Evolutionary History

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16.1 All of Life is connected through its Evolutionary history

Phylogeny- is the history of descent of organisms from their common ancestor. Groups of evolutionarily related species are represented as related branches in a PHYLOGENETIC TREE. - A group of species that consists of a common ancestor and all its evolutionary descendants is called a CLADE. Named clades and species are called TAXA. - HOMOLOGIES are similar traits that have been inherited from a common ancestor. - A trait that is shared by two or more taxa and is derived through evolution from a common ancestry. CONVERGENT EVOLUTION and EVOLUTIONARY REVERSALS can give rise to such traits, which are called HOMOPLASIES.

16.2 Phylogeny can be reconstructed from traits of organisms Phylogenetic trees can be inferred from synapomorphies and using the PARSIMONY PRINCIPLE. Sources of phylogenetic info include morphology, patterns of development, the fossil record, behavioral traits, and molecular traits such as DNA and protein sequences Phylogenetic trees can be inferred with MAXIMUM LIKELIHOOD methods, which calculate the probability that a particular tree will have generated the observed data.

16.3 Phylogeny makes biology comparative

Phylogenetic trees are used to reconstruct the past and understand the origin of traits
Are used to make up appropriate evolutionary comparisons among living organisms Biologists can use phylogenetic trees to reconstruct ancestral states Phylogenetic trees may include estimates of times of divergence of lineages determined by MOLECULAR CLOCK analysis

16.4 phylogeny is the basis of biological classification
Taxonomists organize biological diversity on the basis of evolutionary history.
Taxa in modern classifications are expected to be clades, or MONOPHYLETIC groups. PARAPHYLETIC and POLYPHYLETIC groups are not considered appropriate taxonomic units.
Several sets of rules govern the use of scientific names, with the goal of providing unique and...
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