Chapter 3.1 Flashcards
Biodiversity
Biodiversity is the study of all the variation that exists within a living system with respect to the range and variety of habitats, species and genes within a particular region.
Ecosystem resilience
Ecosystem resilience is the capacity of an ecosystem to withstand disturbance and still maintain the same functions of organisms working together to maintain a balanced sustainable ecosystem
What does high biodiversity indicate?
Usually high biodiversity indicates a healthy ecosystem, but low diversity is still possible in stable healthy ancient sites where conditions are harsh, for example, the Arctic.
Species diversity
Species diversity is a product of species richness and species evenness
Species richness
The number of variety of species there is
Species evenness
The abundance or number of organisms of each species
Diversity index
A diversity index gives a quantitative estimate of biological variability in space or time and describes and compares communities.
Simpson’s reciprocal diversity index
A numerical value that can be used to measure species richness and species evenness. The higher the number, the greater the species diversity with one being the lowest possible value.
Genetic diversity
The range of genetic material present in a population of species
Individual genetic diversity
Each individual in a species has a slightly different set of genes from any other individual in that species. So more individuals means higher genetic diversity and thus a bigger gene pool
Population genetic diversity
If a species is made up of two or more different populations in different places, then each population will have a different total genetic make-up.
Do all species have the same amount of genetic diversity?
No, not all species have the same amount of genetic diversity.
How does genetic variation affect survivability?
A population with no genetic variation cannot evolve in response to environmental or situational changes. A population with high genetic variations has a higher likelihood of including a few individuals carrying gene version that provide protection from threats. Such populations can evolve in response to new threats instead of going extinct.
Habitat diversity
The range of different habitats in an ecosystem or biome
Describe the difference in genetic diversity from habitat to habitat.
Some habitats such as coral reefs and rainforests have high species diversity.
Tropical rainforests are high in habitat diversity because there are many ecological niches due to the layering of the forests.
Urban habitats and polar regions have much lower species diversity by comparison.
How can humans alter genetic diversity?
Artificial breeding (domesticated dogs), genetic engineering of populations (altering the DNA of bacteria as in the manufacture of medicinal drugs)
Describe the advantages and disadvantages of genetic engineering
It reduces variation in genotypes. Can be advantageous if it produces a high-yielding crop or animal but is a disadvantage if disease strikes and the whole population is susceptible.
Why is ecosystem complexity important?
The more complex a food web, the more resilient it is to the loss of one species or reduction in its population size.
If one type of prey or food source or predator is lost, the other will fill the gaps left.
This resilience of more complex communities and ecosystems is a good thing for biodiversity overall.
What are the stages of succession in simple terms?
n plants and animals colonise a bare piece of land, only a few pioneer species colonise it at first.
As time passes and conditions become more favourable, species diversity increases until a climax community is reached.
Species composition is stable.
How does biodiversity change throughout succession?
In the early stages of succession, abiotic conditions are harsh and limiting factors are numerous and thus, biodiversity is lower.
Communities in young ecosystems that are undergoing succession tend to be more vulnerable to disturbances and less resilient.
How do limiting factors impact ecosystem stability?
If it is difficult for the organisms in an ecosystem to get enough raw materials for growth, diversity is limited. If the abiotic factors required for life are available in abundance the system is more likely to manage if one is reduced.
How does the age of an ecosystem determine its total biodiversity?
As a rule, the older the ecosystem, the greater the biodiversity is likely to be. If the ecosystem is undisturbed for a long period of time, more habitats can develop allowing for greater diversification of species.
What are the advantages of high biodiversity?
Resilience and stability due to the range of plants present, of which some will survive drought, floods, insect attack or disease.
Genetic diversity, resistance to diseases
Some plants there will have deep roots to cycle nutrients, bringing them to the surface making them available for other plants.
Why might high biodiversity indicate an unhealthy ecosystem?
Diversity could be the result of fragmentation of a habitat or degradation when species richness is due to pioneer species invading bare areas quickly.
Managing grazing can be difficult as plant species have different requirements and tolerance to grazing.
Some stable and healthy communities have few plant species so are an exception to the rule.
