Biodiversity and the variety of Life

All organsims contain the biochemicals- proteins, carbohydrates, lipids and nucleic acids

Biodiversity

-Abundance of differnet species of organisms on a local, national or gobal scale as well as the genes they conatin, and the ecosystems of which they form a part.

- Variety of organisms within a given area and is often used as a measure of the health of biological systems

Biodiverstity involves several organisational levels:

1. Genetic diversity- diversity of genes within a species

2. Species diversity- diversity among species in an ecosystem

3. Habitat/ecosystem diversity- variety ecoysytems within the biosphere

Genetic Diversity can be measured:

• directly by genetic fingerprinting i.e. biochemaical analysis of the DNA
• indirectly by observing differences in the physical features of the organisms within the population

Wide genetic diversity

The existance of different forms (morphs) within a population is called polymorphism. This is an advantage to a population because if the envronment changes, theres is a good chance that one will be adapted to the new environment.

Narrow genetic diversity

Genetic fingerprintig of individuals within some populations such as cheetahs has indicted that there is very little genetic variability.

Due to their lack of genetic diversity, if the environment changes, the population would be wiped out.

Species diversity relates to the variation among the species in an ecosystem. It takes into account the number of different species present and the abundance of the individuals of each species present along with the eveness of distribution among the species present.

Measured by Simpsons Index

Species Richness - number of different species in an area

Values of D range from 0-1

Closer to 0, higher diversity

The diversity of habiats or ecosystems within an area

An example of high diversity species rich countryside is one with ponds, rivers, woodlands, hedgerows, meadows and grassland.

Narrow habitat diversity is found in countryside with ploughed fields, land drained and without wet areas and devoid of woods and hedgerows

Taxonomy is the science of naming, describing and classifying organisms

Two main areas:

• Nomenclature - the scientific naming of organisms using the biominal system (two Latin names)
• Systematics - placing organisms into groups based on a phylogenetic hierarchy
  • generic names (genus) beginning with a capital letter
  • specific name (species) beginning with a lower case letter

Before defining a species in the present day, taxonomists will look at:

• Morphology - external features
• Anatomy - internal features
• Cell Structure - prokaryotic or eukaryotic
• Biochemistry - DNA, RNA and protein

                   Human        Domestic Dog

Kingdom   i  Animalia         Animalia   i - Largest most inclusive group

Phylum      i Chordata  i      Chordata    - Organisms consttructed in a similar plan (divisions in plants)

Class          iMammalia       Mammalia  - A grouping of orders within a phylum

Order        i iPrimates  i      Carnivosa   - A group of related families

Family   i   i lHominidae      Canidae     - A group of related genera

Genus       i  Homo      i      Canis        i- A group of similar and related species

species        sapiens           familiaris   - A group of organisms, which show a close similarity in morphological and biochemical characteristics and are capable of interbreeding to produce fertile offspring

Biochemistry

A protein called Cytochrome C is used in respiration in all living organisms. If we compare the primary sequence of this protein in different species, we can draw the following conculsions:

• If the sequences are the same, the two species are closley related
• The greater the differences in amino acid sequences, the less closely related the species
• The greater the variation in the base sequence, the more distantly related two species are.

Cell structure

The key difference is whether the orgainism is eukaryotic or prokaryotic. Eukaryotic cells evolve and four of the main kingdoms are eukaryotic

Defining Features

• Made up of prokaryotic cells- no membrane bound organelles
• A cell wall is present
• Naked Circular DNA
• May possess plasmids (small loop of DNA)
• Reproduce by an asexual process called binary fission (cell spilts in two)
• Lysotrophic - secreting enzymes onto organic matter
• Heterotrophic or autotrophic
• Includes bacteria and blue green algae
• 70S Ribosomes

Defining Features

• Eukaryotic (membrane bound organelles)
• Mainly Unicellular
• If mutlicellular, the cells show limited differentiation
• Cellulose cell wall
• Some are heterotrophs(feed on other organisms) - Paramecium
• Others are autotrophic(make their own food) - Pleurococcus
• Reproduction can be sexual or asexual

- including moulds, mildews, yeasts and mushrooms

Defining Features

• Eukaryotic (membrane bound organelles)
• Heterotrophic/Lysotrophic (feed by breaking down dead material through lysis involving lytic enzymes and bringing about decomposition in the process)
• Have a mycelium which consists of hyphae
• Feed by extracellular digestion. They secrete hydrolytic enzymes out of their cells into their food and absorbing only small, simple organic molecules. Vesicles found at the tips of hyphae are involved in nutrition. The vesicles discharge digestive enzymes outside the hyphae through excoytosis. This results in extracellular digestion and the soluble products are then absorbed back ino the hyphae.

Plantae Defining Features

• Eukaryotic (membrane bound organelles)
• Multicellular
• Cellulose cell walls
• Chloroplasts containing chlorophyll
• Autotrophic - by photosynthesis
• Starch is the storage carbohydrate

Animalia Defining Features

• Eukartotic (membrane bound organelles)
• Multicellular
• No cell walls
• Heterotrophs
• Capable of locomotion

Carl Woese introduced a system in 1990 that classified living things under three domains (super kingdoms). It allowed him to classify all living things as Prokaryotes, Eukaryotes or Archaea. Archaea showed they had an independent evolutionary history and numerous differences in their biochemistry.

The three domain model groups organisms into three unique domains, all with rRNA that is unique to them. It recognises Eukaryote, Prokaryotes and Archaea as three sperate groups of living things.

What is Biodiversity?

• The existence of many different species with a wide range of genes and allels which live in many different habitats. 

Biodiversity has been significantly reduced mainly due to intensive agriculture. Intensive farming is the growing of high-yeilding, single species crops using fertilisers and pesticides to maximise productivity.

Hedgerows

The removal of hedgrows gives larger fields making the sowing and harvesting of crops, using heavy machinery, easier, faster and cheaper, and giving a large area to grow the crops increasing the yeild and profits.

Farmers can apply for grants to aid in the replanting of hedges - this aims to:

• provide a variety of niches for a large diversity of animal species
• offer habitat diversity 
• promote genetic diversity

Why are they important?

• Acting as a screen against bad weather - native flora and fauna 
• Providing cover for game - animals such as rabbits and pheasants are provided with camouflage against predators
• Act as a wildlife corridor - allowing dispersal and migration to other habitats. They prevent interbreeeding and therefore help to ensure organisms are well adpated to their habitats

Regulations and guidlines are in place to ensure they remain a diverse and viable habitat:

• Cuttting hedges should be refined to autumn and winter on a two-yearly cycle (Biennial Trimming), in order to avoid disturbing nests and destroying food sources such as berries
• Hedges should be cut in an A-shape, in order to provide different widths and hence different microhabitats
• Coppicing - The hedge is cut at ground level and sprouts from the base. This provides better shelter for livestock and wildlife and better nesting sites for birds. 

High yeilding strains (genetically identical) of single-species crops are grown over large areas of land. They increase the farmers profit and decrease the effort needed to harvest.

Artificial fertilizer is applied as the same nutrient is continually being taken from the soil making it quickly become depleted of particular minteral ions, however the fertilizer does not improve the soil quality. As plants in a monoculture are genetically identical they are all susceptible to the same pests and disease.

Monocultures decrease biodiversity due to:

• Only one food source is available which will only support a narrrow range of consumers
• Large scale fertilizer, leading to runoff and eutrophication (effecting equatic systems)
• The use of pesticides which kills beneficial insects

Crop rotation is often used as:

• There is increased soil fertiliry as different plant species have different mineral requirements
• Pest and pathogens are less likely to become established
• It allows for savings on fertilizer and pesticide, however costs are increased with labour

Growing more than one crop in the same area of land - intercroppping

Intercropping

• Crops may mature at different times or may be planted with a view to their mutual benefit
  • Growing onions with carrots masks the smell of the carrot for the carrot fly

Polyculture advantages:

• Pests and pathogens are not able to spread as easily through a crop
• Increased soil fertility as different plants have different mineral requirements
• Species and habitat diversity is supported

Disadvantage:

Greatly increases labour costs through planting, harvesting and marketing a number of crops within the same year

Herbicides/Insecticides/Fungicides

Managing Pest Populations

• Uncultivated field margins (hedges)
  • Provides additional habitat and food sources for a range of inscets, birds and mammals.
  • Extend wildlife corridors
• Persistant pesticides may also be non-biodegradable and so concentrations build up along a food chain - bioaccumulates and may reach toxic levels in predators
•  Pesticides may be toxic to species other than the pest species - pest resurgence - secondary pest outbreak 

Bringing together more than one element of pest control in order to balance pest reduction with the care of the environment.

• Crop rotation/intercropping making it harder for pests to become established
• Using photodegradable plastic around to reduce the growth of weeds and use of herbicide
• Biological control - introducing natural predators or parasites of pests

Overuse of a pesticide will remove natural predators meaning that there is the potential for the pest to develop resistance.

Water pollution is caused by organic pollution or through eutrophication

Organic Pollution

Pollution of water by organic material e.g sewage, slurry and silage effluent. If organic pollutants enter waterways they provide a rich source of nutrients for decomposing bacteria. This results in decomposing bacteria using up most of the oxygen in the water due to aerobic respiration.

Biological Oxygen Demand (BOD) - is an indication of water quality, measured as the usage of oxygen in the water

A - Organic pollution. High BOD as oxygen levels fall due to decomposing bacteria

B - Bacteria has been decomposed. Less bacterua down stream

Species such as the sludge worm (Tubfiex) are adapted to survive in water that has very low levels of oxygen. Tubifex worms are rich in haemoglobin which acts as an excellent oxygen store. They have a low metabolic rate and have reduced oxygen needs.

Species  that are adapted to particular levels of polltuion are referred to as indicator species.

DARD guidelines on farming practice -

• Stores of slurry, as well as silage bales, should be kept at least 1m away from water courses
• Spreading manure is only permissible at certain times of the year (Feb-Oct)

- The leaching of minerals, in particular nitrates and phosphates (as opposed to organic waste)

It results in the following sequence:

Reducing eutrophication of waterways:

• Testing the ion content of soils before fertiliser applictaion. Ensures only the correct amount and balance of fertiliser is applied.
• Not appling fertiliser when heavy rain is forecast
• Adequate storage facilities for slurry and other farm wastes 

SACs - Special Areas of Conservation are strictly protected sites with habitat types and species of which are considered to be the most in need of conservation at a European Level. E.g. Peatlands Park

ASSIs - Areas of Special Scientific Interest are habitats which support rare or important species and earth science features in Ni (ie sites of ecological and geologiacl interest) E.g. Strangford Lough

Why do we need these?

• Ecological reasons - prevents disruption of food chains / maintains ecosystems
• Economic reasons - species not yet discovered may have medicinal properties / tourist potential
• Ethical reasons - moral requirement to protect biodiversity for future generations

Action plans set out the tasks that need to be undertaken to safeguard a habitat or promote the well-being of a species

Agri-environmental Schemes

• Hedge replanting and maintenance
• Leaving ungrazed margins in fields to allow insects and wildflowers to grow
• Maintenance of priority habitats on farmland

Natural Gases - Carbon Dioxide, Water Vapour, Methane

Man-Made Gases - CFC's, Nitrogen Oxides

The greenhouse effect is a natural process

Evidence of Global Warming:

• Mountain glaciers have declined and polar ice caps are melting - sea-levels rise
• Animal and plant species are responding to earlier springs

Climate change involves increased temperature and changes in rainfall, atmospheric pressure and winds

Scientists are 95% sure global warming is caused by -

• An increase in the amount of fossil fuel being burnt
• Deforestation - fewer trees to take up carbon dioxide for photosynthesis
• Methane has increased e.g rice growing, cattle rearing and rottting material in landfills
• Nitrogen dioxide, nitric oxide and nitrous oxide, together are termed NOx emmitted from car exhausts and denitrifying bacteria on nitrate fertilizer.

The most significant increase has been in carbon dioxide levels which have risen by 10% in the last 30 years

Climate change can expect to have these consequences - 

• Distribution of species will shift northwards or to higher altitudes
• The extinction of some species
• The polar bear is threatened as the Arctic ice sheet decreases
• Sea levels will rise

How to prevent global warming:

• Reduce fossil fuel use
• Use alternative power sources
• Reforestation