Genetic Diversity And Adaptation Flashcards
How does phylogenetic classification arrange species
According to their evolutionary origins and relationships
What do the length of lines on a phylogenetic tree represent
The time passed
What do the branch points on a phylogenetic tree represent
The last common ancestor both species are related too
Advances in what specialties have improved the accuracy of taxonomy and phylogeny
Immunology and genome sequencing
Explain the relationship between species sharing a recent common ancestor and similarities in DNA
The more closely related the species the higher the degree of similarity in the base sequence of thier DNA
Explain why comparing DNA nucleotide sequences gives better information than comparing amino acid sequences
DNA is degenerate which means silent mutations can occur and the same amino acid is coded for. If you count the amino acid there could seem to be less difference as the mutations could be silent
What is dna hybridisation and how does it show close relations
DNA from 2 different sources binding together
The more hydrogen bonds formed the more similar the species
What is hierarchy
System of groups ranked successively
Groups at each level are made up of several groups from lower levels
No overlap between groups at the same level
What is taxonomy
Classifying biological organisms into groups
What is the binomial naming system
Genus then species eg Homo sapiens
Define a species and how are they similar
2 organisms that can breed together to produce fertile living offspring
In terms of appearance, biochemical process and behaviour
Why is courtship essential
Essential for successful mating
It ensures other member is in a physiological state to breed
To synchronise mating
What does courtship form
A pair bond which is important for survival of offspring
What does a mate need to be
Fertile mature and receptive
Courtship identifies a mate capable of breeding
How does courtship change per species
Different behaviour per species
Allows recognition of own species
What is genetic diversity and what does it enable
The number of different alleles of genes in a population enables natural selection to occur
Types of variation
Discontinuous and continuous
What is discontinuous data
A characteristic with only a small number of different possible values
Caused by one gene, not affected by environmental factors
Bar graph
What is continuous data
A characteristic with a large range of possible values
Caused by several genes working together, environmental factors make a significant contribution to
A line graph
Steps for natural selection
Variation- in any population there is a large range of characteristics caused by different alleles
Overproduction- more offspring are produced than will survive
Survival of the fittest- only the best adapted organisms survive (the ones with the most beneficial allele)
Reproduction- only the best adapted organisms reproduce passing on the most beneficial allele to their offspring
Repeat- this is repeated over many generations until all individuals in the population have the characteristic. The frequency of the beneficial allele increases in the population
What is a selection pressure
Factors that cause poorly adapted organisms to die- they remove the least beneficial allele from the population
Selection pressure examples
Predation, disease competition for food/mates/breeding sites
PH light intensity
Stabilising selection
Most abundant phenotype is best adapted to environment
Frequency of the most common allele increases
Genetic diversity decreases as it is only selecting for one type
Graph = squashed in, parabola gets taller and thinner
Directional selection
A less abundant phenotype gains a selective advantage
Frequency of most common allele decreases
Species evolves gradual change in phenotype
Graph stays same shape but shifts over to create an ‘m’ shape
Disruptive selection
Both extremes phenotypes gain a selective advantage
Frequency of most common allele decreases
Population splits into 2 varieties /new species
Graph new shape is an ‘m’ with the dip in the middle over the original point of the graph
What are the three types of adaptations
Physiological
Behavioural
Anatomical
