Lecture 8: Evolution and Early Diversification Flashcards
What are some factors that affect a genetic systems model?
Mutations
Chromosomes & plasmids
Genes/alleles
Sexual & asexual reproduction
What are some factors that affect a population process model?
Death rate
Birth rate
Mate searching
Competition
Biotic/abiotic interactions
What is hard selection in natural selection?
Extra mortality (reduced reproduction) for maladapted individuals
What is soft selection in natural selection?
No extra mortality, but who dies depends on fitness compared to other individuals
What are some factors that affect a space and time model?
Movement & migrations
Abiotic & biotic interactions
Spatio-temporal variability
Environmental complexity
Local adaption
What is the current hypothesis on eukaryote origins?
Involve some sort of symbiosis and/or fusion of prokaryotes that results in the larger, more complex eukaryotic cell via endocytosis
Ex: mitochondria and chloroplasts probably some bacteria
Are eukaryotes closer to archaea or bacteria?
Archaea
What were some early processes that allowed marine plankton to thrive?
Increased size of genome
Sexual reproduction
Increased structural complexity (locomotion, protection)
O2 for energy or photosynthesis
What is the colonial hypothesis?
Dividing unicellular organisms did not separate after division due to a potential mutation in cell membranes or walls.
Why would colonial life (in terms of cellular life) be beneficial?
Increased complexity in organisms
Separate functions for individual cells
Different metabolic pathways can be turned on and off
What are some characteristics of Ediacaran life?
Vendian animals –> worms, round pads resembling jellyfish and sponges
Very unique and unlike current known animals
Still only existing in water
What is Pikaia?
Ancestor of Chordates –> all vertebrates including humans
What was the Cambrian explosion?
A huge diversification within the animal kingdom and the establishment of all modern animal body plans.
What sparked the cambrian explosion?
A predator-prey “arms race”
predators started hunting worms so worms started burrowing. Predators had to dig for worms so they developed jaws and spines and shells and modified their hunting behaviour.
