (or sometimes breeds, varieties or races) and they may in time become distinct species, or they may remain an interbreeding single species
• Biodiversity

  The variety of all the life on Earth
• Levels of biodiversity

  • Diversity within species
  • Diversity between species
  • Diversity of ecosystems
• Gene pool

  All the genes in a species
• Members of the same species all have the same genes, but different combinations of alleles
• New alleles arise through mutation and existing alleles are recombined by meiosis and random fertilisation during sexual reproduction so that every individual within a species is genetically unique
• Genetic diversity of a species

  The number of different alleles within a species' gene pool
• A species with a high genetic diversity is likely to have some individuals with the characteristics required to survive a change in the environment, so some members of the species will survive
• Low genetic diversity means a species will be unable to cope with environmental changes and so is more likely to become extinct
• Genetic diversity is generally higher in large populations and lower in small populations
• Genetic Erosion

  The loss of genetic diversity in wild and domesticated species
• Genetic diversity is dramatically reduced by selective breeding, since only a small number of alleles are selected
• Species diversity

  The variety of species in a community
• Species diversity is useful because it tells us about the complexity, quality and stability of an ecosystem
• Species richness

  The number of species per m²
• Richness alone is not a good measure of diversity because it doesn't take into account the size of each species population - its abundance (the number of individuals per m²)
• The higher the Simpson Diversity Index, the higher the species diversity
• Harsh habitats tend to have low species diversity, as only a few species are adapted to the harsh environment
• Mild habitats support a high species diversity, which leads to high productivity and a large, complex food web
• Ways human activities are reducing biodiversity

  • Deforestation
  • Mining
  • Building
  • Farming
  • Hunting
  • Habitat destruction
  • Selective breeding
  • Competition with humans
• Conservation

  The attempt to conserve biodiversity worldwide
• To maintain the gene pool we need to preserve species diversity, and to conserve species diversity we must provide suitable niches for all species by preserving habitat diversity
• The aim of conservation today is the management of our environment to keep the land as a productive resource, but in a sustainable way that maintains biodiversity and will continue to do so in the future for all our descendants
• Ethical reasons for conservation

  • The needs of humans to use and exploit nature for our survival
  • The needs of other animals to live their lives without human interference
  • The needs of humans to enjoy the natural beauty of untouched nature
  • The needs of our descendants to enjoy or use ecosystems as we do
  • The needs of everyone on the planet to avoid catastrophes such as global warming or mass extinctions
• Ecosystem Services

  The benefits of the natural world that are used to persuade governments and businesses to conserve it