Ecology and Evolution Year 11

Ecology

The study of plants, animals, decomposers and their interactions with the environment

Biotic

All the living organisms that inhabit an environment

Abiotic

All the non-living factors that affect an organisms life.

Biological organisation

Hierarchal levels of biological organisation from molecule to organism

Species

A group of organisms that are genetically related and can breed to produce fertile offspring

Population

A group of the same species living and interacting in the same area

Community

A group of different populations living and interacting in the same area

Ecosystem

All communities in an area and their interactions with the abiotic factors of that area

What is a biome?

A broad area of the world that contains similar biotic and abiotic conditions.

What types of life can be found in a biome?

Particular types of life that are adapted to the specific conditions of that biome.

Biosphere

Consists of all life on Earth and all parts of the Earth in which life exists, including the hydrosphere, lithosphere and atmosphere.

Taxa

Categories into which related organisms are placed

what is the order of Taxa

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Binomial Nomenclature

Classification system in which each species is assigned a two-part scientific name (Genus - Species)

Gene pool

The sum of all genes in a population

How are communities named?

After the dominant species in the area

Producers

Autotrophs that produce the food for the ecosystem (plants)

Consumers

organisms that feed on the producers and on other animals

Decomposers

Organisms that breakdown dead materials

Species interaction

Species living within an area will need to interact with each other to survive. These interactions may be positive or negative and may occur within populations or between populations

What is competition in ecology?

Organisms that compete for the same resource (light, space or food)

Among which organisms is competition most intense?

Organisms of the same species

Predation

Where one organism feeds on another

Chemical plant defences

Many plants contain a vast array of chemicals to deter herbivores. Some simply taste bad and some are extremely toxic

Physical plant defences

Many plants contain thorns to protect themselves from large predators and waxy layers to protect themselves from hungry insects

Colouration Animal Defences

Colour is used very effectively by animals. these strategies include: bright colours, camouflage and mimicry.

Chemical Animal defences

Many animals have chemical defences to either deter or kill predators (e.g. bees)

Symbiosis

A distinct relationship between two different species

Mutualism

A relationship between two species in which both species benefit

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed

Energy

All living creatures require energy to survive. The source of all energy comes from the sun. Plants and algae are able to use the suns energy to create food in the form of glucose.

Trophic pyramids

All the energy in a system starts with the producers. There are always decreasing numbers of organisms as you move up trophic levels.

what trophic level are plants?

Trophic level 1

what trophic level are Primary consumers?

Trophic level 2

what trophic level are secondary consumers?

Trophic level 3

what trophic level are tertiary consumers?

Trophic level 4

how much of the suns energy are plants able to harness?

about 1%

Energy flow in an ecosystem

Uni-directional and non-cyclic

energy loss in an ecosystem

Losses at each transfer from one trophic level to another (losses as heat from respiration or inefficiencies in processing, etc)

How do plants use energy

Producers use most of the energy they make for themselves. They use this energy for their own life processes: respiration, growth, etc.

Energy transfers in an ecosystem

Some energy in the primary consumer is stored and not lost to the atmosphere or used by the consumer itself. This energy is available for another consumer (carnivore).The process will continue in this fashion up the food chain, with energy being lost at each transfer

Ecological diversity

the variety of different habitats found on the planet

Community diversity

Variety of species in a community.

Genetic Diversity

The range of genetic material present in a gene pool or population of a species.

Threats to biodiversity

habitat destruction and fragmentation, introduced species, pollution, over-harvesting, global change

What is a niche in ecology?

The abiotic and biotic factors that an organism population is optimised for in terms of survival and reproduction.

What determines a biome?

climate (temperature and precipitation)

The importance of decomposers

When organisms die, decomposers are able to recycle elements back into the community. The decomposers release the "trapped" inorganic elements back into the soil/air to be taken up by producers

What are the macromolecules that all organisms contain?

Carbon, Nitrogen, Hydrogen, and Phosphorous

The carbon cycle

The organic circulation of carbon from the atmosphere into organisms and back again

The cycling of carbon

Consumers release carbon into the atmosphere as CO2 through respiration. The CO2 is taken up by plants for photosynthesis and stored in plant tissues, it is then taken up by consumers who feed on plants. When organisms die, decomposers break down the dead material, taking in carbon and releasing CO2 into the atmosphere.

What is carbon important for?

carbohydrates, proteins, lipids and nucleic acids

What is nitrogen important for?

proteins and nucleic acids (ATP)

Cycling nitrogen

Many bacteria are able to convert atmospheric nitrogen to ammonia which can then be converted to nitrates in the soil which are taken up by plants and then ingested by consumers. Dead organisms are decomposed by bacteria to also produce ammonia NH3 which can be converted back to nitrates. Many bacteria can act opposite to this, taking in nitrates and releasing atmospheric nitrogen to complete the cycle.

The phosphorous cycle

Phosphate gets eroded from rock and washed into streams and soil. Plants can then absorb the phosphorous as phosphate ions and consumers can ingest the phosphate from plants. Decomposers can release the phosphates back into the soil from dead material.

What is phosphorous important for?

Nucleic Acids (DNA/RNA), phospholipid membranes, and ATP/ADP

Evolution

When the gene pool changes significantly over many generations of natural selection acting on a population.

What are characteristics?

Characteristics are determined by genes and differences in characteristics are caused by alleles

When does evolution occur?

When there has been a significant shift in the frequency of an allele in a population.

What causes Evolution?

Natural selection or Genetic drift

Natural selection

survival of the fittest

What does VCR stand for?

Variation, Competition, Reproduction

Variation

Individual organisms within a population vary considerably in characteristics. Most variation is due to genetic differences (alleles). Variation is important as it allows populations to survive changes in the environment

Mutations can be:

Lethal, Detrimental, Neutral or Beneficial

Types of variation

Mutation, Crossing over, Random assortment, and Random fusion

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis, creating new gene combinations

Random assortment

The chance distribution of chromosomes to daughter cells during meiosis (new chromosome combinations)

Random fusion

the fusion of gametes during fertilisation (Mixes parents traits)

Competition (the struggle for survival)

Selective pressures and survival of the fittest

Selective pressures

Food, Climate, and predation

Reproduction

Organisms possessing certain characteristics will have a greater chance of survival and reproduction.

Genetic drift

When allele frequencies of a population change over generations due to random chance, not natural selection

Bottleneck effect

A change in allele frequency following a dramatic reduction in the size of a population

Founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

Morphology

DNA codes for proteins and proteins allow for structure and function. So it follows that organisms of the same species, which have similar DNA, will have similar morphology

Step 1 of speciation

two parts of a population become separated by a geographical barrier

Step 2 of speciation

Interbreeding between the groups stops. the gene pools separate and there is little to no gene flow between them

Step 3 of speciation

if the environments differ so will the selective pressures acting on the isolated populations

Step 4 of Speciation

Natural selection occurs

Step 5 of speciation

reproductive isolation occurs and creates two distinct species

Types of pre-zygotic reproductive isolation

Temporal, Mechanical, Behavioural, and gamete

Temporal

Timing (releasing pollen at different times of year)

Mechanical

Genitalia physically doesn't fit together

Behavioural

the behaviour of one species does not attract a member of another species (bird dancing)

Gamete

mating can occur but the sperm and egg cannot fuse

Types of Post-zygotic reproductive isolation

Hybrid sterility and hybrid inviability

Hybrid sterility

when mating occurs and creates a baby, but the baby is not fertile (e.g, donkey)

hybrid inviability

zygotes can from but rarely develop properly and often die before birth or maturity

Divergent evolution

when two or more species sharing a common ancestor become more different due to speciation

Convergent evolution

The development of similar traits on organisms that are NOT closely related due to similar selective pressures in similar niches

DNA hybridisation

Is a technique used to determine the similarity of DNA from different species

What is the first step of DNA hybridisation?

DNA is extracted from different species and cut into pieces using special enzymes.

What happens to DNA during the heating process in DNA hybridisation?

The DNA is heated to separate the double strands into single strands.

What occurs after the single strands of DNA from different species are mixed together?

The mixture is cooled so that double strands of hybrid DNA form.

What does hybrid DNA consist of?

One strand from each of two different species.

What is used to test how well the strands in hybrid DNA have joined?

Heat

What is the relationship between temperature and DNA strand separation in hybrid DNA?

Hybrid DNA strands that separate at a higher temperature have nucleotides that match more closely than those that separate at a lower temperature.

Why does DNA hybridisation work?

organisms that are more closely related have stronger DNA bonds, and therefor separate at much higher temperatures

What is biological succession?

The process by which the composition of a community changes as the habitat changes.