Roles and products of sytematics on modern biology

-Specific roles for Systematic studies and the patterns they produce are as follows:

-collection of samples of organisms

-comparing them with known samples

-determination of possibly newdiscovered species

-Once species have been defined,names are given to them according torules of nomenclature for the group.

-The resulting classifications provide abasis for communication about taxa forthe scientific community and for theworld at large.

-Once we know what organismsexist, we can then ask questionsabout how they came to be asthey are today.

-Phylogenetic analysis allows usto combine data from extantorganisms with data from fossilsto provide hypotheses ofrelationship---to actuallyreconstruct the history of life

-Common ancestry means thatorganisms will have a greater orlesser amount of expectedsimilarity depending upon howclosely related they are.

-This principle can be put toimmediate use when one seeksother taxa that may possess afeature of interest found in aspecific taxon.

Example: Taxol anti-cancercompound found in T. brevifolia(Pacific Yew). Where else will youlook to find other sources of thiscompound.?

-Logical place to look would be in ataxa that are most closely related.

-Armed with this informationabout relationships in the genus,researchers found taxol in closelyrelated species, The European Yew(T. baccata). This alternative sourceis less costly and will alleviate thepressure on the rarer T. brevifolia .

How do we decide, given limitedresources, which to protect?

- In order to maximize diversity, it makes sense to try preservegroups from throughout the tree of life, rather than largenumbers from one branch.

-If we decide that we want to maximizebiodiversity, then the phylogeneticpatterns produced by systematists give usa way to prioritized areas based upon thediversity they contain.

Geologists use data from the Earth itself to reconstruct pastarrangements of land masses. However, there is anindependent source of data for such reconstructions, which liesin the current distribution of taxa when viewed in the light oftheir relationships.

-When continents fragment, the taxa that live on them recordthis change, since the separated taxa will have their ownhistory, but share the common ancestor that was oncecontinuously distributed.

-By constructing organismal phylogenies and mapping oncurrent distributions of taxa, and doing this for many groups,general patterns emerge that may best be explained by historicalgeological events.

Drifting Continents, Changing Seas

Theory of continental drift

Earth’s continents were once part of a single supercontinent that split up and drifted apart

Explains how the same types of fossils can occur on both sides of an ocean

Pangea

Supercontinent that formed about 237 million years ago and broke up about 152 million year ago

Plate Tectonics

The movements of these plates (and the continents) has significantly

affected climates, sea levels and therefore the distribution of vertebrates over

time.

Earth was formed 4.6 billion years ago and life started as such at least3.8 billion years ago.

Wegner believed all continents were once connected into one large land mass called Pangaea.

FOSSIL EVIDENCE

SAME FOSSILS: DIFFERENT CONTINENTS

Support for Continental Drift

fossilized tropical plant found on Antarctica.

Remember: the continents have moved and Antarcticause to be in a warmer climate.

Pioneers of BiogeographyLate 1800s: Charles Darwin, Alfred Wallace and other

naturalists observed patterns in where species live,how they might be related, and how natural forcesmight shape life

Biogeography

Study of patterns in the geographic distribution ofspecies and communities

Wallace and Darwin thought similarities in birds ondifferent continents might indicate a commonancestor

Pioneers of Biogeography

-The long lasting way todocument identity is todeposit a voucher specimenin an appropriatecollection.

-Studies that do not utilizethis service will have lessvalue in the long termbecause of the impossibilityof verifying identification.