Topic 4.3 - Genetic Diversity, Adaptation and Taxonomy Flashcards
Define Species
Group of similar organisms able to reproduce to give fertile offspring
Describe how the binomial naming system work
Each species is given a Latin name that has 2 parts
- Genus
- Has capital letter
- Species
- Lower case letter
- Names are written in italics or they’re underlined if handwritten e.g. Homo sapiens
Why is the binomial naming system used?
Avoids confusion of using common names
Name 3 difficulties of defining species
- Species are not fixed forever
- Can change and evolve over time into new species
- Many species are extinct and most left no fossils
- Some species are sterile
What is phylogeny?
Study of evolutionary history of groups of organisms
What is this known as?
Phylogenetic tree
What does each following branch points represent?
Another common ancestor from which a different group diverged
What is taxonomy?
Science of classification
Why is taxonomy used?
Makes it easier to identify and study organisms
How many taxa are there?
8 taxas
How are the taxa arranged?
In a hierarchy: largest groups at top & smallest at bottom
Organisms only belong to __ group at each level in hierarchy - no overlap
1
Name all the taxa (from largest to smallest)
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
(Taxa Mnemonic: Dear King Philip Came Over For Good Soup)
As you move down hierarchy…
there are more groups but fewer organism in each group & organisms in each group become more closely related
What can be used to help classify species?
Courtship Behaviour
Courtship behaviour is carried out by organism to…
attract a mate of the right species
Describe how courtship behaviour can be used to help classify species
- Courtship behaviour = species specific
- Only members of same species will do/respond to it
- ∵ of this specificity - courtship behaviours can be used to classify organisms
Why do organisms carry out courtship behaviour? Name 2 reasons
- Allows same species to recognise each other
- Prevents interbreeding and making reproduction more successful
More closely related species are = the more _____ their courtship behaviour is
similar
Name 3 advances in techniques that can help clarify evolutionary relationships
- Genome Sequencing
- Comparing Amino Acid Sequence
- Immunological Comparisons
Describe how genome sequencing can help clarify evolutionary relationships
- Advances in genome sequencing = entire base sequence of organism’s DNA can be determined
- DNA base sequence can be compared to DNA base sequence of other organisms = to see how closely related they are
- Closely related species = higher percentage of similarity in their DNA base order
Describe how comparing amino acid sequence can help clarify evolutionary relationships
- Sequence of amino acids in protein is coded by base sequence in DNA
- Related organisms have similar DNA sequences and so similar amino acid sequences in their proteins
(e.g. Cytochrome C = protein found in many species → more similar amino acid sequence of cytochrome C in 2 different species = mores closely related spices are likely to be)
Describe how immunological comparisons can help clarify evolutionary relationships
- Mix together antibody and proteins
- Similar proteins will also bind to same antibodies & form precipitate
- More precipitate = more similarities in protein/DNA between the species (more evolutionarily close)
- Similar species have a similar immune response to a protein
e.g. If antibodies to a human version of a protein are added to isolated samples from other species, any protein that’s like human version will be recognised by that antibody
Explain how courtship behaviour increases the probability of successful mating (4)
- Indication of fertility
- Recognises same species
- Attracts mate
- Stimulates release of gametes
Explain how a phylogenetic system differs from a simple hierarchy (3)
- Phylogenetic system is based on evolutionary history
- Shows ancestry of groups/points of divergence
- Hierarchical system is based on shared characteristics (seen today)
What is meant by a hierarchy?
- Groups within groups
- No overlap between groups
What is meant by a phylogenetic group?
(grouped according to) common ancestry
Describe the process of DNA hybridisation
- Heat DNA from 2 different species
- To break hydrogen bonds and separate strands
- Mix and cool strands to allow h-bonds to reform
- Complementary bases joined together by h-bonding
- Non-complementary bases that cannot pair join together
DNA hybridisation
When two species share a recent common ancestor/are closely related, what are results like (i.e. the hybrid DNA strands)?
- More complementary base pairing
- More hydrogen bonds forming
- More heat/energy needed to break (the hybridised) strands apart
DNA hybridisation
What are hybrid strands where two species are distantly related like & what is needed to separate the two strands?
Few bases are paired up
Lower temperature is sufficient to separate the two strands
Name the 3 domains
Eukarya, Bacteria & Archaea
Name the 5 kingdoms
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
What is meant by species diversity?
Number of species in a community
What is genetic diversity?
The total number of different alleles in the population
What is a population?
A population is defined as a group of individuals of the same species that live in the same place and are able to breed with one another. A species consists of more than one population.
Why is genetic diversity within a population important?
The greater the number of alleles in a population the greater the genetic diversity and therefore the greater the chance that population would survive a change in their habitat
What is meant by the term niche?
The niche of a species is its role within the environment. Species which share the same niche compete with each other.
What is a selection pressure?
A change or factor within a population’s environment that may cause them to adapt. E.g. a change in weather, a new predator, a change in food sources or a disease.
Explain the process of evolution via the theory of natural selection
- When a population is genetically diverse, it means that there is also variation of phenotypes within the population.
- An environmental change may occur which causes a selection pressure
- Some individuals may possess advantageous alleles which gives them a selective advantage which makes it more likely they will survive and reproduce.
- The advantageous alleles are passed on to their offspring
- Overtime, the frequency of alleles in a population changes and this leads to evolution.
Name the three types of selection.
Directional selection, stabilizing selection, disruptive selection
Explain how directional selection occurs
Directional selection occurs when the environmental conditions change and the phenotype best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring. Overtime the mean of the population will move to one extreme.
Explain how stabilizing selection occurs.
In stabilising selection, the phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection doesn’t occur due to changes in the environment. If the environment stays he same then the individuals closest to the mean are favored. Overall, the genetic variation in the population decreases.
Explain how disruptive selection occurs
Disruptive selection occurs when selection pressures favour both extremes of the mean. This causes a decrease in the mean phenotype. Disruptive selection can lead to speciation if the extremes of the mean become so different they are no longer able to breed.
What are some ways that organisms may be adapted to their environment?
Anatomical adaptations are internal and external physical adaptations - e.g. camoflaged fur, or desert-dwelling organisms have a longer loop of Henle to increase water reabsroption.
Behavioural adaptations are changes in behaviour which improve an organisms chance of survival e.g. mating calls
Physiolological adaptations are processes inside an organism’s body that increase its chance of survival - e.g. resistance to a disease or increased regulation of blood flow through the skin.
