How do correlations between climate and biodiversity arise? UPDATED

Anyone who as ever watched a David Attenborough documentary knows that biodiversity differs in areas with different climates. Only a few species an survive in hot and dry deserts whereas warm and wet tropical forests are teeming with life. But have you every stopped to wonder why this is so?

Why are certain climate conditions able to support many species and others not? More specifically, how does this work mechanistically?

This was the question my co-authors and I set out to answer in our most recent paper just published online at Global Ecology and Biogeography.

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What can Sudoku teach us about ecology and evolution?

Evolution is creeping into several different aspects of ecology. The latest buzz is all about integrating ecology and evolution. Perhaps you’ve heard of the  latest research trends in eco-evolutionary dynamics or community phylogenetics?

Theodosius Dobzhansky famously stated that “Nothing in biology makes sense except in the light of evolution“. This claim is undoubtedly true, but I’ve recently found myself wondering whether our obsession with evolution is actually clouding our ability to do good ecological research.

Please don’t misunderstand me, I am not implying that evolution is not important in explaining patterns in nature, nor am I suggesting that we should disregard evolutionary explanations for these patterns. Instead, I believe that in order to gain a deeper understanding of ecology, we should perhaps partially blind our views using “evolution blinkers”. In fact, I’d even be so bold as to claim that unless we blind ourselves to evolution, we will never be able to fully grasp the true nature of ecological processes. Unifying ecology and evolution might actual limit our ability to build ecology as a science.

Richard Feynman used a useful chess analogy to explain how physics works. I’ll borrow this style of argument to explain my stance on ecology and evolution. However, since chess is too complicated for my liking, I’ll use an even simpler game: Sudoku. Continue reading

The “true nature of the university” as told by John Williams

I’ve been appointed as a lecturer a since the beginning of March; my first real academic job. In my short time in the ivory tower, I’ve wondered about my role at the university and how it complements my own career ambitions. This form of navel-gazing rarely results in any meaningful epiphanies, but it does push me towards interesting sources of guidance.

One such source is the novel Stoner, by John Williams (It’s excellent. I highly recommend it). Below is an extended excerpt on the ‘true nature of the university’, which struck a chord with me. I can relate to all the characters and especially to the closing paragraph. It’s a beautifully written novel and I wouldn’t want to spoil it, but, for those in a rush, I annotated the best bits in bold.

To set the scene: three young English lecturers, Mrs Masters, Finch and Stoner, are having a casual conversation after work when the following exchange takes place. Continue reading

Long-term monitoring generally underestimates negative trends in biodiversity

Modern conservation and environmental management rely on data. Unless you can actually show cold, hard evidence of natural deterioration, you open yourself up to criticism from denialists and other eco-skeptics. It is too easy for industry lobbyists to dismiss conservation recommendations as tree-hugger scare-mongering.

So conservationists, being the idealists that we are, decide to gather evidence for downward trends of various aspects of biodiversity. Unfortunately, efforts to quantify biodiversity trends are a major challenge. Not because measuring trends in diversity is particularly difficult, but rather because long-term monitoring is susceptible to sampling artefacts.

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The scalability of macroecology

Russian Dolls

No matter at which scale you look at it, nature is remarkable.

Like many others, I was taught ecology in a very hierarchical way: individual organisms are part of a wider populations of species, collections of species form communities and communities come together to make up ecosystems. Similarly, single trees are nested within forests, which aggregate to form biomes. I’m sure you can come up with many comparable examples.

The trouble with such neat spatial hierarchies is that they lure us into believing that if patterns appear similar at several different spatial scales, then the processes leading to these patterns should also be similar. It’s so easy to assume that nature is like a set of Russian Dolls: each daughter exactly the same as its mother, only slightly smaller. But this is not necessarily the case.

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Species distribution modelling is not as simple as you think

One of the most fruitful sub-fields in ecology is using climate variables to predict species’ geographic distributions. For the uninitiated, species distribution modelling assumes that species are limited in their distributions to suitable climate zones. By studying the environmental conditions where species are known to occur, you can infer the total geographic distribution by calculating the suitability of unsampled regions based on the environmental. Furthermore, using the same principle, species distribution modelling can forecast the effect of future climate change of the distribution of life on earth.

Unfortunately, studies have shown that these fancy climate-based techniques cannot consistently outperform much simpler ones based on spatial phenomena. For instance, spatial interpolation between point occurrences outperforms sophisticated climate-based predictions. Similarly, elaborate climate-based predictions perform no better than expected from random chance.

The trouble lies in the spatially-structured world we live in. Species distributions, especially at large spatial scales, are spatially-autocorrelated due to constrained dispersal. Similarly, climate variables are also spatially structured because the meteorological processes at proximal regions are generally more similar than those at distant sites.

When trying to link species distributions to climate conditions, the challenge lies is separating spatial and environmental correlations in species distributions. Specifically, we should identify three patterns in the geographical species distributions.

  • We must first identify ‘true’ correlations with the environment, which are independent of spatial patterns (E|S).
  • Next, we must identify the environmental-associations that also have a strong spatial structure (E∩S). This is known as exogenous spatial autocorrelation because it is due to autocorrelation is the underlying variables.
  • Finally, we need to identify spatial patterns that are completely independent of environmental conditions (S|E). This is called endogenous spatial autocorrelation because it supposedly stems from spatial processes, such as dispersal.

In our latest study just published online at Ecography, we set out to quantify the degree of environmental correlation, exogenous and endogenous spatial autocorrelation in the distributions of 4 423 species of amphibians, reptiles, birds and mammals in Africa. Continue reading

Some motivation to get you through your PhD

If there is one thing I hate, it’s the stereotype that PhD students are pathetic, dependent, helpless creatures bogged down by self-doubt and self-pity. It annoys me even more that PhD students are responsible for perpetuating this myth. We laugh along with popular websites like Piled Higher and Deeper (a.k.a PhD comics) and What Should We Call Grad School, which regularly make jokes about the futility of grad school.

Sure, these sites are funny because there is an element of truth in them, but I believe that they cause more harm than good. Although they are well-meaning and try to foster a culture of solidarity among students, they are more likely to cause complacency than empowerment.

We don’t need another shoulder to cry on, we need a kick in the arse!

As I am nearing the end of my PhD experience, I thought I’d share a bit of motivational advice I found especially useful. It is the final chapter of Adam Ruben’s book, Surviving your stupid, stupid decision to go to grad school. Some of you may be familiar with Ruben’s writing, because he also writes a monthly column in Science Magazine, Experimental Error.

Here it is, enjoy.

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Camera trap critters: Part 2

I’ve just returned to South Africa, where I’ll spend the next few months adding the final touches to my PhD thesis. Of course, being back home means that I spend my free time playing with my camera trap. I thought I’d share two of my favourite videos from the last few nights.

The first is a very short clip of the small-spotted genet (Genetta genetta). I’m very pleased about spotting this beautiful carnivore because I regularly found the remains of laughing doves and helmeted guineafowl and always assumed that they were killed by feral cats. It’s always nice to spot natural predators.

The second clip is of a male Impala (Aepyceros melampus) scent-marking his territory.

 

Conservation and poverty alleviation: the case of Golden Gate Highlands National Park, South Africa

Biodiversity conservation and poverty alleviation often walk hand-in-hand. At the global scale, most species and the majority of poor people are concentrated in a narrow band near the tropics. This is also true at smaller scales, where formal protected areas for conservation are regularly situated away from urban centres and, therefore, often coincide with poor communities deprived of basic infrastructure. As a consequence, any conservation strategy that hopes to be sustainable in the long-term should pay careful attention to local socio-economic conditions.

Regular readers of this blog might know that I have a soft spot for Golden Gate Highlands National Park (GGHNP) in South Africa (e.g. the history of the park and the guide to the hiking trails). This national park happens to be in one of South Africa’s poorest regions: the Maluti a Phufong local municipality.

Consider these scary statistics for the region:

  • Only 1 in every 4 people (26.8%) has successfully complete secondary school education.
  • Approximately 75 % (155 429 out of 208 296) of people aged between 15 and 64 are unemployed.
  • 80% of households earn less than ZAR 40 000 per annum (that’s roughly US$10 per day shared among 3.35 people per household).

There is no doubt that the region surrounding GGHNP is in dire need of rejuvenation. I suppose it’s unsurprising then that the South African Journal of Science published a commentary in December last year criticising the recently approved 10 year management plan for GGHNP. In short, the authors argued that the management plan failed to highlight the need for conservation strategies that address the harsh socio-economic realities of the region and they suggested that tourism in the region be fast-tracked to generate revenue.

Here are some snippets from their essay:

The GGHNP management plan can only succeed in promoting biodiversity and heritage conservation if it provides livelihood opportunities that safeguard continued socio-economic benefits.”

Park resources, if managed properly, can provide long-term sustainable benefit to individuals, communities and institutions.”

There must be speedy documentation of cultural heritage sites to promote route tourism development.

The GGHNP has rich cultural and heritage resources, yet is unable to effectively preserve them and to turn these assets into tourist attractions that earn revenue and provide opportunities for local economic development.”

At first inspection, this all sounds good. They use all the right buzzwords and seem to tick all the boxes. But I couldn’t help being annoyed when reading this commentary. Along with disagreeing with its general argument, I also had other misgivings, mostly due to the misrepresentation of the current situation at GGHNP.  I pointed out these errors to the editor at South African Journal of Science and these views were published last week (open access). Continue reading

The startup culture of conservation entrepreneurship

I’ve written about the need for self-started conservation initiatives on this blog before. And now I am pleased to boast that some of these ideas have just been published online in Conservation Biology. (If you don’t have subscription access through the publisher’s website, feel free to leave a comment below and I’ll forward the article to you as a PDF).

It’s a short opinion piece that is mainly intended to introduce the concept of social entrepreneurship to an audience of conservation scientists. The article should definitely not be considered as a how-to guide to conservation entrepreneurship, nor is it a comprehensive review of all the ways entrepreneurship can help to protect biodiversity. Instead, I hoped to convey three key points:

(1) there are conservation problems that are especially amenable to small, fast bootstrapped solutions;

(2) there are new ways of funding conservation initiatives that weren’t available 10 years ago; and

(3) most early-career conservation biologists in the current employment landscape will, at some point, be unemployed, so self-started conservation initiatives could become a necessity.

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