1-3: Intro, The First Animals, Metazoans Flashcards
What is convergent evolution?
Same feature, different evolutionary origin eg. wings
What is divergent evolution?
Where closely related species have differentiated
What are ctenophores?
Comb jellies
Features of ctenophora
Radial rotational symmetry
A mouth and anus (unlike anemones)
Complex anatomy with nerves and muscles
Example of a biomarker fossil
24-isoproyl: unique biomolecule found in desmosponges, found a lot in the Ediacaran
2 types of fossil
Biomarker and Body fossils
What era contains the best evidence for sponges, cnidaria and ctenophora?
Cambrian
Order of kingdom etc
Kingdom, Phylum, Class, Order, Family, Genus, Species- kangaroos punch children on family games show
What is a homologous trait?
A trait derived from a common ancestor
What is an analogous trait?
Traits that looks similar, but have different evolutionary origins, eg wings
What is a character?
A feature inherited by an organism
What is a synapomorphy?
A shared/derived trait unique to a clade (group)
What is a pleisomorphy?
An inherited trait shared with ancestors
Example of a fabricational constraint
Biomaterials for limpit shells
Example of a functional constraint
O2 diffusion limiting insect body size
Branching Ediacaran biota examples
Vendobionta- thought to be like sea pens (cnidaria), but actually a different group
Show fractal growth
Another example is Bradgatia
Radial Ediacaran biota
Aspidella- probably hold-fasts or microbial
Possibly bilateral Ediacaran biota
Spriggina- an annelid/arthropod? Had glide symmetry, similar to Vendobionta
Kimberella- a cnidarian/ctenophore? Soft shell, radula, and mantle, so maybe mollusc?
Dickensonia- can see grazing movements
General features of Ediacaran biota
Flat planes Microbial mat surface Mainly epibenthic Almost all sessile, Asexual reproduction 2D world
What are porifera?
Sponges
Features of porifera
Different cell types; flagellated cells called choanocytes create water current through the sponge
Filter feed
No symmetry
No organs
Have spicules for strength- clades are based on the minerals in the spicules, give strength
When was the Phanerozoic?
0-540 mya
When was the Proterozoic?
540-2500 mya
When was the Archean?
2500-4000 mya
When was the Hadean?
4000-4600 mya
Neontology Vs paleontology
Neon is living, paleo is dead
What are phylogenetic constraints?
Basic body plans can’t just be completely changed, just modified
What are cnidaria?
Jellyfish, anemones, corals
Synapomorphy of cnidaria
Nematocysts (housed in cnidocyte cells)
Features of cnidaria
Nematocysts Radial symmetry Diploblastic (endoderm and ectoderm) Have nerves and muscles Can be motile or sessile Medusa or polyp; similar life cycles but emphasis on different bits
Taxonomy definition
Grouping based on shared characteristics
What are systematics?
The study of evolutionary relationships
What is an adaptation?
A characteristic that enhances survival and reproduction
What is an exaptation?
A pre-adaptation- the feature has been co-opted for a new function
What is an animal?
Eukaryotic Multicellular Heterotrophic No rigid cell wall Motile Consume other organisms
What is paraphyly?
One group doesn’t belong (see pictures)
What is polyphyly?
Different evolutionary origins (see picture)
Placozoa features
Only one species (Trichoplax) 1mm wide Flat Move by ciliated epithelium Reproduce by asexual budding (weird for an animal) Moved like Dickensonia?
What is monophyly?
Share a single evolutionary origin (see picture)
Phenetic species concept
Groups can resemble each other but are distinct- identical sibling species, eg. mosquitoes
What do morphological/genomic studies say is the sister to all other animals?
Morphological: sponges, Genomic: ctenophora
What is a sister taxon?
The closest relatives in the evolutionary tree
In what era was first life?
Towards the end of the Hadean
In what era did photosynthesis begin?
Early Archean
When did earth become oxygen rich?
Early Proterozoic
When was snowball earth?
Early Proterozoic
When were the first vertebrates?
Mid Phanerozoic
When were the dinosaurs?
Towards the end of the Phanerozoic
