Module 6 Flashcards
sampling should be module 4
Distribution
Where individual organisms are found within an ecosystem. Is usually uneven throughout the ecosystem as they are generally found where abiotic factors favour them, so their survival rate is high due to having all the resources they need and low predation.
Measuring distribution by systematic, non random sampling
- A line transect is where a line of surveyor’s tape if layed on the ground and samples are taken at regular intervals and describing organisms which touch the line or are are a certain distance away
- A belt transect provides more information and 2 parallel lines are marked and samples are taken in the area between these specific points.
What is an advantage of systematic sampling?
Systematic sampling identifies different areas within the overall habitat to sample separately which allows scientists to study how the differing abiotic factors in different areas of the habitat affect the distribution of species. Can show how plant species changes you move inland from the sea.
Abundance
The number of individuals of a species present in an area at any given time. This may fluctuate daily dur to immigration and births, and emigration and deaths.
What is a population?
Why is abundance hard to measure and how can you make it more accurate?
- A population is a group of similar organisms living in a given are at a given time. They can rarely be counted accurately as not all can be caught and it can be time consuming to count all the members, or the counting process could damage the environment. We therefore estimate using sampling techniques.
- To increase accuracy, use as large a sample size as possible as there is a lower probability that chance will influence the result. Random sampling should be used to reduce bias.
How do you measure plant abundance?
Quadrats are placed randomly in an area and the number of individuals contained in the quadrat are counted.
The number of individuals and area of sample are all the quadrat samples added together
Why can you measure aniamls with quadrats?
What do you need to ensure when handling animals?
How do you measure abundance of animals?
- Animals move so can’t measure with quadrats
- Handle carefully and for as short time as possible
Capture-mark-release-recapture is used to estimate population size
- Capture as many individuals as possible in a sample area
- Mark or tag each individual in a way that doesn’t harm them- toxic paint or reverse camo. Can clip small part of fur or mark snails inside shells
- Release the marked animals back into the sample area and allow time for them to redistribute themselves throughout the habitat
- Recapture as many individuals as possible in the original sample area
- Record the number of marked and unmarked individuals present in the sample (release all individuals back into their habitat.)
- Use Lincoln index to estimate the population size
What is the equation to estimate population size for capture-mark-release-recapture?
What does a greater number of marked individuals captured mean?
How can you compare species eveness?
How do you calculate biodiversity from this?
(SS)
smaller population.
compare the total number of each organisms present
use the Simpsons index of diversity (SS) where D is the chance that any 2 individuals picked at random will be from different species
How is species frequency and species density calculated with quadrats?
Species frequency- calculate the percentage of quadrats that included each species
Species density- the number of individual organisms within a quadrat
How do you identiy organisms?
identification key are used which can contain images to identify the organism into a particular species based on the presence of a number of identifiable characteristics
Why is random sampling used?
How is it done with quadrats?
What is ACFOR?
How are aniamls measured by random sampling?
Reduces bias
- Can place tape measures at right angles to each other along the 2 sides of the sample area and random numbers are generated using an app to give coordinates of where to put the quadrats
- Count number of individuals in the girds. Often have to do % cover for plants as its hard to see the individual plants by estimating or by counting the number of squares the species is present in and converting to a %
- Calculate mean then multiply by total area
- Sometimes species are too numerous to count and plants cant always be isolated to an abundance scale like ACFOR is used (abundant, common, frequent, occasional, rare). First you decide how many plants/ animals have to be present to be considered common…. This speeds up recordings.
Animals are harder as they can be small, and lots just appear at night. Instead of quadrats they use:
- Beating trays- a large white sheet is placed on the ground or supported by struts and held below a tree. The tree is shaken to dislodge animals.
- Pooter- scientists can use this to suck small animals into a gall or plastic tube. Can use it to collect animals from a beating tray.
- Sweep net- large nets catch flying insects and insects that live in long grass
- Pond net- stronger nets lift water from pond and rivers and the water drains through to leave vegetation and animals behind
- Pitfall traps- cans or jars buried in the ground filled, with paper or cardboard to provide shelter, and covered with a lid or stone to keep out rain. Collects ground dwelling insects which are often nocturnal. Deep enough they cant crawl out
- Kick sampling- study organisms in a river to disturb the substrate. Net downstream for set period of time captures organisms
- Slow moving like muscles can be measured using quadrats
- Tullgren funnel
Why can non-random sampling be good?
What are the types of non random sampling?
Random sampling can take too long
Opportunistic sampling:
Walk around until you find an area convenient to sample. However, the area you chose may not be representative of the area. If you don’t have time to look anywhere else, often students pick places easy to reach, safe and don’t involve walking too far.
Stratified sampling:
In ecosystems there may be different habitats occupying different proportions of the total area. To get a fair representation of the biodiversity in the ecosystem, its bets to estimate the proportion of total area occupied by these habitats and then sample accordingly. If 10% if woodland, then 10% of samples should be taken from woodland.
Systematic sampling:
If there is an abrupt change from 1 habitat to another or a gradual change in conditions across the area random sampling won’t reflect the distribution. Transects. Line transect results are converted into a drawing which shows distribution. Shows change down a gradient, like a slope or changing abiotic feature. Belt transects can be continuous or is the distance is long then at regular intervals. Results are converted into a kite diagram. Is biased as you choose where to put the transect and this area may not be representative but is easier as don’t have to measure coordinates.
Why are abiotic factors measured?
What is the advantage of being measured with sensors?
How are the measured?
Needed to draw conclusions about the organisms present and the conditions they need for survival so measured at every sampling point
Can be measured quickly and accurately with a range of sensors which are good because;
Rapid changes can be detected
Human error in taking readings is reduces
A high degree of precision can be achieved
Data can eb stored and tracked on a computer
- Needed to draw conclusions about the organisms present and the conditions they need for survival so measured at every sampling point
Can be measured quickly and accurately with a range of sensors which are good because:
- Rapid changes can be detected
- Human error in taking readings is reduces
- A high degree of precision can be achieved
- Data can eb stored and tracked on a computer
(SS)
Describe this population growth curve
What is the population growth curve of organisms that reproduce asexually?
2- no constraints act to limit the population explosion
3- fluctuations due to fluctuations in limiting factors like predators
Organisms that reproduce asexually can produce a J shaped curve as they exploit the resources when they become available. They reach a peak and then crash often before carrying capacity is reached. They are often controlled more by abiotic factors
Examples of limiting factors for population growth
EG. Competition for resources, build-up of toxic by-products of metabolism, disease
Abiotic- non-living like temp, pH, water availability, oxygen availability, humidity. Remain constant when population density changes.
Biotic- living like predators, disease, competition. Have greater affect when population density increases.
Carrying caacity
the maximum population size an environment can support
Envrionemtnal resistance
the combined effect of that prevent the further increase of a population
Why can migration happen and what are the types?
Can happen when an area reaches its carrying capacity
Immigration- movement into an area increases population size
Emigration- individual organisms move away from a particular area and decrease population size
What are density independent factors?
factors that have an effect on the whole population regardless of size. They can dramatically change the population size. EG- earthquake, fires, volcanic eruptions, storms. They can even remove whole populations of a species from a region.
What type of factor is competition?
Interspecific competition
Intraspecific competition
biotic
competition between different species
competition between members of the same species
Interspecific variation
example
Results in a reduction of the resource they are competing for for both populations. EG food, means less energy for growth and reproduction so smaller populations result.
If 1 is better adapted, then the less well adapted one is likely tot be outcompeted and f conditions remain the same then the less well adapted species will decline in number until it no longer exists in that habitat- competitive exclusion principle
EG. Grey squirrel native to N America was introduced to UK causing the native red squirrel to disappear in many areas as the grey can eat a wider range of food and is larger so can store more fat so has better chance of survival and ability to reproduce An increasing population of greys further reduces food supply for red
Intraspecific variation
Greater availability of resources means larger population size can be supported. This creates fluctuations in number of organisms over time
(SS):
1- plentiful resource for all organisms to survive and reproduce causes population size to increase
2- due to increased population, the resources are limited so population decreases as not enough for all to survive
3- less competition due to smaller population so more survive and reproduce
Niche
the role of a species in a habitat, including its trophic level, its interactions with the abiotic environment and interactions with other species eg as a predator, host or a symbiont, parasite or pollinator. Species with similar niches the competition will be more intense
Competitive exclusion
when individuals of different species compete for the same resources, one species may succeed and the other be excluded from the niche and completely disappear
Resource partitioning
different species competing for the same sort of resource or resources occupy slightly different niches so they avoid direct competition, like having different places to catch the same insects
Character displacement
2 species that compete with each other show differences in characteristics (features) where they exist in the same ecosystem but do not show these differences where they do not coexist
How have predators and prey adapted?
Predators have evolved to be highly efficient at capturing prey by sudden burst of speed, stealth, and fast reactions. Prey organisms have evolved to avoid capture through camouflage, mimicry, defence mechanisms like spines. They have to evolve together so don’t become extinct.
Describe the predator prey graph
- An increase in prey population due to few/no limiting factors provides more food for predators so more can survive and reproduce so predator population increases after lag due to reproduction
- Increased predator population eats more prey so they decline as death rate is greater than birth rate
- Reduced prey means can’t support larger predator population as intraspecific competition for food increases so predator population decreases as die/ less offspring
- Reduced predator numbers means less prey killed so they survive and reproduce increasing the prey population and cycle restarts
What are the issues with the predator prey graph?
- Often more complicated due to other factors like plant food for prey or other predators and seasonal changes in abiotic factors
- Also the decrease in number of prey is often due to intraspecific competition for food than predation
- Often not just one predator and prey so can feed on other prey if one decreases in numbers
Why does sucession occur?
What are the types?
Succession occurs as a result of changes in the environment causing plant and animal species present to change
Primary succession- on an area of land that has been newly formed or exposed like bare rock. No soil or organic material present to begin with
Secondary succession- occurs on new areas of land where soil is present, but it contains no plant or animal species. Eg bare earth that remains after a forest fire
When does primary succession occur?
- Volcanoes erupt depositing lava and when it cools and solidifies igneous rock is created
- Sand is blown by the wind or deposited by te sea to create new sand dunes
- Silt and mud are deposited at river estuaries
- Glaciers retreat depositing rubble and exposing rock
What are the stages of succession called?
What happens at each stage?
These are known as seral stages or sere
At each stage key species are identified that change the abiotic factors like soil so its more suitable for the subsequent existence of other species. Different plant and animals species are better adapted to the current conditions and they outcompete to become the dominant species
What are the main seral stages?
- Pioneer community
- Intermediate community (has seral stages within it)
- Climax community
diagram
Pioneer community-
How do species arrive?
What adaptations do they have?
- Primary succession begins by the colonisation of an inhospitable environment by pioneer species. This is the 1st seral stage. The species arrive as spores or seeds carried by wind from nearby land masses or by animals droppings. They have adaptations:
- Ability to produce large quantities of seeds or spores which are blown by wind and deposited on new land
- Seeds that germinate rapidly
- Ability to photosynthesise to produce own energy
- Tolerance to extreme environments
- Ability to fix nitrogen from atmosphere so adding to mineral content of soil
Intermediate community
Over time weathering of bare rock produces particles that form the basis of soil. It cant support species but when pioneer species die they decompose and release organic products to the soil- humus . the soil can then support new species known as secondary colonisers as it has minerals including nitrates ad ability to retain some water. They arrive as spores or seeds. Animals can start to colonise if pioneer species provide a food source.
Tertiary colonisers arrive as environmental conditions improve. The plants have waxy cuticles for water loss and can survive in conditions without an abundance of water, but do need to get most their water and mineral salts from the soil
At each stage the rock continues to be eroded and the mass of organic matter increases. When organisms decompose, they contribute to a deeper, more nutrient rich soil which retains more water. The conditions are then more favourable for small flowering plants like grasses, shrubs then small tress.
Climax community
How does biodiversity change over succession?
- Final seral stage when the community is in a stable state with little change over time. There are a few dominant species which are different depending on the climate
- Biodiversity tends to increase as succession takes place, but the climax is often not the most biodiverse, as this tends to be mid succession and then decreases due to dominant species outcompeting pioneer and other species, eliminating them
Animal succession- primary and secondary consumers
Primary consumers like insects and worms are first to colonise an area as thy consume and shelter in the mosses and lichen. As they have to move from neighbouring areas, animals succession is slower than plant, especially if the new land is geographically isolated like a new volcanic island
Secondary consumers will arrive once suitable food source is established, and existing plant cover will provide then with suitable habitat. Eventually larger organisms like mammals and reptiles will colonise when biotic conditions are favourable
What causes deflected succession?
What is the name of the final stage?
Give examples of causes:
Human activities can halt the natural flow of succession and prevent the ecosystem reaching climax community. The final stage is then known as a plagioclimax. Often due to agriculture:
- Grazing and trampling of vegetation by domesticated animals so lare areas remain grassland
- Removing existing vegetation like shrub lad to plant crops so crops become the final community
- Burning for forest clearance leads to increase in biodiversity as provides space and nutrient rich ash for other species to grow like shrubs
Definition of conservation
What is conservation
The maintenance of biodiversity and sustainability of biological resources using different methods of in situ and ex situ management
- Management of habitats and species taking into account that both will change over time in response to environmental changes – dynamic
- Allowing managed use of wildlife and habitats by humans -sustainable development so resources can be used without running out
- Also involves reclamation so ecosystems are restored that have been damaged or destroyed eg from floods, a new building project, controlled burning.
- Natural environment
Definition fo preservation
What is preservation
The protection of ecosystems, habitats and species for the future without allowing any use by humans
- Maintaining species and habitats as they are now so they will continue to exist in the future
- Protecting them from any use by humans
- Often used when preserving sensitive resources which can be damaged or destroyed by disturbances eg newly formed caves called virgin caves contain sensitive geological formations or unique systems and walking between them may cause irreparable damage
- No point having a resource that can’t be used?
- Objects and buildings or nature reserves and marine conservation zones
Reasons to conserve biological resources: social, economic and ethical
Sustainable resources definition
Sustainable management definition
a biological resource required as a food or raw material that is renewed by the activity of organisms so that there is always sufficient stocks to take from the environment
aims to provide for the needs of an increasing human population without harming ecosystems, both natural ad artificial, and their ability to provide materials and services for us
Why are fish stocks and treaties needed to provide a sustainable resource?
How are the protected?
example
- Stocks around the world are severely depleted and some have collapsed entirely due to increasing demand for food with population growth
- The regulatory organisation has to determine the maximum sustainable yield (number or biomass of fish that can be caught without reducing the potential of the fish stock to regenerate itself each year
- Setting up exclusion zones where fishing is banned (spawning grounds or nursery grounds where fish reproduce or young fish develop)
- Limit number of boats that can fish a particular species or in a particular area
- Ban fishing at certain times of year (during spawning)
- Rules on type of fishing gear like regulating mesh size of nets and hook size so small fish aren’t taken and can and can survive long enough to breed
- Quotas so can’t take over a certain number or mass of fish per year- common fisheries policy in EU
- Inspection of catches at ports and fisheries protection vessels to police at sea
- Restock sea with young fish
- Fish farming prevents loos of wild species. Placed in rice fields at planting time and grow to edible size when rice is ready to harvest.
Ecosystem approach aims to understand the structure and dynamics of the whole ecosystem including the position of fishing populations within the food web and how they interact with other populations. Includes giving protection to seabed habitats that are at risk from trawling. Fat older female fish are the best spawners so should be conserved, whereas usually older fish are removed as they are easier to catch
EG. Gulf of Maine NW Atlantic closed to fishing in mid 90s and 5 yrs later all recovered except cod
Why does timber need to be conserved?
What types of trees are there?
What are the methods of conservation?
- Heavy requirement for timber in world wars reduced forest in UK
- Tree crops can be fast growing coniferous trees like pine and fir grown for commercial processes like paper making and construction. Slower growing broad-leaved trees include oak, beech.
- Clear felling involves cutting trees over a certain area, taking all the trees usually the same age. Very destructive to biodiversity as soil is exposed so erosion and nutrient loss occur. Followed by replanting rather than waiting for regrowth to ensure biodiversity and water cycle remain and is an economic method.
- Selective felling minimises damage by cutting some mature trees, diseased trees and unwanted species. Leaves space for regeneration. Access for machinery required. Best trees have time to grow to maturity when have higher economic value.
- Strip felling is clearance of small strips or patches leaving adjacent areas untouched. Areas are replanted and adjacent areas cut when have grown to harvestable size. Large areas not felled at same time so less disruption and chance that biodiversity will be affected and little soil erosion.
- Coppicing manages broad leaved woodlands where stumps are left to regrow. Several stems grow from the stump which grow rapidly due to well-developed root systems. After 5 years they are cut down to stumps again. Can be repeated indefinitely. Small patches are cut at different times providing a variety of habitats and high biodiversity as trees never grow enough to block out the light so succession cant occur and more species can survive. Wood can’t be used in construction but can be used for paper industry, burnt in power stations for electricity and fencing. Pollarding is similar but trunk is cut higher up so deer don’t eat new shoots.
- Plant trees optimal distance apart to reduce competition. Higher yield as more wood is produced per tree
- Manage pests and pathogens to maximise yields
Masai Mara national reserve in south Kenya
Farming
Ecotourism
Conservation
Research
How is a balance acheived between conservation and human needs?
- Savannah ecosystem divided by the mara river
- Fertile regions close to the river are combo of rich grassland and woodland and further from it are open plains with scattered shrubs and trees
- Home to wide range of large animals and famous for annual zebra and wildebeest migrations
- Region used to be dominated by acacia bush which was habitat for tsetse fly which carried sleeping sickness
- Government workers and indigenous communities cleared this tree and so did elephants, fire and cattle grazing
Farming - grazing
- Traditionally used by local tribes for livestock grazing. Practiced semi-nomadic farming where tribes frequently moved depending on climate variation and presence of tsetse flies, allowing vegetation to recover
- Grazing is now limited to areas on the edge of the reserve a local tribes are prevented from entering the park. Populations have grown in these marginal areas, larger herds graze the grassland areas and trees are removed for fuel. This increases risk of soil erosion
Farming- cultivation
- Level of cultivation has increased recently as grassland converted to cropland, so natural vegetation is removed and nutrients in soil are used up. Then fertilisers are relied on for crop growth
Ecotourism
- Main economic input as thousands of people visit each year. Supports conservation and is sustainable as reduces impact of tourists on natural environment. Benefits local people as well as visitors
- Can negatively impact environment like walking on hiking trails causing soil erosion and habitat changes
Conservation
- Conservation of endangered species like black rhino which is on ICUN critically endangered list. Trade is illegal but rhino horn is in demand for use in traditional medicine in SE Asia
- An active conservation programme established to balance needs of locals and those of wildlife. Included employment of reserve rangers, provision of communication equipment, vehicles and infrastructure. This helps deter poachers entering reserve, helping rhino populations increase
Research
- Mara predator project monitor lion populations to identify population trends and response to changes in land management, human settlements, livestock movements and tourism
- The Mara-Meru cheetah project aims to monitor cheetah population and evaluate impact of human activity
- Human land sue is incompatible with wildlife survival and increased wildlife density threatens pastoral and cultivation lifestyles. Balance must be maintained
- Elephants threaten cultivation by trampling, and others eat crops. Land may be fenced, but this negatively effects natural migration
- Legal hunting for excess animals to maintain population numbers and bring in money for conservation work. Number must be constantly monitored to maintain natural balance in ecosystem
- Livestock faces threats from migratory wildlife – during annual wildebeest migration they outcompete cattle for grass and diseases are introduced to domesticated animals and vice Vera
- Human population expanding requires new homes and land for agriculture, which decreases wildlife density
Terai region of Nepal
How ecosystems can be managed to manage conflict between conservation and human needs:
- Sustainable forest management
- Species conservation
- Sustianable agriculture
- Rich agricultural area with a belt of well-watered flood plains
- High population density, so natural resources are at risk of being overused
- Lots of biodiversity with subtropical plants and thick forest
- Millions rely on it for livelihoods by tourism, wood products and fuel and national income
- Poverty and corruption have caused large areas to be cleared for agriculture or to sell timber
- This has exacerbated effects of monsoon flooding, causing severe disruption to communities downstream
Sustainable forest management
- Provide a livelihood for locals, conserve forests and provide nepali state with income for general development
- Supportive national legislation and development of local community forestry groups
- Local groups set harvesting rules, rates and prices for products, determine how surplus income is spent
- Small forestry businesses work together to gain forestry stewardship council certification, an international standard which rewards sustainable forestry
- Have improved soil and water management, increased retail price of forestry products so greater economic input, generated employment and income through forest protection and secured biodiversity of the forested areas and conservation of forested areas
Species conservation
- Home to Bengal tiger which is endangered and Indian elephant. These are protected by 14 reserves as they are at risk of poaching for ivory trade and traditional Asian medicine.
- Nepalese government and army patrol national parks to protect animals
- Tigers hard to conserve as are top predators and require a large are to hunt. To conserve them, you need to ensure there is a fully functioning ecosystem with enough land to provide enough prey
- Removal of top predators deceases biodiversity all at levels
- Conserving are areas can be hard when human populations rely n these areas for fuels and grazing livestock
- Even though large enough protected areas are uncommon, wildlife corridors connect protected areas so large animals can use them without threat
Promoting sustainable agriculture
- Promote production of fruit and veg in hills and mountain regions to avoid further intensification of the terai
- Improving irrigation to enhance crop production
- Multiple cropping on one bit of land each season
- Growth of nitrogen fixing crops like pulses and legumes to enhance soil fertility
- Growing crop varieties resistant to various soil, climatic and biotic challenges through genetic engineering
- Fertilisation to enhance crop yields like manure
Peat bogs
Why is conservation needed and how is it being done?
- Wet spongy ground containing decomposing vegetation
- Carbon sink but when dried can be sued as fuel. Need to preserve for climate change
- Peat is important for farmers and gardeners, who mix it with soil to improve soil structure and increase acidity
- Retains moisture very well and prevents excess water killing roots when soil is wet
- Commercial peat extraction by gardeners is a major threat
- Forms when plant material can’t fully decay due to acidic and anaerobic conditions
- Wide range of insects supported
- Lack of predators and human disturbance makes ideal place for birds to nest and the nutritious vegetation provides food for many species. Large open ground provides ideal hunting ground for birds of prey.
- Areas of peat are rapidly diminishing due to afforestation, peat extraction and agricultural intensification including land drainage
- It is important they are conserved due to biodiversity and flood management and carbon storage
- Must restore water levels by blocking ditches which allow water to drain off
- Remove seedling trees for. Areas which remove water
- Using controlled grazing to maintain biodiversity as it ensures diverse wetland surface and provides a wide range of habitats for many are insect species
- Natural England and the wildlife trusts are doing conservation as lots of peat is in poor condition
Galapagos islands, pacific ocean plants and animals
The effect of human activites on plants and animals and how they can be controlled
- Volcanic islands that have never been connected to mainland
- The original flora and fauna that reached the islands had to survive crossing hundreds of km of ocean
- Most land animals are reptiles, with only 1 mammal species, the Galapagos rice rat which arrived floating on rafts of vegetation. Also marine birds
- Many species are unique to the islands, as they adapted to the environment in isolation EG Galapagos giant tortoise, flightless cormorant which has reduced wings better for fishing underwater when flight not needed to escape predators. The marine iguana can swim unlike the land one, and are dark coloured so can bask in the sun to raise their body temperature before swimming
- There are 3 zones, each which support a particular plant species
- Coastal zone has salt tolerant plants like mangrove. The arid zone has drought tolerant species like cacti. The humid zone has dense cloud forest.
- Weren’t visited until 19th century by humans
- Whaling trade disrupted islands fragile ecosystem allowing domestic animals to roam loose like goats outcompeting giant tortoises, chopping forests for fires to render down whale fat and removing live tortoises to sustain the whalers on long voyages as the tortoises can survive long periods without food or water
- Disrupted habitats by urbanisation and tourism development and farming
- Green sea turtles caught in fish nets and overfishing
- Introduced species trampled eggs
- Introduced pathogens like bird flu
- Tourist boats cause pollution and eutrophication from agriculture, oil spills
- National park established in 1959:
- Introduction of park rangers across the islands
- Limiting human access to particular islands or specific parts of islands
- Controlling migration to and from islands
- Strict controls of movement of introduced animals like pigs
Antarctica plants and animals
The effect of human activites on plants and animals and how they can be controlled
- Almost entirely covered in an ice sheet, holding 70% of worlds fresh water
- Only summer and winter (24 hr sunlight and darkness)
- Endothermic animals rely on thick blubber like whales, seals and penguins
- Emperor penguin is the only warm blooded penguin that remains in winter. Females lay an egg in mid winter and leave to spend winter at sea whereas male remain on land keeping the egg warm
- A few invertebrates live on the continent all year like the wingless midge
- Plants can only grow in the ice free regions. Lichens and moss grow in sand, soil, rock and on the weathered bones and feathers of dead animals. Algae can grown in sheltered areas. Phytoplankton makes use og high concentration of minerals in summer waters, which feed many animals.
- However global warming causing ice sheet to break up and ozone depletion are caused from human activity elsewhere. Species can then survive further. Loss of ice can loose phytoplankton and then reduced species, and reduce breeding ground for penguins
- Tourist are bringing alien animal and plant species
- Hunting of whales , seals and fishing has depleted species
- Soil contamination around scientific research stations
- Discharging of waste into sea like human sewage
- Visits are only allowed for a few hours to selected areas
- The Antarctic treaty protects unique nature of Antarctic continent and includes:
- Scientific cooperation between nations
- Protection of the Antarctic environment
- Conservation of plants and animals, sustainable fishing
- Designation and management of protected areas
- Management of tourism
Snowdonia national park, Wales, plants and animals
The effect of human activites on plants and animals and how they can be controlled
- Highest mountain range in England and wales and contains lakes, rivers and ancient woodland ad heath
- Rich diversity provides home for wide range of birds like coast and estuary birds like oystercatchers, forest birds like redstart and moorland and mountain birds like sparrow hawks.
- Over 40 species of land animals like badgers, voles, deer
- Plants species are diverse with arctic alpine plants at the top and woodland at the bottom
- Snowdonia national park conserves the biodiversity of the region
- The park is home to over 25,000 people, many of whom work on the land. This attracts lots fo visitors for climbing, walking, water sports
- Rhododendrons form large bushes or shrubs and were introduced as a horticultural plant. Now they prevent light reaching the ground so few plants can survive and killed local vegetation. They don’t support any other species as their eaves are poisonous. When they die the branches grow roots and establish new plants. The leaves decompose slowly so ruin soils
- Try to cut them down and burn them with herbicides sprayed on after. Stem injection involved drilling holes and applying herbicides
The park authority:
- Conserves and enhances natural beauty, wildlife and cultural heritage of area
- Promote opportunities for the understanding and enjoyment of the special qualities of the park
- Enhance the economic and social wellbeing of communities in the park
- To preserve the natural beauty of Snowdonia, the Dinorwig HEP station was built deep inside a mountain inside caverns, minimising impact on environment and meeting human demand for energy
Lake district plants and animals
The effect of human activites on plants and animals and how they can be controlled
- England’s largest national park, with regions of moorland and fell, lakes dammed by glacial moraines at end of last ice age, and ancient woodland
- The varied landscapes provide habitats for a wide range of animals including water voles, bat, red deer and golden eagle, red squirrel is under threat as is vendace a fish only found here and that’s on ICUN endangered list
- Habitats ca exist above the central tree line in the fells which is rare in the UK, supporting arctic-alpine plant communities
- Lake district national park authority conserves he region while enabling access for millions of visitors each year
- Active management of countryside involves replanting native tree species
International wildlife law and programmes
SSSI (sites of special scientific interest)
A conservation designation denoting a protected area, usually describing an area with rare species of flora or fauna or important geological features
HAPS (Hadley angling and preservation society)
A small club to control fishing in Jacks lake, Hadley woods, Hertfordshire. The lake is available to members and day tickets
UNCLS (united nations convention on the laws of the sea)
International agreement which defines the rights and responsibilities of nations with respect to their use of the worlds oceans, establishing guidelines for businesses, the environment and the management of marine natural resources
What are the factors affecting the evolution of a species?
- genetic bottleneck
- genetic drift
- founder effect
- stabilising selection
- directional selection
- disruptive selection
What is a genetic bottleneck?
Example
Sharp reduction in the size of a population which lasts for at least 1 generation. Due to limiting factors. They can be density dependent factors- dependent on population size and include predation, competition, parasitism and communicable disease. Density independent factors affect populations of all sizes in the same way including climate change, natural disasters, seasonal change, human activities like deforestation. A smaller population has less genetic diversity and cannot adapt to change so are more likely to become extinct than evolve. Can be positive as a beneficial mutation will have greater impact and lead to quicker development of new species.
EG. Cheetahs experienced initial bottleneck 10,000 years ago with others more recently. They share 99% of their alleles with members of the species instead of 80% so are having interbreeding a reduced fertility issues.
What is genetic drift?
A change in allele frequency due to the random nature of mutation in a small population creates new alleles or by chance if an allele is passed. As it is in a small population there is a greater impact.
What is the founder effect?
example
An extreme example of genetic drift where small populations can arise due to the establishment of new colonies by a few isolated individuals. The smaller populations have smaller gene pools than original population so less genetic variation. The frequency of alleles are much higher so have a bigger impact in natural selection.
EG. The Afrikaner population in S Africa descended from a few Dutch settlers and have a high frequency of Huntington’s disease as only 1 original settlers had that allele.
What is stabilising selection?
Example
Survival of the fittest/ natural selection, where those with average phenotypes are selected for and extremities of the phenotype are selected against. The extremities reduce the survival chances and those with average phenotypes are more likely to survive and reproduce. This results in a reduction in the frequency of alleles at the extremities and an increase in frequency of average alleles, so a population remains stable for a particular character.
EG. There is a higher death in very small and very large babies, so birth weight remains fairly stable, as a new extreme phenotype has no selective advantage so wont be selected.
What is directional selection?
Example
When there is a change in the environment and the most common phenotype is no longer has the competitive advantage. Organisms that are less common and have more extreme phenotypes are positively selected. The allele frequency than shifts towards the extreme phenotypes and evolution occurs as they survive and reproduce.
EG. Peppered moths the darker ones became advantageous as pale lichen died and soot covered trees.
What is disruptive selection?
Example
The extremities are selected for and the norm selected against.
EG. Feather colour of male lazuli buntings in N America. Feather colour of young males can range bright blue to dull brown. There is competition for territory and female birds. Dull male birds are seen as non-threatening and bright ones too threatening. The intermediate colour is attacked by adult birds so fail to mate and establish territories.
What is speciation?
What causes it?
Speciation is the formation of a new species through the process of evolution
- Due to isolation so lack of interbreeding so now gene flow between the 2 groups
- Alleles within the groups undergo random mutations and different environments mean different selection pressures
- Accumulation of mutations eventually lead to large changes in phenotype so species can no longer interbreed as so different species
What is allopatric speciation?
Example
When some members of a population are separated from the rest of the group by a physical barrier such as a river or the sea. The environments of the different groups are often so different so different selection pressures result in different adaptations. The founder effect often occurs, and genetic drift further enhances differences in the populations.
EG. Finches on Galapagos islands flew to and were stranded on different islands from the mainland. They have evolved due to different food sources on each island- phenotypic divergence. New species evolved.
What is sympatric speciation?
Example
Occurs within populations that share the same habitat, less frequently than allopatric and more common in plants. When members of 2 different species interbreed and form fertile offspring a hybrid is formed and is a new species. It may no longer be able to interbed with members of either parent population which stops gene flow and isolates the hybrid organism. Also due to reproductive differences so that individuals in close proximity can’t interbreed with the rest of the population.
EG. blind mole rats are found in different types of soil in N Israel but they only interbreed with rats in the same soil type. The lack of gen flow is causing genetic differences and they could accumulate so that they are unable to interbreed and are separate species. As they are in the same habitat, gene flow sometimes still occurs.
Reproductive barriers can prevent the formation of a zygote and fertilisation. They can also reduce the viability of offspring after fertilisation.
What hapens in the lac operon when glucose is present?
- The regulator gene (l) is expressed and the repressor protein is synthesised.
- The repressor protein binds to the Operator site
- The repressor protein blocks the Promoter site
- this stops RNA polymerase from binding to the promoter.
- The structural genes are not transcribed so the enzymes are not synthesised.
What hapens in the lac operon when glucose is absent but lactose is present?
- Lactose (the inducer molecule) fits onto the repressor protein at another active site
- This causes the repressor protein to change its shape (a conformational change).
- Repressor dissociates from the operator site.
- RNA polymerase can now reach its promoter site and bind to the promoter
- The structural genes are transcribed, and the enzymes are synthesised.
- E. coli can then make use of the lactose.
Role of CAP binding site and regulatory sites
- In addition to the structural genes, the lac operon contains a number of regulatory DNA sequences. These are regions of DNA to which particular regulatory proteins can bind, controlling transcription of the operon.
- CAP binding site is a positive regulatory site. The catabolite activator protein (CAP), when bound to cAMP binds to the CAP binding site promoting RNA polymerase binding to the promoter and hence transcription.
promoter is the RNA polymerase binding site
operator is a negative regulatory site bound by the lac repressor protein. The operator overlaps with the promoter, and when the lac repressor is bound, RNA polymerase cannot bind to the promoter and start transcription.
Standard growth curve and pahses
Lag phase: adapting to new environment. Growing, synthesising specific enzymes, switching on genes. Taking in water. Cells active but not reproducing.
Log phase: rate of bacterial production is close to or at its theoretical maximum. Population doubles each generation. Plenty of space and nutrients.
Stationary phase: growth rate= 0. Number of cells by binary fission cancelled by number of cells dying. Nutrient levels decreasing, waste products build up.
Death phase: reproduction almost ceased and death rate increases. High levels of toxic by-products, nutrients used up
N=N0x 2n is the formula for number of individual organisms
