1. In Pursuit of the 'Beetle Daisy'
I've begun this blog to document our second field season in Namaqualand, South Africa, working on the Gorteria diffusa species complex (research led by Beverley Glover and Alan Ellis). Gorteria diffusa is also called the 'Beetle Daisy' due to its unusual raised dark spots in the centre of the 'flower', which look not unlike beetles. It turns out that these spots actually look like female bee flies (Megapalpus capensis) - so much so that the male bee flies attempt to mate with the imitation females, and, in doing so, greatly increase the uptake and transfer of pollen, pollination efficiency, and presumably seed set. This is in fact the only example of sexual deceit pollination known outside of the orchids (famous for their insect mimicry). But of course its complicated - variation within Gorteria diffusa is immense, with at least 14 different floral types, only three of which are sexually deceptive. We are interested in the evolution of sexual deception - the floral spot morphology and the fly behaviour that the spot elicits. The current goal is to describe the relationships between the many floral types, and to do this we need DNA. Hence the field trip. We will be collecting tissue from hundreds of individuals from all over the Northern Cape and extracting their DNA. By comparing the DNA will we work out relationships between different flower types and begin to understand the context and heritage underlying the evolution of the sexually deceptive flower spots.
2. The Long Road
We drove about 400km today: through the Pakhuis Pass to Clanwilliam, north up the Olifants river valley past Vanrhynsdorp, east up the Bokkeveldberge escarpment to Nieuwoudtville, and finally on a long unmetalled road across the high veld to the spectacular Cederberg. Actually to be precise, Greg Mellers drove whilst I was hanging out the passenger window on flower watch. One of the tricks of roadside collecting is spotting your species of interest whilst driving above 80kph. The problem is further exacerbated because everything is flowering and there are a lot of different species of orange coloured daisies out there! It's like looking for a needle in a stack of needles. Fortunately Gorteria diffusa has a certain gestalt - the flowers are smaller, it has a low lying habit, and a singular burnt orange hue that is quite distinctive from a distance. Recent heavy rains have also led to an exceptional flowering display this year, which means Gorteria is well-represented (although a few roads were impassible). All in all though we had a succesful day - we located three of the four archetypal Nieuw floral types and added GPS data for a bunch of additional populations. Eleven hours later, with 4 herbarium specimens, 40 packets of silica dried leaf tissue, 40 fresh flowers, and over 120 photos, we are back in our little cabin taking stock. Long roads and long days. But with the reward of seeing the Southern Cross set amid a crystal clear Milky Way.
3. Crown of Kamies
Namaqualand, traditional homeland of the Nama people, lies in the northwestern corner of South Africa. The region stretches from the Namibian border in the north, to the Olifants river in the south, and from the Atlantic Ocean in the west, to Bushmanland in the east. It is arid country, and with an annual rainfall of 50-400mm almost qualifies as desert. For three quarters of the year it is hot and barren, but in winter the bulk of the precipitation arrives, partly in the form of sea fogs. Cooler temperatures mean less evaporation and with the available water comes a burst of annual plant life and intense flowering. Approximately 3,500 flowering plant species survive here and close to half of these species are endemic to the region - marking Namaqualand as one of the world's few arid biodiversity hot-spots. The diversity of life forms and strategies is truly remarkable (more on that later). Almost at the centre of Namaqualand, at the north-western tip of the Kamiesberg mountain range, lies the town of Kamieskroon or 'The Crown of Kamies'. It is here that we are based, in a disused boarding school-come-research station, perfectly positioned to access the surrounding morphotypes of Gorteria diffusa. Kamieskroon is a one horse town (without even the horse) and takes its name from a regal looking outcrop on a nearby summit. Although I personally think this rock formation looks less like a crown, and more like the fossilized deposit left by some passing canine deity.
4. Volharding
The town of Garies lies about 40km south of Kamieskroon along the Cape-Namibia route. As you enter the town you are greeted by a 'Welcome to Garies' sign, and beneath it the town's motto. It is a single word - Volharding - which in Afrikaans means perseverance. Volharding is the essential quality in this austere landscape, where life, both plant and human, clings to existence. Our work, governed by the environment and vagaries of the weather, also has its own peculiar frustrations that require perseverance. On Tuesday we struck out to find Gorteria populations along the Buffels river. And after three hours of jaw-jolting driving had only covered 30km before being forced to turn back empty-handed, lest we tore out the bottom of the car. On Wednesday a cold front brought rain and freezing temperatures - both of which pose a challenge. In hot weather Gorteria flowers open diurnally between 10am and 4pm but in cold weather the flowers do not open at all and the populations are harder to find and difficult to photograph. As luck would have it, it is now snowing which is a phenomenally rare event in this part of the world. Furthermore we need to extract DNA from the leaves we collect, and DNA is best preserved by rapid dessication of tissue in silica gel. Rain-soaked material is far from ideal. So it was I found myself in the local shop yesterday with a packet of sanitary towels in one hand and a roll of toilet paper in the other, wondering which would work best for drying Gorteria leaves in the field. I'll let you know.
5. The Spring of the Blue Wildebeest
When I was a boy my dad used to read John Buchan novels to me. Anachronistic tales of empire, they expose the now antiquated values of their time. But as great stories they are timeless. One of my favourite Buchan novels is ‘Prester John’, set in South Africa in and around the town of Blauwildebeestefontein – The Spring of the Blue Wildebeest. The name is surely fictitious, but this corner of Africa has its fair share of poetic place names. Alan Ellis named his Gorteria diffusa floral types after geographical vicinities, and as a result, obscure localities such as Oubees, Okiep, Kleinsee, Koebus and Soebatsfontein have all entered our botanical lexicon. Place names here are a mix of the Afrikaans and Khoisan languages, reflecting the competing cultural claims in the region. The turbulent contact between these cultures is nicely captured in the name Soebatsfontein or 'The Begging Spring'. It was here that an Afrikaans voortrekker and his Khoi-Khoi companion settled on the fertile lands around the spring, unaware that the waters were considered holy by the indigenous San bushmen. Angry about the desecration, the San bushmen seized the intruders and performed a sacrificial ceremony, during which the captives begged for their lives. The voortrekker died but his Khoi-Khoi companion lived to tell the tale, and so the spring was named. Soebatsfontein is also famous as the place where my left buttock accidentally made contact with the Namaqualand National Park fence. It's electrified. Somewhat stronger than your average sheep fence. They have to keep the rhinos in you see.
6. A Collection of Miniatures
When working with Gorteria populations, we adopt a hang-dog pose, scouring the surroundings for suitable specimens, and then crouching over the individual plants with lens and ruler. We are often close to the ground, but then so are many of the plants in Namaqualand. If you leave the Kamiesberg mountains, head west through Spektakle Pass and descend eight hundred metres, you reach the coastal plains. Here, the winds whistle straight off the Atlantic and the crystalline soils are baked and cooled by severe shifts in temperature. Plants on the coastal plain hug the ground, with beautiful strategies to cope in this environment. The left hand photo illustrates a species of Dorotheanthus. Each individual comprises just four tiny leaves and a single flower, its entire life cycle completed almost without casting a shadow. The central photo is of a 'curly-whirly', a bizarre leaf shape that is common in Namaqualand. Functioning as both a condenser and water slide, the leaf traps moisture from sea fogs and funnels it back to the plant's roots. And on the right, most likely some species of Oxalis. A miniature succulent that lacks the trifoliate condition, it is a far cry from our British native, Oxalis acetosella. To me it looks like a column of baby velociraptors clamouring for some regurgitated morsel. Or for a bit of maternal affection perhaps. But out on the coastal plains this seedling is very much on its own.
7. Fat Cakes
Evening meals in the research station are a good time. The kitchen becomes a place where we cook, update spreadsheets, dissect flowers, make plans, share stories and ideas, and discuss the days observations. It's an intense if unsustainable kind of scientific commune. And inevitably we talk a lot about food. Sampling of the local cuisine has been almost as rigorous and systematic as our sampling of Gorteria. The first Sunday after we arrived in Kamieskroon, the folks from the Cape Leopard Trust invited us to a braai (a barbecue). We drove to a farm east of Springbok, coralled the trucks on a vast expanse of granite next to a seasonal reservoir and spent the afternoon eating daisy-fed mutton chops, gem squash, and sweet potatoes. Courtesy of Alan Ellis we enjoyed a lamb Potjie, a sort of al fresco stew cooked in a three legged pot on the open fire. And under the expert guidance of Caroli de Waal we have sampled Springbok Jaffels (Wild Game Pasties); Droewors (dry spiced sausage); Boerewors (traditional sausage); Biltong (Beef Jerky); Sosaties (Meat on a Stick); Braaibroodjies (charcoal toasted sandwiches); Koeksisters (hot donuts twists plunged into cold syrup), Hertzoggies (a dry bakewell tart); Rusks (unsweetened biscotti), Skuinskoek (aniseed flavoured donuts); and Mrs H.S. Balls Chutney (this last with everything). But you can't be too reckless on these culinary adventures. When Greg Mellers returned from a hard days collecting the other day I was immediately struck by the expression on his face - a peculiar mix of delight, pride, self loathing, and panic. It turns out he'd eaten a Vetkoek or 'Fat Cake' for lunch. It's a large donut stuffed with curry. He purchased it in a furniture store. They microwaved it for him. Enough said really.
8. Lichen it
It was six o'clock when we came off the escarpments, heading due west, racing the sunset. We drove straight into the reflected glare of the sea and sands, through which Port Nolloth emerged mirage-like from a bank of sea fog. Built on long exhausted stocks of alluvial diamonds, Port Nolloth is attempting to survive on a diet of fishing, tourism, and the occasional Gorteria hunter. Greg Mellers counted forty De Beers employees carefully cleaning the Grazia De Beers Beachfront, but they may have been looking for the last scrapings of stones, as sunbathers are in short supply. Much of this region is diamond country, and it is the first time in the past month that I've felt uncomfortable collecting and photographing our specimens. In these exceptionally arid areas, Gorteria diffusa hugs the run-off channels and our close inspection of dry river beds understandably raised suspicion. At one site we were questioned, permits demanded, and our semi-precious envelopes of dried leaves examined with polite skepticism. But this is a beautiful corner of wilderness, where the flat coastal plains take on the soaring escarpments of the Richterveld. Here among the most northerly populations of Gorteria we were treated to a few moments of absolute silence, a shimmering blanket of stillness. And it is here that we encountered great fields of orange lichen stretching into the distance. It is the stuff of dreams. The wild hallucinations of a half-starved reindeer.
9. A Numbers Game
Our trip has ended much as it began. In rain. We've just driven the six hours from Kamieskroon to the the Cape of Good Hope, or as it is more aptly named here, the Cape of Storms. I'm sitting here thinking about the numbers; 15 morphotypes, 102 herbarium specimens, 1020 leaf samples, 2807 macro-photos, and over 4000km of road. Aside from from collecting leaves for DNA we have also been trying to quantify the traits that occur across the different morphotypes, to understand the developmental forces constraining petal spot formation. So for each morphotype we have collected and dissected 40 flowers. Each batch takes 4 hours to dissect and photograph and about the same time to measure the photgraphed traits. That's 10,515 flower measurements in total. The tools and techniques are relatively simple, but the material and numbers accumulate at an alarming rate. This translates into long evenings and late nights, labelling and re-labelling, sorting, repackaging, and entering data into spreadsheets. The period of my PhD more or less spanned the time when plant biology moved into the post-genomic era. Almost overnight it seemed, we were grappling with the promises and challenges of Big Data. But field biologists have been coping with the travails of big data for much longer. So while I've been writing mostly about the context of this trip, the romance of working in a different country, and the variety of the physical and social experience, it doesn't quite explain why we're feeling so wrung out.
10. Through the Bushmans Window
One late afternoon in the Cederberg we walked down the Brandwyn River, where San Bushman once lived in the caves and overhangs lining the valley. The San are the hunter-gatherers of Southern Africa, and one of the ancestral populations from which all modern humans are descended. They were prolific artists, and the ten sites along this river valley record their lives through cave paintings. Each site is a gallery of warriors, bowmen, shapely bottoms, dancing girls, demons, medicine men, and many kinds of animal. Most moving of all is the handprint of a young child, pressed in red ochre. It is easy to imagine the absorbed artist with an infant playing at her feet, the paw print in that carefully prepared palette, and the mother hoisting her child to the roof of the cave. But turn your back on the artwork and look through the bushman’s window. Look out on the river valley in the evening light, with its bluffs of acacia trees, sandy river beaches, and lakes teaming with water birds and small game. Think of the families of San who hunted, danced, and played on the banks of the Brandwyn River, all those years ago. Then recall the lines popularised by the great naturalist Denys Watkins-Pitchford - 'The wonder of the world, the beauty and the power, the shapes of things, their colours, lights and shades, these I saw. Look ye also while life lasts.' And I'd like to think that is what this kind of work has been about.
11. Baie Dankie
This entire trip would not have been possible without the benificence of Beverley Glover. Through her we thank the Royal Society for funding and also Sidney Sussex College, Cambridge. Many thanks to Alan Ellis for hosting us, accompanying us on several trips, and providing all the insight into the Gorteria diffusa species complex. A huge thank you to Caroli de Waal for her many kindnesses, the finer shades of Karen Blixen. And a thank you to San Parks for allowing us to stay in their facilities. If this blog has sparked your interest in the Gorteria system you should read some relevant publications from the Ellis and Glover labs (listed below). This field trip was undertaken primarily to collect material for Greg Mellers' PhD project, and you can follow updates on that here. This final image is a view of the Cederberg when driving in the early evening from Nieuwoudtville to Pakhuis Pass.
- Ellis AG & SD Johnson. 2009. The evolution of floral variation without pollinator shifts in Gorteria diffusa (Asteraceae). American Journal of Botany 96 (4): 793-801.
- Thomas MM, PJ Rudall, AG Ellis, V Savolainen and BJ Glover 2009. Development of a complex floral trait: The pollinator-attracting petal spots of the beetle daisy, Gorteria diffusa (Asteraceae) American Journal of Botany 96 (12): 2184-2196.
- Ellis AG & SD Johnson. 2010. Floral mimicry enhances pollen export: the evolution of pollination by sexual deceit outside of the Orchidaceae. American Naturalist. 176 (5): E143-E151.
- Ellis AG & SD Johnson 2012 Lack of floral constancy by bee fly pollinators: implications for ethological isolation in an African daisy. Behavioral Ecology
- Ellis AG*, Brockington SF*, de Jager ML*, Mellers G, Walker RH, Glover BJ (2014) Floral trait variation and integration as a function of sexual deception in Gorteria diffusa Philosophical Transactions of the Royal Society B 369: 20130563 [joint first author]
