01:119:115 Lecture Notes - Lecture 25: Molecular Phylogenetics, Convergent Evolution, Silt
15 Feb 2018
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Document Summary
In recent decades, systematists have gained a powerful new tool in molecular systematics, which uses comparisons of nucleotide sequences in dna and rna to help identify evolutionary relationships between individual genes or even entire genomes. Scientists are working to construct a universal tree of life, which will be refined as the database of dna and rna sequences grows. Concept 25. 1 phylogenies are based on common ancestries inferred from fossil, morphological, and molecular evidence. Sedimentary rocks are the richest source of fossils. Fossils are the preserved remnants or impressions left by organisms that lived in the past. In essence, they are the historical documents of biology. Morphological and molecular similarities may provide clues to phylogeny. Similarity due to convergent evolution is called analogy: when two organisms from different evolutionary lineages experience similar environmental pressures, natural selection may result in convergent evolution. Systematists compare long stretches of dna and even entire genomes to assess relationships between species.
