Species extinction? Huge or not so Huge?

[Dustin Kesselberg]

I hear alot about species extinction in modern times being comparable to that of the dinosaur times. I'm skeptical of this but would like to know the truth and see the evidence.



How many species have gone extinct in the past 150 years? How many Mammals? Reptiles?


At what rate are species gonig extinct in modern times?


I saw an episode of Penn&Teller about this and they were skeptical of it and saying only a few species have gone extinct and the claims that half of the species in the world will be gone in 100 years is false.

Is this true?


What's the "down low" on this?

[geni]

Tricky. Problem is we don't know how many species there are.

[Polaris]

There is a school of thought that the numbers are overblown for sensationalism (not how you garner sympathy in the long run, IMHO).

Check out Bill Bryson's A Short History of Nearly Everything, and read the final chapter, entitled "Goodbye". It covers the controversy and what is more likely to be fact.

[Dustin Kesselberg]

Let's stick with known species.


How fast are "known species" becoming extinct?

At what rate are species dying out?


In 100 years what percent of known species will be extinct? Based on current estimates.


Try as I might I can't find solid scientific answers for these questions, But I know there are answers.


So someone give me some good scientificaly supported answers with some sources to read.



Please!

[geni]

Let's stick with known species.


How fast are "known species" becoming extinct?


Again we don't know. So many beetles are known from maybe one specimen.

[Dustin Kesselberg]

Where is the science behind the claim that "50% of the worlds species will be extinct by the end of this century."?

[geni]

Where is the science behind the claim that "50% of the worlds species will be extinct by the end of this century."?

You estimate how many species exist in a certian habitat. You try and figure out how much of that will be left in 100 years and do the maths. Ok it is probably a bit more subtle but that is the basis.

[Dustin Kesselberg]

You estimate how many species exist in a certian habitat. You try and figure out how much of that will be left in 100 years and do the maths. Ok it is probably a bit more subtle but that is the basis.



You aren't really answering my questions.


Where are the studies?

Post the links.

[geni]

Post the links.

Links? What journals do you have subscriptions to?


You are probably looking for things like:

How species diversity responds to different kinds of human-caused habitat destruction
Lin ZS, Liu HY
Source: ECOLOGICAL RESEARCH 21 (1): 100-106 JAN 2006

[Dustin Kesselberg]

I'm looking for links that I can click that lead me to a site I don't have to pay for. Nothing much asked.

What scientific studies support the claim that 50% of the worlds species will die out by the end of this century? Any? Simple question.





Someone else please post who has knowledge of the area.

[geni]

I'm looking for links that I can click that lead me to a site I don't have to pay for. Nothing much asked.

You want studies you don't have to pay for. That generaly doesn't happen.

[Dustin Kesselberg]

Someone who can answer my questions please post.

[athon]

I read last year a metastudy done on the topic, which was interesting. Sorry I can't produce the details of the paper; I had it sent to me by a friend who worked in the field. It was an ecology journal but that's all I can recall, however it was interesting because it involved something I was interested in during my uni days and that's molecular phylogeny.

The short of it was that it's impossible to predict species destruction without knowing a speciation rate. Drawing lines between individual species is misleading and does not give an accurate portrayal of what constitutes an extinction. It's obvious when there are no more African elephants, however the extinction of the striped Madagascan grey beetle in respect to the related spotted Magagascan grey beetle might be a little bit harder to describe.

Additionally, there is no supporting evidence to link biodiversity with the strength of an ecosystem (when measured in terms of productive biomass). If strength is examined in terms of an ecosystem's ability to sustain abiotic changes, the story gets even more vague and uncertain.

The answer; we don't know. Genotype combinations are lost and created every day with changes in organism population. Describing the details is a Herculean task that requires precise definitions, something we are only now working out.

Athon

[Dustin Kesselberg]

So there isn't science behind the claim that "50% of the worlds species will be extinct by the end of this century."?

Considering I hear it alot from T.V. and News reports about massive species extinction currently occuring.

What are the studies supporting a massive species extinction currently occuring?

[athon]

I don't know where the '50%' statement came from. I'd ask that to be sourced. I've read a range of figures although can't say I've read any papers that give confident estimates. I suspect most percentages touted in the media are extrapolated from local surveys, and therefore are wild estimates.

Biodiversity is one of the most disputed fields in ecology, mostly because good information on the topic is so thin. I could find five different ecologists - all respected in their relevant fields - who could give you five different scenarios.

Biodiversity in selected localities over the planet is decreasing; there's little to argue there. And there is undoubtedly a strong anthropological impact. Our impact on a diverse range of environmental factors is influencing the competition of numerous species; some for better, some for worse. How this pans out in the future is anybody's guess.

Are there large numbers of species disappearing? Define large. Is there an anthropological bias? Yes. However the size and the relevant impact of these changes on the future productivity and health of various ecosystems is still unclear. The rate at which biodiversity changes depends on diverse factors such as migration, mutation rates, population proximity and relatedness... the list goes on.

I think it is important to note that conservation is significant purely because a genetically diverse system offers more options than one without the diversity. And since we aren't certain on the fate of many ecosystems, sustainability is the best option until we have more control over our decisions.

Athon

[Polaris]

Someone who can answer my questions please post.

Go to the library. Check out Bryson's book. That's free, and if it doesn't answer your questions, there's a good bibliography that should.

[andyandy]

the 50% figure seems to have come from here....

According to a 1998 survey of 400 biologists conducted by New York's American Museum of Natural History, nearly 70 percent of biologists believe that we are currently in the early stages of a human-caused mass extinction, known as the Holocene extinction event. In that survey, the same proportion of respondents agreed with the prediction that up to 20 percent of all living species could become extinct within 30 years (by 2028). Biologist E.O. Wilson estimated [3] in 2002 that if current rates of human destruction of the biosphere continue, one-half of all species of life on earth will be extinct in 100 years.

http://en.wikipedia.org/wiki/Extinction

Extinction is usually a natural phenomenon; it is estimated that more than 99.9% of all species that have ever lived are now extinct. Currently, many environmental groups and governments are concerned with the extinction of species due to human intervention, and are attempting to combat further extinctions. Humans can cause extinction of a species through overharvesting, pollution, destruction of habitat, introduction of new predators and food competitors, and other influences. According to the World Conservation Union (WCU, also known as IUCN), 784 extinctions have been recorded since the year 1500, the arbitrary date selected to define "modern" extinctions, with many more likely to have gone unnoticed. Most of these modern extinctions can be attributed directly or indirectly to human effects

784 doesnt sound like that much to me....(although i'd probably have felt differently if i'd been a dodo....:D )

but as regards to future extinctions i think its a real stab in the dark as to how many creatures/plants will be extinct in 100 years....we're messing up the natural eco-systems in so many ways that it's definitly possible that there will be a crash of the pyramid....a knock on effect where the extinction of one thing brings about the extinction of many more....

but as has been posted already, the time-frame is arbitary, the future planetory conditions conjecture and the number of organisms around now unknown......so it pretty hard to nail anything down :D

[BPScooter]

From what I remember of my grounding in evolution, from a US public school, no less, is that the interplay between the deviations (mutations) of the particular organism and its evironment determine survival. Survival is a prerequisite for reproduction, hence, the fittest survive. The time frame for a gigantic and complex system, like a forest (including trees that live for hundreds of years, fungi that live for a few years, birds and mammals for less, and bugs that live for a couple days) is something beyond our current ability to understand. We can grow cultures of the smallest creatures, we can cultivate trees, even. But I think the thing that bothers people most is that if we just rip-roar through a system, we might not be able to bring anything like it back.

Everybody has a favorite place, some bit of woods or something, that is "different" now, I would guess. Maybe the ocean, a favorite piece of the earth. However, some systems were so inhospitable to man that it was OK to wipe out the mosquito, or to thin out the predators.

It's a question of the primacy of humans. Frankly, humans have demonstrated their primacy already, and will continue. Those of us that care about the broader systems will clean up some messes, to be sure, but we won't have malaria in the meantime.

[Roboramma]

I think one of the methods used to look at species extinction is looking at the sizes of ecosystems.
E. O. Wilson showed that there is a relationship between the size of an ecosystem (in area) and the number of species that it supports. He did this by studying the number species that could be found on islands of varying size. I don't remember the exact formula but it's something like if the area is 1/10 the size, there will be 1/2 as many species.
So, he suggests that, if, for instance, we cut down 90% of the rain forest, we will lose 1/2 of the species it contains. (that's a simplistic example to explain how the idea works).

I don't know how well this all stands up, but it makes plenty of sense to me. Often a species will "go extinct" in a locality, but other members of that species will recolonise later from somewhere else. If there is no "somewhere else", or no way to get from there to here, that local extinction can't be turned around. Of course, there are other reasons why a large habitat might be necessary. For large animals and plants, some of those are obvious.

Again, I don't know if the number 50% can be justified, but I think that methods such as this can probably inform us to some of the dangers of our actions.

[drkitten]

So there isn't science behind the claim that "50% of the worlds species will be extinct by the end of this century."?

Apparently "studies you have to pay to read on-line" aren't real science?

[Dustin Kesselberg]

Apparently "studies you have to pay to read on-line" aren't real science?



Your question makes no sense. I never implied that.

[Dustin Kesselberg]

Most biologists believe that we are at this moment at the beginning of a tremendously accelerated anthropogenic mass extinction. E.O. Wilson of Harvard, in The Future of Life (2002), estimates that at current rates of human destruction of the biosphere, one-half of all species of life will be extinct in 100 years. In 1998 the American Museum of Natural History conducted a poll of biologists that revealed that the vast majority of biologists believe that we are in the midst of an anthropogenic mass extinction. Numerous scientific studies since then—led by the 10,000 scientists who contribute to the IUCN's annual Red List of threatened species—have only strengthened this consensus.

http://en.wikipedia.org/wiki/Holocene_extinction_event

[BPScooter]

I might not be on the main sense of the thread here, but this is an issue that it's hard to have a black/white or right/wrong position on. As a little kid I was in tears after watching the Dr. Seuss cartoon about the Lorax. As an adult I am personally trying to create a mass extinction of weeds in my backyard biosphere. Dandelion evolution is faster than lawn technology.

Some of the things in WA/OR/ID that were predicted to be very BAD were: Mt. St. Helens ash makes us all sick, or kills the plants. Clearcuts never grow back, and will always be blighted spots on the map. Irrigation is harmful. Reservoirs and dams are bad, in all cases, and the alternative is preferable. These things haven't come true, as far as I know. The main threat to salmon runs (as some say) is unrestricted fishing by the tribes at the moment. The dams hurt, but the gill nets are really bad.

I'm not sure how many tropical beetles and soil bacteria are presently identified, there are many to be sure. It seems to me that to have 50 percent, one half, of all the SPECIES on Earth disappear would be a very huge event. Or does that mean the species that we have happened to discover and name? What has been the general process for discovering and naming? What constitutes a distinct species, after all, if I can go out and double the number of species, and then declare in the next breath that they are rare and endagered, I've just cut the number in half.

[athon]

Dustin, I'm not understanding what you're saying. You've asked if 50% seems like a large number and we've given you some things to consider in order for you to determine it for yourself. You've ignored those comments in favour of seeking reasons to believe in it, as if you have some desire for the number to be right.

IMO, I can't see where they got the figure from, and I would need to know how to classify a 'mass' extinction event. In the research I've done on biodiversity, man has made a negative impact in many environments, however the extent of the diversity reduction and the implications of this are dubious and open to speculation.

It's not a simple matter.

Athon

[The Painter]

99% of all life forms that ever existed on Earth are now extinct.

[Euromutt]

What has been the general process for discovering and naming? What constitutes a distinct species, after all, if I can go out and double the number of species, and then declare in the next breath that they are rare and endagered, I've just cut the number in half.There you lay your finger on part of the problem: taxonomy is far from an exact science, at least in practice, which has a lot to do with the fact that Linnaeus laid the groundwork two centuries before anyone worked out what DNA was. In a North American example, take grey wolves and scrubjays. Grey wolves are considered a single species worldwide (Canis lupus), and there are five commonly recognized subspecies in North America: the arctic wolf (C. l. arctos), the Eastern timber wolf (C. l. lycaon), the Great Plains wolf (C. l. nubilus), the Rocky Mountains/Mackenzie Valley wolf (C. l. occidentalis, English name depends on whether you're American or Canadian) and the Mexican gray wolf (C. l. baileyi). The arctic and Mexican gray are easily distinguished by the shape of the ears, coloration, fur patterns and what have you, but they are subspecies. By contrast, the Western, Island and Florida scrubjay are classified as distinct species (Aphelocoma californica, A. insularis and A. coerulescens, resp.), even though most ornithologists would probably need to break out the Sibley's (http://www.sibleyguides.com/) to tell them apart other than by geographical location. The main distinguishing feature between the Western and Island scrubjay is that the latter is "about 10 percent larger." I mean, what?

[Roboramma]

99% of all life forms that ever existed on Earth are now extinct.

And yet biodiversity has tended to increase.

I for one don't like the idea that it's now decreasing, though the degree to which that is happening (which is uncertain) could be range from very bad, to not such a big deal for many of us.

But even in the not such a big deal scenarios, I find some extinctions horribly tragic for many reasons. One of them being that these are lifeforms that we don't know that well (if at all), and we are losing the chance to learn about them.

[BPScooter]

Here's a funny thought I just had:

Maybe a human settlement can be characterized by its animal enemies!

What was the enemy, in the days of plague, cholera? As we know now, it was microscopic animalculae that really did it, but some of the wisdom was to, well, stay indoors (prevents bug bites), boil yer water (kills tiny things in water).

I have to go back to the original question--are indeed 50%, one half of all presently living species, including bugs, microbes, plants ABOUT TO DIE OFF FOREVER?

[CACTUSJACKmankin]

99% of all life forms that ever existed on Earth are now extinct.

Exactly, that simply means that extinction is a natural process that is essential to shaping the life on this planet, it does not give us carte blanche to remove species willy nilly because "they're all gonna go someday anyway". 100% of all people will eventually die, it doesn't make murder okay.

The massive dieoffs aren't necessarily with cute thing and not necessarily in industrialized nations. The ecosystems that are having the most trouble happen to be the ones that are the most diverse, rain forests and coral reefs. The habitat loss in these areas has eradicated thousands if not millions of spieces simply because there is so much there. Rain forests house two-thirds of the land species on this planet and coral reefs are home to a quarter of the fish species. You can't destroy these on such a massive scale without killing off significant precentages of the world's species.

[Dustin Kesselberg]

Exactly, that simply means that extinction is a natural process that is essential to shaping the life on this planet, it does not give us carte blanche to remove species willy nilly because "they're all gonna go someday anyway". 100% of all people will eventually die, it doesn't make murder okay.

The massive dieoffs aren't necessarily with cute thing and not necessarily in industrialized nations. The ecosystems that are having the most trouble happen to be the ones that are the most diverse, rain forests and coral reefs. The habitat loss in these areas has eradicated thousands if not millions of spieces simply because there is so much there. Rain forests house two-thirds of the land species on this planet and coral reefs are home to a quarter of the fish species. You can't destroy these on such a massive scale without killing off significant precentages of the world's species.


"Natural" doesn't mean good or ok.

Secondly Humans are causing the massive extinction of animals. This isn't some "natural process" occuring despite humans. We're the cause.

[The Painter]

Exactly, that simply means that extinction is a natural process that is essential to shaping the life on this planet

Correct me if I'm wrong, but aren't humans part of nature? Nature can be cruel.

[CACTUSJACKmankin]

"Natural" doesn't mean good or ok.

Secondly Humans are causing the massive extinction of animals. This isn't some "natural process" occuring despite humans. We're the cause.

I thought the "it does not give us carte blanche to remove species willy nilly", "100% of all people will eventually die, it doesn't make murder okay.", and "The habitat loss in these areas has eradicated thousands if not millions of spieces simply because there is so much there." parts should have hinted that my feelings are that humans are causing the current wave of extinctions. I apologize if this point wasn't clear enough.

Correct me if I'm wrong, but aren't humans part of nature? Nature can be cruel.

We removed ourselves from nature several thousand years ago, what we are doing is NOT part of a natural cycle or process. It is by our actions that most species go extinct these days, not natural processes. Mass Extinctions are rare and take millions of years to complete, this is happening in a few centuries. BTW the life on this planet is only about 10,000 years from a sizable extinction that wiped out most large mammals. It is insane that species should go extinct because of human development. Won't you love to hear your kids or grandkids ask you what an elephant or a tiger is and you have to use the past tense?
WE HAVE NO RIGHT TO REMOVE A SPECIES FROM THIS PLANET... NONE!!!

[BPScooter]

Hey brother, I am only going to do a parody, with mine after yours. Parody is not a bad word.

We removed ourselves from nature several thousand years ago, what we are doing is NOT part of a natural cycle or process. It is by our actions that most species go extinct these days, not natural processes. Mass Extinctions are rare and take millions of years to complete, this is happening in a few centuries. BTW the life on this planet is only about 10,000 years from a sizable extinction that wiped out most large mammals. It is insane that species should go extinct because of human development. Won't you love to hear your kids or grandkids ask you what an elephant or a tiger is and you have to use the past tense?
WE HAVE NO RIGHT TO REMOVE A SPECIES FROM THIS PLANET... NONE!!!

BPScooer parody:

"We used the word nature several hundred years ago, what we are doing IS part of a natural process, perhaps cyclic. Species and extinctions are fascinating topics, as are other areas of science. The evidence and causal mechanisms for the idea of periodic mass extinctions is a fine area of science. Life on this planet is very old, we agree. I would be more interested if a tiger or elephant evolved to the point that human language was available to them. I have never removed a species from this planet, I'm sure. I love my children very much; no other species has the right to take them from me, either.'

[fuelair]

Go to Dogpile, enter "species extinction list" or "IUCN" (former broader) for data. I don't mean to be nasty/rude but this is a standard search procedure which I would assume that anyone who operates as a sceptic could handle - and the topic really doesn't lend itself to reasonable answers in the relatively short space of answers on one of these threads.

[Roboramma]

Correct me if I'm wrong, but aren't humans part of nature? Nature can be cruel.

Yes, humans are a part of nature. What is your point, though?
That extinction is natural, humans are natural, and therefore human caused extinction is not a bad thing?

The background extintion rate (that is, the average rate at which extinctions have occured) is something on the order of 1/million years/species. That is, the average species lasts something like 1 million years.
If there are 10 million species alive that means something like 10 species/year. That's a small number, when you realise that this includes all the beetles, grasses, and maybe microbes (I'm assuming) out there. And that number doesn't bother me that much.
It's also made up for by speciation - that is, as species go extinct, new species are born.

But what we're talking about is something different. We're talking about a mass extinction event. Do you consider that to be a good thing?

You can't compare such an event (if it is underway) to the background extintion rate. We're not talking about a few species, we're talking about thousands.

I don't care if it's natural. If it was being caused by something other than humans, I'd still care about it too. What I care about is the fact that it's a good idea to look at this and say, "Hm. Maybe we should do something about this." Why? Because if it is happening (and we probably need to more data to see the extent of it - data I think we should be trying to collect faster than we are), then it is a bad thing. Something that we should do something about, natural or no.
It's the increasing extinction rate - increasing at an increadible rate - that is bad, not necessarily the simple fact that some extinctions occur. And it that that we need to do something about.

[The Painter]

We're talking about a mass extinction event

OK, this has been brought up a couple of times. What mass extinction?

We're not talking about a few species, we're talking about thousands

Really, thousands, or did you make that up? From your statement, I guess a few would be OK.

[Paul C. Anagnostopoulos]

WE HAVE NO RIGHT TO REMOVE A SPECIES FROM THIS PLANET... NONE!!!
Do all the other specifies feel similarly?

Just askin'.

~~ Paul

[neil]

Hi Jack: If you want to use your money to reduce the number of extintions and/or help endangered spicies, I sulute you; but please don't urge that our tax money be spent on preventing extintions. Neil

[CACTUSJACKmankin]

So, It's okay to force all of us to pay money to stop murder of a small number of individuals of a species, that's what our police and courts are here for, but to ask all of us to break the bank to prevent the eradication of not just one but many thousands of species is insulting? That's not to say that I put equal weight on human and animal life, it's just to point out the profound nature of what it means to eradicate an entire species!!!

[Roboramma]

OK, this has been brought up a couple of times. What mass extinction?
This is silly. This thread is about whether or not there is a mass extinction going on. No, I am not assuming that there is one. But you commented "99% of all species that ever existed have gone extinct" in relation to that discussion. Clearly the implication is that it doesn't matter whether or not there is a mass extinction.
My comments address that argument - it does matter whether or not there is a mass extinction. I am not arguing that there certainly is one occuring, just that if there is one, it is a very bad thing, and that we should do what we can to prevent it. The first step, as I have pointed out, though, is to find out more about what our impact actually is.



Really, thousands, or did you make that up? From your statement, I guess a few would be OK.
Yes a microbe here, a beetle there, I'm not so worried about that. On the other hand, based on my airchair science (in other words my numbers might not be perfect, but if you can find fault with them I'd love to see them improved) even if there were 10,000 species of mammal (I don't know the number) we should only see 1 mammalian extinction/century.
That few extinctions that would be okay is a few out of the millions of species on this planet. But most of those aren't the large animals that we see.
Most of the extinctions we have observed have been amount larger animals because they are easier to study. Most of the extinctions that are likely to be occuring are amoung the smaller lifeforms of this planet, because there are so many more of them.

Thousands? probably. Even a thousand species represents maybe 0.1% of the species on this planet. I picked that broad figure (thousands could refer to anything from 2-900 thousand, but I was thinking more between 1 and 20), as a conservative number. Did you read my post about biogeography and how the number of extinctions from habitat destruction might be estimated?

Given the rate that the rainforests are being cut down, the damage being done to coral reefs worldwide, etc. do you really find that number outrageous?

Maybe it is. But that's beside the point, because that's what this thread is about. Your point seems to be that it doesn't matter either way, and my post was addressing that. I was not saying "there are certainly this many extinctions happening". I was saying "if there are this many extinctions happening, then it is a bad thing and something we should think about, it's far more than the background extinction rate, and whether it's natural or not makes no difference about whether we should do something about it." Notice the if at the beginning of that sentence.
Do I think that this is happening? Sure, though I don't know to what extent.
But that wasn't my point. That's what this thread is discussing: whether or not this is happening. You seem to think it doesn't matter either way.

[Roboramma]

Do all the other specifies feel similarly? I doubt they even know what a species is. ;)