While habitat loss is the main factor affecting species survival, other factors are also working against at-risk species. These other factors are known as the “extinction vortex” by conservation biologists and include environmental and demographic stochasticity.
Environmental stochasticity has to do with changes in climatic conditions that can occur at different scales: small (e.g., an early spring), medium (e.g., a three-year drought) and large (e.g., global warming).
- When populations are large they can adapt to these changes, even if a large proportion of individuals die in the process.
- When populations are smaller, adaptations to the environment are more costly to the species, and the population suffers greatly with the loss of each individual.
- Human activity exacerbates this situation by impeding species’ responses to environmental changes: for instance, if a highway blocks the migration route of woodland caribou as they adapt to seasonal fluxes in food availability and weather patterns.
Demographic stochasticity addresses changes to mating and genetics at low population numbers.
- As fewer individuals from a population are present, the chances of finding a suitable partner becomes harder and harder. In this case, the definition of a “suitable partner” changes as well; as some species are prone to in-breeding, the genetic quality of surviving offspring suffers.
- We all know of pure-bred dogs with hip problems – an obvious consequence of years of in-breeding. When this situation occurs in nature, wildlife are less able to forage, evade predators, respond to the environment and attract mates.
Eventually, the effects of a small population size will bring into play one or more of the many factors of the extinction vortex. For the most part, the role of humans in this situation has been to make animals increasingly vulnerable to natural phenomena that increase the probability of species extinction.
Thus, we cannot limit the vision of endangered species protection to the prohibition of destroying a “residence”; rather, society must find ways to provide wildlife with the space needed to continue their existence in a dynamic environment.
It also said one in seven species were threatened with extinction, and 41% of species studied have experienced decline since 1970.
Providing the clearest picture to date, the State of Nature report examined data from almost 7,000 species.
It drew on expertise from more than 70 different organisations.
These included wildlife organisations and government agencies.
The report said 26% of mammal species were at risk of disappearing altogether.
A separate report outlined the picture in Scotland, where the abundance and distribution of species has also declined.
Scotland saw a 24% decline in average species abundance, and about one in 10 species threatened with extinction.
In an assessment of the state of Europe’s biodiversity, the International Union for Conservation of Nature (IUCN) finds that 58% of endemic trees (those that exist only in this region) in Europe are threatened by extinction. The assessment aims to improve knowledge of the continent’s biodiversity and evaluate overlooked species for the European Red List.
The report titled, ‘European Red List of Trees,’ looks at the conservation status of the 454 tree species native to Europe and finds that 42% of trees regionally are threatened with extinction. Among Europe’s endemic trees, the assessment classifies 58% as threatened and 15% as critically endangered. The Sorbus genus, which includes the Crimean Rowan and the Mountain-ash, are particularly affected, with 75% of Europe’s 170 Sorbus species classified as threatened.
The assessment identifies invasive species, unsustainable logging and urban development as key threats to Europe’s tree species. The leaf-miner moth, for instance, is an invasive species that originated in the mountainous regions of the Balkans. It invaded the rest of Europe, damaging horse-chestnut trees (Aesculus hippocastanum), which are now classified as vulnerable. Additional threats to Europe’s tree species include agriculture and climate change.
IUCN Red List Unit Head, Craig Hilton-Taylor said the European Red List assessment highlights the importance of both conserving these species and integrating them into “regular conservation planning and land management.”
Given the real threat of a sixth mass extinction event brought about by human-caused climate breakdown and habitat disruption, we wanted to find out how long the ocean ecosystem took to reboot after the last one. What we found has grave implications for the long-term outlook of marine ecosystems should we tip the critical base of its food chain over the threshold of extinction.
The nanoplankton almost totally wiped out 66m years ago—also known as coccolithophores – are now widespread once more in the sunlit upper oceans. Although roughly 100 times smaller than a grain of sand, they are so abundant that they are visible from space as swirling blooms in the ocean surface.
A warning from the past
Today’s marine ecosystems are still just as dependent on the plankton at their base as they were in the past. Studies show that populations of modern-day plankton have already declined by as much as 40%, and that 70% of species are migrating towards the poles. We still don’t fully understand how plankton species might finally be driven to extinction, but the fossil record shows us that extinction is strongly shaped by climate change.
If we carry on emitting carbon and interfering with marine ecosystems, we run the risk of losing one of its critical carbon-storing and food-providing players. Research shows that that could take nature millions of years to reverse.