Class notes
Class notes introductory biology (BIOL1010) Lesson 12
- Course
- Institution
Perfect notes for studying and allowing you to focus your time in class to new materials the professor gives out in order to create meaningful notes
[Show more]
Seller
Follow
nkohoot
Content preview
Phylogeny, Systematics and Microbial DiversityPhylogeny
● A hypothesis for the evolutionary history of a species/ group of species
Systematics
● A discipline focused on classifying organisms and determining their evolutionary
relationships
Linnaean Classification Systems
Binomial nomenclature
- Two-part format of a scientific name
- The first part is the genus, the second part is the specific epithet
Hierarchical classification
- Groups species into a hierarchy of increasingly inclusive categories
Classification Issues
- A phylogenetic tree represents a hypothesis about evolutionary relationships
- If a species has lost a key feature shared by its close relatives it will be
reclassified to reflect evolutionary history
Reconstruction of phylogeny
● Focus on features that result from a common ancestry (homologies)
● Do not be tricked by analogies because these are convergent evolutions and do
not represent a common ancestor
Homology vs. Analogy
Homology: Similarity in characteristics from shared ancestry
Analogy: Similarity between two species due to convergent evolution
Homologous forelimbs but Analogous as wings (Birds & Bats)
● Had common tetrapod ancestor
● Skeletal systems of bats and birds are homologous
● Bats have stretch membrane for wings, birds have feathers
● Wings arouse independently
● Wings are analogous to another
, Molecular systematics: the discipline that uses data from DNA and other molecules to
determine evolutionary relationships.
Problems with nucleic acid comparisons
- Species closely related differ only at a few sites. This can be from an insertion or
deletion causing the bases to shift a notch.
- However, the computer will not take this into account
- Difficult to distinguish between homology and analogy
Cladistics: common ancestry is the primary criterion used to classify organisms.
Species placed in groups called clades, which includes an ancestral species and all of
its descendants
Monophyletic clade
● Consists of ancestral species and all of its descendants
Paraphyletic clade
● Consists of some ancestral species and some of the descendants
Polyphyletic clade
● Includes taxa with different ancestors
Shared ancestral characters
● A character that originated in an ancestor of the taxon
Shared derived characters
● An evolutionary novelty unique to a clade
Phylogeny and shared derived characters
● Characters unique to particular clades
● Possible to determine the clade where each shared derived characters first
appeared
● Infers evolutionary relationships
Ingroup
● The species being studied
Outgroup
● Species/group of species form evolutionary lineage that is known to have
diverged before the lineage of the studied species
○ By comparing we can determine which characters are derived at various
branch points of vertebrate evolution
○ Identifies early branch point
How systematist use principles in reconstructing phylogenies
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller nkohoot. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.69. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79202 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now