Chapter 26 2.06.08

Chapter 26 2.06.08 - Chapter 26 1 Honors Biology Book Notes...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 26 1 Honors Biology Book Notes Chapter 26 – Phylogenies and the History of Life 2/06/08 - Phylogenies and the History of Life o Phylogeny: evolutionary history of a group of organisms, usually summarized in form of phylogenic tree o Phylogenic tree: shows ancestor-descendent relationships among populations/species o Fossil: physical trace of organism that lived in past o Fossil record: total collection of fossils that have been found through out world o Phylogenic tree terms Branch: represents population through time Node: occurs when ancestral group splits into 2+ descendent groups Polytomy: when more than 2 descendent groups emerge from ancestor Tips: terminal nodes, represent trees endpoints depicting species that live today or an extinction Sister taxa: groups that occupy adjacent branches on tree Taxon: any named group of organisms Rooted tree: one in which bottom represents most ancient Outgroup: a taxonomic group that is known to have diverged prior to rest of taxa in the study Monophyletic group: consists of ancestral species and all of its descendents Clade/lineage: same as monophyletic group o Two approaches to classifying similarity between species (1) Phenetic approach: phonetic approach to estimating trees is based on computing a statistic that summarizes the overall similarity among populations based on the data [ex. Using DNA to examine genetic distance, or average percentage of different bases in DNA sequences] (2) Cladistic approach: cladistic approach is based on realizing that relationships among species can be reconstructed by identifying shared derived characters [called synapomorphoes] in species being studied Mutation/selection/genetic drift cause evolutionary changes that are shared in groups derived from same common ancestor Convergent evolution becomes problem to both approaches – biologists just pick most parsimonious option when convergent evolution a question
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chapter 26 2 Parsimony: states that most likely explanation/pattern is one that implies least amount of change/least complexity o Fossilization occurs most readily when remains of an organism are buried in sediment, where decay is slow Once organism is buried in sediment, 4 things can occur
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Chapter 26 2.06.08 - Chapter 26 1 Honors Biology Book Notes...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online