Showing posts with label extinctions. Show all posts
Showing posts with label extinctions. Show all posts

Monday, April 3, 2017

Biodiversity conservation in a human world: do successes involve losses?

It's become commonplace to state that the world is in the midst of a mass extinction event. And there is no doubt about the cause. Unlike previous mass extinction events, like the cretaceous extinction event that saw most dinosaurs disappear, the current extinction event is not caused by a geological or astrological event. Rather, the current extinction event is caused by a single species, humans. Through habitat destruction, wildlife harvesting, pollution, and the introduction of pest species to other regions, the current extinction rate is 100 to 1000 times higher than it should normally be. We often think of human legacy in terms of art or architecture, but a permanent scar in the biological record of the Earth is our greatest legacy.

Of course many people and some governments are very concerned about our impact, and have committed to try to conserve elements of the remaining natural world. How best to do this is largely influenced by conservation biology, a field of research and applied management that includes biology, economics, and sociology, amongst others. There are many debates within conservation biology, and a big one is about how much to involve people, and their activities, in conservation areas versus attempting to completely exclude people from protected areas.

Two conservation conversations have explored this dichotomy in meaningful ways. First is a recent paper by Elena Bennett (Bennett 2017), who argues that strategies for environment and conservation protection needs to take a human-first approach and focus on human well-being. The second is a talk I saw from Daniel Janzen the other day. Janzen is a world-renowned ecologist and has dedicated his life to conservation in Costa Rica for the past 30 years. This debate was central to his talk about the conservation successes at the Area de Conservacion Guanacaste (ACG), where Janzen developed and implemented a conservation philosophy that included local people in the managing and research in the conservation area. Before Janzen, the Park relied on the traditional approach of excluding people to protect nature and it was failing. Janzen’s approach has been immensely successful, and the Park is now considered a conservation success story.

People can be convinced to appreciate biodiversity around
-if it provides a benefit. (photo by M. Cadotte)
Including people in nature conservation is bound to have successes. People feel more familiar and involved with nature protection, which gives them a sense of ownership. If people understand the benefits of nature, economic and otherwise, then they will be invested in its protection. It all seems so logical, but as I listened to Janzen’s talk (and read Bennett’s paper), I kept thinking: “would there be any losers under a human-first approach to conservation”. I think the answer is yes, and the reason is that we are prone to use a shifting baseline to evaluate success. Let me explain what I mean.

The human-nature story is one that is about a continual 30,000 year retreat. All of our successes -our population growth, our art, our medicine, have all come at the expense of nature. Anywhere on Earth where there are humans, there are losses. Habitat alteration and destruction, and species extinctions are the defining feature of our presence. This legacy has permanently altered the biology of our planet.

Why is this important? Because we really don’t care. We don’t miss wholly mammoths in northern Europe. We don’t miss giant sloths in California. We don’t miss black bears in downtown Toronto. We don’t miss lions in Cape Town. The definition and acceptance of nature  for most people is not influenced by what is not there, but rather the critters we are familiar with and are willing to accept. Big mammals simply have no place in human dominated landscapes and we don’t bemoan their absences.

Can human-first conservation protect jaguars?
(Photo from wikipedia)

Human-first conservation strategies work simply because we accept a less valuable system as acceptable and perhaps normal because of our shifting baselines. Would a human-first conservation strategy work in Costa Rica’s ACG if there was a huge jaguar population that was attacking livestock? Not likely.

The United States government spends billions on national parks to conserve nature (among other things), but if it was up to ranchers living near Yellowstone, for example, all the top predators will be exterminated. Hunters and ranchers in Germany are similarly up in arms (literally) over the re-appearance of wolves and lynx in restored forests within Germany’s borders. Some there consider the extermination of large predators a commendable feat of an advanced society.

The point is that we like the nature we know, and the nature that is not likely to kill us. People are most often invested, familiar, and willing to conserve nature around them, which already works for them.

Costa Rica’s ACG human-first conservation works in certain contexts. It gets people involved, it protects certain facets of nature, and it has a high likelihood of long-term success. If this is the model for a successful conservation philosophy, then we must accept that not all of nature can be protected. In all likelihood, many large mammals will go extinct in my childrens’ lifetime, regardless of how well we do conservation. So perhaps, moving forward with the human-first strategy is the best option, but a part of me hopes that there is a place for real nature in our world. The rest of me knows that there isn’t.


Bennett, E. M. 2017. Changing the agriculture and environment conversation. Nature Ecology & Evolution 1:0018.

Monday, February 27, 2017

Archiving the genomes of all species

There is so much bad news about global biodiversity, that it is nice to hear about new undertakings and approaches. One of these is the 'Earth BioGenome Project' which proposes to sequence the genomes of the entirety of life on earth. Given that sequencing services have never been more affordable and more available to scientists, without question, though ambitious this is a feasible undertaking. Still, with perhaps 9 million eukaryotes on the planet, a rough prediction suggests it could take 10 years and several billion dollars to achieve.

The cost suggests a certain agony of choice - what is the best use of that amount of money (in the dream world where money can be freely moved between projects)? Direct application to conservation and management activities, or a catalog of diversity which may be the only way to save some of these species? 
Leonard Eisenberg's tree of life (https://www.evogeneao.com).

Saturday, February 13, 2016

The vanishing pangolin: How do you change the value of an endangered species?

Extinction is forever. Extinction reduces the biological heritage of the Earth and is something that we cannot undo.

While living in China, and traveling around Asia, I have said something to my children I have never said before: “I want you to take a really good look, these animals will go extinct in your lifetime”.  I said this as we were watching 8 of the 60 remaining Hong Kong pink dolphins.

Hong Kong pink dolphin (photo by Shirley Lo-Cadotte)

Species become rare and endangered for many reasons, like habitat destruction, pollution, human facilitated spread of problematic species (rats for example), and direct harvesting. While all of these factors are subject to laws and regulations that attempt to control them, it is the last one, harvesting, that relies most on altering peoples' wants and desires. I don’t know why, but to me it is also the saddest cause, the idea that a species dies out because we desire it and kill it or chop it down, just doesn’t seem right.  

Walking through the market alley near my apartment in Guangzhou, China, I saw something that both intrigued and horrified me: a dead and quartered pangolin. You may not be familiar with pangolins –also called scaly anteaters; they are mammals about the size of a large cat or medium-small dog (like a cocker spaniel), with a very long and thick prehensile tail that they use in trees. Their most unique feature is that they are covered in large flat scales that are made of keratin –the same as your fingernails. 

A Chinese pangolin, Manis pentadactyla (https://commons.wikimedia.org/wiki/File:Pangolin%27s_tail.jpgsted to Flickr by verdammelt cc-by-sa-2.0) 
Pangolins are critically endangered. They also have the distinction of being one of the most trafficked animals in the world. In China and Vietnam there is high demand for pangolins because they are considered a delicacy and more importantly their scales are used in traditional medicine. These scales are believed to provide a cure for a number of diseases, including cancer. The incidence of cancers in China is skyrocketing, which is not surprising given the level of pollution, and couple this with increasing affluence, the desire and ability to pay for pangolin parts has never been greater.

Obviously pangolin scales do not cure cancer. You might as well save your money and suck on your fingernails instead, but evidence and logic are not likely to sway mortal fear. There are groups in Asia dedicated to protecting endangered animals and educate citizens about wildlife. Such organizations have an opportunity to capitalize on recent attitude shifts in China and elsewhere, where animal wellbeing is increasingly seen as important. In China, pet ownership has increased dramatically over the past decade and pets are now seen as companions –which I suspect was partially a result of the one-child policy. But the demand for pangolins still exists. When we visited the Angkor Conservation Centre in Cambodia, which works tirelessly to rehabilitate animals and educate people, they were recovering from the theft of one of their pangolins from an enclosure, which they knew was transported to China.

The Chinese authorities are coming down hard on the illegal pangolin trade. They now routinely arrest individuals selling pangolins and seize large shipments. While such seizures and arrests show that the Chinese government is taking pangolin protection seriously, there is only so much they can do while demand is high.

Police confiscating a large illegal pangolin shipment bound for China (photo originally from news.163.com) 

My Mother-in-law, who is from southern China, said it best when I told her about the dead pangolin in the alley: “people just need to be educated”. That is really where the answer lies. Laws can only change peoples’ behaviour so much; education campaigns are desperately needed. Currently, there is an internationally funded billboard campaign in China to stop people from buying elephant ivory. Ivory demand is high in China. Despite the importance of reducing ivory purchases, I would argue that this type of education campaign needs to focus a little closer to home, and Pangolin conservation efforts are in desperate need of help. 

When we were visiting the conservation centre in Cambodia, I told my children that the Pangolin would go extinct in their lifetime. I really hope that I am wrong.




Tuesday, November 10, 2015

Culling Koalas for Conservation

Guest post by Stefanie Thibert, who is currently enrolled in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough


Euthanizing diseased koalas may be the most effective management strategy to save koalas from extinction in Queensland. A recent study published in the Journal of Wildlife Disease suggests that if 10% of terminally diseased and sterile koalas were culled while other infected koalas were treated with antibiotics, chlamydial infections could be completely eliminated and population sizes could increase within four years. 
The beloved koala relaxing in a eucalyptus tree
(Source:
http://www.onekind.org/be_inspired/animals_a_z/koala/) 

Although koalas are under pressure from habitat degradation, dog attacks and road accidents, disease burden is the largest threat to its population sizes. It is estimated that 50% of the current koala population in South-East Queensland is infected with the Chlamydia spp. The sexually transmitted disease causes lesions in the genitals and eyes, leading to blindness, infertility, and ultimately death. Rhodes et al. (2011) suggest that reversing the observed population decline in Queensland koalas would require either entirely eliminating deaths from cars and dogs, complete reforestation, or reducing deaths caused by Chlamydia by 60%. It is clear that the best conservation tool is to reduce the prevalence of chlamydial infection.

In the study, Wilson et al. (2015) examined the potential impact of euthanizing koalas infected with Chlamydia. As shown in Figure 1, computer simulation models were used to project koala population sizes based on four separate intervention programs: “no intervention”, “cull only”, “treat only”, and “cull or treat”. In the “cull or treat” program, sterile and terminal koalas were euthanized, while infected kolas that were not sterile or terminal were treated with antibiotics. It was concluded that the “cull or treat” is the most successful intervention program for increasing long-term population growth and eliminating chlamydial infections. 
The projected numbers of koalas in the Queensland population under different intervention programs.(From Wilson et al. 2015)
Without intervention, it is estimated that merely 185 koalas will persist in 2030. Under both the “cull only” and “treat only” intervention, it would take seven years before there would be greater koalas numbers than there would be without intervention. Under the “cull or treat” program, the population size was projected to overtake the no-intervention population after four short years. The population size in 2030 is also greatest under the “cull or treat” intervention. The increase in koala numbers in the “cull or treat” strategy is due to the considerable decrease in the prevalence of Chlamydia.
As expected, the proposal received considerable attention and was scrutinized by the public. Some argue that it is inhumane, while others suggest alternative management strategies. However, when it comes down to it, the science is clear. Euthanizing can be done in a humane way, and it is the most effective method for conservation of the species. The only real alternative to culling is treatment with antibiotics, which is costly, requires an immense amount of monitoring, and has been shown to take much longer to eliminate the disease and increase population sizes.
The question we must ask ourselves is: we cull other species, so why not koalas? For instance, in the United States, the culling of four million cattle successfully prevented bovine tuberculosis from spreading to humans. Even when based on sound scientific research, culling has always been dismissed as a management option for the iconic Australian marsupial. In 1997, culling was suggested as a method to protect the overabundant koala population on Kangaroo Island, but sterilization and relocation was used instead. It is amazing that a program that was significantly more expensive and less effective was chosen because the public could never think of killing the adorable and innocent koala.
Managing koala populations is clearly a case in which science intersects with emotion. However, it is essential that we put our emotions aside, and make a decision that is based on scientific evidence. Let us remember that the study only suggests culling or treating 10% of the population each year, which is equivalent to approximately 140 koalas. It is also important to improve the communication of science to the public. It needs to be made abundantly clear that without culling, the koala populations will continue to decrease.


To read the full article visit: http://www.bioone.org/doi/full/10.7589/2014-12-278 

References:

Oliver, M. (2015, October, 20). Proposal to euthanise koalas with chlamydia divides experts. The Guardian. Retrieved from: http://www.theguardian.com/world/2015/oct/20/proposal-to-euthanise-koalas-with-chlamydia-divides-experts.

Olmstead, A.L., & Rhode, P.W. (2004). An impossible undertaking: The eradication of bovine tuberculosis in the United States. Journal of Economic History, 64, 734-772.

Rhodes, J.R., Ng, C.F., de Villiers, D.L., Preece, H.J., McAlpine, C.A., & Possingham, H.P. (2011). Using integrated population modeling to quantify the implications of multiple threatening processes for a rapidly declining population. Biological Conservation, 144, 1081–1088.

Wilson, D., Craig, A., Hanger, J., & Timms, P. (2015). The paradox of euthanizing koalas to save populations from elimination. Journal of Wildlife Diseases, 51, 833-842.


Monday, May 11, 2015

Is there a limit to how many species can the earth hold?

Counting species (bird lists, plant guides) is as old as ecology itself. And yet surprisingly, there are still different opinions on how many species the planet holds, and even, whether there are limits on how many species it can have. If the number of species has ecological limits, the assumptions ecologists often make – that species pools are limited and knowable, dynamics can reach equilibrium, competition should usually be important – would be stronger. Things would be more predictable. 

But is the production of diversity self-limited? There isn’t consensus but two recent articles in the American Naturalist (continuing a debate at the American Society of Naturalists meeting) provide some excellent debate of this question.

The debate is whether the majority of variation in continental-scale species richness is regulated by diversity-dependent feedbacks. In these papers, Dan Rabosky and Allen Hurlburt argue that species richness has ecological limits, while Luke Harmon and Susan Harrison take the contrary position, that species richness is dynamic. First, to define some terms: here, species richness is being considered at the largest spatial scale (e.g. terrestrial plants at the continental scale) so that dispersal limitation should be comparatively unimportant (because diversity changes are mostly driven by in situ speciation).

The crux of the Rabosky & Hurlburt argument is established in the Ecological Limits Hypothesis (ELH), which states that species richness will reach a dynamic (i.e. stochastic) equilibrium, where equilibrium richness reflects density dependence in speciation and/or extinction rates. Speciation and extinction rates are ultimately limited by total resource availability for the continent. Therefore variance in richness through time and between places should be driven these ecological limits, and richness should be predictable.
From Rabosky & Hurlburt 2015 - the Ecological Limit Hypothesis.
The evidence presented for the ELH comes from phylogenies and macroevolutionary models, the fossil record, and macroecological observations. First, there are well known patterns between species richness and energy, productivity, or habitat area, and these span multiple regions and groups of species (e.g. Jetz and Fine 2012). Further, Rabosky & Hurlburt argue that geological records suggest that changes in diversity are not unbounded or exponential, but instead rise and fall, correcting toward some equilibrium. Molecular phylogenies are often evaluated by looking at speciation rates over time, and the authors suggest that these frequently show declines, where speciation declines during adaptive radiations. One prediction that arises from the ELH is that perturbations will be followed by particular responses: “negative perturbations—mass extinctions, in particular—should lead to diversity recoveries. Second, positive perturbations—increases in the resource base available to a biota—predict increases in species richness to stable but greater equilibrial levels”.

The rebuttal article from Harmon & Harrison takes a strong and contrasting view, although it focuses mostly on poking holes into Rabosky & Hurlburt’s arguments, rather than laying out a competing hypothesis. If Rabosky & Hurlburt focused on evidence over huge evolutionary scales and spatial expanses, the Harmon & Harrison response has a particular interest in the temporal and spatial scales of interest to community ecologists (local, present day) and how these seem to disagree with Rabosky & Hurlburt's hypothesis.

First, Harmon & Harrison argue that that the macroevolutionary evidence (molecular phylogenies, fossil data) is not nearly so convincing as Rabosky & Hurlburt suggest. There are important limits to its utility resulting from issues of ambiguity in interpretation and methodological limitations. In addition, for most of the patterns Rabosky & Hurlburt highlight, there are other papers concluding that the pattern was not present in their data. With reference to the lack of relationship between clade age and diversity: “A common interpretation of these results is that a lack of a relationship between age and diversity is evidence for ecological limits.... However… this pattern is far from ubiquitous in real data and is compatible with other explanations”. They also take issue with the tendency for hand-wave-y interpretations of patterns in such data, and emphasize the need for better statistical analyses and consideration of alternate models. Fossil data has obvious limitations as well (hence the field of taphonomy), including the fact that fossils are rarely classified to the species-level, which means they do not represent species richness, but rather lineage richness.

But Harmon & Harrison's real disagreement is based on their view that ecological evidence from local communities does not at all suggest ecological limits. Energy-richness correlations, although common, may have alternative explanations: the tropics may have higher diversification rates for other reasons, or niche conservation means that more species niches suited to the tropics, confounding energy-diversity relationships. Further, local communities do not regularly show a positive energy-diversity relationship. In particular, Harmon & Harrison suggest that the logic from the ELH, if followed, predicts that if species richness is ultimately tied to the availability of energy, then competition should necessarily be very important in most ecological communities. They cite a stat from the invasion of California flora in which alpha diversity has risen by more than 1000 invasive species, with only 28 native extinctions (as of 2002), suggesting that local (or even regional) communities are not full. 

To this, Rabosky & Hurlburt rejoins that invasion is about dispersal changes, and not resources. Further, they believe that large evolutionary scales are most useful as evidence for the ELH, since they are most likely to show zero sum game, rather than temporary dynamics, and since confounding factors should become minimized.

The debate left me feeling a little unsatisfied (since expecting the authors solve the problem is a bit unreasonable), in part because the authors are really arguing from different scales and approaches. And both sides are clearly right in some cases (and in others, perhaps, clearly overreaching). And of course, proving whether or not there is an ecological limit on diversity is a rather difficult thing. When Harmon and Harrison argue that the ELH, which assumes that richness approaches some equilibrium value but varies about it in a stochastic fashion, isn’t parsimonious, they’re wrong – ecological processes are innately stochastic and it hardly seem un-parsimonious to assume as much. But they’re right that this view makes testing and model fitting very difficult since having high replication and good quality data is necessary (to capture accurately a distribution, rather than single value). Given the variety of issues with data representing diversification over evolutionary time, and frequently an inability to capture extinction rates with evolutionary data, having quality, replicated tests of the ELH is difficult.

On the other hand, at local scales over ecological time, observations may be less relevant. It’s not clear how to reconcile statements about saturation (or lack thereof) of local communities with richness at continental scales. Rabosky & Hurlburt suggest that local assemblages can be dynamic in diversity as long as there is a zero sum across all communities and through time. But a connection between continental scales and local scales is innate, and understanding how diversity relates over multiple spatial scales is an area of ecological research we need to continue to develop.

Given there are no easy tests of this sort of question (though bacterial microcosm provide some interesting results), we have been forced to draw conclusions based on weak tests and weak evidence. But ecologists do this because this is a truly important question, with huge implications across ecology and evolution. Ecological and evolutionary models make assumptions that implicitly or explicitly about carrying capacity, about determinants of rates of speciation and extinction, about invasion, about why global diversity changes, and these need to be confirmed. Further, if there is a strong ecological feedback of diversity, one of the most important implications is that major perturbations such as extinctions should be followed by major recoveries. In the Anthropocene, that’s an important implication. 

Monday, November 17, 2014

Northern White Rhinoceros – On the Brink of Extinction

*Guest post by Monica Choy -one of several posts selected from the graduate EES3001 Scientific Literacy course at University of Toronto-Scarborough.

Photo credit: Elodie A. Sampere, Getty Images
Suni, a 34 year old male northern white rhinoceros, died on October 17, 2014 of natural causes. His death reduced the total number of known northern white rhinos to an alarming six individuals, which has brought his species one step closer to extinction.1

Suni was born in a zoo in the Czech Republic and was the first of his kind to be born in captivity. Unfortunately, northern rhinos are a finicky species when it comes to breeding and with increasing pressures from poaching, it became critical to provide the animals with a natural, comfortable space.

As a result in 2009, Suni and three others were transported to the Ol Pejeta Conservancy in East Africa.  It was believed this change in scenery would most accurately imitate their natural environment.2 Rhino conservationists anticipated that the rhinos would then breed naturally and provide a healthy calf that would bring new hope for the waning species.

Even before these desperate attempts to keep the species going however, the history of the northern rhino has been a sad one. At the time of Suni’s birth, his species was on a very slow rebound. Northern white rhinos had been excessively poached for their horns, and their initial population of over 2,000 animals declined to a shocking 15 rhinos by the late ’80s. Conservation efforts were ramped up in the ’90s and it looked as though the animals were making a gradual comeback. Unbelievably, poachers also increased their efforts and knocked the numbers back down to below 10 individuals by the mid-2000s.3

Northern white rhinos were declared extinct in the wild by 2008.

The likelihood that Suni’s species will become extinct in our lifetime has increased significantly with his death. And although the Ol Pejeta Conservancy will continue trying until the bitter end with the use of techniques such as artificial insemination, the precarious position the northern white rhino is in, as stated in their press release, is “a sorry testament to the greed of the human race.” 1

The extinction of such a charismatic species is a tragedy and should bring awareness to how heavily humans really affect our environments. Although the northern white rhino may be on the brink of extinction, there are still a countless number of other species out there that need our help. It is up to us to work together in order to keep other species as far from the fate of the northern rhino as possible.


More information
1Ol Pejeta Conservancy press release  - http://www.olpejetaconservancy.org/about/news/breaking-news-ol-pejeta-conservancy-loses-one-its-northern-white-rhinos
2Northern white rhino conservation project - http://www.olpejetaconservancy.org/sites/default/files/NWR_FAQ_FINAL.pdf

3WWF profile of the northern white rhinoceros - http://wwf.panda.org/what_we_do/endangered_species/rhinoceros/african_rhinos/white_rhinoceros/