Option G - Ecology and conservation Flashcards
Which factors affect the distribution of plant species?
- Temperature
- Water
- Light
- Soil pH
- Salinity
- Mineral nutrients
How do temperature and water affect the distribution of plants?
Marram grass:
- adapted to very hot and very dry conditions
- has long roots which find water even in very dry sand
- its long narrow leaves can curl up to save water and resist heat up to 50°C
The fern:
- adapted to low temperatures and moist conditions
How does light affect the distribution of plants?
Marram grass:
- must live in conditions where light is constantly available
- does not have wide leaves adapted to catch sunlight
- its leaves are adapted to reduce water loss and withstand heat
- is found in sunny areas
Ferns:
- found in shady areas
- wide leaves to capture the small amount of light which filters through the leaves of other plants
How does soil pH affect the distribution of plants?
Marram grass:
- thrives at 7.5
Heathers
- like acidic soil in the grey dune
How does salinity affect the distribution of plants?
Marram grass:
- likes salty environment
Shrubs, mosses and lichen:
- live far from the shore, where conditions are much less salty
How do mineral nutrients affect the distribution of plants?
- The grey dune shows diversity of plants
- Contains loads of mineral nutrients in the soil
- Minerals make the plants thrive
What are factors that affect the distribution of animal species?
Affected by both abiotic and biotic factors:
- Temperature
- Water
- Breeding sites
- Food supply
- Territory
How does temperature affect the distribution of animals?
- External temperatures affect all animals, especially those that do not maintain constant internal body temperatures
- Extremes of temperature require special adaptations, so only few species can survive
How does water affect the distribution of animals?
- Animals vary in the amount of water they require
- Some animasl are aquatic and must have water
- Some animals are adapted to survive arid areas where they are unlikely ever to drink water
How do breeding sites affect the distribution of animals?
- All species breed at some point
- Many species need a special place for breeding and can only live in areas near to these sites (e.g. mosquitoes need stagnant water)
How does food supply affect the distribution of animals?
- Many species are adapted to feed on specific foods and can only live in areas where these foods are obtainable
- For example blue whales feed mainly on krill and live in areas where krill is abundant
How does territory affect the distribution of animals?
- Some species establish and defend territories
- This tends to give these species an even distribution
What is a random sample?
A sample in which every individual in a population has an equal chance of being selected
How are quadrats used to perform random sampling?
- Mark out gridlines along two edges of the area
- Use a calculator to generate two random numbers to use as coordinates and place a quadrat on the ground at those coordinates
- Count how many individuals there are inside the quadrat of the plant population being studied. Repeat steps 2 and 3 as many times as possible
- Measure the total size of the area occupied by the population
- Calculate the mean number of plants per quadrat. Then calculate the estimated population size using the following equation:
What is a transect?
A method of investigating plant or animal distributions along a line marked out across a site. Very useful when there is a gradient in an abiotic variable.
How is a transect used?
The transect is laid out at right angles to the edge of the area so that it follows the gradient of the change in soil or other factor
What is an organism’s niche?
The organism’s role in a speficic ecosystem
What does the concenpt of niche include?
Where the organism lives (its spatial habitat), what wnd how it eats (feeding activities), and its interactions with other species
What are the five interactions between species?
- Competition
- Herbivory
- Predation
- Parasitism
- Mutualism
What is meant by herbivory interaction? Give two examples
A primary consumer feeding on a plant or other producer. The producer’s growth affects food availability for the herbivore
Beetle Epitrix atropae:
- Feeds only on leaves of Atropa belladonna, often causing severe damage to them
- To most other organisms the leaves are toxic
Algae:
- Algae growing on rocks in shallow seas are often heavily grazed
- A snail Lacuna pallida feeds on the brown seaweed Fucus serratus
What is meant by preatory interaction? Give two examples
A consumer feeding on another consumer. The number of the prey affect the predator.
Canada lynx:
- Predator of the Arctic hare
- Changes in the numbers of hares are followed by similar changes in lynx numbers
Bonitos:
- Feed on anchovetas in the Pacific Ocean
- When the anchoveta population crashed, starving bonitos were found with completely empty stomachs
What is meant by parasitic interaction? Give two examples
A parasite is an organism that lives on or in a host and obtains foord from it. The host is always harmed by the parasite.
The tick:
- A parasite of deer and some mice
- Fedds by sucking blood from its hosts, thus weakening them
Sphingomonas bacteria:
- Cause a disease in elliptical star corals
What is meant by competitive interaction?
Two species using the same resource compete if the amount of the resource used by each species reduces the amount available to the other species
Douglas Fir and Western Hemlock:
- Grow together in mixed forests
- Compete with each other for light, water, and minerals
Species of coral:
- Compete with each other on coral reefs
- Either species benefits when predators feed on the other species
What is meant by mutualistic interaction? Give two examples
Members of different species that live together in a close relationship, from which both benefit.
Lichens:
- Consist of a fungus and an alga growing mutualistically
- The alga supplise foods and the fungus absorbs mineral ions
Cleaner wrasse and damsel fish:
- Cleaner cleans parasites from the gills and body of damsels
- The cleaner benefits because the parasites are its food
What is meant by the competitive exclusion principle?
If two species have a similar niche, they will compete in the overlapping parts of the niche, but will usually be able to coexist.
If two species have exactly the same niche they will compete in all aspects of their life until one of the two species will prove to be the superior competitor. The other species disappears from the ecosystem
What is the fundamental niche of a species?
Its potential mode of existence, given the adaptations of the species
What is the realised niche of a species?
Its actual mode of existence, which results from its adaptations and competition from other species
What is biomass?
The total dry mass of organic matter in organisms or ecosystems
How can the biomass of different trophic levels be measured?
Measuring biomass is a destructive technique, so the asmples are as small as possible
- Representative samples of all living organisms in the ecosystem are collected, for example from randomly positioned quadrats
- The organisms are sorted into trophic levels
- The organisms are dried, by being placed in an oven at 60–80°C
- The mass of organisms in each trophic level is measured using an eletronic balance
- Drying and measuring the mass may be repeated to check that samples were completely dry
What is gross production?
The total amount of organic matter produced by plants in an ecosystem (lowest bar of an energy pyramid)
gross production = plant respiration + net production
What is net production?
The amount of gross production in an ecosystem remaining after subtracting the amount used by plants in respiration
net production = gross production - respiration
Why is sorting organisms into trophic levels sometimes difficult?
Because many species exist partly in once trophic level and partly in another
Describe examples of problematic species in trophic levels
- Euglena
- Unicellular organism found in ponds
- Has chloroplasts and photosynthesises
- Also feeds heterotrophically by endocytosis
→ producers and primary consumers
- Chimpanzees
- Mainly feed on fruit and other plants
- Also eat termites and even larger animals such as monkeys
→ primary and secondary consumers
- Herring
- Secondary consumers when feed on copepods
- Tertiary consumers when feed on sand eels
→ secondary and tertiary
- Oysters
- Consume ultraplanktonic producers
- Consume microplanktonic consumers
→ primary and secondary
Why do higher trophic levels have small biomass and low numbers of organisms?
Because energy is lost at each trophic level.
- Respiration causes loss of both energy and biomass through heat and excretion
- The energy content per gram of food does not decrease
- The total biomass of food available to higher levels is small → cannot support large numbers of organisms
- Very small numbers of large organisms with a low total biomass per unit area
Construct a simple pyramid of energy
What is the difference between primary and secondary succession?
Primary succession starts in an environment where living organisms have not previously existed, for example a new island created by volcanic activity.
Secondary succession occurs in areas where an ecosystem is present, but is replaced by other ecosystems, because of a change in conditions. For example, abandoned farmland developing into forest
What is the relationship between rainfall and temperature, and the type of ecosystem that develops in an area?
What is the Simpson diversity index?
The overall measure of species richness in an ecosystem
N = total number of organisms
n = number of individuals of a particular species
What is the cause of biomagnification? Use a named example
- Some toxic chemicals were deliberatly put in the environment to kill insect pests
- One example was DDT, which was used to control mosquitoes and other pests
- At the time it wasn’t known that DDT didn’t break down and would persist for decades in the environment
- DDT was spread on plants and absorbed by microscopic organisms
- The organisms were eaten by small fish and the small fish eaten by larger fish
- DDT built up in the fatty tissue of the fish
- When the fish were eaten by birds the magnification of DDT was even greater
How are indicator species used in monitoring environmental change? (HL)
- Indicator species are very useful, as they need particular environmental conditions and therefore show what the conditions in an ecosystem are
- Species also often used to assess pollution levels in aquatic ecosystems:
What is the difference between r-strategies and K-strategies? (HL)
An r-strategy involves investing more resources into producing many offspring, having a short life span, early maturity, reproducing only once and having a small body size (Californian poppy, lemming, herring)
A K-strategy involves investing more resources into development and long-term survival. This involves a longer life span and late maturity, and is more likely to involve parental care, the production of few offspring, and reproducing more than once (sessile oak tree, African elephant, leatherback turtle)
There are organisms that display extreme r- or K-strategies, but most organisms have life histories that are intermediate on the continuum.
Some organisms such as Drosophila switch strategies depending on environmental conditions
What is one technique used to estimate the population size of an animal species based on a capture-mark-release-recapture method? (HL)
The Lincoln index:
