Ceballos, G. 2015. Accelerated modern human-induced species losses: Entering the sixth mass extinction.
Blog Author:Angel Sumpter
Paper Author: Gerardo Ceballos
● Undergraduate degree in Biology from the Metropolitan Autonomous University (UAM) Campus Iztapalapa, Mexico
● Master's degree in Ecology from the University of Wales under the supervision of ecologist John. L. Harper
● PhD in Ecology from the University of Arizona with Dr. James H. Brown.
● Has published 124 scientific articles, 39 dissemination articles, 187 book chapters and 31 books
● Started the Long Term Ecological Research Network Chapter in Mexico
Background/Introduction:
● At this current rate, valuable ecosystem services are at risk. The dwindling number of diverse species plagues the world with critical environmental problems. With over 1000 bird species extinct within approximately 2000 years, rates grow at an alarming rate over pre-human times, not only in the island tropical Oceania, but all over the world. Records from far back as the 19th century detail more accounts of the various species extinct. Sadly, there is even worry for species not yet extinct due to their direct negative correlation between population level and ecosystem.
Question:
● Are modern rates of mammal and vertebrate extinctions higher than the highest empirically derived background rates?
○ (ii) How have modern extinction rates in mammals and vertebrates changed through time?
○ (iii) How many years would it have taken for species that went extinct in modern times to have been lost if the background rate had prevailed?
Materials/ Methods
● The 2014 IUCN Red List was used to compile data on the total number of described species and the number of extinct and possibly extinct vertebrate species. Modern extinction was calculated in two ways: estimation of a highly conservation modern extinction rate and a highly modern extinction rate. The conservations were compare to each other by assuming the background extinction rate of 2 E/MSY. This ended up with a result of a mass extinction on the way.
Results
● Modern rates of vertebrate extinction were much higher than a background extinction rate of 2 E/MSY.
○ For example it was expected that there would be 9 vertebrate extinctions starting from 1900, instead more than 468 vertebrates have gone extinct.
● Modern extinction rates have increased greatly and are higher than the background rates.
○ What should have taken between 800 to 10,000 years (the extinction rate) disappeared in 2 E/MSY.
Discussion
● The world can be very worried if it continues eliminating any percent of biodiversity. The rates from this analysis show major increase in extinction rates than in natural average rates. It is imperative we focus solely pm species. If things don’t change soon the Earth could be heading towards a sixth mass extinction. Effects of this could take millions of years to rediversify and normalize extinction rates.
Comments
● I really appreciate how the author had the results at the beginning of the paper. I feel like this author truly did think about his audience because he wrote this paper in the simplest form starting with what I consider the most important part after the introduction.
● I know that we’ve talk about the sixth extinction but wow.. It never actually clicked until this paper explained how many vertebrates are dying and at what rate.
Their most important point, in my opinion, was that extinctions of populations (extirpations) are extremely detrimental to ecosystems, are very common, but cannot be quantified. Scary.
ReplyDeleteThe number that really stood out to me was that the expected number of vertebrate extinctions since 1900 (based on the 2 E/MSY) is 9, and we had 477. I wish they had converted recent extinction rates to the same E/MSY so we could compare them directly. But, to go along with what Angel said, yikes.
This is a very depressing paper to read, although I expected more substance. The rate of extinction increasing over the last century paints a clear picture of the immense amount of effort that would be needed to stall it enough just to avoid another mass extinction. But it is interesting how you can follow human culture changes with the types of species going extinct. When overhunting was more of an issue between 1500 and 1900 so mammal extinctions are highest, but after 1900 pollution becomes the more detrimental issue, impacting the fish and amphibians, if the numbers are accurate.
ReplyDeleteMammal extinction would definitely be impacted by the lack of mammal movement and would have more ecological consequences than most would guess. I feel that HFI is a variable measurement based on a lot human factors and studies like this could breakdown the data to determine the most influential factors
ReplyDeleteWhat a sad paper. Specially if we take into account that their numbers are probably large underestimations. The projection of losing a large part of biodiversity in just three human generations is scary.
ReplyDeleteI wander how the extinction rate would look if the anthropogenic prehistoric extinctions are included. Guess it would be much higher?.
Also, I think it would be interesting to compare these rates with the background rates at times of biological and geological change (e.g. the great American biotic interchange).
It was interesting and also very sad that Barnosky changed his mind about the sixth mass extinction between 2011 and 2015. Also I was surprised that Science let them put those two huge tables in there since they could have been condensed and combined.
ReplyDeleteI appreciate the research moving away from the previously rates of extinction calculated from marine invertebrates. Throughout the semester, it's always struck me as odd how much research applies theories or calculations to groups of animals that were not intended to have those theories applied to. It makes sense that extinction rates based on marine inverts are lower than terrestrial vertebrates. I also appreciate that the authors made a concerted effort to not over-inflate their rates as other research has.
ReplyDeleteThis is study is based on vertebrates, because are the ones with more information that makes it possible to do the calculations required. However, I wonder how many species from insects would have gone extinct and how much would they go extinct in the near future? If vertebrates go extinct, would insect become the dominant species, such as mammals did when dinosaurs were out? I don't think insects would increase in size, but I wonder how would the net biodiversity overall (not just considering vertebrates) would change... could it even increase if invertebrates become more abundant?
ReplyDeleteI do not know how likely this would be considering how humans are also limiting resources for invertebrates too, but I just wonder if this would led to a change in the scenario that are not visualized in this kind of papers.
I agree with the other comments. This is a really sad paper. In the result section where it says "it was expected that there would be 9 vertebrate extinctions starting from 1900, instead more than 468 vertebrates have gone extinct." That is just incredibly terrible
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ReplyDeleteI still strongly stand on the conservation of biological diversity and ecosystems. This is not the complete and perfect approach but that is all we have at this point to buy a little more time to advance our nature-friendly technology to get energy and preserve more nature. So sad.
DeleteAlways a shame to read just how detrimental our actions have been. What's the biggest roadblock to getting this information to the masses? I see some conversation on it, but clearly not enough. Getting the layman to care seems a tough sell.
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