Seen in this light, the environmental damage caused by resource extraction and the vast changes that humans have wrought on the landscape seem extremely high risk. The world has never before experienced these disturbances all at the same time, and it is quite a gamble to assume that we can so damage our planet while at the same time maintaining the seven billion humans that live on it.
Some environmental damage can be reversed, some failing ecosystems can be revived. Extinction is irrevocably final. Studies of threatened species indicate that, by looking at their characteristics, we can predict how likely a species is to become extinct. Animals with larger bodies , for example, are more extinction-prone than those of smaller stature — and the same holds true for species at the top of the food chain. For plants, growing epiphytically on another plant but not as a parasite leaves them at greater risk, as does being late blooming.
This means that extinction does not occur randomly across an ecosystem, but disproportionately effects similar species that perform similar functions. Given that ecosystems rely on particular groups of organisms for particular roles, such as pollination or seed dispersal, the loss of one such group could cause considerable disruption.
Imagine a disease that only killed medical professionals — it would be far more devastating for society than one which killed similar numbers of people at random.
Some closely related groups of species are restricted to the same threatened locations such as lemurs in Madagscar or share vulnerable characteristics such as carnivores , meaning that the evolutionary tree could lose entire branches rather than an even scattering of leaves. Some species with few close relatives, such as the aye-aye or tuatara , are also at higher risk. This means that extinction does not occur randomly across an ecosystem, but disproportionately effects similar species that perform similar functions.
Given that ecosystems rely on particular groups of organisms for particular roles, such as pollination or seed dispersal, the loss of one such group could cause considerable disruption. Imagine a disease that only killed medical professionals — it would be far more devastating for society than one which killed similar numbers of people at random.
Some closely related groups of species are restricted to the same threatened locations such as lemurs in Madagscar or share vulnerable characteristics such as carnivores , meaning that the evolutionary tree could lose entire branches rather than an even scattering of leaves. Some species with few close relatives, such as the aye-aye or tuatara , are also at higher risk. Their loss would disproportionately affect the shape of the tree, not to mention erasing their weird and wonderful natural history stories.
First of all, so is death, but it does not follow that we meekly surrender to it especially not prematurely or at the hands of another. But secondly, fossil records show that current extinction levels are around 1, times the natural background rate.
They are exacerbated by habitat loss, hunting, climate change and the introduction of invasive species and diseases. Amphibians seem particularly sensitive to environmental change, with estimated extinction rates up to 45, times their natural speed. Most of these extinctions are unrecorded, so we do not even know what species we are losing.
But does it really matter that the world contains fewer types of frog? The frog has never been described by science, so no one is the wiser about its loss. It evolved over millions of years to be adapted for its particular niche — to us, the authors, the loss of that perfectly balanced individuality makes the world a lesser place.
So how far should our aversion to extinction extend? We cannot answer this question — but like all good philosophical conundrums it belongs to everyone, to be debated in schools, cafes, bars and market places across the world. We may not all agree, but extinction is broadening its reach, so consensus and urgent action are needed if we hope to control it.
This article was originally published on The Conversation. Read the original article. Not looking to cloud your day but winter is knocking! No need to wait until next weekend to score sweet sales on gadgets, gear. Sign up to receive the daily top stories from the National Post, a division of Postmedia Network Inc. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species. Use the resources below to teach the theory of evolution in your classroom.
Dinosaurs gambol and charge through our imagination as scaly reptilian creatures with menacing teeth, claws, spikes, and hammering, bony bulbs. They roamed Earth roughly million years ago, and most were wiped out by an extinction event roughly 65 million years ago. Thanks to ongoing scientific research, we continue to revise our theories about how dinosaurs evolved, what they ate, and how they moved through their environments.
Students collaborate to build deeper knowledge about the first five extinctions as they prepare to create an action plan to save endangered species from extinction.
Teams design conservation pamphlets promoting endangered species, and suggest action steps to protect the species and the planet. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image Dinogorgon Skull Many species have gone extinct throughout history and all that marks their presence on Earth are fossils, such as this one of a dinogorgon.
Photograph by Jonathan Blair. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Cambrian Explosion of Life. Cretaceous period. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Media If a media asset is downloadable, a download button appears in the corner of the media viewer.
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