LIFESCI 4 Chapter Notes - Chapter 25.1 - 25.3: Geologic Time Scale, Paraphyly, Ingroups And Outgroups
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25. 1 phylogenies are based on common ancestries inferred from fossil, morphological, and molecular evidence (5, and intro) Phylogeny is the evolutionary history of a species: scientists construct phylogenies by drawing on the fossil record, scientists also use systematics which is an analytical approach to understanding the diversity and relationships of organisms. Systematics also uses a new tool, molecular systematics which uses comparisons of dna, rna, and other molecules. Sedimentary rocks are the richest source of fossils: created by sand and silt that are eroded and are carried by rivers to seas, where the minerals settle at the bottom. The fossil record is based on the sequence in which fossils have accumulated in the strata. Morphological and molecular similarities can indicate phylogenetic history: organisms that share similar morphologies/similar dna sequences are likely to be more related. Convergent evolution is called analogy rather than homology (ancestry: make sure to know the difference between analogy and homology:
