Bot350 Exam1

Native

Taxa that evolved locally.

Non-native synonyms

Naturalized, exotic, invasive, introduced.

Endemic

Taxa restricted to a single place.

Introduced taxa

Taxa introduced by human interference.

4 major components of taxonomy

Description, identification, nomenclature, classification.

Description

The assignment of morphological characteristics to a taxon.

Identification

The process of associating an organism with a taxon name.

Nomenclature

The naming of taxa based on a standardized system.

Binomials

Genus + specific epithet.

Deficiencies with the current taxonomic system

Eurocentric, unfriendly to non-roman alphabet, TEK ignored.

Classification

The arrangement of taxa in hierarchical order.

Hierarchy of taxa

Order, family, genus, species.

Artificial classification

Classifications based on morphological similarities, not based on evolutionary relatedness, before the theory of evolution.

Cal Linnaeus’s legacy

Standardized binomial name, and fundamental system of classification (phylum, order, family, etc).

Two other classification systems

Jussie and De Candolle.

Natural classification

Classification representing evolutionary history.

How do we classify today

Starting in the 90s DNA replaced morphology.

Phylogeny

A diagram depicting evolutionary relatedness.

Nodes/branching points on a phylogeny tree are

Speciation events.

Evolution

Change + speciation + conservatism.

Conservatism

Keeping ancestral traits.

Sister taxa

Taxa that share an immediate common ancestor.

Monophyletic group/clade

Includes an ancestor and all its descendants.

Rules for taxonomic groups

A single element or monophyletic set of elements.

Synapomorphy

Derived shared characteristics.

Apomorphy

Derived characteristic.

Symplesiomorphy

An ancestral shared characteristic.

Convergent evolution

Homoplasy.

Monophyletic

An ancestor and all of its descendants.

Polyphyletic

Organisms with no recent common ancestor, based on homoplasy.

Paraphyletic

An ancestor and some of its descendants, based on symplesiomorphy.

Monocot synapomorphy

One cotyledon.

Eudicot symplesiomorphy

Two cotyledons.

Dicotyledons are

Paraphyletic.

Eudicots are

Monophyletic.

Monocots are

Monophyletic.

Basal Angiosperms are

Paraphyletic.

Polytomy

An unresolved node (a node with more than 2 immediate descendants).

Parsimony

The simplest explanation is usually correct; fewer transitions indicates a more likely event.

Phylogeny chart ancestral and derived symbols

0 = ancestral, 1 = derived.

Autoapomorphy

Derived trait exclusive to a taxon.

Where is DNA in a plant cell?

Nucleus, chloroplast, mitochondrion.

Nucleus DNA

Two versions of each chromosome, >1Gb.

Chloroplast DNA

Single and circular molecule of DNA, 150Kb.

Mitochondria DNA

Single and circular molecule of DNA, 500Kb.

Mutation types

Point mutation, base or gene insertion, whole gene duplication.

Why is DNA more reliable than morphology for phylogenies?

More characters, characters are discrete, unambiguous.

Are DNA traits immune to homology?

no

Single markers

A marker is a contiguous sequence of DNA used for phylogenetic/genetic analysis, < 2000 base pairs.

The first phylogenies of flowering plants were inferred from a single chloroplast gene:

Rbcl.

Concatenated (linked).

Single markers can be