Wednesday, 30 July 2014

Two bugs, predation and evolution



I grew up by the sea, so it is not surprising that I developed a fascination for marine shores and the plants and animals that live there. 1 I loved looking in rock pools at low tide and seeing some creatures dart away, while others clung tightly; and lifting drying seaweed to see what sheltered under the wet fronds beneath. As a teenager, there were plenty of other things to occupy my mind, but I retained my love of Natural History and always enjoyed walking through the Devonshire countryside and around the coast. It was while at University that I discovered the flora and fauna of fresh waters and I then went on to have a research career looking at stream and river ecosystems, while retaining a fascination for all aspects of Aquatic Science. It fuelled my teaching and I hope that my curiosity rubbed off on some of my students, as it is enriching. Underlying my interest has always been a child-like approach - “Look at that!”, “Why is that?” etc. - and I’m pleased that I have failed to grow up in that regard.

While collecting damselfly larvae from a weedy lake for a University vacation project, I first came across two creatures that so interested me that I took them home and kept them in large jars. One was a solitary water stick insect, Ranatra linearis (below left, total overall length 7 cm) and then several specimens of the water scorpion, Nepa cinerea (below right, total overall length 3 cm). Although it is similar in appearance to a stick insect, Ranatra is not related to members of this group, but has evolved the same mechanism to avoid detection by resembling a twig. Nepa looks a little like a scorpion, at least at the front end, but it is not related to the scorpions and is very close, in evolutionary terms, to Ranatra, both being members of the Nepidae group of bugs. Nepa is dark brown in colour and resembles the decomposing leaves amongst which it lives so it, too, is camouflaged.


As they are closely-related, one would expect many similarities in the structure, and behaviour, of these insects. Both are true bugs and thus have incomplete metamorphosis, with larval stages that are similar in form to the adults and that undergo a series of moults, and thus increase in size, until the fully-grown insects emerge. During the larval stages, wing buds are present and the adults have wings, although they do not fly well - or often. All aquatic insects have terrestrial ancestors but these bugs spend almost their entire life in water, retaining a system of tubes within the body for air breathing. Whereas some aquatic insects have developed gills containing branched air tubes, both Ranatra and Nepa have two long extensions at the hind end of the body and these are closely applied and form the equivalent of a snorkel that is held at the surface when the bugs need to replenish air supplies.

The majority of insects have six walking legs, allowing them to move over the substratum by having three points of contact at all times, each tripod providing stability. Ranatra and Nepa have six legs, but the first pair is adapted for catching and holding prey, the other four legs being used to crawl slowly through vegetation. Their camouflaged appearance gives the bugs some protection against attack and, together with their lack of movement, makes them good “wait and see” predators. Any suitable prey that comes within range is grabbed by the fore-limbs and, in Nepa, these have become modified so that the lower part folds into a notch in the upper part, much as a blade folds into a penknife (see the video clip below). Any organism that is caught cannot escape and the bug uses its rostrum of piercing mouthparts to both inject salivary secretions and then suck up the body fluids and digested contents of their prey. It was this predation that fascinated me and the bugs that I kept in jars fed on a range of animals, including water fleas and insect larvae of several types. Especially impressive was the capture by Ranatra and Nepa of tadpoles and I was fascinated by their feeding. There’s something about watching predation that captures our attention, perhaps because it seems a little shocking, as we are witnessing "nature in the raw". I saw both bugs complete several meals and was impressed by how little effort appeared to be required from initial capture to the time the remains of the prey were discarded.

                             

Unless one is a Creationist, Ranatra and Nepa provide excellent examples of evolution. They share the same method of catching prey, using modified fore-limbs, feed using a rostrum, they have invaded fresh waters form a previous terrestrial existence, and both have a breathing tube to enable them to remain submerged. It is likely that these were all features of a common, now extinct, ancestor and the two forms then diverged, with the evolution of different body forms that enable them to live in slightly different parts of habitats. Thinking about their structures, and how they evolved, is as fascinating as watching the bugs “in action” and I’m pleased that I’m not a Creationist. Of course, we can all share a sense of wonder in watching Ranatra and Nepa, but to think of evolution, and all the changes that have occurred through time is amazing, as we have no way of conceptualising a million years, let alone the many millions of years over which changes in body form and behaviour occurred. Natural History is not a religion, but it is certainly rewarding to all of us lucky enough to observe all the extraordinary adaptations that evolution has provided.

  video


[Please play without sound - you know my views on this. 1 The red spots on the legs are water mites.]

1 Roger S. Wotton (2012) Walking with Gosse: Natural History, Creation and Religious Conflicts. Southampton, Clio Publishing.


Monday, 21 July 2014

Meadows, lawns, and human eccentricity



A walk through a lush meadow in spring and early summer is always uplifting, especially when it is sunny and there is a gentle breeze. Each meadow is slightly different in the types, arrangement, and quantities of the wild flowers it contains, with mixtures of scarlet, pink, yellow, mauve, blue, white and other hues, all complementing the background green of the abundant grasses. If left, the grasses and flowering plants produce seeds that disperse and ensure the development of new individuals and some seeds may remain dormant for years, while others germinate in the next growing season.





All meadow plants are fed upon by animals, both invertebrate and vertebrate, and this affects the survival of flowering plants as they may then not be able to produce seeds. Grasses, in contrast, continue to thrive and have evolved to cope with grazing pressure by growing from near the base of the leaves. Grazing encourages the growth of more leaves, and seed heads are produced on rapidly-growing stems, some of which may escape the attention of grazers. Grasses are also perennial, while most flowering plants in meadows are annuals.

At some point in human evolution, our ancestors decided to grow plants for aesthetic reasons, rather than for food production, or for grazing by domesticated animals. We humans are eccentric in developing this practice, when compared to other members of the Animal Kingdom, and our replicates of natural meadows are lawns. Grazing animals are not permitted and have been replaced by repeated mowing to encourage the growth of grasses and to remove other plants. Any flowering plants that appear are now called weeds and we do all we can to control them and the mosses that successfully colonise any bare patches of soil not shaded by the grass blades. The term control is important here as it is a human characteristic that we want to dominate Nature rather than be part of it. Most people do not like meadow plants in their lawns because they prevent the ideal of a uniform growth of grass. As Wordsworth put it:

How does the Meadow-flower its bloom unfold?
Because the lovely little flower is free
Down to its root, and, in that freedom, bold 1

It is the boldness and freedom of the plants we love to see in meadows that so annoys us when they appear in our lawns.

We like to exert further control by having clear margins to our lawns and many gardeners also prefer the striped effect provided by rolling, first in one direction and then in the opposite one, successively across the lawn. This is considered to be the epitome of a lawn and large expanses of carefully mown grass feature in the grounds of stately homes, their lawns reflecting a larger-scale power over Nature than in most gardens. With a ha-ha marking the beginning of the rural landscape, the landed gentry could truly impress their visitors.


I look after the lawns at my home and keep them as free of moss and meadow plants as I can, with the aid of chemicals and much time spent with a trowel. I certainly have respect for the dispersal capabilities of the plants that appear regularly and wonder at the efficiency of the various mechanisms. By weeding and treating, I am aware that I am arresting a natural process of succession in my lawns and that, if they were not mown, they would become colonised over time by larger, shading plants that would prevent the growth of both flowering meadow plants and grasses, ending up as patches of woodland. Now, I’m not going to allow that to happen.


1 William Wordsworth - an extract from the 1842 sonnet ‘A Poet!’ - He hath put his heart to school’. The Complete Poetical Works of William Wordsworth (1888). London, Macmillan.

Monday, 14 July 2014

“Natural History is the handmaid to the study of medicine and surgery”



Frank Buckland had a passion for Natural History. It developed from his earliest years and he was encouraged in his interest by both his mother and his father, the famous Dean of Westminster, Dr William Buckland. Frank was always inquisitive and enthusiastic and he was a gifted communicator on many topics in Natural History, both in articles and lectures. He is probably best known for being a member of the Acclimation Society, a group formed with the aim of importing, and farming, wild animals to provide food for humans. He had a highly developed taste for zoophagy, 1 having eaten portions of several different animals at his father’s dinner parties. 2

After leaving Winchester College, Frank became a student at Christ Church, Oxford and, after studying Classics and Sciences, graduated with a BA in 1848, at the second attempt. Frank was not suited to formal study and examinations and, while at Christ Church, was more famed for his menagerie than for his diligence. The most famous of his pets was a bear named Tiglath Pileser (“Tig”) that was dressed in a cap and gown 2 and eventually ended up in London Zoo 3 (without academic costume). On leaving Oxford, Frank decided to study medicine and entered St George’s Hospital in London, writing in July 1848: “My object in studying medicine (and may God prosper it!) is not to gain a name, money, and high practice, but to do good to my fellow-creatures and assist them in the hour of need”. 2 After training, he became a surgeon in the Life Guards, but, after failing to gain a promotion, resigned to become a full-time writer and lecturer (he had kept up both activities while in the army), and then Fisheries Inspector.


Frank Buckland wrote these interesting paragraphs in The Preface of the First Series of his Curiosities of Natural History:

Without the knowledge of the structure and physiology of the lower members of the animal kingdom, it would be difficult rightly to understand many functions of the human economy; and much light has been thrown upon the art of healing by the study of the lower links in the chain of animal life.

I would wish it, therefore, to be understood, that the following pages have not been written to the neglect of purely professional subjects of investigation. It has been acknowledged by many of our greatest medical men, that Natural History is the handmaid to the study of medicine and surgery.. 4

It should be stressed that Frank Buckland was a Creationist and his ideas on training in medicine and surgery were not influenced by thoughts that structure and function had evolved (and, although there was discussion of evolution at the time, the lines were written two years before Darwin published his hugely influential ..The Origin of Species..).

Many medical discoveries have been made, and continue to be made, after investigations in Natural History. The development of drugs from chemicals extracted from microorganisms (e.g. penicillin, discovered in 1928) and plants (e.g. aspirin, first prepared in the 1850s, but with the effects of willow bark known for millennia) are well known, and ethnobotany has been a rich source of information. In addition, many types of animals provide analogues for the study of systems in humans (e.g. research during the mid-Twentieth Century on the optic nerves of the squid has provided information on the functioning of nerve-muscle systems). Animals are also used widely as test beds for assessing treatments and in studies of the expression of genes that are also found in humans. However, this is moving rather far forward from the time when Frank Buckland wrote the second paragraph quoted above and he was also referring to research in Zoology, Anatomy and Physiology. Frank tended not to be precise in the use of language.


Natural History covers organisms of all kinds and, in the mid-Nineteenth Century, involved observations using microscopes and the human eye - in situ, in cages, in aquarium tanks, and in other forms of enclosure. This is quite different to contemporary medical research, which seems to focus on internal mechanisms during an era when anthropocentricity and determinism dominate our thinking. Yet the wider environment also has an essential role to play in health and welfare.

Social and physical surroundings are important in the incidence of diseases of many kinds. This applies not only to developing countries, but also to the developed World, with cities like London having some districts with large adverse effects of environment on health. 5 On an individual scale, there are many examples of surroundings affecting health. It is accepted that being able to pet animals has a beneficial effect on the recovery of patients and the same is true of peaceful and beautiful natural locations. Pharmaceutical, surgical and other investigative approaches are essential in modern medicine, but a love of Nature may also aid healing, as it leads us away from introspection. Appreciating the huge diversity of plants and animals, and their inter-relationships with each other and with the environment, can also be an aid in meditative therapies, such as mindfulness. 6


If Natural History (in its widest context) really is the handmaid to the study of medicine and surgery, how much time is given to these aspects of the care of patients when training today’s doctors and surgeons?



1 Lynn Barber (1980) The Heyday of Natural History 1820-1870. London, Jonathan Cape.
2 George C. Bompas (1885) Life of Frank Buckland. London, Smith, Elder & Co.
3 G. H. O. Burgess (1967) The Curious World of Frank Buckland. London, John Baker.
4 Francis T. Buckland (1857) Curiosities of Natural History. London, Richard Bentley.
5 Michael Marmot and Mai Stafford (2005) Places, People and Socio-Economc Differences in Health. In:  London’s Environment: Prospects for a Sustainable World City (ed. Julian Hunt). London, Imperial College Press.
6 Shamish Alidina (2010) Mindfulness for Dummies. Chichester, John Wiley.

Tuesday, 1 July 2014

Torquay, Philip Henry Gosse, and Creation



Last week, I spent a few days staying at the Livermead Cliff Hotel in Torquay. I used to pass it every day on my way to, and from, school 1 and it is situated a few metres from the rocky shore where Philip Henry Gosse, the great Natural Historian, collected sea anemones and other marine creatures. Having been sufficiently fascinated by Gosse to write a book about him and his son Edmund (later Sir Edmund), I find it easy to imagine the two of them at Livermead. 


Henry Gosse came to live in Torquay after the death of his wife, Emily, in 1857, the same year in which his book Omphalos 2 was published. This was Gosse’s attempt to reconcile the literal Biblical account of Creation with the growing awareness among scientists, and others, of geological time scales. In the book, he presents the case for geological time, rock strata and fossils and, after presenting his theory of prochronic existence - where organisms appear to have existed before Creation - then goes on to justify his beliefs by repetition of the single point that Creation was as described in Genesis. It is interesting that the book is presented as though the case for, and against, was made in a Court of Law, with Henry providing both sides. He certainly had an excellent knowledge of developments in Geology and Palaeontology in the mid-1800s, as evident in the first part of Omphalos. The book pleased very few, and the hostile, and indifferent, responses – especially those from friends and fellow Creationists – disappointed Henry. Fortunately, time, together with his collecting work in South Devon, brought a change of spirits.


Like many evangelical Christians, Henry Gosse felt most comfortable in the company of those with similar beliefs and, in Henry’s case, this was made more so by his having his own congregation of Brethren, to whom he preached each Sunday. His single-minded religious approach alienated the growing Edmund and relations between them became strained, as described in Edmund’s Father and Son. 3 

I sometimes wonder what would happen if I had been able to meet Henry at Livermead. I suspect I would have admired his knowledge of shore animals and plants, and also his energy and enthusiasm. No doubt, I would stop myself from discussing views on evolution, or anything that he might interpret as anti-Christian (although why should I be so cautious?). Yet, many Christians today accept evolution and have a less rigid adherence to the literal truth of The Bible, while others retain the Gosse-like position of belief in Creation over six days. I continue to find it baffling that believers in the same religion have such disparate views and that the debate that Omphalos set out to resolve (very unsuccessfully) continues today among Christians. Why is that?


1 Roger S. Wotton (2012) Walking with Gosse: Natural History, Creation and Religious Conflicts. Southampton, Clio Publishing.
2 Philip Henry Gosse (1857) Omphalos: an attempt to untie the geological knot. London, John van Voorst.
3 Edmund Gosse (1907) Father and Son. London, William Heinemann.