Plant Taxonomy
Characteristics of speciation
-once gene flow ends, populations begin to undergo genetic divergence -divergence is due to mutation, natural selection, and genetic drift operating independently in each population -eventually genetic differences are great enough to bring about reproductive isolation
Characteristics of morphological species concept
-organisms that look alike belong to the same species; those that look different belong to a different species -morphological similarity is the species criterion -disadvantage of being subjective
Characteristics of biological species concept
-species are groups of actually or potentially interbreeding organisms -ability to interbreed and produce VIABLE AND FERTILE offspring is the species criterion -offers a more objective and testable definition
Characteristics of embryological characters
In plants, embryology involves studying the development of pollen grains and ovules Embryological characters are usually more useful for phylogenetic studies than for identification
Define mechanical isolation
Individuals cannot mate or pollinate due to physical constraints
Define ecological isolation
Individuals inhabit different areas
Define behavioral isolation
Individuals of different species ignore or do not receive required cues for sex (common in vertebrates)
Define temporal isolation
Individuals reproduce at different times
What are the characteristics of the comparison method?
Involve comparing an unknown plant with photographs, illustrations, descriptions, or previously identified plant specimens
What is the order for the Linnaean hierarchy
Kingdom Phylum Class Order Family Genus Species
What are the prerequisites for making accurate identification?
Knowledge of taxonomic methods, terms and characters Familiarity with manuals and other resources for identification Experience in the process of identification
What are the goals of modern plant systematics? (4)
To provide useful and convenient methods of plant identification To inventory the plant life of the world To provide a classification system that expresses the natural relationships of plants To detect evolution at work, discovering its processes and interpreting its results
Define phylogenetic classification
ordering organisms into groups on the basis of their evolutionary relationships
What are the three systems of classification?
artificial systems Natural or phenetic systems Evolutionary or phylogenetic systems
What are the three general categories that methods for plant identification fall into?
Expert determination Comparison methods Taxonomic keys
Describe species
Species is the basic or fundamental unit if classification It is the only unit that can be defined without reference to another unit
When a species is described in one genus, the original ___ ___ must be retained
Specific epithet
Describe the evolutionary species concept
-Also termed the phylogenetic species concept -States that species should be recognized based on their evolutionary relationships -Separate evolutionary lines should be recognized as separate species
Characteristics of nomenclature
-An integral part of plant systematics -Conveniently refer to the groups recognized by the process of classification -Some systematics study the naming of plants and nothing else
What are the six principles of "the Code"
-Botanical nomenclature is independent of zoological nomenclature -Application of names to plant groups is determined by the use of type specimens -Nomenclature is based upon priority if publication -Each taxonomic group can have only one correct scientific name -Scientific names treated as Latin, regardless of origin -Rules are retroactive to 1753 "species plantarum"
What is the difference between scientific and common names (5)?
-Common names are ordinarily applicable in only a single language -only a relatively few species have common names -common names are often applied to indiscriminately to plants of different taxonomic ranks -two or more unrelated plants may share the same common name -a single species may have more than one common name
Describe hierarchy
-a framework for classification composed of a sequence of groups at different levels arranged such that each group, except the lowest, contains one or more subordinate groups
Family names are produced by adding the suffix ____ to the root of the generic name
-aceae
Define herbarium
A collection of pressed and dried plants that have been identified and mounted on sheets of paper
Define taxon
A group of real organisms recognized at any level of a taxonomic hierarchy
Define key
A sequence of choices between pairs of contrasting statements that identifies plants plants by the process of elimination
What are the advantages and disadvantages of taxonomic keys
Advantages: available for most areas, comprehensive Disadvantages: require practice and experience to use effectively
What is the third principle of classification?
All taxa should be monophyletic
Characteristics of Natural Classification
Also known as phenetic classification Uses as many characteristics as possible for classification with each characteristic being given equal weight Classification is a posteriori and is based on overall resemblance Goal is to remove all subjectivity from process of classification
Define taxonomic character
Any feature of an organism that can be counted, measured, described, or otherwise assessed
What is the first principle of classification? Describe this
As many characteristics as possible should be used in assessing relationships Classification should be based on correlations of characters Character correlations give classification a predictive value
What are the characteristics of expert determination?
Ask someone who knows Most universities has a plant systematist who is familiar with the local flora Other resources also exist: botanical garden staff, consultants, master naturalists etc.
Characteristics of phylogenetic classification
Assumes that evolutionarily primitive characteristics can be identified and the features of an organism can be used to reconstruct its phylogeny
Define artificial classification
Based on a priori definition of the groups to be recognized Classifier decides beforehand how the objects will be grouped and then fits them into the categories Usually only one or very few characteristics are used for classification
Characteristics of classification
Based on similarities and differences among organisms Should provide a means for referring to different groups of organisms Should express the relationship among these groups
How did Theophrastus classify plants?
Basis of growth form Plant kingdom divided into four major groups: trees, sub shrubs, shrubs, herbs Each category subdivided into cultivated and uncultivated plants
What is the basis of scientific names?
Before mid-1700s naming was unstructured Plants often named using a sequence of descriptive terms
What are the advantages of expert determination?
Best method in terms of accuracy and reliability
Most plants conform fairly well to the ____ ____ ____
Biological species concept
Define easily recognized species
Characterized by outcrossing, unrestricted fertility among its members, and strong RIMs Most vascular plants (and most vertebrates) fit this pattern
What is a difference between classification and identification?
Classification deals with groups of organisms, while identification deals with individuals Identification requires that some system of classification already exist
What are the characteristics and advantages and disadvantages of comparison with herbarium specimens?
Comparing to dried samples in a collection Advantages: comprehensive, unknown plants are compared with actual plant Disadvantages: requires access to an herbarium, can be time consuming
What are the two general categories of comparison methods and characteristics of each?
Comparisons with illustrations/descriptions Comparison w/ herbarium specimens
What are other names for micro species?
Cryptic species Agamospecies
Who is the "father of botany"
Theophratus
What are the four steps in naming a new plant species?
Discover a new species and collect a type specimen Select an appropriate name Prepare a Latin or English diagnosis Publish name in scientific journal
Define geographically isolated species
Divergence has occurred without reproductive isolation
What are the advantages of scientific names?
Each taxon has only one correct scientific name Scientific names are universal
If two or more previously distinct species are combined to form a single species, the ___ ____ specific epithet must be used
Earliest legitimate
What is a supra specific category?
Everything above the rank of the species The phylum is the most inclusive category
What is an infraspecific category?
Everything below the rank of the species The sub form is the least inclusive category
What are the categories most commonly used in classification of flowering plants?
Family Genus Species Subspecies Variety
What are the characteristics and advantages and disadvantages of comparison with illustrations/descriptions?
Favored by those with little training in process of identification Advantages: easy, does not require technical knowledge Disadvantages: most field guides are not comprehensive
Characteristics of reproductive characteres
Features of the inflorescence, flower, fruit and seed are the most important characters used in classification Tend to be less variable than vegetative characters More numerous than vegetative characters
Define speciation
Formation of a new species of organism
Define gametic mortality
Gametes of different species are incompatible so fertilization does not occur
Speciation usually results from ___
Gene flow
The first word in a scientific name is called the ___ and the second word is called the ___
Generic name Specific epithet
What are sources of specific epithets?
Geographic locality Adjective describing aspect (must agree in number and gender)
Define hybrid inviabilty
Hybrid embryos die at an early stage of dvlpmt or hybrid individuals die before they can reproduce
Define hybrid sterility
Hybrid individuals do not produce functional gametes
What are the two types of Postzygotic RIMs?
Hybrid inviabilty Hybrid sterility
What two important respects makes systematics basic to all other fields of biology?
Identification Relationships
For specific epithets, what does the -i or -ii mean? What does the -ae or -iae mean?
Male is honored Female is honored
Define honorifics
Many generic names are created to honor individuals who have made a contribution to botany
What mechanisms are categorized in prezygotic RIMs?
Mechanical isolation Temporal isolation Behavioral isolation Ecological isolation Gametic mortality
Define micro species
Minimally differentiated series of populations derived from uniparental reproduction
Define monophyly and polyphyly
Mono: derivation of a taxon from a single ancestral taxon Poly: derivation of a taxon from more than one ancestral taxon
Characteristics of cytological characters
Most widely used cytological characters involve chromosomes Chromosome number and structure are often characteristic of different plant groups
What are the characteristics of taxonomic keys?
Most widely used method of identification When properly used, allows to quickly and accurately identify an unknown plant
Define gene flow
Movement of alleles into and out of a population; results from immigration and emigration
What is an authority in a scientific name?
Name of the individual who named the particular species Complete species name: Quercia viginana L.
Characteristics of vegetative characters
Often tend to be more plastic or variable than reproductive characters Commonly used to delimit species and subspecific taxa
What is the second principle of classification?
Only genetically controlled variation should be used for classification
What is the fourth principle of classification?
Parallel evolution must be distinguished from convergent evolution
What is the suffix for the following: phylum, class, order
Phylum: -ophyta Class: -opsida Order: -ales
What two groups are RIMs categorized into?
Prezygotic RIMs and Postzygotic RIMs
____ ___ ___ are the barriers to interbreeding
Reproductive isolation mechanisms
What are the disadvantages of expert determination?
Requires access to, and the time of, and expert, which may cause delays in identification
Define convergence
Resemblance between different evolutionary lines resulting from adaptation to similar environments
Define parallelism
Resemblance due to a similar genetic background resulting from common ancestry
Define polynomial
Scientific name composed of three or more words; some names consisted of as many as twelve words
Define Systematics
Scientific study of the diversity of organisms and of any and all relationships among them Broad field of study that cuts across many sub disciplines of biology
Why is identification important? (2)
Scientists working on a group of plants will eventually need to communicate the results to others, to do so they must be able to identify the organisms Data collected about unidentified organisms is generally worthless scientifically
In cases of parallelism there will be more overall ____ than ____, whereas vice versa is true for convergence
Similarities; differences
What are the characteristics of artificial classification?
Simple system that is easy to use Usually does not accurately reflect evolutionary relationships Artificial systems continued in use for nearly 2000 yrs
The number of categories used in a particular classification scheme is determined by:
Size of the group of plants being studied Diversity of the group How intensively the group has been studied
Define Taxonomy
Study of classifcation, including its principles, procedures, and rules Term often used synonymously with "systematics", but technically has a very different meaning
Characteristics of anatomical characters
Study of internal structure can provide useful information Anatomical characters are used more often for understanding phylogeny than for identification
____ are not acceptable in botanical nomenclature
Tautonyms : scientific name in which the genus name and specific epithet are the same
Characteristics of phytochemistry
Technically includes the study of any and all chemical constituents of plants In practice, phytochemists generally study secondary chemical compounds (perform non-essential functions: pigments,attractants, defensive compounds, etc.) Examples include alkaloids, flavonoids and cyanogenic compounds
Define nomenclature
The application of distinctive names to the groups recognized in a classification
Define category
The levels in a hierarchy to which taxa are assigned
Define Classification
The ordering of organisms into groups on the basis of their relationships An essential part of systematics, but the terms are not synonymous
Define taxonomic rank
The relative position of either a taxon or a category in a taxonomic hierarchy
Why is classification and identification essential? (3)
Two of the natural preoccupations of humans For successful communication, b/c we need a system for recognizing and naming objects Critical processes in our daily lives (chair example)
Define binomial nomenclature
Use of two Latin words to name each species
What are the two major types of morphology characters?
Vegetative characters- features of the stem,leaf and root Reproductive characters- features of theflower, fruit and seed
When does speciation occur?
When gene flow between populations ceases
What are considered "good characters"?
genetically determined largely unaffected by the environment relatively constant throughout a population of individuals
Define palynology
study of pollen grains
What is Linnean's sexual system?
system was based on the numbers of reproductive parts in the flower Plants divided into 24 classes based on the number of stamens Each class subdivided into orders based on number of styles in the flower
