Describe the features of multicellular organisms:
- Differentiation/specialisation of tissues
- Full sexual reproduction
- Metamerism
- Symmetries
- Body cavities
- Cephalization and encephalization
What’s metamerism?
Process of segmentation in which a body have many simple copies and they differentiate and specialise in different tasks.
What are the four type of symmetry?
- Radial
- Bilateral
- Modified radial
- Spherical
Why is colagen important?
Colagen it’s a connective tissue and glue many different cells together. Furthermore it’s one of the unifyng features of animals.
What are stromatolites?
Layered accretionary structure, comunities of cells formed from binded sediments trapped in biofilms and reinforced with CaCO3.
What are the characteristics of ediacaran biota?
- Soft body (No shell or mineralized skeleton or armor)
- No eyes
- No evidence of predation
- No symmetry
- No supporting development
- They were only marine/Acquatic.
What might be the cause of extinction of ediacaran fauna?
The beginning of predation
What are the features of cambrian fauna?
- Skeletal structures, hard bones and teeth.
- Appearence of predation
- Metamerism
Why there was a quick differentiation of animals?
- Predation could have driven evolution
- Rise of O2
- Maybe snowball earth suppressed precambrian life
- Genetic changes: diversification of homeotic genes.
Why there was the rise of O2?
Because phytoplankton increased
What are homeotic genes?
Any multicellular organism developed as an animal because these genes were inherited to create symmetrical body and its structures.
Why is the rise of O2 so important?
Because it allowed organism to achieve increased size (important for predation) and metabolic rates were speed up.
Who was the ancestor of chordates?
Pikaia
What’s adaptive radiation?
It’s evolutionary divergence of members of a single phyletic line into a series of rather different niches or adaptive zones.
Describe the process of adaptive radiation:
After a mass extinction event niche spaces are opne and orgnanism fiil into these space and diversifiy to fill the gaps.
Define the 3 conditions of adaptive radiation:
1-Occur at edges of a species
2-It’s facilitated by the absence of competitors.
3-May involve general adapatations.
What’s cambrian explosion?
Rapid diversification of life after a mass extinction of ediacaran biota.
