Topic 4B (Part 2) - Diversity Classification and Variation Flashcards
What is phylogeny?
The study of the evolutionary history of groups of organisms, to tell us who’s related to whom and how closely related they are
What does the 1st branch of a phylogenetic trees represent?
It represents a common ancestor of all the family members in a phylogenetic tree
- This ancestor is now extinct
How do we know if species are closely related on a phylogenetic tree?
They would diverge away from each other more recently
What is taxonomy?
Naming and organising organisms into groups, so that they could be classified, identified and studied
How has the study of classification changed over the years?
Scientists now take into account phylogeny and group organisms according to their evolutionary relationships
What is a taxon? (PLURAL: taxon)
One of the 8 levels of groups used to classify organisms
How are taxons arranged?|
They are arranged in a hierarchy, with the largest groups at the top and smallest at bottom
- Organisms can only belong to one group at each level in the hierarchy - there’s no overlap
Name the 3 domains
- Eukarya
- Bacteria
- Archaea
Name the 8 taxons
Daddy Kylie Puts Carrots on Fish Goat Soup
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What happens as you move down the hierarchy?
- There are more groups at each level but fewer organisms in each group
- The organisms in each group also become more closely related
Define a species
It is a group that:
- contains only 1 type of organism and
- is made up of similar organisms that are able to reproduce to give fertile offspring
Why are classification systems always updated?
Because of discoveries about new species and new evidence about known organisms
What nomenclature (naming system) is used in classification?
The binomial system
How does the binomial system work?
All organisms are given 1 internationally accepted scientific name in Latin that has 2 parts
- 1st part is genus name and has capital letter (italic)
- 2nd part is species name and start with lower case (italic)
Why is the binomial system used?
To avoid confusion of using common names
What type of behaviour can be used to classify organisms?
Courtship behaviour
Why is courtship behaviour used to classify organism?
Its species specific: only members of same species will respond to it
How does the specificity of courtship behaviour benefit organisms?
It allow members of same species to recognise each other, preventing interbreeding and making reproduction more successful
Give examples of techniques/technologies that have helped clarify evolutionary relationships.
- Genome sequencing
- Comparing amino sequence
- Immunological comparisons
How has genome sequencing helped clarify evolutionary relationships?
Advances in genome sequencing have meant that entire base sequence of organisms DNA can be determined and then compared to DNA base sequence of another organism, to see how closely related they are (Closely related species will have a higher % of similarity in DNA base order)
How have immunological comparison helped clarify evolutionary relationships?
Similar proteins will also bind to same antibodies
- If antibodies to human version of a protein are added to isolated samples from other species, a protein that’s like human version will also be recognised by antibody
Look at questions on interpreting data on DNA and protein similarities
page 98
How was genetic diversity/variation of alleles investigated in the past?
By looking at frequency of measurable and observable characteristics in a pop
- As different alleles determine different characteristics, a wide variety of characteristics in a pop indicate a high number of different alleles = high genetic diversity
Nowadays, how can we measure genetic diversity directly?
- Comparing DNA base sequences
- Comparing mRNA sequences
- Comparing amino acid sequences
- Observing the frequency of measurable or observable characteristics
What causes variation?
- Genetics
- Environmental factors e.g. climate, food, lifestyle
Variation is usually caused by a combination of both
How do you study variation?
By sampling a population
How do you make sure your sample isnt biased?
It should be random: pick a random location, divide the site into a grid, and use a random number generator to select co-ordinates
How do you make sure your results, in your sample, isnt due to chance?
Analyse results statistically
How do you calculate the mean from your sample in variation?
Mean = total of all values in data/ number of values in data
What curve should you end up with when using a sample to study variation?
A bell-shaped curve
What is standard deviation?
It is the spread of values about the mean
Look at questions on interpreting data that includes standard deviation
pg 101
Dfine biodiversity
The variety of living organisms in a habitat
Define habitat
The place where an organism lives
Define Community
All the populations of different species in a habitat
What is ‘local biodiversity?’
The variety of different species in a small habitat that’s local to you e.g. pond/back garden
What is ‘global biodiversity’?
The variety of species on Earth (8.7 million)
In which part of earth is biodiversity greatest?
At the equator
What is ‘species richness’ and how is it worked out?
It is a simple measure of biodiversity/a measure of the number of different species in a community
- It is worked out by taking random samples of a community and counting number of different species
What is the main problem with ‘species richness’?
The number of different species in a community isn’t the only thing that affects biodiversity, population sizes also does.
- Species that are in a community in very small numbers shouldnt be treated the same as those with bigger populations
What is the 2nd, more accurate, way of measuring biodiversity?
An index of biodiversity
How do you calculate an index of diversity?
DO QUESTIONS
d = N(N-1)/sum of n(n-1)
N = total number of organisms of all species n = total number of organisms of on species
(the higher the number the more diverse the area is and if the individuals are of the same species, the index is 1 = no biodiversity)
Give 5 agricultural practices that can reduce biodiversity
- Woodland clearance - Whilst this increases farmland area, it reduces number of trees and sometimes, number of tree species. Also destroys habitats so some species lose shelter and food source. This means species will die or migrate to other area, reducing biodiversity
- Hedgerow removal - Involves turning lots of small fields into fewer larger ones. Reduces biodiversity because of same reason as above
- Pesticides - Reduces biodiversity by killing pests, and species that feed on pests
- Herbicides - Reduces biodiversity by killing unwanted plants and species that feed on plants
- Monoculture - Reduces biodiversity as farmers have fields containing only 1 type of plant. This system may also support fewer organisms
Give examples of conservation schemes that help preserve biodiversity
- Giving legal protection to endangered species
- Creating protected areas, that restrict further agricultural development e.g. SSSIs (Sites of Special Scientific Interest) and AONBs (Areas of Outstanding Natural Beauty)
- Environmental Stewardship Scheme which encourages farmers to conserve biodiversity
