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