1 Classification & Phylogeny of Animals Zoology Chapter 4 Homework: Read pages (up to Taxonomic char…) Do Questions 1, 2, 3, 4 page 86 Due: Tuesday 2/16/10

2 Linnaeus & Classification Carolus Linnaeus ( )  Botanist who introduced a comprehensive classification system for naming organisms It is important to classify (group) organisms b/c it makes learning about them easier This system based on hierarchy of major to minor groups (taxa, taxon) having certain characteristics The characteristics used to group organisms vary; this will be discussed in a later slide

3 Hierarchy of the system The major classification ranks are:  Kingdom  Phylum  Class  Order  Family  Genus  species

4 Binomial Nomenclature (2 Name Naming System) Every organism has a scientific name that is the Genus + species name (which is italicized or underlined); uppercase Genus, lowercase species Naming system uniform throughout world Often the species epithet (name) may be similar for several organisms b/c the species epithet is usually descriptive (adjective), therefore, the genus name must always be included!  For example:Anolis carolinensis (green anole) & Poecile carolinensis (Carolina chickadee) & Sitta carolinensis (White-breasted nuthatch)  Note there are 3 organsims all with the same species name

5 Criteria for Recognition of Species (But what is a species?) We defined it as a group of individuals in a population which successfully breed producing fertile offspring.  B/c the naming system relies on “what is a species”, defining it properly matters So, biologists have several definitions of what constitutes a species, we will look at those:  Biological species concept  Evolutionary species concept  Phylogenetic species concept

6 Biological Species Concept Introduced by Theodosius Dobzhansky & Ernst Mayr in “A species is a reproductive community of populations that occupies a specific niche in nature.”  Note that species here is defined according to reproductive properties of populations, not based on morphology A species is an interbreeding population of individuals having a common descent inhabiting a particular niche in nature.

7 Evolutionary Species Concept Proposed by George Simpson in the 1940s. “A species is a single lineage of ancestor- descendant populations that maintains its identity from other such lineages and that has its own evolutionary tendencies and historical fate.”  Applies to both sexually & asexually reproducing organisms  Common descent is a factor in this definition

8 Phylogenetic Species Concept “A species is an irreducible grouping of organisms diagnosably distinct from other such groupings and within which there is a parental pattern of ancestry and descent.”  This definition implies common descent, as well as, referring to both sexually & asexually reproducing organisms

9 Sources of Phylogenetic Information In order to construct phylogenetic relationships, information is gathered from many sources:  Comparative morphology Organism structure & developmental origins  Comparative biochemistry Amino acid sequences (proteins); nucleotide sequences (RNA & DNA)  Comparative cytology Variation in #, shape, & size of chromosomes  Fossil Record Fossil remains showing appearance of morphological characteristics

10 5 Kingdoms Monera  Unicellular prokaryotes  Now broken into Eukarya (true bacteria) & Archaebacteria Protista  Unicellular eukaryotes Fungi  Uni- & Multicellular eukaryotic heterotrophs (decomposers) Animalia  Multicellular eukaryotic heterotrophs Plantae  Multicellular eukaryotic autotrophs