Developed the hierarchical classification scheme that is still used today (Linnaean system)
Believed in special creation, so evolution was not considered when he classified organisms.
classifications built off similarities.
under this system, birds would be placed in their own order, because nothing else resembles them.
Three Main Methods of Systematics
Classification involving relatedness as well as morphological diversity (overall similarity)
Endorsed by Ernst Mayr and George G. Simpson
Numerical Phenetics (Numerical Taxonomy)
Based on similarities and differences among taxa
All characters are given equal weight (not realistic)
Lots of characters, lots of math
Identifying and understanding evolutionary relationships among the many different kinds of life on earth, both living and non living\
Relationships established by phylogenetic systematics often describe a species' evolutionary history and its phylogeny.
The study of ancestor/descendant relationships among taxa revealing "family trees" of taxa
Father of phylogenetic systematics.
Systematics should reflect the known evolutionary history of lineages as closely as possible.
Hennig's Auxiliary Principle
Never presume convergent or parallel evolution; always presume homology
Relative Apomorphy Rule
Homologous characters found only in the in-group are apomorphic (derived) while homologous characters shared with a sister group are plesiomorphic (basal/primitive or ancestral state)
Only synapomorphies provide evidence of common ancestry.
Information from two transformation series can be combined into a single hypothesis of relationship if that information allows for the complete inclusion or exclusion of groups which fomred by the separate transformation series.
All species share a common ancestor, and all species derived from that common ancestor are included. This is the only form of grouping accepted as valid by cladists
All species share a common ancestor, but not all species derived from that common ancestor are included
Species that do not share an immediate common ancestor are lumped together, while excluding other members that would link them.
Cain's rule of thumb
Criteria used/aused for indicating center of origin of taxon
1. Location of greatest differentiation of a type (greatest number of species)
2.Location of dominance or greatest abundance of individuals (most successful area)
3.Location of synthetic or closely related forms (primitive and closely related forms)
4. Location of maximum size of individuals
Importance of styding multiple groups to determine biotic patterns
Noted similar patterns of disjunction
Drew "tracks" to indicate historical connections
Nelson and Platnick
Phylogeny of taxa will match the historical relationships among geographic localities if speciation resulted from vicariant events.
This is not expected to hold if isolation resulted from jump dispersal
importance of rigorous and objective methods in the analysis of biogeographic data
Strongly advocated for the application of Hennigian Cladistics
Biogeographic Histories: Hawaii
Some show a simple progression of old island colonization and subsequent colinization of newer islands in order they emerged.
Others reveal more complex patterns of colonization across the archipelago.