Sunday, March 1, 2009

Chapter 26: Phylogeny and the Tree of Life

Hi ladies! I hope everyone had a good weekend. Friday in class we took a quiz on chapter 24 and a Unit 8 Essay. We also got a take home for chapters 26 and 27 which is due this Wednesday March 4th. Test corrections for the Midterm and Unit 4 and 5 Exam are due Thursday! Below are the notes for chapter 26.

Phylogenies show evolutionary relationships

Phylogeny is the evolutionary history of a group of related species. It is constructed by using evidence from systematics, a discipline that focuses on classifying organisms and their evolutionary relationships. Its tools include fossils, morphology, genes, and molecular evidence.

Taxonomy is an ordered division of organisms into categories based on a set of characteristics used to asses similarities and differences.
Binomial nomenclature uses two a two part naming system that consist of the genus to which the species belongs, as well as the organisms’ species within the genus, also called the epithet. The system was developed by Carolus Linnaeus. For example Panthera pardus is the binomial of a leopard.

The hierarchal classification of organisms consists of the following levels, beginning with the most general or inclusive: domain, kingdom, phylum, class, order, family, genus, and species. Each categorization at any level is called a taxon. At each level of the Linnaean classification system, species are placed into groups belonging to more inclusive groups.

Systematics use branching diagrams called phylogenic trees to depict hypotheses about evolutionary relationships. The branches of such trees reflect the hierarchal classifications of groups nested within more inclusive groups.

Phylogenies are inferred from morphological and molecular data

Homologous structures are similarities due to shared ancestry, such as the bones of whale’s flipper and tiger’s paw.

Convergent evolution has taken place when two organisms developed similarities as they adapted to similar environmental challenges—not because they evolved from a common ancestor. Example: the streamlined bodies of tuna and a dolphin show convergent evolution.
A phylogeny based on DNA data reveals that-- despite appearances-- animals (including humans) and fungi are more closely related to either than either is to plants.

1.) The named unit at any level of the classification heirarchy is called...
a. branch point
b. root
c. taxon
d. phyloCode

2.) The most general level of the taxonomic system is the domain
a. true
b. false

3.) In binomial nomenclature, the epithet is always...
a. capitalized
b. lower case
c. italicized
d. bold

Answers: c,a,b

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