But walls can be circumvented by changes in technology, population pressures on the other side and the mobility and stealth of the enemy.
They found a significant increase in the frequency of both protective alleles, indicating their positive selection in the course of high disease prevalence and demonstrating the importance of host genotype and changes in population gene pools under high selective pressure.
The substantial declines in coronary and stroke death rates for those born in England and Wales are similar to those in other Western European countries and are consistent with favourable long-term changes in population risk factors (smoking, cholesterol, blood pressure) and in treatment.
Of course, changes in population density can also change selective pressures in ways that cause unexpected evolutionary change (Lankau and Strauss 2011).
The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure.
Thus, demographic data were used to see trends of population changes in the study area over larger portion of the study period so that comparison can be made possible among LULC change and population pressure.
Transboundary water issues have gained increasing importance due to growing water scarcity in climate change and increasing population pressure.
Changes in anthropogenic pressure on land were assessed from changes in population and livestock.
The approach defines current pressures on water resources and evaluates future changes in water allocation in the medium term under climatic and water use scenarios, considering changes in population and in irrigated areas.
While numerical changes in population size may seem like a purely ecological issue, in fact these ecological changes will likely be followed by evolutionary changes, because the selective pressures on many traits will change with changing community contexts.
