BIOL 371 Theme 2

Monophyletic

An ancestor and all it’s decendants

Polyphyletic

The most recent common ancestor is not included. Bad.

Paraphyletic Taxon

Some decendants of the common ancestor are excluded ex. Reptiles excluding birds

Opisthokonts

Animals, fungi, choanoflagellates

Choanoflagellates

Single or colonial set of cells. Flagellated and small

Where do plants and Opisthokonts separate?

Before fungi. Heterotrophy vs autotrophs is the prime separation point with Opisthokonts being heterotrophs.

First step of gastrulation

Colonial protist with flagella

Second step of gastrulation

Hollow sphere (Blastula) of unspecialized flagellated cells

Third stage of gastrulation

Certain cells become specialized for feeding and other functions

Fourth stage of gastrulation

Feeding cells fold in producing a two layered animal with a gastrula

Features of Opisthokont animals

• Multicellular eukaryote

• Chemoheterotrophic

• No cell walls

• Motile at some life stage

• Oxydative phosphorylation

• Sense and respond to environments

• Dominant diploid stage, haploid stage short lived

Opisthokont diagnostic characteristics

• develop a blastula

• Certain extra cellular matrix molecules (ex. Proteoglycam complex)

• Certain cell-cell membrane junction