The immediate effect of a population bottleneck is to decrease genetic diversity, promoting the effects of stochastic genetic drift over natural selection.

"The value of mixing rich people and poor people," he says, "is real only if it contributes to the poor people becoming less poor, which is to say, if it decreases economic diversity."

Land management in the form of grazing tends to decrease diversity with increased intensity.

Small groups of animals with little opportunity for exchange between them face the risk of inbreeding, decreased genetic diversity, and even extinction.

Decreased genetic diversity, in tandem with hunting, natural disasters, predation, and disease, can easily wipe out small populations.

The school district generally did not permit transfers that would decrease racial or ethnic diversity.

It was found that the isolated and highly fragmented populations had increased differentiation, or divergence from other populations, and decreased genetic diversity in comparison to non-fragmented populations.

Construction of dams and other irrigation facilities seriously decreases habitat availability and diversity for the eels.

On the other, it decreases genetic diversity, increasing the severity of disease outbreaks among other risks.

Throughout the northern hemisphere, the last 70 or so years have seen an intensification of agricultural systems, which has decreased the abundance and diversity of wild flowers.