Animal Phylogeny Flashcards
What organism do we believe that animals originate from?
Choanoflagellates
What makes an Animal? 7 key traits
Multicellular eukaryotes Heterotroph Most have tissues Locomotion at some point in life React to stimuli Capable if sexual reproduction Have a blastula at some point during life cycle
What types of symmetry are organisms classified by?
Asymmetrical
Radial
Bilateral
What are the three types of Bilateral Symmetry?
Fluctuating asymmetry
Directional asymmetry
Antisymmetry
What is meant by fluctuating asymmetry?
When they are not entirely symmetrical across their sagittal section, this is us.
What us meant by directional asymmetry?
Weighted to one side
What are the advantages of cephalization?
Increases effectiveness of a bilateral animal to find food and detect enemies
What are the key characteristics of protostomes?
Spiral cleavage
Blastopore becomes mouth
Schizocoelous
What are the characteristics of deuterostomes?
Radial cleavage
Blastopore to anus
Enterocoelous
What is an acoelomate?
No coelom
What is a pseudocoelomate?
Have a fake coelom, not completely surrounded by mesoderm
What are coelomates?
Animals with a body cavity surrounded by mesoderm
What does the ectoderm become?
Body covering and the nervous system
What does the endoderm become?
Gut lining and digestive organs
What does the mesoderm become?
The muscle
What are the categories in animal phylogeny, in descending order?
Domains Kingdoms Phyla Class Order Family Genus Species
What are the 6 kingdoms?
Archaebacteria Eubacteria Protista Plantae Fungi Animalia
What are the 3 domains?
Archae
Eubacteria
Eukarya
What is a monophyletic taxon?
All the descendants of the most common ancestor are included
What is a paraphyletic taxon?
A group with a common ancestor however not all common ancestors are included
What is a polyphyletic taxon?
These do not share a common ancestor, but share homoplastic features
What is a molecular clock?
A method of measuring the time since the divergence from a common ancestor by the number of differences in nucleotides or protein sequences.
What is the main problem with the molecular clock?
It relies upon the rate of change being constant
What is a phyla?
A phyla is a largest generally accepted group of animals which share fundamental aspects of their Biology
What is outgroup analysis?
Seperate ancestral and derived characeristics
What does cladistics do?
Emphasises common ancestry over phenotypic similarity
What is the cambrian explosion?
A time period over 500 mya when all the major phyla orginated
What is molecular systematics?
Determining evolutionary relationships by comparing macromolecules
What is a homoplasy?
superficially homologous characteristics, which are actually independently acquired
What is a homology?
A structure derived from a recent common ancestor
What is a plesiomorphic characteristic?
A shared ancestral characteristic from a distant common ancestor
What is a synapamorphic characteristic?
A shared derived characteristic from a more recent common ancestor
