chapter nine: determining the relatedness over time Flashcards
understand that we use various forms of evidence to determine relationships between species
- nucleotide sequences
- homologous structures
- vestigial structures
- analogous structures
give examples of homologous structures and explain how the arise
homologous structures show:
- a species relatedness over time
- the idea that they were deprived from the same ancestor but evolved differently due to different selection pressures
- shows that they are related
- e.g. forelimbs of vertebrates
state how vestigial structures provide evidence of evolution using an example
vestigial structures show:
- shows that there has been evolution
- they are the non-functional remanants that are passed on from ancestors that were once functional in their lives
- e.g. Tailbone
Define molecular homology
molecular homogology involves comparing the similarities in DNA and protein sequences to infer relatedness
Describe the link between similarities in DNA or amino acid sequences between species and time since the species shared a common ancestor
- species that are more closely related to related are expected to have fewer differences in the aminos acid sequence of their corresponding proteins that species that are more distantly related to
State why the differences in molecules can indicate time since a common ancestor was shared
the more differences in molecules, the more time has passes since a common ancestor was shared.
- this is because over time, more mutations would occur, meaning more molecules would be different and the more distinct the differences would be from the current species and their pass ancestors.
explain why conserved proteins are more useful to determine the relatedness of species
conserved proteins have the same function, even in different organisms and species.
- it determines the relatedness because you would be able to tell the difference between mutations if they are similar, rather than a protein that has gone through so many mutations that it is not recognisable
explain whether the use of structural morphology or molecular homology will allow a more accurate understanding of relatedness
molecular homology will more accurately prove relatedness because:
- DNA can more accurately prove whether a species is closely related or not dur to the nucleotide sequences
- structural morphology can tell whether a species is related but it isn’t as accurate since different species can evolve under the same selection pressures
- molecular homology can tell the exact different between the DNA molecules between two species
features of a phylogenetic tree
- tips represents species or group
- nodes show the common ancestors
- line length indicates time
- branch indicates speciation event
- root indicates the common ancestor of all the descendant groups in the tree
what information is displayed in phylogenetic trees
evolutionary relationships between species