Transcript Systematic Implications of DNA variation in subfamily

Recognition, Identification and
Names
Spring 2014
Recognition versus Identification
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Recognition relies upon previous experience with the organism.
You “know” it is this, because you’ve seen it before, and have
learned the name from some authority.
The process of identification relies upon an analytical review of
the characters observed, and following a logical order of
inclusion and exclusion, to finally arrive at the name through the
use of identification keys, for example, or some other resource.
Confirmation of the name is done through comparison with a
known “standard” (e.g., checking the specimen against
previously identified specimens in a reference collection, the
herbarium), or consulting with an authority who has much
experience with the plant group, or checking a published
treatment of the plant diversity of your region (flora) or a
photographic atlas or web resource for that group of plants.
Elements of Understanding
Biological Diversity
Description of Diversity
Classification of Diversity
Naming of Diversity
Identification of Diversity
Elements of Understanding
Biological Diversity
Description: requires observation and measurement
of characters and their states and synthesis of this
information
Classification: requires hierarchical organization of
taxa based on evolutionary relationships
Naming: requires following nomenclatural
conventions and enables communication
Identification: requires tools such as keys that are
based on previous description, classification, and
naming of taxa
Description
• Provides some basic identifiable set of
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characteristics to associate with the
organism.
Can be as general or as detailed as
practicality dictates.
Needs to contain enough data to provide
adequate discrimination between similar
organisms.
Needs terminology.
Descriptions are linked with a name when
there is consistency in the set of observed
characters for a given organism.
Fig. 16.2
Description of Bambusa from
the Flora of China
Classification
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Classification provides ORDER to the group of entities.
Relies on observations, many definable and comparable
characters, and an ability to discern them.
Completely effective classifications can be artificial, that is,
not necessarily reflecting evolutionary relationships: i.e.,
trees vs. shrubs vs. herbs.
But modern classifications are based on evolutionary history
(phylogeny) because this provides predictive power.
Biological classifications are hierarchical.
Hierarchical (nested) categories
and phylogeny
GENUS
TIME
FAMILY
ORDER
CLASS
PHYLUM
Taxonomic Ranks…
…have only RELATIVE meaning, not absolute
meaning!
…are artificially created to accommodate
different hierarchical levels of organization.
…rely on inclusiveness of various shared
characteristics that all members of the
group should possess.
…are subject to modification as data
accumulate!
Naming and Nomenclature
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We need names to communicate about plants with
others.
Organized system of names enables fitting the plant
into an accepted scheme.
Following formal naming rules is nomenclature
(International Code of Nomenclature for algae, fungi & plants)
The system must allow for changes as new
information (and other species) are discovered.
Will discuss the rules of nomenclature in more
detail later in the semester.
Names of taxonomic ranks:
standardized endings*
Kingdom Chlorobionta (Viridiplantae)
Phylum/Division: Magnoliophyta
(Angiospermae)
Class: Liliopsida
Order: Poales
Family: Poaceae
Subfamily: Bambusoideae
*These are for plants and fungi; there are different ones for animals.
Names of taxonomic ranks:
standardized endings*
Kingdom Chlorobionta (Viridiplantae)
Phylum/Division: Magnoliophyta
(Angiospermae)
Class: Liliopsida
Order: Poales
Family: Poaceae
Subfamily: Bambusoideae
*These are for plants and fungi; there are different ones for animals.
Name of a bamboo
Class: Liliopsida (Monocots)
Order: Poales
Family: Poaceae
Subfamily: Bambusoideae
Genus: Chusquea Kunth
Species: Chusquea pohlii L. G. Clark
Genus names
• Do not have standardized endings
• Must be italicized
• Often the name of the author follows
the genus name
Chusquea Kunth
Species names
• Are always a binomial (genus name
or epithet + species name or epithet)
• Must be italicized
• Often appear with the name of the
author(s) of the species
Chusquea pohlii L. G. Clark
Classification and Names
• Ideally, classification should reflect
phylogeny
• And names should reflect the
classification and phylogeny
Identification
• Relies on previous description,
classification, and naming of taxa
• Keys are the primary means of plant
identification
• Keys can take different forms, but the
most common is still the dichotomous key
Dichotomous keys
• Consists of a series of two contrasting
statements (each called a lead); each pair
of statements is called a couplet
• Should be able to eliminate one set of
possible identifications at each couplet
• Rules for constructing dichotomous keys
are found on pp. 29-31 of the lab manual
Fig. 15.1
Interactive keys
http://www.eeob.iastate.edu/research/bamboo/keys.html