Evolution, variation, biodiversity, classification Flashcards
Which two factors can cause variation in the phenotype?
Genotype and environment
What is continuous variation?
Variation that shows a gradation from one extreme to another. Often affected by more than one gene in combination with the environment
What is discontinuous variation?
Characteristics that are clear cut and easy to tell apart with no intermediates. Eg blood group. Controlled by different alleles of one gene with no effect from environment
Variation that is passed on via the genes is called?
Heritable variation. Otherwise it is non heritable variation
What are interspecific and intraspecific competition?
Intraspecific is between individuals of the same species, interspecific between individuals of different species
Name three ‘selective agents’ that could impact survival of organisms
Supply of food, climate, breeding sites, human impact
What is a gene pool?
All the alleles of all the genes of all the individuals in a population at any one time
Give the steps of natural selection
- Mutation causes variation 2. A change in the environment causes a selective pressure 3. Individuals that have alleles causing them to be better adapted will survive and reproduce 4. Advantageous alleles are passed on 5. Over many generations the advantageous allele becomes more frequent in the population
What are the two Hardy Weinberg Equations and what do the letters stand for?
p+q= 1 (where p is frequency of dominant alleles and q the recessive allele). p^2+q^2+2pq=1 (where p^2 is homozygous dominant, q^2 is homozygous recessive, 2pq are heterozygotes)
What conditions must be true for the Hardy-Weinbert principle to apply?
A large population (so little genetic drift), no selection, mating is random, no mutations, no migration
What is genetic drift?
Random changes in allele frequencies
What is allopatric speciation?
Speciation that is caused by a physical/geographic barrier which prevents interbreeding between two groups
What is sympatric speciation?
Speciation that occurs despite the two groups being in the same location.
What could cause sympatric speciation?
Behavioural mechanisms such as courtship displays, differences in morphology or breeding seasons, hybrids being infertile due to odd number of chromosomes
What is the founder effect?
A new population is established by a small group of individuals from a larger population. The new population will have reduced genetic variation and may not be representative of the original population.
What is a genetic bottleneck?
A reduction in genetic diversity due to a drastic decrease in population size
What is the definition of a species?
A group of organisms that can interbreed to produce fertile offspring
Give the taxa from largest to smallest
Kingdom, phylum, class, order, family, genus, and species.
What is classification?
The organisation of living organisms into groups according to shared characteristics
What is a phylogenetic hierarchy?
When organisms are split into smaller and smaller groups according to evolutionary relatedness
What is the proper term for a diagram that shows how related organisms are in terms of evolutionary history?
Phylogenetic tree/cladogram
How should species names be written?
As a binomial that has the genus and species. Genus capitalised, species lower case. It should be in italics.
Why should species be known by their latin name?
It avoids confusion of local common names and different languages
Why is classification described as tentative?
Classification may change as additional information becomes available