3.3- biodiversity Flashcards
why is biodiversity so important?
-when one organism in disrupted, so is another
-some organisms needed to purify air and water
-plants contribute oxygen through photosynthesis
-provides genetic variation within ecosystems, helping with resistance to disease
how do we assess biodiversity? 2 ways
1.species richness
-number of diff species in an area
-wet tropics generally most diverse
2.species abundance
-eveness of distribution of diff species
-shows relative number of diff types of organisms
-more even= more diverse
what is endemism
-number of species in an area which are found nowhere else
-the areas with highest biodiversity are not always the areas with highest endemism
-makes conservation difficult as hard to prioritise certain areas
3 componants of variety in organisms
1.species deiversity- number of diff species and individuals in a community
2.genetic diversity-the variety of genes within a population of a species
3.ecosystem diversity- the whole range of different habitats on all scales
the index of diversity
-another way or measuring species diversity
-calculation on flashcard
places with the highest biodiversity
-stable ecosystems
-areas with higher productivity (more photosynthesis)
-areas where organisms grow and replicate quickly
-because more mutations can occur leading to adaptations
genetic variation definition
the number of different alleles in a given species
aspects of biodiversity- genetic variation
-greater genetic diversity means species more likely to adapt to environmental changes
-because a wider range of alleles means a wider range of characteristics
-high probability that an in dividual posesses characteristics to survive in new environment
what are mutations?
-changes in DNA structure
-increase the gene pool of a population by increasing number of different alleles
-if a mutation results in the production of an advantageous feature, the frequency of that allele will increase within the population due to natural selection
increasing genetic diversity
-meiosis contributes to genetic variation
-further genetic diversity can be increased through genetic mutations creating new alleles
-‘gene flow’ happens when individuals from a diff population migrate and reproduce
why do trees have a high species diversity?
-different layers within trees
-these provide different habitats/ niches food sources
-species diversity is high
-when deforestation occurs, lots of these are lost decreasing diversity
2 ways humans reduce species diversity
1.deforestation- permanent clearing of forests
2.agriculture- large scale use of land for crop growth
these both remove habitats and food sources
why does agriculture reduce species diversity
-farmers grow a specific crop
-single crop is grown all year round (monoculture)
-other species of plants or animals become excluded
-some plants outgrown by more rapidly growing plants
-pesticides and fertillisers can be very harmful
benefits and risks of human activity
risks=
-deforestation has many disadvantages
-reduces species diversity
-makes ecosystems less stable
-increases CO2
-loss of potential medicines
advantages=
-more space to grow crops means cheaper food
reasons to maintain biodiversity
-deny future generations natural resources if we destroy
-ecosystems provide fibre for clothing
-source of pleasure
-cause global climate change
-ecosystems maintain air quality
