Biodiversity

The number of different alleles of genes in a population

Natural selection: organisms are better adapted to their environment, survive and reproduce in greater numbers, resulting in an increase in allele frequency. Principles: Better adapted means higher survival rate so they reproduce Increases likelihood of passing on their characteristics Less adapted means lower survival rate so die Lower likelihood of passing on characteristics Organisms therefore subject to selection pressures due to their environment.

Alleles may be ad/disadvantageous providing adaptations that a re anatomical/physiological/behavioural.

Original population mean represented optimum characteristics for existing conditions. Introduction of antibiotics as a selection pressure favours bacteria with the favourable allele for antibiotic resistance Survival rate of Ab resistant bacteria increases and other die Reproductive success will increase allele frequency of Ab resistance, over many generations. Shift the mean to new optimum for existing conditions.

Mutation Gene flow (new alleles by migration)

Increased reproductivity means increasing allele frequency over many generations, increasing the spread of an allele within the gene pool.

Anatomical: structural/physical eg colour fur for camouflage. Physiological: biological processes eg chemicals produced in venom. Behavioural: cold blooded reptiles bask in the sun to absorb heat.

Occurs in stable environment. Selection pressures of unfavourable phenotypes, too light and too heavy at either end. Babies too light tend to have a lower survival rate outside the womb. Babies too heavy are difficult to remove so also have lower survival ayes. Reduced variability and range of population Reducing opportunity for evolutionary change.

Disruptive selection: 2 selection pressures at either end. Favours 2 extreme characteristics 2 extremes dominate and mean shifts to both directions.

Binomial naming: generic name (genus) + specific name (species) underlined when written.

Group of similar organisms that reproduce to produce fertile offspring

Artificial: differences useful at the time such as number of legs (and other analogue features = same function but different origin) Phylogenetic: evolutionary relationships between organisms and their ancestors. Classifies species into groups using shared homologous features. In a hierarchy: groups within groups with no overlap.

Study patterns of evolutionary history: relatedness to a common ancestor.

Delicious King Prawn Curry Or Fat Greasy Sausages Doman Kingdom Phylum Class Order Family Genus Species

Organisms which are more closely related display similar patterns of courtship behaviour,, genetically predetermined. Species specific examples: Fireflies give off light pulses Birds have displays of feather colours Male butterflies release distinct chemicals

Attracts same species Attracts Opposite sex Indication of fertility Stimulates gamete release Form a pair bond

Cannot always observe reproductive behaviour of a species. Cannot tell if their offspring are fertile. Reasons: Extinct Produce asexually Ethical/practical issues

Number of different species and the number of individual of each of thees epics within any one community.

Natural plants and animals are lost when land is cleared and ploughed. Reduce variety in food sources and habitats. Growth of crops and animals is controlled or stopped. Pesticides may be used to kill unwanted species and fertilisers encourage growth of a dominant species.

Measure of the number of different species in a community.

Differences in DNA sequence.

Differences / variety in ecosystems and habitats.

Measure of biodiversity that takes into account species richness and evenness. D= sum of every individual in all species x sum-1 / sum of each species x sum of each species -1 Greater diversity in X than Y

Maintaining biodiversity prevents extinction Some species may be important financially: Medical uses Commercial products Tourism Saving local forest communities