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• A phylogenetic tree displays the evolutionary relationship between organisms and their ancestors
• Classifies species into groups using shared features derived from their ancestor
• Arranges the group into hierarchy in which the group are contained within larger composite groups with no overlap
• Phylogeny is the study of the evolutionary history of a group of organisms
• The further the to the right a species is indicates that it is a younger species

Species Diversity: The number of different species and the number of individuals of each species within one community

Genetic Diversity: The variety of genes possessed by individuals that make up any one species

Ecosystem Diversity: The range of different habitats within a particular area

Impact of Agriculture bible

• Natural ecosystems develop from complex communities
• Agriculture is controlled by humans closely
• Farmers select crops that are more profitable
• The frequency of alleles therefore decreases
• Economically, the area has to be large to maximise profits
• One area can only sustain a limit to the biomass. Of the most of the area contains only one plant, then there is little space for anything else, therefore there is a low biodiversity

Reducing Biodiversity:

• Pesticides and man-made fertilisers kill off unwanted pests
• Herbicides kill unwanted weeds
• Hedgerow are a source of food, habitat and a pathway for many species
• ponds being removed
• Deforestation causes great habitat loss as it contains a wide variety of species

Practises that decrease species biodiversity

• Creating monocultures (the cultivation of a single crop in a given area.)
• Removal of ponds or forest land
• Effluent leakage (liquid waste, usually sewage) from silos
• Lack on intercropping and absence of crop rotation

Practise that increase biodiversity

• Maintain or plant hedgerows instead of fences
• Maintain or create ponds
• Plant native trees
• Use of organic fertilisers
• Crop rotation with nitrogen-fixing crops instead of fertilisers
• Use intercropping rather than herbicides to control weeds and other pests

 

• Members of the same species have similar or exact genes to one another. As a result, they share both physical and biochemical properties
• These specific traits to the species enable members to distinguish themselves from different species
• This extends to behaviour, where members of the same species have similar behavioural traits to other members.
• Each individual has adaptations that help to ensure that their DNA is passed onto he next generation
• The females of the species only produce eggs at specific time, often just once a year. It is therefore essential that successful maternity occurs to ensure the alleles can be passed on
• Courtship is behaviour helps to achieve this by enabling individuals to:
• Recognise members of their own species (to produce fertile offspring)
• Identify a mate that is capable of breeding (fertile, sexually mature and receptive to mating)
• Form a pair bond
• Synchronise mating (sexual activity occurs when the female is fertile)
• Being able to breed

 

Directional selection

• Occurs when one extreme phenotype is favoured over other phenotypes
• This happens when the environment changes in a particular way such as :

Biotic		Abiotic
Predators		Temperature
Food		pH
Competition		Weather

The original population, in this example are non-resistant bacteria. The Population after selection are resistant to bacteria.

The remaining bacteria of the original bacteria has a mutation (extreme phenotype) which allowed them to become resistant

The new bacteria replicate rapidly, thus overtaking the population of the old bacteria whilst also having the resistant phenotype.

Stabilising (normalising) selection

• Occurs when the immediate phenotype is selected over extreme phenotypes
• Extreme phenotypes such as overly small or overly big do not likely carry their genes on
• The result is a ‘normal range’ is produced
• This could be, for example birth mass, where a low mass has an increase chance of mortality but equally a high mass also has an increased chance of mortality. As a result the middle (being the normal) survives and thus the extreme phenotypes are removed.

The original population, for example had a wide range of birth masses. However the extreme phenotypes do not carry their gene onwards due to an increased chance of mortality.

The result is the population after selection have a ‘normal range’ where mortality rate decreases as there is a reduced number of ‘extreme’ birth masses.

 

Classification: The arrangement of organisms into group of various sizes on the base of shared features

Taxonomy: A form of classification that focuses on physical similarities between different species for naming and classification

Phylogeny: The classification of organisms by their evolutionary relationship so that every group shares a common ancestor

Binomial System

 Universal system based on Latin

 The first name, known as the generic name, denotes the genus to which the organism belongs to (equivalent to someone’s last name)

 The second name, known as the specific name, denotes the species to which the organisms belongs to. This name is unique to the species (Equivalent to someone’s first name)

Rules of the Binomial System

 The names are printed in italics (or underlined if handwritten) as they are scientific names

 The first letter of the generic name is upper case but the first letter of the specific name is lower case

 If the specific name is not known, it can be replaced with ‘sp’

 If a subspecies is found, the extra name is added to the binomial species name

e.g. Siberian Tiger = Panthera tigris altaica

where Panthera = large cat

tigris = tiger

altaica = Unique Siberian tigers

Rank	e.g. Tiger
Domain	Eukarya
Kingdom	Animalia
Phylum	Chordia
Class	Mammalia
Order	Carnivora
Family	Felidae
Genus	Felix
Species	Tigris

All members of the same species share the ability to bread among each other to produce fertile offspring

What is meiosis?

Meiosis is the process where the gametes are produced by cell division, however the number of chromosomes are halved (haploid). Meiosis differs to mitosis as in mitosis the cell divides only once (diploid), however the cell divides once further in meiosis (haploid)

What is Genetic Diversity?

Genetic diversity is the total number of different alleles in a population. A population is a group of the same species that live in the same area that can interbreed.

A species is a group of organisms that can reproduce with each other which produces fertile offspring.

Natural Selection

Natural selection uses the process of organisms having an allele which gives it an advantage to survive. In this example, the bisto-betularia has a light background of the lichen-covered trees on which it rests. Through the industrial revolution, the trees become more black due to soot. However, with this a new black moth appeared. The black moth was the product of a mutation that occurred due to pressures form the environment. The dark colour allows for the moth to better blend with the environment, therefore prolonging its life as predators could not see them. The moth was thus able to survive and pass its allele on. The allele frequency of the black moth results in being increased.