Biodiversity and its measures Flashcards
What is the definition of biodiversity?
The variety of living organisms in an area
What is the definition of a species?
A group of similar organisms able to reproduce to give fertile offspring
What is the definition of a habitat?
The area inhabited by a species, including the physical factors and the living factors. E.g a pond
What are the first 3 scales that biodiversity can be measured on?
- Species diversity
- Genetic diversity
- Habitat diversity
For species diversity, explain the two measures.
- Species richness- This is the number of different species in an area
- Species evenness- This is the abundance of species in an area
For species diversity, how are the two measures measured?
Taking a random sample of a habitat and counting the population of each species and the number of species
What increases the species richness? Give an example
The higher the number of different species, for example a woodland could contain many different species of plants, insects, birds and mammals
What increases the species evenness?
The more similar the population size of each species
When would an ecosystem be considered diverse?
When the species richness and evenness are both high, giving a high biodiversity
What does species diversity as a measure take into account?
The stability and health of food chains
Explain what genetic diversity is
This is the variation of alleles within a species or a population of a species
Give an example of genetic diversity
Human blood type is determined by a gene with 3 different alleles
Explain what habitat diversity is
The number of different habitats/ ecosystems in an area
What makes habitat diversity the most difficult aspect of biodiversity to calculate?
The boundaries of habitats/ ecosystems are difficult to determine.
Give an example of somewhere containing many different habitats.
A coastal area- beaches, sand dunes, mudflats, salt marshes etc
How is habitat diversity affected by humans?
Agricultural land has larked ploughed fields making a uniform habitat
What is genetic biodiversity?
It determines how easily a species is able to adapt to changes in its environment
Why is genetic biodiversity so crucial for a species survival?
A species with high genetic diversity will contain a wide range of traits on which natural selection can act, therefore increasing the chance of a species adapting and surviving environmental changes, allowing evolution to occur
What can cause the genetic diversity of a population to increase?
- DNA mutation
- Gene flow from another population (breeding between populations of the same species)
What can cause the genetic diversity of a population to decrease?
- Selective breeding
- Captive breeding
- Genetic bottle necks (when a population is reduced to a small size due to disease, habitat destruction etc)
Genetic diversity can be measured by genetic polymorphism. Explain how this is done and give the equation
- Alleles are different versions of genes
- Alleles of the same gene are found at the same point on a chromosome (locus)
- polymorphism described a locus with 2 or more alleles
- working out the proportion of polymorphic gene loci in an organism gives you a measure of genetic diversity
Proportion of polymorphic gene loci=
number of polymorphic gene loci / total number of loci
What may happen if a population has a low genetic diversity?
It might not be able to adapt to a change in the environment and the whole population could be wiped out by a single event e.g a disease
Give examples of populations where genetic diversity may be low.
- Animals bred in captive breeding programmes (e.g zoos)
- Populations of pedigree animals (e.g dogs bred to meet kennel club criteria)
- Rare breeds
Does a species that has a high percentage of monomorphic genes (only 1 allele) have high or low genetic diversity?
-low, and with a low percentage of monomorphic genes has high genetic diversity
