Long Distance Dispersal Thwarted

"An Australian man has saved a kangaroo from drowning in shark-infested waters by using his surfboard to rescue the exhausted animal." From the Telegraph

From the Wollongong Herald

In what has been described as the biodiversity bombshell, Australian fauna are dispersing from Down-under. "We have up to 600 volunteers patrolling beaches for any fleeing kangaroos, parrots or wombats" says Eric Hedgers of Dispersal Watch. "Last month we had two successful escapees, a goanna [large lizard] and an echidna". Biologists closely monitoring the exodus believe there is an overwhelming preference for New Zealand. Mr. Hedgers seems amazed at all the media attention. "I mean it's so close, why wouldn't you disperse? It seems unusual that a small freshwater Alpine fish wouldn't cross 1000kms of deep sea and migrate up a mountain. We’re surprised this hasn't happen earlier".

However Prof. Bush from the Wellington University of Technology believes the Aussie invasion is only temporary. "They've got their minds set on South America, possibly Chile or the Amazon. A small lizard for instance could easily raft across the Pacific on the back of an otter for over six months - except Australia doesn’t have any otters". Could this mean the end for Australia's biodiversity?

Australian ornithologist, Dr. Betty Simmons has her doubts. "We'll just get all the African species". Navy officials have confirmed the sightings of three elephants and a hippo 300 kilometers off the South Australian Coast. "On the positive side this could potentially save our economy. Tourists can save time and money visiting Uluru and going on safari at the same time".

An outback filled with wildebeest, lions and giraffes have conservationists like Mr. Hedgers worried. "Can you imagine Australia without its iconic fauna?" There is however some hope. "The echidna came back after a week. I think it didn’t like the ants".

Biology & Teleology

“Met the ghost of Stephen Foster at the Hotel Paradise
This is what I told him as I gazed into his eyes:
Rooms were made for carpets,
Towers made for spires,
Ships were made for cannonades to fire off from inside them ..." (Squirrel Nut Zippers, 2002)

Findings of a recent study published in Cognition state that:

"... college-educated adults display scientifically unwarranted teleological explanations with ease. Such findings highlight the challenges faced by educators in both the life and physical sciences. The source of popular resistance to scientific ideas appears to run deep" (Kelemen & Rosset, 2009: 143).

They certainly 'run deep' in biological systematics and in the philosophy of biology as a newly published article in the Journal of Biogeography by Heads (2009) clearly demonstrates.

According to Heads, Darwin's move away from teleological argumentation was rejected by neodarwinists who preferred purpose over structure:

"... as his knowledge of biology and laws of growth deepened, Darwin learned to avoid teleology. Through this process he left his background behind and evolved into a modern (Renaissance) scientist. Nevertheless, Darwin's later work has been ignored whereas his earlier arguments have been co-opted as support for teleology, panselectionism and centre of originism." (Heads, 2009: Online)

Teleology and biology have been inseparable since Aristotle despite the attempts by Roger Bacon, Rene Descarte, Baruch Spinoza and Wolfgang von Goethe to undermine it completely. German idealists didn't help, neither did 19th century English naturalists, who like Kant sought to replace a theological or 'higher purpose' with Natural 'intention'.

Heads provides several excellent examples of natural teleology in systematic biology:

"... many features of organisms are teleological, a bird's wings are for flying; eyes are for seeing ..." (Ayala, 2004:65).

"A rock may not have a purpose but an eye does. Eyes and hands do not just happen for no reason" (Ruse, 2003:33).

Teleology, according to Heads, seems to be embraced by some philosophers of biology:

"... a vitally important tool for looking into the organic world" (Ruse, 2002: 47).

The problem of teleology is rampant in systematics and biogeography, with few opposing it and others, like Ernst Mayr, using weak arguments:

"[Mayr] recognized that the teleology in biology was a serious problem. His solution was to suggest that the modern synthesis is not really teleological, and that it uses teleological language but not teleological thinking" (Heads, 2009: Online).

I believe that Heads, like Kelemen & Rosset (2009), has pin-pointed the problem behind teleology, namely we start out as teleologists. Once we accept this fact, we have a lot of unlearning to do. I whole-heartily recommend Heads (2009) for students of systematics and biogeography.

Malte C. Ebach

References
Ayala, F.J. (2004) Design without designer: Darwin's greatest discovery. Debating design: from Darwin to DNA (ed. by W.A. Dembski and M. Ruse), pp. 55–80. Cambridge University Press, New York.
Heads, M. (2009). Darwin’s changing views on evolution: from centres of origin and teleology to vicariance and incomplete lineage sorting Journal of Biogeography DOI: 10.1111/j.1365-2699.2009.02127.x
Kelemen, D., & Rosset, E. (2009). The Human Function Compunction: Teleological explanation in adults Cognition, 111 (1), 138-143 DOI: 10.1016/j.cognition.2009.01.001
Ruse, M. (2002) Evolutionary biology and teleological thinking. Functions: new essays in the philosophy of psychology and biology (ed. by A. Ariew, R. Cummins and M. Perlman), pp. 33–62. Oxford University Press, New York.

The Dispersal Myth

Organisms disperse. We do it, birds do it, plants do it. Dispersal is a fact of life. As an unobserved mechanism that explains distribution and evolution, dispersal fails. The evidence that 'supports' hypotheses of dispersal is the same 'evidence' that discredits the same mechanism. Like any explanatory mechanism, evidence that apparently 'supports' it is the same that also supports a competing and conflicting hypothesis and so forth. Dispersal in its descriptive form (i.e., iguanas disperse within their area of distribution) can be shown empirically. Dispersal as an explanatory mechanism (i.e., iguanas dispersed to an oceanic island and subsequently evolved into a new species) is merely hearsay.

Despite its non-empirical and highly subjective nature, many still feel that dispersal is the best or unifying theory for organic distribution and subsequent evolution. However, the less evidence there is it seems, the greater validity the hypothesis gains. In the case of pan-Pacific distributions, for instance, there is little or no geological evidence to suggest what the Pacific Plate looked like 200 million years ago. Without such geological evidence, dispersalism gains greater validity as being the only possible mechanism to explain distribution. The option of not knowing how things got to where they are, or using phylogenetic patterns to retrodict former area relationships, are rarely considered. For the most part a trivial answer will suffice - How else do things get to where they are?

The introduction of the molecular clock has only increased our obsession with dispersal (see de Querioz, 2005). These 'clocks' are based on geological (i.e., palaeontological) data (i.e., the age of fossils) in order to measure divergence times. Since we will never know if we have the oldest fossil, the chance that a single fossil will tell us any more is highly unlikely. But yet proponents of the molecular clock believe it does. This reinforces what I herein term the Dispersal Myth, namely, the less data there is, the more likely things are to disperse (Figure 1).

But what if we lack data altogether, that is, we have no information regarding the organism and its distribution? Do we still speculate in a highly subjective and non-empirical manner, or do we give up this flight of fancy altogether?

This week in Astrophysics and Space Science: An International Journal of Astronomy, Astrophysics and Space Science Wickramasinghe & Wickramasinghe (2008) push the limits of the Dispersal Myth. In short they propose the hypothesis that life may have dispersed from Venus to Earth.

The thinking behind this incredulous theory (first proposed by Barber in 1963) links three ideas together:

1. The discovery of complex "molecular structures" in Martian meteorite ALH84001.
2. Possible "transfer pathways" between Venus and Earth via solar winds and;
3. The possibility that extremophilic "Venusian microbes" may form within the atmosphere of Venus.

So why resurrect something endemic to the psychedelic 60s? Namely "at the time a mechanism for aerosol transfer between the planets was not identified ...", that is, there was no satisfactory explanatory mechanism proposed at the time. In other words, the mechanism makes the theory appear real, even if evidence, in this case extremophilic "Venusian microbes, are completely missing or unknown. What is more, the theory gains acceptance because the explanatory power of the mechanism now makes the eventuality of life on Venus more likely or predictable.

The hypothesis proposed by Wickramasinghe & Wickramasinghe (2008) is extremely subjective. It puts the cart in front of the horse. It proposes a mechanism to explain data before the data even exists. Even if life was discovered on Venus, it does not make the explanatory mechanism more likely. In fact, the reverse is true. If we, for arguments sake, we investigated Venusian microbes, we would know more about their physiological limits to disperse via solar winds than if they did not exist. Therefore the possibility of microbial dispersal from one planet to another is far more likely if the evidence was non-existent.

The message in figure 1 rings loud and clear - the less data there is, more "relevant" or "likely" dispersal appears. Dispersal, as an explanatory mechanism, is highly subjective, non-empirical and is nothing more than a myth.

References
Barber, D. (1963) Perspective 5: 201–208.
de Queiroz A. (2005). The resurrection of oceanic dispersal in historical biogeography. TREE 20: 68-73.
Wickramasinghe, N.C. & Wickramasinghe, J.T. (2008) On the possibility of microbiota transfer from Venus to Earth. Astrophys Space Sci. DOI 10.1007/s10509-008-9851-2

The Enduring Legacy of Misinterpreting Darwin

Kevin Padian's (2008) claim that Charles Darwin founded the main principles of biogeography and ecology is clearly incorrect. Biogeography was alive and well long before Darwin's birth, in fact Augustin Pyramus de Candolle and Alexander von Humboldt produced the founding works of biogeography four years before Darwin was born, while the younger Alphonse Candolle and Ernst Haeckel erected the foundations for chorology and ecology in 1855 and 1861 respectively.

Prior to the publication of Origin of Species in 1859, Darwin would have had access to an extensive array of literature, including biogeographical concepts espoused by Charles Lyell, Louis Agassiz, Joseph Dalton Hooker and Phillip Lutely Sclater. Furthermore, Padain's claim that in "Darwin's day, dispersal through migration was the only mechanism thought possible for species to move among continents" (p. 633) is also erroneous as concepts such as vicariance were already in existence. Darwin's contribution to biogeography and ecology was to provide a synthesis or unifying mechanism that explains why organisms are distributed the way they are today, namely natural selection.

References
Padian, K. 2008. Darwin's enduring legacy. Nature 451: 632-634.
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