Lecture 1 – Introduction and Importance of Systematics

Mayr - “the theory and practice of classifying organisms”.

a-Taxonomy – includes species descriptions, taxonomic keys, and diagnoses.

b-Taxonomy – includes identification of natural groups and biological classes.

g-Taxonomy – includes study of evolutionary processes and patterns.

Biosystematics

Society of Systematic Biologists“The study of organismal diversity, including both the pattern of that diversity

and the processes that have generated it.”

II. Roles of Systematics.

A. Provide a-taxonomy.

There may be ~5 million extant species on Earth (Costello et al. 2013), and we’ve only described 1.5 million (maybe around ~ 30 %) of them.

57% of the 150 most prescribed drugs contain active ingredients derived from natural compounds

B. Provide specimen identification

Indirectly, via keys.

Directly, via expert examination.

II. Roles of Systematics.

C. Maintain Collections

Provide reference for identifications.

Serve as permanent repository for important specimens.

Type specimens

Voucher specimens

Physical evidence of range shifts

II. Roles of Systematics.

D. Classification

Provide a framework of names that is universal.

This must reflect evolutionary history – monophyletic groups

It also must be stable (we should resist change).

Do we want taxonomic ranks to be equilibrated across groups?

II. Roles of Systematics.

E. Phylogeny estimation.

ISI Web of Science “phylogen*” >643,500 papers published since 2004

Understanding Adaptation

Study of Evolutionary Patterns and ProcessesCo-speciation – for example between parasites and their hosts.Historical Biogeography – molecular phylogeographyHybridizationGene Duplication and Genome StructureDeep-time evolutionary Patterns

extinction and speciation rates (e.g., lineages-through time)species selection and the study of evolutionary trends

II. Roles of Systematics.

Molecular Epidemiology

HIV transmission in Edinburgh

Inferred a single donor infected the blood supply.

“The current outbreak is likely caused by a Zaire ebola virus lineage that has spread from Central Africa into Guinea and West Africa in recent decades, and does not represent

the emergence of a divergent and endemic virus.”

II. Roles of Systematics.

Molecular Epidemiology – Ebola Virus: Spread from central Africa or new variant?

II. Roles of Systematics. Forensics

http://www.genomenewsnetwork.org/articles/01_03/hiv.shtml

Richard Schmidt, M.D.Janice Trahan

Schmidt was accused of intentionally injecting Trahan with HIV he collected from his HIV+ patients.

Louisiana v. Richard J. Schmidt

This allegation predicts that HIV collected from Trahan should be very closely related to HIV collected from one or more of his patients.

Why Study Phylogenies? Epidemiology & Forensics

Trahan’s HIV

This (along with other evidence) lead to Schmidt’s conviction.