#minimum viable population

I have found many numbers for minimum viable population sizes ranging from 15 based on the Tristan de Cunha to 10 000 but generally accepted number for a minimum viable population for humans is 4169 based on computer models and better researchers than me. 

So The New Eden Project is based on a two ship structure, the first ship, N.E.P. Adam, having a population of around 400-600 people and the second ship N.E.P. Eve having a larger population of around 1000 people that follows around 10 years after the Adam. Assuming a trip lasting 80-100 years, both populations are genetically diverse enough to sustain a population independently for the trips duration which would only be 3-4 generations without genetic disease or genetic intervention, but might not be enough for growing colony.

the smaller the population, the higher the risk of catastrophe due to disease or disaster is however, This can be countered with medical treatment making sure everyone is healthy. You can counter the risk caused from disaster and contagions by separating you population into smaller yet groups. In the case on the New Eden Project, the populations is separated into 12 habitation modules, each capable of semiautonomy. and each habitation module can further be separated into areas as to reduce the effected area of a disaster such as loss of atmosphere or chemical leak to as small an area as possible.