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.
What are morphological features?
The shape, size, structure etc of organisms.
Appearance
What are physiological features?
The normal functions of living organisms and their parts; the way in which a living organism or bodily part functions.
(Genetic)
What do phylogenetic trees show?
Evolutionary relationships between species from a common ancestor.
- branch length is proportional to time
- does at branching points represent common ancestors
- the closer the relationship between two species, the more recently they will have branched from a common ancestor
- branches for extinct species will end before present day
What’s an adaption?
A trait that benefits an organism in its environment and increases chances of survival.
What are the types of adaption? (3)
Behavioural
Physiological
Anatomical
What are behavioural adaptions?
Adaptions in behaviours, from simple reflex responses to courtship displays (by birds).
What are physiological adaptions?
Biochemical and cellular characteristics relating to the types of enzymes and hormones produced.
E.g. icefish produce enzymes to function in cold temperatures.
What are anatomical adaptions?
Adaptions relating to the evolution of structures that help an organism in its environment.
E.g. elephants have large ears to increase SA:V ratio.
What anatomical adaptions do humans have?
Bipedalism
Brain size
What’s bipedalism?
An anatomical adaption of humans.
Humans can walk on two feet, allowing hands free for communication, tool use and improved hunting ability.
How is brain size an adaption to humans?
It’s an anatomical adaption.
Brain size has tripled over human evolution, allowing more complex information to be processed, plus the development of language and social interaction.
What are the behavioural adaptions in humans?
Tool use
Social adaption
How is tool use an adaption to humans?
It’s a behavioural adaption.
Hands were no longer needed for movement due to bipedalism and increased brain size processes more information so tool use leads to improved hunting ability.
How are social adaptions a benefit to humans?
They’re behavioural adaptions.
Human behaviours e.g. laughter are similar to how chimpanzees groom one another, enabling social bonds to form.
What are the physiological adaptions in humans?
Lactose tolerance
Skin pigmentation
How is lactose tolerance an adaption to humans?
It’s a physiological adaption.
Infant mammals produce the enzyme lactase, allowing them to digest lactose in their mother’s milk, providing humans with a source of calcium.
How is skin pigmentation an adaption to humans?
It’s a physiological adaption.
It evolved from the loss of body hair - production of the pigment melanin in skin cells protects individuals from potentially dangerous UV-B radiation.
What abiotic factors affect plant growth?
Temperature
Water
Light
Mineral concentration
(and CO2, humidity and wind speed)
How are plants adapted to temperature?
Plants in cold ecosystems have adaptions to maximise the amount of heat energy they receive to prevent frost damage e.g. some are dish shapes to focus sun to the flower centre.
They are also low growing to prevent freezing and dark to absorb radiation.
Plants in hot ecosystems produce heat resistant seeds and are light coloured to reflect radiation.
How are plants adapted to water?
Xerophytes, adapted to live in dry conditions, have closed stomata when water supply is low to reduce transpiration and conserve water.
They store water in their swollen stems and their roots are spread over a wide area.
Their waxy, needle leaves reduce surface area, minimising water loss by evaporation.
Hydrophytes, living in water conditions, have floating leaves and seeds and the stems have air spaces for buoyancy and are flexible to move with currents.
How are plants adapted to light?
Hydrophytes live on the water surface to increase sunlight exposure.
Plants living in deeper water have evolved colours to increase their light absorption e.g. are red to absorb blue wavelengths that penetrate deeper water.
How are plants adapted to minerals?
Carnivorous plants overcome shortages of nitrogen-containing compounds by obtaining nitrogen from animals that they trap and digest.
Insectivorous plants gain most of their energy from photosynthesis.
What’s evolution by natural selection?
A change in allele frequency in a population over time which will lead to the development of a new species.
What are the (5) main points when answering an evolution / natural selection question?
1) A population has some naturally occurring genetic variation with new alleles created through mutation.
2) A change in the environment causes a change in selection pressures acting on the population.
3) An allele which was previously of no particular advantage now becomes favourable.
4) Organisms with the allele are more likely to survive and reproduce, thus producing offspring.
5) Their offspring are more likely to have the allele, so become more common in the population.
What’s a selection pressure?
An environmental factor that drives evolution in a particular direction. Therefore members of a species must have particular traits to enable them to survive.
Selection pressures include: predators, diseases, climate change, change in food availability, toxic chemicals e.g. antibiotics etc.
Which two scientists first studied evolution?
Charles Darwin and Alfred Russel Wallace
What evidence is proposed for evolution?
Fossils
Molecular evidence
How are fossils used to study evolution?
Carbon dating is used to find their age and gradual changes in appearance occurring in a species over time are analysed.
What methods are used to study the evolution language?
Genetics
Comparison with other species
Fossils
Computer simulations
How have genetics been used to study language evolution?
The FOXP2 gene, found in many organisms, may be involved in speech production and language in humans.
DNA from fossils of human ancestors enables estimates of when mutations linked to language occurred.
What are the two main theories for the evolution of langauge?
The gossip/grooming theory
Mother tongues theory
What’s the gossip/grooming theory?
A theory for language evolution, suggesting that ‘vocal grooming’ replaced physical grooming as a way of maintaining social bonds, due to larger social groups and increased brain size.
However this struggles to explain how the simple sounds would have evolved to a complex language.
What’s the mother tongues theory?
A theory for language evolution where words and basic language could have evolved from communication between mothers and offspring.
It doesn’t answer how language extended to non-relatives and why other animals haven’t evolved language for communication between mothers and offspring.
What is biodiversity?
The variety of life.
What’s genetic diversity?
A measure of the variety of genes in members of a species.
It determines how easily a species is able to adapt to changes in its environment.
What does a high genetic diversity mean?
Genetic diversity is a measure of the variety of genes in members of a species.
A species with high genetic diversity will contain a wide range of traits on which natural selection can act.
This increases chance of a species adapting and surviving environmental changes.
What’s species diversity?
A measure of the number of species in a habitat (species richness) and the relative abundance of individuals in each of these species (species evenness).
How’s an ecosystem formed?
From a community of species (biotic component) and their non living surroundings (abiotic component e.g. air, water etc) interacting together.
What’s ecosystem diversity?
A measure of the range of ecosystems in a particular area.
What do values of genetic diversity mean?
A species with a high percentage of genes and only one possible variant would have a low genetic diversity.
A species with a high percentage of genes with several possible variants would have high genetic diversity.
What methods are used to calculate genetic diversity?
- Calculating the number of alleles per gene
- Heterozygosity: Calculate the proportion of individuals in a population that have two different alleles for a particular gene.
- Calculate the proportion of genes for which more than one allele exists. A gene that has 2 or more possible variants/alleles is known as a polymorphic gene. (A gene for which only one variant/allele exists is called a monomorphic gene).
What’s the formula to calculate the proportion of polymorphic genes?
Proportion of polymorphic genes = number of polymorphic genes / total number of genes
