Speciation Flashcards
Species
a group of organisms that can reproduce with one another to produce fertile offspring
Biological Species Concept
the set of all actually all potentially interbreeding natural populations whose members are VIABLE, FERTILE OFFSPRING and are reproductively isolated from other groups (AKA cannot breed with other groups)
KEY: reproductive isolation
Ecological Species Concept
A population which is adapted to a certain ecological niche (set of habitat/resource requirements) and where individuals have the opportunity to interbreed (RESOURCES, NICHE)
Do the organisms occupy the same niche?
KEY: habitat-caused reproductive isolation
Morphological Species Concept
a population with a common morphology that is measurable different from other groups (whether individuals LOOK SIMILAR)
KEY: morphology
Phylogenetic Species Concept
The smallest possible smallest set of organisms that share a common ancestor and can be distinguished from other such groups (how closely related individuals are EVOLUTIONARILY)
how closely related individuals are evolutionarily
KEY: smallest monophyletic group
Speciation
the PROCESS that results in new species when an ancestral population splits into 2+ descendent species that are genetically distinct and unable to interbreed
- ALL ABOUT GENE FLOW, THE LESS GENE FLOW, THE MORE LIKELY A NEW SPECIES WILL FORM
- reproductive isolation is key
- one population becoming two separate species
2 Mechanisms of Speciation
- Allopatric
- Sympatric
Based on how gene flow is prevented
Allopatric Speciation
two populations are physically isolated from each other, creating the absence of gene flow
- mountains, rivers, deserts, oceans, etc.
- the separated populations experience different selection regimes and diverge through time
Sympatric Speciation
two populations in the same location become unable to breed due to REPRODUCTIVE ISOLATION, which reduces gene flow
Order to look for what type of speciation
ESC > BSC > PSC > MSC
2 Reproductive Isolating Mechanisms
- prezygotic
- postzygotic
sympatric speciation reproductive isolation!!
Prezygotic Reproductive Isolation
isolation that occurs BEFORE the gametes fertilize
- temporal
- habitat
- behavioral
- gametic
- mechanical
Prezygotic Reproductive Isolation Types
- Temporal: populations are isolated because they breed at different times
- Habitat: populations are isolated because they breed in different habitats
- Behavioral: populations do not interbreed because their courtship displays differ
- Gametic: mating fails because the egg and sperm are incompatible
- Mechanical: mating fails because the male and female reproductive structures are incompatible
Postzygotic Reproductive Isolation
isolation that occurs AFTER gametes fertilize - used to reduce the viability or fertility of offspring
- Hybrid Inviability
- Hybrid Sterility
Postzygotic Reproductive Isolation Types
- Hybrid Inviability: developmental failures and spontaneous abortion (embryo does not develop properly and is inviable - not capable of living)
- Hybrid Sterility: growth and development of a viable adults offspring that are sterile and cannot reproduce (hybrid offspring mature but are sterile as adults)
