Speciation + Phylogenetics Flashcards
What is life?
- reproduction
- metabolism
- ability to respond/adapt
- growth
- homeostasis
When did life evolve?
about 4.5 billion yrs ago
Where did life first evolve?
- shallow seas
- deep sea thermal vents
- extraterrestrial origins
Spontaneous generation
- little atmospheric O
- lots of E
- no competition
LUCA
Last Universal Common Ancestor
3 domains
- bacteria
- eukarya
- archaea
Miller-Urey hypothesis - origin of life
- abiotic synthesis of small org molecs/monomers
- joining of these small molecs into polymers
- membrane-bound protocells
- origin of self-replicating molec
prokaryotes flourished
3.7 mill yrs ago
biological species concept
- mate & prod fertile offspring, then they are the same species
- actually or potentially interbreeding pops that are reproductively isolated from all other such groups
morphospecies concept
members of the same species usually look alike
ecological species concept
a group of organisms adapted to a particular niche
niche
conditions and resources that define the requirements of a species
the species problem(s)
- hybrids
- fossils (only morphospecies)
- asexuals
- bacteria (horizontal gene transfer)
pre-zygotic barriers
- behavioral
- physical
- time
- space
post-zygotic barriers
genetic incompatibility
speciation
the evolutionary process by which new biological species arise
general model of speciation
- genetic drift
- natural selection
- mutation
allopatric speciation
speciation that depends on an external barrier to gene flow (geographic isolation) to begin/complete the event
sympatric speciation
speciation in which new species evolve from a single ancestral species while inhabiting the same geographic region (common in plants)
adaptive radiation
rapid diversification in which natural selection accelerates the rates of speciation
co-speciation
when 2 groups of org’s speciate in response to each other at the same time (eg. parasite/host)
instantaneous speciation
2 species hybridize and prod offspring that are reproductively isolated from both parents (plants, not animals)
Linnaeus
- father of taxonomy
- plants & animals
Whittaker
- 5 kingdom system
1. monera
2. protista
3. plantae
4. fungi
5. animalia - problems:
1. 2 distinct lineages of prokaryotes
2. protista not monophyletic
gene flow
- movement of genes btwn pops
- inhibits speciation events
phylogenetic tree
a branching diagram that represents a hypothesis about the evolutionary history of a group of orgs
Louis Pasteur
disproves modern day spontaneous generation (regeneration)
what evolves faster, the non-coding or coding sections of genes?
non-coding -> more mutations
cladistics
classifying organisms into clades based on common descent
monophyletic
the ancestor and all of its descendants
character is similar because (2)
- convergent evolution
2. common descent
shared common ancestor
character that originated in an ancestor (eg. backbone)
shared derived character
evolutionary novelty unique to a particular clade (eg. hair)
parsimony
simplest form; reqs the smallest amount of changes
Permian extinction
- 250 mya
- claimed about 96% of marine species
- plants not impacted much
Cretaceous extinction
- 65 mya
- dinosaurs
extinctions
opportunity for adaptive radiations
