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Chapter 25: Reconstructing and Using Phylogenies
Life: The Science of Biology, Eighth Edition
20
Biology
Undergraduate 1
07/21/2010

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Term
Phylogenetic Tree
Definition

Root-Common ancestor

Node-Indicates speciation

Branch order is arbitrary

Term
Taxon, or taxa
Definition
Any group of species we designate.
Term
Clade
Definition
A taxon that consists of all the descendants of a common ancestor.
Term
Homology
Definition

A trait directly inherited by common descent from an ancestor

Charles Darwin, 1859

 

Old definition: Same organ in different animals in different forms and functions

Term
Synapomorphies
Definition
Derived traits that are shared among a group and are viewed as evidence of the common ancestry of the group
Term
Evolutionary Reversal
Definition
Reversion from a derived state to the original.
Term
Homoplastic Traits, Homoplasies
Definition
Traits that are similar for reasons other than inheritance from a common ancestor(like convergent traits).
Term
The Parsimony Principle
Definition

The simplest explanation of observed data is the preferred explanation.

 

Occam's Razor - The simplest explanation with the least amount of speculation and assumption.

Term
Protozoans
Definition

Some used to be considered animals; lumps phylogenetically unrelated groups; most are ingestive heterotrophs.

Algae also lumps a lot of photosynthetic microbial eukaryotes and doesn't reflect phylogeny.

Term
Amoeboid Motion
Definition
Amoebas form pseudopods as extensions of the cell; a network of cytoskeletal micro-filaments squeezes the cytoplasm forward.
Term
Cilia and Flagella
Definition
Cilia beat in coordinated fashion, flagella use whip like motions; both have 9+2 arrangement of microtubules as the basic structure.
Term
Contractile Vacuoles
Definition
Used to excrete excess water due to osmosis.
Term
Food Vacuoles
Definition
Formed by Paramecium and others when solid food particles are ingested by endocytosis. Food is digested in the vacuole; smaller vesicles pinch off to aid in absorbtion.
Term
Pellicle
Definition
Paramecium use a covering of surface proteins for a resilient and flexible cell membrane.
Term
Shell
Definition

Some amoebas make a shell or test from bits of sand beneath the plasma membrane.

Diatoms have cell walls of silica.

Term
Microbial Eukaryotes: Reproduction
Definition

Sexually and asexually

Binary Fission

Multiple fission

Budding

Spores

Term
Ciliates
Definition
Sex, no reproduction. No gametes through conjugation due to nuclear duality.
Term
Alternation of Generations
Definition
Diploid spore forming organism(sporophyte) gives rise to a haploid gamete forming organism(gametophyte) which in turn gives rise to the sporophyte in a life cycle.
Term
Haplontic Life Cycles
Definition
Reduces one of the generations to a minimum.
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