Eureka Tokteka – by Joh HenschelArchimedes discovered that immensity of volume and weight, give density. He expressed his Eureka, by becoming a streaker, and is now iconic for that propensity. As every Namib toktokkie knows, the solution to the puzzling quiz “why so many Tokteka?” gets its own Eureka: when newcomers come, nobody goes.
Now, seriously, why are there so many species of toktokkies in the Namib? At Gobabeb alone, there are over eighty species, and at one site on the gravel plains, forty-one species are recorded. There is usually scant water, nutrients and food in this desert. Its productivity is thus low, and so is the overall abundance of Namib organisms, though not always their diversity, such as toktokkies and some other animal groups. Over time, new species may have appeared by arriving by Desert Train over aeons of time. But then, why didn’t others disappear? The puzzle remains as to what keeps so many flightless species, all muesli-munching detritivores, together in one place.
The concept of global biodiversity had a big Eureka moment in 1859 with the publication of Charles Darwin’s “Origin of Species”, evoking natural selection. Another biodiversity Eureka came in 1967, when Robert MacArthur and Edward Wilson found that the biodiversity on islands was determined by the balance of arrival and extinction of species, depending on the degree of isolation and size of islands, as well as the complexity of their habitats.
The Namib had its biodiversity Gosh moment in 1959 when Charles Koch noticed its many toktokkie species, many more than found in other deserts. There are over 300 species in the whole Namib – a “land island” of 130 thousand square kilometres. Attributing the development of species to the Namib’s great age – 60 million years – is fair enough, as even the slowest of Desert Trains are bound to get somewhere during that time. But how come, when push comes to shove during the only-too- frequent lean times, that one or the other species is not shoved into oblivion?
Paradoxically, the Namib’s leanest times may actually help enrich its biodiversity. The toktokkie species we see today are those that have undergone many hard times in the past, when entire populations have been pushed back by extreme hunger and thirst to only a few survivors. These diehards are tough, long-lived and good at finding bits of whatever water and food can be scrounged from wherever. Crucially, they are ever ready to parent the next population boom, whenever sudden flushes of water and food occur. Then they quickly build up populations before things get lean again.
Different species have developed different ways of managing to survive when things get tough, each using its particular tricks to squeeze through the population bottlenecks, and make species richness possible. However, this richness is threatened, as those few lean survivors are easily shoved into oblivion by one particular species: Homo sapiens.
Zophosis moralesi marvels at the paradox of the Namib’s anvil of biodiversity – richness from leanness. This sudden realisation gives Moralesi impulse to streak: Eureka Tokteka.
Toktok Talkie is a popular series written by Joh Henschel – to connect for more, join Joh’s Toktok Talkie mailing list by emailing him at firstname.lastname@example.org