Ecologists have begun to recognize the competition between younger and older generations within the same species, with startling conclusions about nature’s mortality needs.
Environment
October 18, 2022
The death of one individual can benefit another Alexia Khrusheva/Getty Images
East of Amsterdam is a stretch of reclaimed marshland, site of an epic regeneration project called Oostvaardersplassen. It is sometimes nicknamed the Dutch Serengeti due to the profusion of large herbivores that graze there. But during the freezing winter of 2017-18, deeply shocking images began to emerge. Thousands of deer, cattle and horses lay dead or starving. Desperate onlookers threw bales of hay over the fences in an attempt to help – it’s clear something had gone wrong.
Theoretical ecologist André de Roos was neither shocked nor surprised. His research had predicted this disaster years earlier. Without the herbivores’ natural predators, he reported, overpopulation was inevitable, leading to mass death when food ran out. The cold weather may have accelerated mortality, but it would have happened anyway. “There were only ever two options: allow mass starvation or introduce slaughter,” de Roos explains. One way or another, nature has what he calls a “mortality requirement.”
This requirement occupies a central place in the work of de Roos. But it is often overlooked by other ecologists, whose models fail to take into account the complexity within a population – in particular, the fact that individuals can vary enormously depending on their life stage, which can lead to intergenerational conflicts. In addition to pointing out the benefits of death, de Roos’ thinking can explain some of ecology’s most difficult puzzles. It also suggests new ways to tackle important economic issues, such as the collapse of fisheries and the impact of noise pollution on marine mammals. …
