The Origin Of Species Flashcards
Biological species concept
Group of organisms that reproduce with each other and produce offspring that are viable and also fertile
What are the majority of organisms alive right now
Asexual organisms such as bacteria
They are excluded in the biological species concept
Ecological species concept
Species based on the set of resources they use
Morphological species concept
Based on look
Phylogenetic species concept
Based on shared ancestry and phylogenetic trees
Pre-zygotic barriers
Habitat isolation- two groups occupy different spaces, don’t come into contact
Temporal isolation -time come into contact but not at the right time such as sexual seasons differ
Behavioral isolation-together at the right time and space but don’t because of behavior they choose not to
Mechanical isolation - they want to mate but physically can’t because they don’t match
Gametic isolation-sex cells are not compatible
Post zygotes barriers
Reduced hybrid viability-hybrid gets produced through a zygote but the process of making an adult isn’t viable.
Reduced hybrid fertility- like a mule. A sterile hybrid that can’t have fertile offspring
Hybrid breakdown- hybrids are able to reproduced other hybrids but not indefinitely. After generations they become sterile
Allopathic speciation
Forms a new species while geographically isolated
Turns off gene flow
Natural selection occurs differently in isolated species and when time passes the reproducible capability may become impossible
Sympatric speciation
A sub group of a population begins to now reproduce with the others creating a new species
Polyploidy
A ploidy more than 2
Creates new species immediately through an accident called non disjunction
Non disjunction is what happens during anaphase where a gamete gets more than half chromosomes or non. This is what happens in Down’s syndrome
Autopolyploidy
Self
Habitat differentiation
A subgroup of a population exploits a different resource than the rest creating separate species in the long run. Sympatric speciation
Hybrid zone
Hybrids are produced through a certain amount of gene flow that is reintroduced between species
Reinforcement less contact with each other
Fusion. More gene flow and hybridization which leads to the same species again
Stability- the separateness of the species is stable leaving a constant amount of hybridization
Punctuated model
Quick divergence during after speciation. Short number of generations
Gradual model
Stay similar and gradually become very more different.
