What is extinction? - Eniscuola
See "Rarity, Species Richness, and the Threat of Extinction—Are Plants . the evolutionary relationships among plant genera based upon. pollution”)—and even extinction Invasive species also affect biodiversity by .. to examine relationships between environmental variables and biodiversity. We're in the midst of the Earth's sixth mass extinction crisis. Harvard biologist E. O. Wilson estimates that 30, species per year (or three planet and the momentum of human population growth, together with the imperative for further a serious threat to global biodiversity associated with our growing human population.
In the Cape, extinction risk is higher for young and fast-evolving plant lineages and cannot be explained by correlations with simple biological traits.
Critically, we find that the most vulnerable plant species are nonetheless marching towards extinction at a more rapid pace but, surprisingly, independently from anthropogenic effects.
Our results have important implications for conservation priorities and cast doubts on the utility of current Red List criteria for plants in regions such as the Cape, where speciation has been rapid, if our aim is to maximize the preservation of the tree-of-life.
Author Summary The rapid loss of biodiversity is the most significant ecological challenge we face today.
- Human Population Growth and extinction
- Biodiversity and Extinction
Over the past few years, the International Union for Conservation of Nature has published Red Lists documenting the inexorable slide towards extinction of species; recent losses include the Hawaiian crow, golden toad, Baiji dolphin, and the West African black rhino. In groups we know well, such as mammals, the risk of extinction has been related to biology, with the most vulnerable species tending to be large, slow breeding, and narrowly distributed.
Biodiversity loss from species extinctions may rival pollution and climate change impacts
Although plants are the basis for life on Earth, our knowledge of the drivers of plant extinctions is poor. Here, we disentangle the causes of plant extinctions. We show that the processes linked with extinction risks in plants of the Cape, South Africa differ from those for vertebrates more generally. The most vulnerable species are found within young and fast-evolving plant lineages, opposite to patterns in vertebrates. Our results illustrate the intricate link between the processes of speciation and extinction.
We also show that the most threatened species are marching towards extinction at faster rates, but surprisingly, the risk appears independent of human effects. The third and largest wave began in with the harnessing of fossil fuels.Extinction of Species - Biology for All - FuseSchool
No population of a large vertebrate animal in the history of the planet has grown that much, that fast, or with such devastating consequences to its fellow earthlings. More atmospheric nitrogen is now fixed by humans that all other natural processes combined .
Extinction Risk and Diversification Are Linked in a Plant Biodiversity Hotspot
The authors of Human Domination of Earth's Ecosystems, including the current director of the National Oceanic and Atmospheric Administration, concluded: The rates, scales, kinds, and combinations of changes occurring now are fundamentally different from those at any other time in history.
We live on a human-dominated planet and the momentum of human population growth, together with the imperative for further economic development in most of the world, ensures that our dominance will increase. One constant, however, is human population pressure.
A study of nations found that human population density predicted with percent accuracy the number of endangered birds and mammals as identified by the International Union for the Conservation of Nature . Current population growth trends indicate that the number of threatened species will increase by 7 percent over the next 20 years and 14 percent by When the population of a species grows beyond the capacity of its environment to sustain it, it reduces that capacity below the original level, ensuring an eventual population crash.
Edward Wilson estimates 27, species are currently lost per year. Niles Eldridge estimates 30, per year currently. Paul Ehrlich, using another approach based on total energy use estimates extinction rates at 7, to 13, times the background rate, 70, tospecies per year which he says is higher than figures based on data for higher orders of animal indicates, but we have little data on insects and micro flora and fauna.
Human Population Growth and Extinction
Species extinctions are very difficult to quantify. In the past the man caused extinctions have been primarily due to hunting. As man crossed over from Asia and entered the North American Continent, a series of extinctions occurred caused in part by man's predation of slow moving species like the mammoth and other mega-herbivores and perhaps, according to a new hypothesis, by the introduction of new diseases by man or his domesticated animals.
The loss of these species caused other dependent species to go extinct like the giant vultures and the long nosed bear. A similar wave of extinctions happened as the Polynesians colonized the pacific islands. This time it was the flightless birds that were defenseless against the new predators.
The cascade of current extinctions, however, is related mostly to destruction of habitat, and displacement by introduced species.
Chemical pollutants, over harvesting and hybridization have played smaller but still significant role. While the actual extinction rate is difficult to pin down, there is no doubt that the planet is in the midst of a mass extinction of major proportions.
Diversity and Extinctions
The most conservative estimates place the extinction rate at times the background rate. These numbers are more easily accepted when placed in the context of habitat destruction. Pre-agricultural revolution energy use is estimated at.