Category Archives: Alfred Russel Wallace

Are tropical plants and animals more colourful? Not according to a new study!

Cinnabar caterpillars 1 P1020535

The notion that tropical ecosystems are somehow “different” to those at higher latitudes is a pervasive one in ecology and biogeography, that has its roots in the explorations of 18th and 19th century Europeans such as von Humboldt, Darwin, Wallace, and Belt.  All of these authors expressed their amazement at the biological riches they observed in their tropical explorations, and how different these habitats were to those they knew from home.

In many ways the tropics are special, of course and we know that they contain many more species than most other parts of the world; indeed my own work has shown that the tropics have significantly more types of functionally specialised pollination systems, and that the proportion of wind pollinated species is lower in tropical communities.  However tropical plants are not, on average, more ecologically specialised (that is, they do not use few species of pollinator) and, as the recent guest blog on Dynamic Ecology argued, there is a growing body of evidence to say that overall tropical interactions between species are not stronger and more specialised than those in the temperate zone (though there are others who dispute this and it’s an ongoing debate).

One of the central tenets of the “tropics are special” idea is that the tropics are more colourful; or rather that the biodiversity of the tropics tends to be more garish, gorgeous, and spectrally exuberant, than that of other parts of the globe.   Now a new study by Rhiannon Dalrymple, Angela Moles and colleagues, published in the journal Global Ecology and Biogeography, has challenged this idea for flowering plants, birds, and butterflies in Australia, using sophisticated colour analysis rather than relying on human impressions. Following that link will take you to the abstract and you can read it yourself; however I wanted to summarise their findings by quoting from the first section of the discussion in the paper:

Contrary to predictions…[our]…results have shown that tropical species of birds, butterflies and flowers are not more colourful than their temperate counterparts. In fact…species further away from the equator on average possess a greater diversity of colours, and their colours are more contrasting and more saturated than those seen in tropical species.”

It’s a really, really interesting study that, as the authors say, runs counter to all of our expectations.  Gradually ecologists and evolutionary biologists are testing some long-standing assumptions about the tropics and the results are proving to be a challenge to preconceived ideas about patterns in the Earth’s biodiversity.


Full disclosure: senior author on the paper Angela Moles was my co-author on that Dynamic Ecology blog, based on which we’ve written a short review article that (hopefully) will be published soon.  Other than that I have no vested interest in the study.

Hedge on the edge

It’s been a convoluted month and I’ve tried to find a thread that links it all together in a way that relates to the topic of this blog: biodiversity.  Not sure that I’ve been altogether successful but the linking theme seems to be…….hedgerows?  Perhaps the link is too tenuous in places, we’ll see.

The start of this trail is close to Swanage in Dorset where I spent a weekend away with some friends from my undergraduate days in Oxford at what was then the Polytechnic, now Oxford Brookes University.  A group of anything up to 10 of us try to get together once or twice a year, often camping on the south coast or revisiting Oxford haunts, and pretend that we’re once again in our early 20s and not really in our 40s with careers, mortgages, kids and life issues.  Beer is drunk and the same stories get told, each year more embellished than the last.  Most of us work, one way or another, in the environmental sector and share a love of evocative landscapes, rural and urban.  During this latest reunion we walked along a section of coastal path through some beautiful cliff top grasslands.  The area is riddled with former Portland Stone quarries and deep galleries, making for a dramatic, human-influenced cliffscape.

The plants we encountered were a combination of typical species of chalk and limestone grasslands, together with others that can tolerate (or perhaps require?) the particular combination of salt and exposure found in such maritime habitats, for example sea aster (Aster tripolium).  These cliff top grasslands host a wider variety of crop plant ancestors than any other habitat I know of; on our walk we spotted the wild progenitors of carrot (Daucus carota), beetroot (Beta vulgaris) and cabbage (Brassica oleracea).  Along the path we were protected intermittently by wind trimmed natural hedgerows containing blackberry (Rubus fruticosus), a wild rose (Rosa sp.), blackthorn (Prunus spinosa) and ivy (Hedera helix).  They clung to the edge of the cliff,  exactly pruned to curved shapes as though by an obsessive topiarist.

Our destination was the small 13th century chapel of St Aldhelm’s, an odd little building that may not have had an original religious function at all and was possibly a coastal watch tower for Corfe Castle.  From the chapel we followed more hedges down towards the shore line at Chapman’s Pool where the fissile Kimmeridge Clay deposits yielded some very nice fossil ammonites. One of the fascinating things about this coastline is the way that the modern, living biodiversity is underlain by deposits created by the ancient organisms that built the limestones during the Jurassic period.  Life builds upon life.

The walk ended where all good walks should, in a pub; in this case the 18th century Square and Compass in Worth Matravers (“Twinned with Royston Vasey” according to a very professional looking addition to the village sign).

Back from Dorset on Sunday evening, I packed for an early start the following day to get to the University of Staffordshire for the Hedgerow Futures conference.  I was only able to attend the first day but this proved to be an interesting and diverse set of talks.  In the afternoon I spoke about the research conducted by one of our former PhD students, Louise Cranmer, on how bumblebees use hedgerows to navigate around the landscape.  This work was published last year in Oikos and picked up by the Guardian newspaper as one of their research features.  The talk was well received and there were some interesting questions and comments afterwards.

The latter half of that week was spent in Dublin acting as external examiner for University College Dublin’s MSc Environmental Science course.  I had a chance to chat with a keen group of students on the course and to talk to them about their research theses.  The range of topics studied was impressive, as was their interaction with external bodies and agencies and their use of historical data as a comparison to recent environmental changes.  None of the students worked on hedgerows though I did see some nice ones as I flew into Dublin airport.  The School of Biology and Environmental Science has a large display case containing a number of skeletons, books and other biological artefacts, including a box of glass slides presented to the department many years ago by Alfred Russel Wallace, co-discoverer of evolution by natural selection.  It reminded me that 2013 is the centenary of his death.  Hopefully it will give him more of the attention he deserves, a process that has already started with the launch of the Wallace Online project and a campaign to erect a statue of the great man in the Natural History Museum in London.

Returning to Northampton, work began in earnest to get ready for the start of the new academic year.  It’s always exciting seeing the university coming back to life again after the slower pace of summer and the last two weeks have been a bustle of activity as we welcomed new students and said hello to those returning for their second and third years.  Preparations are under way for student laboratory work and field visits this term, always a process of hope over weather as we leave summer behind.  The month culminated in the announcement that Led Zeppelin’s 2007 reunion gig is to be released as a movie.  This is good news for those (many millions) of us who applied for tickets to the event but were unsuccessful.   So this autumn, if there’s a bustle in your hedgerow, don’t be alarmed now.  It’s probably some of our students doing field work.

Flattery Gets You Nowhere (reduce, reuse, recycle part 1)

It was always my intention, when I began this blog, to use it as a vehicle to rework and reuse scraps of writing I’ve done over the years that had no real “official” outlet .  Hence the subtitle of this posting.  The following is a book review I wrote on the Amazon website in 2007, after I had read Christine Garwood’s book Flat Earth: The History of an Infamous Idea.  It’s a really interesting and well written piece of science history that gives a perspective to science that goes far beyond the immediate topic area of cranky ideas.  I have to confess to a potential bias: the author is a friend of mine.  But that doesn’t make the review any less genuine: if I’d not enjoyed the book I’d have kept quiet!

The pathways through which the history of scientific progress can be mapped are strewn with the remains of overturned ideas and outdated pronouncements, some cranky and (with hindsight) nonsensical, others perfectly reasonable given the state of knowledge at the time. Newtonian physics, though sensible at the human scale, suddenly fails to convince at a subatomic level, not because of any failings on the part of Newton, but because technological and mathematical advances have allowed modern physicists to probe closer and deeper.

Similarly, in biology, many established taxonomic ideas concerning the evolutionary relationships between major groups of flowering plants, mammals and other large clades are, thanks to molecular phylogenetics, shown to be erroneous. And so science advances, from the clearly wrong to the (probably) correct, leaving in its wake the cast off ideas of previous generations.  Except sometimes, when science (or at least fringe perceptions of scientific understanding) takes a backwards stride of such length that one begins to question whether scientific “facts” mean the same thing to everyone.

The concept of the Flat Earth may be a unique example of how a fact (the globularity of the Earth) could be established very early in the development of the rational analysis of nature, only to be rejected by a minor, but vociferous, cohort of “true believers”.  As this fascinating book by Christine Garwood relates, observations by Aristotle confirmed the true shape of the world, and there were no serious challenges to this idea until the 19th century.  Mediaeval scholars accepted a spherical Earth (disc-shaped mappae mundi, I was interested to learn, were symbolic, not cartographic, in intention) and the fears raised by the prospect of Columbus plunging over the edge of the world were a nineteenth century fiction concocted by the author Washington Irving.

The emergence of Flat Earth views in Victorian England as a serious (at least to their promoters) attack on received scientific wisdom has to be seen as an unusual reverse in thinking, not least because the “Zetetic” Flat Earthers sought to use science against itself to accumulate evidence to support the idea of the Earth as a plane, not a planet. In this vivid and well researched account, Christine Garwood moves easily between historical scholarship and popular science to follow the development of Flat Earth thinking from its rejection by the Ancient Greeks through to its Victorian revival, when learned men as distinguished as Alfred Russell Wallace could be convinced to take part in parochial experiments along England’s canal system to try to prove that the Earth was a globe. Darwin, Huxley and others saw little value in rising to the Zetetics’ bait, and Wallace himself regretted his involvement in later years (but seems to have needed the cash at the time).

As the author demonstrates, the death of the early major movers in the sphere of Flat Earth promotion was followed by the emergence of other, equally committed and frequently just as eccentric personalities, until eventually popular support for the notion of a Flat Earth ebbed away with the first manned space flights, and the photographs and experiences which were returned to Earth. Flat Earthism did not entirely die, however, and no amount of “proof” could dissuade the opinion of zealots such as Samuel Shenton, founder of the International Flat Earth Research Society. Like fundamentalists of all persuasions, he had an answer for everything, however contrived and paranoid.

In Garwood’s thought provoking book our understanding of the development of fringe ideas in the history of science is advanced through an analysis of the primary sources relating to an intriguing subject. The book is scholarly but accessible, at once entertaining and authoritative, and also topical in the context of the increasingly widespread anti-evolutionary views promoted by some religious groups. Unsurprisingly Garwood finds parallels between Creationism and Flat Earth thinking, not least because until recently they were promoted by groups with similar world views and memberships.

Flat Earth ideas continued to be advanced in the late 1960s and early 1970s, as both an academic jest with serious anti-establishment overtones by the International Flat Earth Society of Canada, and as a continuation of Zetetic thinking by other groups. Currently these ideas are defunct and even the most literal of Biblical literalists reject the notion, making it unlikely to re-emerge. Even if it did, no modern scientist would risk credibility by debating it.

Creationism is a different matter entirely and some professional scientists (myself included) have opted to debate with Creationists despite the views of (amongst others) Steve Jones and Richard Dawkins that such exposure only provides oxygen for their cause. Unlike the Flat Earth theorists, however, anti-evolutionists are not simply going to fade away and their influence is now felt in American classrooms and textbooks. How should scientists respond? With reasoned arguments that convince the public and politicians (if not the fundamentalists, who can believe what the hell they like as far as we’re concerned) or by ignoring them and hoping they might disappear in their own infighting?

Both Flat Earthism and Creationism reflect wider social and attitudinal differences regarding the role of Homo sapiens in nature: as rapacious exploiter; or careful steward of the Earth; or as an ecosystem component in its own right. Science can provide data and theories and models, but it is up to individuals how they choose to interpret and act on such information, or whether they decide to deride or ignore it. Christine Garwood’s first book is a marvellous insight into just how deeply self-delusional beliefs can become embedded in the minds of intelligent, but blinkered, individuals, and it is hoped that her subsequent books examine these themes in more detail. Perhaps her successors 200 years in the future will be similarly taken to write about the incredulous movement that denied that Earth’s climate was changing and that the human species was fundamentally altering the biosphere through pollution and over-exploitation of resources, despite the weight of data. And let us hope that we still have a society that can appreciate the irony.