C10 - Evolution and Classification Flashcards
What’s the biological species concept?
A species is a group of organisms that can interbreed successfully and produce fertile offspring and share common morphological, physiological and behavioural characteristics.
What’s the issue with the biological species concept?
It only applies to sexually reproducing organisms.
What’s the phylogenetic species concept?
A species is a group of organisms that share a common ancestor and have the same evolutionary history.
This includes organisms that reproduce sexually and asexually.
What are taxa?
The groups in the classification system.
They’re organised in a hierarchy.
How are species given their binomial names?
The first part indicates their genus (taxonomic ranking).
The second word is the species it belongs to.
What’s classification?
The arrangement of organisms into groups of various sizes on the basis of shared features.
What’s taxonomy?
Classification focussing on physical similarities.
What’s phylogeny?
Classification by evolutionary relationships and a common ancestor.
What is the sequence of taxonomy? (Highest to lowest)
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What’s the highest taxonomic group?
Domain
There are 3 domains: eukarya, eubacteria and archaebacteria.
What are the 3 domains?
Eukarya
Eubacteria
Archaebacteria
What’s the second highest taxonomic group?
Kingdom
There are 4 kingdoms in the eukarya domain: animalia, plantae, fungi and protista.
What are the 4 kingdoms (2nd highest taxonomic group) in the eukarya domain?
Animalia
Plantae
Fungi
Protista
What’s the third highest taxonomic group?
Phylum (e.g. Chordata in vertebrates)
What’s the fourth highest taxonomic group?
Class e.g mammalia. (In the arthropoda phylum, classes include insects.)
What are the 5th, 6th, 7th and 8th highest taxonomic groups?
5 - order e.g. primates
6 - family
7 - genus
8 - species
How are humans and gibbons related?
They are related up to the same order, however they belong to different families.
What types of evidence have been put forward when classifying organisms into taxa?
Biochemical/molecular evidence - using DNA or amino acids
Anatomical evidence
Fossil evidence
Immunological evidence
Behavioural evidence
Embryological evidence
DNA barcoding
How’s phylogenetic information obtained / how are DNA barcodes produced?
DNA samples are taken from each organism being studied and are amplified by a polymerase chain reaction (PCR) to multiply the number of DNA copies in each sample.
Samples are dyed and placed in holes in a sheet of electrophoresis (gel). A voltage across the gel separates the molecules by size.
This creates a DNA barcode, which can all be compared and shown in an evolutionary tree.
In animal eukaryotes, what is used to produce a DNA barcode?
The cytochrome c oxidase gene in mitochondrial DNA, as it has a faster rate than chromosomal DNA.
In plant eukaryotes, what is used to produce a DNA barcode?
A pair of chloroplast genes, rbcL and matK are used.
This is because cytochrome c oxidase has a much slower rate of mutation in plants than in animals so is less effective.
How has biochemical / molecular evidence be used to classify animals?
DNA sequences can be compared. These would be more similar between closely related species.
The DNA sequence determines the order of amino acids in a protein. Thus amino acid sequences can be analysed e.g. cytochrome c oxidase.
How has anatomical evidence been used to classify animals?
Use of microscopes has helped to compare the appearance of species, however this can be inaccurate.
This is based on morphological similarities.
The issue is that it doesn’t account for the fact that members of the same species can look very different.
How has fossil evidence been used to classify animals?
It enables extinct species to be classified.
DNA can sometimes be retrieved also however it isn’t always preserved well. Therefore evolutionary relationships must be estimated based on morphological differences.
How has immunological evidence been used to classify animals?
Proteins in different species are compared based on their immune response.
Proteins from one species will act as antigens if injected into another, causing an immune response.
Closely related species will have similar antigens and therefore a similar immune response.
How has behavioural evidence been used to classify animals?
Shared behaviour provides insights into relationships between species e.g. living in social groups, communicating with facial expression etc.
How has embryological evidence been used to classify animals?
Early embryos of different species can look very similar, suggesting they evolved from a common ancestor.