Biodiversity Flashcards
(151 cards)
What is biodiversity?
Variety of living organisms present in an area ; this includes all living organisms
Why is biodiversity important?
Maintaining a balanced ecosystem for all organisms - all species are interconnected as they could provide habitats, food cycles, help in decomposing dead plants and animals to return nutrients to the soil
Why do we rely on balanced ecosystems?
As they provide us with the food, oxygen and other materials that we need to survive ; many human activities such as farming and clearing land for housing can lead to a reduction in biodiversity
How does biodiversity vary across the globe?
Tropical/moist regions have the most biodiversity - warm all year round
Temperate region (U.K.) warm summers and cold winters have less
Extreme environments - very cold Arctic or very dry deserts have the least biodiversity.
Closer a region is to the Equator, greater the biodiversity
Why do we measure biodiversity?
Important role in conservation - informs scientists of the species that are present thus providing a baseline for the level of biodiversity in an area and then you can measure the change to an environment (disease/human activity/climate change)
What is an EIA?
Environmental Impacts assessment which is taken before big infrastructure projects - predicts the positive and negative effects of a project on the biodiversity in that area
3 levels that biodiversity can be studied at
Habitat biodiversity
Species biodiversity
Genetic biodiversity
Habitat biodiversity
Number of different habitats found within an area - each habitat can support a number of different species thus greater species biodiversity is as a result of greater habitat biodiversity. U.K. has a higher habitat biodiversity than America which is covered almost entirely by an ice sheet - very few species live in this region. On a smaller scale - countryside that is habitat rich (hedges/rivers) will be more species rich than farmed countryside with large ploughed fields which make up a single uniform habitat
What is species biodiversity composed of?
Species richness and species evenness
What is species richness!
Number of different species living in a particular area
What is species evenness?
Comparison of the number of individuals of each species living in an community
What is a community?
All the populations of living organisms in a particular habitat
Cornfield vs Grass Meadow
May both contains the same number of species (species richness) by in the cornfield, corn will make up 95% of the community with the remaining 5% made up by other organisms including insects mice etc. in the grass meadow the species will be more balanced in their populations.
Genetic biodiversity
Variety of genes that make up a species - humans have about 25000 genes but some other species may have 400000 (flowering plants) ; for many genes there are different versions (alleles) which leads to genetic biodiversity within a species
What can genetic biodiversity lead to?
Intraspecies - it can lead to different characteristics being exhibited ; some genes are the same for all breeds of dog which define the organism as a dog but some genes have many alleles that code for the wide variation in characteristics seen between different breeds of dog (coat colour and length)
What does greater genetic biodiversity lead to?
Allows a species to better adapt to a changing environment - if there are any adverse changes then the species can cope and also is more likely to result in individuals who are resistant to disease (not good for us if those individuals are bacteria)
Why is sampling used?
Impossible to measure all of the organisms present in an area
What is sampling?
Taking measurements of a limited number of individual organisms present in a particular area - estimate the number of organisms in an area without having to count them all ; number of individuals of a species present in an area is known as the abundance of the organism.
What can you do with a sample
Use the results to make generalisations/estimates about the number of organisms - distribution of species or measured characteristics throughout the entire habitat ; CAN BE DONE IN TWO WAYS : NON-RANDOM OR RANDOM
What is random sampling?
Selecting individuals by chance - in a random sample, each individual in the population has an equal likelihood of selection. Random number tables/computers are used so that there is no involvement in deciding which organisms to investigate
How to take a random sample at a grass verge?
Mark out a grid on the grass using two tape measures laid at right angles
Use random numbers to determine the x and y coordinate on the grid
Take a sample at each of the coordinate pairs generated
What is non-random sampling
Alternative sampling method where the sample is not chosen at random - it can be opportunistic/stratified or systematic
Opportunistic (non-random sampling)
Uses organisms that are conveniently available - least representative of the population thus weakest form of sampling
Stratified (non-random sampling)
Some populations can be divided into a number of strata based on a particular characteristic - population can be separated into males and females and then a random sample is taken from each of these strata proportional to its size