biodiversity Flashcards
define biodiversity
number of species and the number of individuals of each of the species within any one community.
define species richness
no. of different species in community.
define community
All the individuals of all the species living together in the same area at the same time.
define species
- Group of similar organisms / organisms with similar features / organisms with same genes;
- Reproduce to produce fertile offspring;
define genetic diversity
difference in DNA/base sequence/alleles
define ‘niche’
An organism’s role / in the ecosystem / community;
It describes what the species is like, where it occurs, how it behaves, how it interacts with other species and how it responds to the environment.
No 2 species occupy the same niche due to interspecific competition.
define ‘habitat’
place organism normally lives in ecosystem (characterized by biotic & abiotic factors)
what is diversity index?
diversity index = N(N-1)
——————-
sum of n(n-1)
N = total no. organisms of all species
n = total no. organism in each species
What information is required to calculate an index of diversity for a particular community?
Number of species;
Number of individual in each species;
The number of species present is one way to measure biodiversity.
Explain why an index of diversity may be a more useful measure of biodiversity.
Also measures number of individuals in a species / different proportions of species;
Some species may be present in low/high numbers;
Give 2 advantages of using an Index of biodiversity rather than an indicator species
You do not need to identify each species;
Index takes into account the number of organisms of each of the species.
some species may be present in high/low numbers
what does high diversity show about an ecosystem?
- high stability
- has suitable climate, nutrients, shelter, space to support large range of species
- less likely disease or climate change affect every organism so ecosystem can continue
Suggest one economic argument for maintaining biodiversity.
- medical / pharmaceutical uses;
- commercial products / example given;
- tourism;
- agriculture;
- saving local forest communities;
A forest was cleared to make more land available for agriculture.
After the forest was cleared the species diversity of insects in the area decreased.
Explain why. (4)
- Decrease in variety of plants / fewer plant species;
- Fewer habitats/niches;
- Decrease in variety of food / fewer food sources;
- Aspect of clearing forest (killing insects) eg machinery, pesticides;
Farmers clear tropical forest and grow crops instead. Explain how this causes the diversity of insects in the area to decrease
- Lower diversity of plants/ few species of plants/less variety of plants/few plant layers;
- Few sources/types of food/feeding sites;
- Few habitats/ niches;
- Fewer (species of) herbivore so few (species of) carnivores;
- Aspect of agriculture (killing insects);