Genetic drift
What are the two types of genetic drift
Bottleneck & Founder effect
What are abiotic factors and biotic factors?
Abiotic= non-living components of an environment i.e. water, temp, pH, salinity
Biotic= living components of an environment i.e. bacteria, fungi, animals, plants
2 Behavioural adaptation examples
huddling, migration, seeking shade/shelter
What is a population?
A group of organisms of the same species living together in a particular area
Definition of genetic diversity
The variety of genes or alleles in a population or species.
Definition of genetic drift
Random changes in allele frequencies due to chance events
What is population density?
The number of individuals per unit of area or volume.
2 Structural adaption examples
Rolled leaves, thick cuticles (plants)
Thick fur/blubber, large ears to increase heat loss, small ears to reduce heat loss, webbed feet, bright feathers to attract mates
What is a community?
Different species living together in a particular area
What is a gene pool?
The collection of alleles in a population.
Definition of bottleneck effect
A sudden reduction in population size of a population due to an environmental activity or natural disaster.
- Bonus 100 points for saying: The smaller the population, the greater the effect and impact
What graph type represents exponential population growth?
J-shaped curve
What is torpor and provide some examples:
Physiological state in which the metabolic rate is lowered to save energy.
E.g.: hibernation, brumation, aestivation
What are the two types of mutualism? Give a definition of both.
Facultative: both species benefit but do not rely on one another
Obligate: both species are completely reliant on one another for survival and reproduction
What are key sources of genetic diversity? Which one introduces new genes/alleles?
- Crossing over of chromatids during meiosis
- Independent assortment
- Mutation (new genes)
- Gene flow
Definition of founder effect
When a small group is isolated from a larger population, either by migration or habitat fragmentation. The smaller population only has a small portion of the alleles of the original population and has lower genetic diversity.
In the new environment, the different selection pressures cause differences in allele frequency and genetic diversity b/w smaller and bigger pop.
I.e. frogs, snails, tortoises and crocodiles
Relate to the functioning of an organism at a cell, tissue, organ, system and organism level.
E.g.: CAM photosynthesis, frost tolerance mechanism, shivering, heat exchange system, camouflage, venom, hibernation, bioluminescent
What is commensalism and what type of interaction is it?
Benign. It is an interaction where only one species benefits but the other is unharmed.
What is natural selection?
Individuals with phenotypes that are well-suited to their environment and are more likely to survive and reproduce.
A large population of lizards living on a mainland has two color variations: brown (60%) and gray (40%). Both colors provide equal survival advantages in their environment.
During a severe tropical storm, a piece of driftwood carrying only 8 lizards breaks away from the mainland and floats to a small, uninhabited island. By chance, 6 of these lizards are brown and only 2 are gray.
The lizard population grows rapidly over the next 20 generations. After this time, researchers visit the island and find that 95% of the lizards are brown and only 5% are gray.
What type of genetic drift is this?
Compared to the mainland population, the island population after 20 generations would most likely have?
Founder effect
Lower genetic diversity due to the small founding population
What are density-independent factors? Provide some examples.
E.g.: Bushfires, droughts, floods, man-made changes, abiotic conditions.
What is the difference between tropism and nastic movement?
Tropism is plant GROWTH in response to environmental stimuli, whereas nastic movement is the MOVEMENT of a plant in respond to environmental stimuli
What is a keystone species and what will happen if we remove it? Give one animal example.
A species that plays a crucial role in maintaining the structure and functioning of its ecosystem. If we remove it many other species will become at risk, there will be an imbalance in the ecosystem and even abiotic factors may be affected.
E.g.: grey wolves, bees, Great white sharks, P. ochraceus sea star
Why is genetic diversity important?
- Is the basis for adaptation
- maintains heath and stability of pop
- improves biological fitness
- improves long-term evolutionary potential.