The Variety of Life Flashcards
Ecosystem
This is an ecological unit which includes all the organisms living in a particular area interacting with one another. It has its own pattern of energy flow and nutrient cycle. An ecosystem can be any size
Community
Is a group of species which occur in the same place at the same time. A woodland community includes all the living organisms within the wood
Population
This is a group of organisms of the same species living in the same area at the same time, varying in age from the very young to the very old (human population)
Environment
These are the conditions, which surround an organism and are composed of biotic and abiotic factors
Habitat
Particular place where a community of organisms is found
Niche
This describes the precise way that an organism fits into its environment and relates to the manner in which the organism obtains food and how it itself is a sources of food for other organisms
Biodiversity
Is a measure of the variety of life in an ecosystem
How does the complexity of a biological community depend on the number of different species it contains (species richness)?
Varies geographically with warmer areas tend to support more species than colder areas, wetter areas more species than dry areas, less seasonal areas more strongly than strongly seasonal areas and areas with varied topography and climate support more species than uniform species
What does the complexity of a biological community depend on?
1: No. different species it contains (species richness)
2: Relative numbers of individuals of each species
What are adv of species richness?
Simple concept and rel easy to perform on a practical level
What are the disadv of species richness?
Incomplete measure of diversity and has limitations when it comes to comparing the diversity of 2 dif areas sites or countries
How is diversity of ecosystems often assessed?
Counting number of individuals of each particular species
What does species richness often omit?
Info concerning the rel abundance of each particular species
What does diversity indicate?
Number/ richness of species + also inc the measure of the evenness of distrib of species.
What does biodiversity indicate?
Indication of both the range of species in a habitat and also how evenly balanced the number of individuals are across the different species
NOT SAME AS SPECIES-RICHNESS
In Simpson’s Index what does
N
n
E
D
stand for?
N= total number of organisms of all the species
n= total number of organisms of each individual species
E= Sum
D= Diversity
What does ecosystem diversity rep?
Divers of ecosystems within the biosphere (part of the earth and its atmosphere that is inhabited by living organisms)
How does Agriculture reduce diversity?
Farmers tend to grow large fields containing the same crop
A field of wheat is not very species rich
Dairy farmers will tend to have a herd of the same variety of cattle and will feed their stock the same type of grass
How does pollution decrease biodiversity?
In rivers, div of the bottom living organisms decreases sharply downstream due to sewage inputs from large human settlements.
What factors affect the genetic diversity?
How long a particular species has been in existence since it evolved
Degree of directional selection that has taken place in dif populations
Where is genetic variability greater?
In species that have become adapted to a wide range of env
Why would certain species be more genetically variable?
Species subjected to higher rates of mutation in their DNA than other species
What is genetic variability?
variation of DNA and species
State the difficulties of defining species:
Species evolve and change over time
Artificial selection brings about variation
Many species are extinct and have left no fossil record
Isolated species may/may not be different species
Some species are sterile e.g the mule
