Lecture 2 Flashcards
What is taxonomy
- Is the study of Identifying, naming and classification of organisms
Explain the history of naming
- Greeks (Aristotle) and Romans started system of naming
- In the Middle ages - Organisms were described using long Latin descriptions
Explain John Ray
- Suggested that each organism should have a set name.
Explain the Binomial System
- Expeditions greatly expanded number of known taxa during 1800’s
- Carolus Linnaeus (1701-1778) developed the Binomial system
Explain the parts of the binomail system fully
- 1st part is the genus: it includes closely related species in the same genus
- 2nd part is specific epithet; descriptive
Scientific name: genus + specific epithet
(eg. Microacontias lineatus and Protea cynaroides )
Both names must be italicized or underlined;
first letter of genus Capitalized
Explain the genus epithet and species in binomial system
- Genus epithet
-Always a capital letter
-Includes groups of organisms with similar structure
- Species
- Always lower case letters
- Organisms possessing unique characters not found in other members
- Describes the organism
What is a species
- A species can interbreed and share the same gene pool
Explain Linnaeus recognizing a unique and distinct characteristics of each species
- Taxa exhibit variation among themselves
- Males vs females differ; likewise juveniles vs adults (sexual dimorphism and ontogeny)
- Problem distinguishing species on the basis of reproductive isolation. If they breed, a hybrid would form.
- Some species do not reproduce sexually
- Some species hybridize
- Reproductive isolation can be difficult to observe
Explain subspecies fully
- Where species have a wide geographic range, variant types may tend to interbreed where their boundaries overlap
eg ) The burrowing skinks Acontias meleagris meleagris, A. m. orientalis are subspecies of Acontias meleagris
What is the classification approach based on
The relationship to other species
What do species with the same genus have
- Share a more recent common ancestor than other taxa
- Common ancestor is held by at least 2 lines of descent
Explain species and taxon
- Species: taxonomic category below rank of genus
- Taxon: group of organisms in classification category
Explain the classification categories fully
- Aristotle classified life into 14 groups (eg. Mammals, birds, etc.) and then subdivided them by size.
- Linnaeus grouped plants by flower parts; his categories were published in Systema Naturae.
- Previously, we used a minimum of 7 categories of classification
What is the order of classification
Species, genus, family, order, class, phylum (or division in plants), and kingdom
Explain the Domain fully
- Added to the 7 categories of classification
- More inclusive
- Members of the kingdom share general characters, members of the species share unique characters specific to that group
- Additional levels of classification can be added by adding super-, sub-, or infra (eg., suborder)
What are fossils
Living specimens, by observing the structures and functions
Explain relative and absolute fossil dating
- Relative dating = to determine afossilsapproximate age by comparing it to similar rocks andfossilsof known ages.
- Absolute dating = to determine a precise age of afossilby using radiometric dating to measure the decay of isotopes, either within thefossilor more often the rocks associated with it
Explain fossils fully
- Remains of organisms and tell story of the past either through imprints, impressions of soft tissue or hard elements and can be dated
- Mostly found in sedimentary
[L.sedimentum, a settling] rock. Sediments form layers = strata (stratum) of different age structure - Fossils are deposited in strata
- Fossil record often incomplete because soft bodied organisms do not fossilize well and decay
- When complete enough, a lineage can be traced through time
What is systematics’s 3 branches
- Phenetic systematics = number of similarities
- Traditional systematics = Common ancestor and structural differences
- Cladistics = derived characters for classification
What is systematics
Study of the diversity of organisms using data from cellular to population levels
Explain phenetic systematics fully
- Species classified according to number of similarities to produce a phenogram-Not based on phylogeny
-Results in a phenogram
Explain traditional systematics fully
- Anatomical data, construct phylogenetic tree using evolutionary principles
- Look at common ancestor and degree of structural difference
Explain cladistics fully
- Analyses primitive and derived characters
- Uses shared derived characters to classify organisms and arrange taxa in a phylogenetic tree or cladogram
What is phylogeny
The evolutionary history of a group of organisms
What is classification
Reflects phylogeny; one goal of systematics is to create phylogenetic trees
What is a phylogenetic tree
Indicates common ancestors and lines of descent
What is primitive character
A trait that is present in a common ancestor and all members of the group
What is derived character
- Present only in a specific line of descent
- Different lineages diverging from a common ancestor may have different derived characters
What is an outgroup
- Defines primitive characters of study group
- Also tells you which traits are shared/derived traits – synapomorphies
What is study / in group
Taxa grouped into clades in a cladogram
What is primitive characters
Structures present in outgroup and study group
What is clade
Evolutionary branch of cladogram – common ancestor and descendents
What is monophyletic taxon
Single common ancestor and its descendents
What is parsimony
Uses minimum number of assumptions to produce simplest tree
What is an ancestral / primitive trait
Any trait in both outgroup and ingroup
Explain Kingdom naming
- Early biologists recognized two kingdoms: animals (kingdom Animalia) and plants (kingdom Plantae)
- The microscope revealed unicellular organisms; in the 1880’s, Ernst Haeckel proposed the kingdom Protista
- Haeckel originally placed bacteria and cyanobacteria in Monera since they lacked a nucleus
What was RH Whittaker’s 5-Kingdom system based on
- Cell type (pro- or eukaryote)
- Organization (uni- or multicellular)
- Motility
- Mode of nutrition
- Mode of reproduction
What are the parts of Whittaker’s 5-Kingdom System
- Monera
- Protista
- Plantae
- Animalia
- Fungi
Explain Monera
Prokaryotic bacteria that obtain organic molecules by absorption or photosynthesis
Explain Protista
Mainly unicellular eukaryotes that obtain organic molecules by absorption, ingestion, or photosynthesis
Explain Plantae
Multicellular eukaryotes, autotrophic (photosynthesis)
Explain Animalia
Multicellular eukaryotes, heterotrophic by ingestion, are generally motile
Explain Fungi
Multicellular eukaryotes, heterotrophic saprotrophs; form spores, lack flagella and cell walls containing chitin
Explain the three-domain system
- Recent research suggests one group of prokaryotes is so distantly related it should be in separate domain
- Sequencing of rRNA suggests all organisms evolved along three distinct lineages: Domains - Bacteria, Archaea and Eukarya
- Bacteria diverged first
- The Archaea cell wall is diverse but not the same as the Bacteria cell wall; both are prokaryotes
- Archaea and Eukarya are more closely related than either is to Bacteria
- The Archaea mostly live in extreme environments; methanogens in anaerobic swamps, halophiles in salt lakes and thermoacidophiles in hot acidic environments
