Evolutionary Relationships Flashcards
In the past scientists encountered many difficulties when trying to determine the evolutionary relationships of species
Using the physical features of species (such as colour/shape/size) has many limitations and can often lead to the wrong classification of species
Advances in genome sequencing and immunology has allowed scientists to further investigate the evolutionary relationships between species
Genome Sequencing
Three types of sequence data are used to investigate evolutionary relationships
DNA
mRNA
Amino acids (of a protein)
Sequencing technology can determine the order of DNA bases, mRNA bases and amino acids within an organism’s genome
This technology is especially useful for comparison with an
extinct species (using ancient DNA) or when distinguishing between species that are very physically similar
Scientists will choose specific proteins or sections of the genome for comparison between organisms
Looking at multiple proteins or multiple regions of the genome will allow for a more
accurate estimate of evolutionary relatedness
Note the protein used needs to be present in a wide range of organisms and show sufficient variation between species
Cytochrome c is often used as it is an integral protein to respiration (in the electron transport chain) which is used by all eukaryotic organisms
For all types of sequence data it can be said that the more similar the sequences, the more
closely related the species are
Two groups of organisms with very similar sequences will have separated into separate species …………. recently than two groups with less similarity in their sequences
more
Species that have been separated for longer have had a greater amount of time to accumulate …………… to their DNA,mRNA and amino acid sequences
mutations and changes
Sequence analysis and comparison can be used to create family trees that show the evolutionary relationships between species
