tags: 
  - bio
topic: Biodiversity
date: 2023-10-31

Glossary

key concepts

Population:: Group of the same species living in a particular area.
Community:: Group of different species living in a particular area.
Ecosystem:: Self-sustaining system formed by the co-existence of different organisms in a particular area at a particular time, as well as the abiotic factors.
- If keystone species are removed, the system collapses.
Biodiversity:: The variety and variability of organisms and species in a specific ecological area.
- The higher the biodiversity, the increased chance of surviving selection pressures.
Species richness:: A measure of the number of different species
Species evenness:: A measure of the spread of different species.
Molecular diversity:: The genetic variety and variability of a population.
- These changes are expressed through genotypes and phenotypes (physical expression of gene)
Abiotic factors:: Non-living parts of ecosystems, such as temperature, salinity, currents and light that shape its environment.
Biotic factors:: Living parts of ecosystems, such as predation, diseases, and human activity that shape its environment.
Zonation:: Change in ecosystems along an environmental gradient. Most commonly seen in intertidal rock platform ecosystems (i.e., along the beach) 'horizontally'
Stratification:: Change in ecosystems along an environmental gradient (vertically) e.g in a rainforest, where different organisms subsist on different strata (ground -> canopy) due to different levels of humidity, sunlight etc.

Microevolution

Microevolution:: Evolutionary changes that occur over a short period of time, diversifying within a species. Diversification can occur through::
- Mutations:: Random change in the DNA base sequence, changing the gene composition.
- Random mating:: New gene combinations introduced through random mating.
- Gene flow:: The transfer of genetic information from one gene pool to another.
- Genetic drift:: Change in the composition of a gene pool as a result of a random event, killing off a certain population.
  - Founder effect:: A small group (subset) breaks away to colonise a new territory. Over time, this subset (which lacks the genetic diversity of the original group)
  - Bottlenecking:: Type of genetic drift that originate from natural disasters wiping out a subset of the population.

Macroevolution

Macroevolution:: Evolutionary relationships that occur over long periods of time that results in speciation (variation between different species) - changes across large populations
Divergent evolution:: When multiple species evolve from a common ancestor. - they have different selection pressures now.
- Convergent evolution:: When multiple unrelated species adapt similarly with similar selection pressures.
- Parallel Evolution:: When multiple species, subsequent to divergent evolution, continue to develop similar characteristics.
- Coevolution:: When a species evolves in response to another's adaptation (usually through a predator-prey relationship)
Selection pressures:: Factors which influence the occurrence of natural selection in macroevolution.
- PANDAPAWS:: An acronym used to recall selection pressures.
  - Density dependent factors:: Predators - Availability of Resources - Nutrient Supply - Disease - Accumulation of waste
  - Density independent factors:: Phenomena (natural disasters) - Abiotic factors (, temperature levels) - Weather conditions

Additional Consumers

Parasites:: Consumers which live and feed upon another organism, causing them harm.
Scavengers:: Consumers that eat dead organisms.
Detritivore:: Consumers which eat small particles of dead plant and animal matter (known as detritus)
Decomposers:: Consumers which break down (decompose) dead material with the aid of enzymes.

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Symbiosis

Mutualism:: Relationship in which both host and symbiont benefit (e.g bees spreading pollen from flowers, which allows the flowers to reproduce while also allowing bees to obtain nectar)
Commensalism:: Relationship in which one partner benefits, and the other neither benefits nor is harmed (e.g fish consuming scraps of food off a shark).
Parasitism:: Relationship in which one organism benefits and the other is harmed (e.g ticks and leeches)

Succession

Primary succession:: Communities develop on entirely new land without any established soil.
- Original species which colonises area known as pioneer species (usually lichen or moss)
  - Decomposition of lichen and moss creates organic soil, allowing growth of larger plants.
Secondary succession:: Natural environmental disturbance means replacement of one ecosystem by another.
- Soil is already developed; dominance achieved by fastest growing plants.