A4 Unity and Diversity of Ecosystems Flashcards
What is biological evolution?
Change in the heritable characteristics of a population / change in allele frequency overtime in a population
What was Lamarck’s theory of evolution?
Adults acquired characteristics over their lifetime, based on environmental stressors and pass this on
Why was Lamarck’s theory of evolution falsified?
Offspring inherit DNA. Changes during lifespan cannot be passed on
What was Charles Darwin’s theory of natural selection?
Only traits are heritable can be passed on. Alterations to heritable material give rise to different traits. Some traits aid survival/reproduction, and organisms that survive are able to pass on successful traits. This means that the frequency of this allele increases.
What does it mean for a theory to be falsified?
Shown not to be true
What generates strong support for a theory?
If many lines of evidence fail to falsify it (i.e. evidence for lack of falsification)
What are three different forms of molecular evidence for evolution that are studied?
DNA
RNA
Proteins (indirect way to study DNA)
What patterns would be found in DNA comparisons that suggest evolutionary similarity?
A high level of DNA similiarity between species supports the idea of common ancestory with evolution occuring via small changes to DNA overtime
What are the Hox genes?
Gene family that plays a role in determining the body plan of organisms during development.
How are Hox genes related to evolution?
The similarity in these genes across very different types of organisms would be hard to explain without looking at common ancestry/evolution
What are phylogenetic trees?
Visual diagram that shows similarity via organisms being on closer branches.
What have we added onto Darwin’s theory of evolution?
That inheritance is due to DNA, which does not change during the lifetime.
That differences/variation arise because of changes to DNA due to mutation.
Variation is genetic
What is the outcome of Natural selection?
Evolution
What are the steps involved in natural selection (according to Darwin)
Differences exist in heritable material.
This leads to variation in a population.
There are threats to survival.
In this environment, some variations increase likelihood of survival.
Those with the adaptation produce more offspring, because they survive longer (survival of the fittest)
Since adaptation is heritable, the adaptation is passed onto their many offspring
Over many generations, there is an increased frequency of this adaptation + evolution has occured
What are some threats to survival?
Abiotic factors
Competition for resources
Predators + disease
What is fitness (in relation to survival of the fittest)?
Ability to pass on more offspring (by surviving longer)
How is a base sequence comparison of DNA molecular evidence for evolution?
More similiar the DNA is, the more closely related.
If evolution is true, similiar organisms will have…
Very similar DNA
What are the strengths and limitations of DNA modelling?
Difficult to isolate and sequence. Overly complex if not closely related
Provides more information. All differences are detected including silent mutations. Good for if closely related
When is RNA sequencing used?
Studying viral evolution, that only has RNA
How is RNA used for molecular evidence for evolution?
Using mRNA, base sequencing concept.
Usually difficult to sequence, harder to isolate
Where does most older data about molecular evidence for evolution come from?
Protein studies
How are proteins used as molecular evidence for evolution?
Compare amino acid sequences of a shared protein.
What are the strengths and weaknesses of using proteins for molecular evidence for evolution?
Easier to sequence and obtain
Less data/differences detected. Does not include silent mutations