biodiversity Flashcards
biodiversity
Biodiversity is a measure of the variety of living organisms.
- the variety of living organisms - it can be measures in terms of species diversity (number of species in a community) ecosystem diversity (range of different habitats) and genetic diversity
Habitats with high biodiversity = rainforests, coral reefs
Habitats with low biodiversity = desert, tundra, agricultural land
differences in bird richness example
There is more biodiversity around the equator, decreases as you move towards the poles.
due to higher temp, light intensity and less seasonal changes
plant diversity
Best growing conditions for plants, leading to a higher diversity of plants.
A higher plant diversity leads to a higher diversity of animals because:
1. More types of food sources.
2. More types of habitats (for nests, burrows)
biodiversity over time
The repeated biodiversity pattern over time has been an increase in the number of species, followed by a mass extinction event (climate change triggered by meteorite, volcanic activity, continental drift). Organisms are not adapted to the new climate, become extinct at a faster rate than the rate at which they can adapt (ie, extinction is faster than evolution).
biodiversity in area
Biodiversity also changes over space, ie, geographically both over a global level (graphs above) and over a local level.
Measured using a transect (ie, a straight line along which regular measurements are taken).
species richness
the number of species in an area / habitat / ecosystem
- does not take into account the number of individuals of each species therefore gives undue importance to rare / infrequent species
index of diversity
takes into account the number of species as well as the number of individuals of each species - more reliable
D = N(N-1)
sum of n(n-1)
N - total number of individuals of all species = total of a collumn
n - the number of individuals in each species = total of a row
community
all the different species that live in one area and interact with each other
what impact does agriculture have on species diversity
decreases species richness
farmland typically used for only 1 species - monoculture
use of pesticides / herbicides
what impact does agriculture have on genetic diversity
decreases as farmers select for certain characteristics, which reduces number of different alleles in the population
how can biodiversity be increased in areas of agriculture
use of hedgerows instead of fences
grow different crops in the same area, or rotate crops around after a season
limit use of pesticides and herbicides
name four ways we can measure genetic diversity
frequency of observable characteristics
base sequence of DNA
base sequence of mRNA
amino acid sequence
what is meant by gene technology
sampling DNA or mRNA in order to read and compare the base sequence of organisms
alternatively the amino acid sequence can be studied as this will also provide information on the organism’s mRNA and DNA sequences
why do scientists prefer to use gene technology instead of observation
simply inferring DNA characteristics by observing organism’s characteristics is not reliable
the characteristics could be coded for by more than one gene, or could be influenced by the environment
what is meant by interspecific and intraspecific variation
interspecific = differences between individuals of different species
intraspecific = differences between individuals of the same species
