Unit 2; Continuity of Life; Biodiversity
- Created by: Former Member
- Created on: 18-11-16 13:38
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- Biodiversity
- Refers to:
- species richness: number of species
- number of organisms in a species
- Varies spatially due to:
- light intensity; high = more plants = more herbivores = more carnivores
- amount of energy in region; equatorial regions have more energy to support life
- environmental changes
- Variance Over Time
- Succession
- change in composition of community over time
- makes more suitable for particular species
- increases animal biodiversity but decreases that of plants
- natural selection
- Human Influences
- farming
- over-fishing
- eutrophication
- deforestation
- urbanisation
- conservation benefits
- Succession
- needed for food, raw materials & medicines
- Assessing Biodiversity
- Simpson's Index
- describes bio-d of motile organisms
- numerical value, higher=better
- Number of Alleles
- locus is genes position on chromosome
- polymorphism if 2+ alleles at frequencies greater than mutation alone
- > alleles = > biodiverse
- Proportion of Alleles
- if 98% have recessive allele then low bio-d
- if 50% have recessive allele then high bio-d
- Molecular Assessment
- mutations change base sequence, sometimes only 1 base
- regions of DNA that often repeat many times are hyper variable regions or short tandem repeats
- more mutations = different DNA fingerprint
- many varying fingerprints in biodiverse population
- Simpson's Index
- Natural Selection
- 1. mutation occurs causing difference in DNA
- 2. there's variation in the population due to different characteristics
- 3. individuals with specific characteristics have competitive advantage & out-compete for resources
- 4. Survival of the fittest means individuals most suited to habitat survive
- 5. the survivors can reproduce
- 6. advantageous alleles passed to offspring so they can also out-compete
- habitats continually change so biodiversity occurs
- Adaptations
- change in a species as a useful characteristic becomes common
- Anatomical Traits
- different body structures can make organism more adept e.g. stream-lined dolphin
- Physiological Traits
- different characteristics are better e.g. polar bears are endothermic so save energy in cold
- Behavioural Traits
- different behaviours cause better suitability e.g. mating rituals
- Refers to:
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