System	Systematic Inbreeding	Pen	Kennel	Stud	Outcross	Random	Feral	Terminal Cross	Hybrids
Example	Laboratory strain	Smallholder's rare breed chickens	Dog breeder during world war	Alpaca breeder	Endangered breed to similar breed	Computer simulation	Animals in a large conservation park	Battery chicken farmer	Nursery breeding ornamental plants
Effective population size relative to actual population size	Very low -- ideally only half an individual!	variable depending on how many pens and breeders	variable depending on how many kennels	generally moderate	generally done as a last resort due to diminished genetic diversity beyond the point of recovery	high	high	very low	very low
Individual heterosis	NONE	MODERATE/POOR	MODERATE/POOR	MODERATE	MODERATE/GOOD	MODERATE/GOOD	MODERATE/GOOD	GOOD	GOOD
Population-wide diversity	NONE (or as close as possible)	HIGH	MODERATE/HIGH if enough groups maintained	MODERATE	MODERATE, if managed properly	MODERATE/HIGH depending on population size	MODERATE/HIGH depending on population size	LOW	LOW
Risk of outbreeding depression	LOW	LOW	LOW	LOW/MODERATE	MODERATE	MODERATE depending on size and distribution of starting gene pool	LOW/MODERATE	MODERATE/HIGH	HIGH
Greatest risk to genetic survival	Loss of line through genetic susceptibility to disease. Terminal inbreeding depression during creation of the strain	Gradual loss of small pockets of genetic diversity over time, overreliance on linebreeding and loss through inbreeding depression	Maintaining balance between overreliance on linebreeding and loss of genetic character through influx of outside genetic material	Popular sire syndrome (males of superb type become overrepresented in the breed and genetic diversity suffers or obscure genetic diseases become widespread)	Outbreeding depression, introduction of undesirable traits, loss of breed type	Generally resilient to genetic effects other than genetic drift	Generally resilient to genetic effects other than genetic drift and excessive selection, natural or otherwise	No breed as such and no genetic diversity; dependent on the survival of parent strains; specimens generally useless for further breeding	No breed as such and no genetic diversity; dependent on the survival of parent strains; specimens generally useless for further breeding and often biologically incapable of reproduction
Greatest strength	Genetically highly predictable	Excellent preservation of breed-wide genetic diversity in many small populations at the expense of individual heterosis	Good preservation of breed-wide genetic diversity in several moderate populations, but often at some expense to individual heterosis	Ability to improve rapidly on desired type and traits through access to highly selected males	Makes it possible to save a breed that has become genetically unviable, hopefully without compromising too much on the type and character of the breed	Used as a 'gold standard' model which other models can be compared against, but practically speaking does not exist	Allows animals to exhibit natural behaviour and choice of breeding partners; as close as possible to wild models	Creation of consistent animals that are able to survive in intensive farming situations to feed the masses	Creation of novelties, often because products cannot reproduce and are self-limiting, can prove lucrative to those who experiment with or discover hybrids