A picture worth forty-one words: Charles Elton, introduced species and the 1936 admiralty map of British empire shipping.
Long distance transportation of people, goods and materials serves many purposes but has unintended consequences. Retailers' point-of-origin labels attest to global movement of live plants, animals and other organisms (biota) and derivative products. Special packaging and climate controls help ensure such perishable cargos arrive at their destinations in acceptable condition. Until recently, scant attention has been paid to preventing collateral entrainment and transport of ambient biota. (1) Every transportation mode has some potential to attract and/or entrap organisms. It is thought that most organisms do not survive the move or find suitable habitat where discharged, although hard data are understandably scarce. Even the number of species imported with clear objectives in any given place remains arguable. For naturalised species, animals imported and released or plants reproducing spontaneously, points of origin range from obvious (in cases of limited distribution) to obscure. (2)
Naturalists, geographers, historians and scientists of many origins have taken interest in organisms that survived (even thrived) when released after long distance transport. Francis Bacon opened the discussion in the early 1600s by relating an anecdote from an unnamed Italian source; many accounts and analyses followed over the next four centuries, mostly organised according to taxa or locations of interest. These writings rarely became known beyond parochial boundaries. (3) Historians (by training or inclination) began tracing or inferring the origins of many domesticated plants and animals beginning in the late nineteenth century. (4) Their efforts also catered mainly to narrow interests. Historian Alfred W. Crosby achieved a kind of breakthrough with The Columbian Exchange (Westport: Greenwood Press, 1972) and Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (Cambridge University Press, 1986). Still, even Crosby's highly regarded syntheses overlooked some significant but regionally and biologically insular reviews.
A subdiscipline of ecology devoted to introduced species coalesced in the 1980s. (5) Early 'invasion biologists' relied on the 'tens rule' first proposed in 1986, a heuristic stating that roughly ten per cent of introduced species [those transported and deposited alive] become established, and ten per cent of those go on to become pests. (6) By the tens rule, one could presumably estimate the number of introductions to a specified region as ten times the number of introduced species found established there. A quarter century after its debut, debunking the tens rule has become something of a cottage industry. But it is the case that uncountable numbers of individuals representing perhaps tens of thousands of species have been unwittingly transported about the planet. Enough have survived the process, persisted and reproduced at their sites of deposition or liberation to constitute an ongoing biogeographical revolution, suitable for cartographic depiction.
Charles Elton and British ecology
The Ecology of Invasions by Animals and Plants by Charles Sutherland Elton remains the single most celebrated account of species introductions, their outcomes and generative processes. Elton attended Oxford University (his well-connected father's alma mater) after World War I. (7) Elton read zoology under E. S. Goodrich. Family friend Julian Huxley was his primary tutor, but Elton credited his own eldest brother Geoffrey (d. 1927) as his mentor. (8) He was also influenced early on by the ideas of Oxford sociologist Alexander Carr-Saunders, American animal ecologist Victor Shelford and Norwegian zoologist Robert Collett. (9) Elton became an important figure in the 'second generation' of British ecologists, alongside (notably) botanist Arthur J. Tansley and ornithologist Max Nicholson. At Huxley's behest, Elton compiled the seminal synthetic review Animal Ecology (1927) in which he linked former and future regimes by framing ecology as 'scientific natural history'. The book remained a standard introductory text for decades, garnering praise from the likes of G. E. Hutchinson and other major ecologists to come. (10)
Elton never earned a Ph.D. But he remained at Oxford as a Lecturer, Demonstrator and Research Fellow, supervising many graduate students of his own until he retired in 1967. (11) An appreciative colleague wrote, 'His name is inseparable from the Bureau of Animal Population [an Oxford unit Elton founded], which attracted zoologists from around the world'. (12) Much of Elton's personal research focused on small mammal populations. He mapped the spread of American grey squirrels across Oxfordshire and used the advent of American muskrats in Britain to pique public interest during a 1933 BBC radio series and in a related opinion piece for The Times. (13) These may have facilitated his first outside research funding from the New York Zoological Society following the privately conducted 1931 Matamek Conference on Biological Cycles. (14) During the 1940s, while his staff and students supported Britain's war effort by killing rats, Elton worked with Tansley on formulating Britain's postwar nature conservation and research plans. (15) Each of his several books on ecological topics considered introduced species to some extent, but only The Ecology of Invasions focused on them. (16)
Among its Figures, Elton's slim, plainly alarmist Cold War popularisation included several borrowed maps illustrating the spread of pest populations via temporal isolines. To bolster his 'invasions' trope, Elton played up the similarity between such maps and those showing successions of wartime battle lines and occupation zones. (17) One map Elton mentioned briefly without reproducing it illustrated a procession of cargo ships along global sealanes. As he described it, in forty-one words, 'A government map made for one day, 7 March 1936, shows the position of every British Empire oceangoing vessel all over the world. There are 1,462 at sea and 852 in port; and this map does not include purely coasting vessels'.18 Elton did not formally cite or reference the map, but it was headed 'British Empire Shipping, 1936' and more properly titled Distribution of British Empire Shipping of and above 3,000 Tons Gross on the 7th March 1936, and Percentage of Certain Important Commodities Obtained by the United Kingdom from the Principal Regions Supplying them in 1934 (Figure 1). It is published here apparently for the first time since 1949, and referred to as 'B. R. 84', its Admiralty document number. (19)
Remaining to be seen
As an object, B. R. 84 is described in the British Library Main Catalogue as being 1465 mm by 805 mm, accompanied by a six page tabular statement. (20) It appears to consist of a Mercator base map centered approximately on the intersection of the Prime Meridian and Tropic of Cancer, depicting the outlines of continents and islands lacking internal features other than seas and major lakes. It is cropped at 76[degrees] north and 62[degrees] south latitudes, thus including all British possessions except some Canadian islands, and excluding irrelevant Arctic areas such as northern Greenland, Franz Josef Land and Severnaya Zemlya. Likewise, all of continental Antarctica and adjacent islands below the South Orkneys were omitted. Spitsbergen (Svalbard), an island figuring importantly in Elton's early personal research and his first publication mentioning species introductions, is obliterated by the heading text. No scale or compass rose appears, but the stated scale of a Mercator projection is only relevant at the equator, and orientation is self-evident. A strip five longitude degrees wide including most of New Zealand's north island, some minor Pacific islands and a slice of Siberia is duplicated at each edge of the sheet. Only the equator and fortieth (north and south) and seventieth (north) parallels are plotted across the map, as are the prime meridian and others at forty-degree intervals east and west of Greenwich. Landmasses are shaded gray except for British possessions, coloured bright red. Place names were given only for seaports harbouring British ships. The legend (placed over central Asia) is more of a caption. Individual vessels were plotted with icons signifying two ranges of displacement: '3000-10,000 [long] tons' (3048-10160 tons) or 'above 10,000 tons' displacement. At least 122 of the 1462 ships shown on the map fell into the larger displacement category. (21) Positions were approximated because the ships would be invisible if drawn proportionally to the map. In particularly crowded waters, positions would necessarily have been expediently adjusted to represent them all in the available space.
Fifty hand-lettered tables, each listing up to thirteen (of thirty-eight total) commodities are scattered around B. R. 84 in ways that more or less associate them with fifty 'principal' regions. Although none of the regions are named, some are huge (e.g., Canada exclusive of Newfoundland) and others tiny (e.g., the island of South Georgia). The commodities represent a peculiar classification system freely lumping and splitting arguably intuitive categories. For example, there are separate categories for 'butter', 'oils and fats', 'fats' and 'oil nuts', but 'fertilizers' (perhaps ranging from mined guano and saltpeter to manufactured ammonia) were undifferentiated. Each regional table includes a percentage number for each listed commodity. The smallest percentage shown for any commodity on any individual table is two per cent (as is the smallest percentage shown on a single-commodity table); the largest shown is 100 per cent. Only two listed commodities (jute and tin) total 100 per cent, suggesting that Britain's entire supply of these were imported from identified regions. Thirty more of the listed commodities have numbers totaling eighty-nine to ninety-nine percent. Two are at sixty-six percent, and the remaining three range from three to fifteen percent, but it isn't clear whether that means further imports came from non-'principal' regions, supplies were domestically produced, or both. Some, like rubber and esparto (a natural fibre), were unlikely to have domestic sources; others including wheat and maize certainly did.
Despite his lack of personal experience in marine biology, Elton suspected and others subsequently confirmed that transoceanic ships were accomplishing a great deal of long distance biotic redistribution. (22) Such transportation has occurred ever since humans took up navigation, but the taxonomic expertise needed for recognising it is much more recent. Until the nineteenth century advent of steel-hulled ships, these collateral cargoes included hull-fouling aquatics, shipboard inquilines like beetles and rodents, parasites, intestinal flora and disease organisms affecting crews and manifested live cargoes, an assortment of airborne arthropods, all else unwittingly occupying containers, commodities and crate woods and anything that could survive the rough handling of dirt and cobblestone ballast materials (most often seeds that germinated where ballast was offloaded). Steel hulls initiated the age of water ballast tanks. Water was collected along with ambient plankton and nekton. In well-used anchorages these introductions, occurring in conjunction with habitat-altering activities such as water pollution, damming, flood control, dredging and harbour improvements, led to substantial replacement of pre-existing ('native') species assemblages. An early study demonstrating the outcome of such processes reported, 'in some regions of [San Francisco] Bay, 100% of the common species are introduced, creating "introduced communities"'. (23)
The lives of B. R. 84
None of that had anything to do with the advent of B. R. 84, which illustrated the global reach of British commerce and the material dependency of the United Kingdom on its Empire. But seen in another light it made a striking argument for the idea that ocean-going ships had permanently connected once insular hemispheres, waters, continents and islands. Charles Elton gave no reasons for describing rather than reproducing B. R. 84, either in the text of The Ecology of Invasions or in his other surviving writings, but a few may be surmised. Firstly, because the original map was a full size chart, larger than a modern 'A0' sheet, very little detail would be discernible if it were reduced to fit the octavo format of the book. However, such concerns notably failed to deter Elton's publishers from reproducing another map--his Figure 2--in hopelessly illegible form. (24) Secondly, most of B. R. 84's text was (at best) irrelevant, distracting and potentially even counterproductive to Elton's purpose. He meant to paint modern oceangoing transportation as a problem, not demonstrate its contribution to material wellbeing. In any case, his forty-one word summary seems woefully inadequate. In fact, a thirty-six word version had been struck out of the script of Elton's March 1957 BBC Radio lecture 'The Invaders', the first of three Third Programme talks that eventually formed the nucleus of the book. (25)
Given the terseness of his 1957-58 treatments, one might well wonder whether Elton had ever personally seen the map were it not for less understated remarks in a 1943 commentary so obscurely published that it was formally cited only once by Elton himself (in 1944, in a journal he edited) and once by zoologist K. A. Wodzicki (in a 1950 report). (26) During World War Two expatriate Polish academics sheltering in Britain produced a series of booklets collectively titled Polish Science and Learning. So as to 'contribute something now towards maintaining the concept of international cooperation in science after the war is over', Elton submitted an essay titled 'The Changing Realms of Animal Life' including these remarks:
The continental faunas are no longer cut off from communication with one another. For example, a chart issued by the British Government in 1937 showing the exact position of every unit of British Empire shipping on March 7, 1934 [sic], gives a vivid impression of the immense transport streams constantly crossing the world: on this chart were 1,462 vessels at sea, besides 143 on coasting and other service, and 410 in harbour, making a total of 2015 vessels. We know that each of these would have in it a semi-permanent fauna of lower animals such as insects and spiders, and growing on its outer hull a selected sample of marine animal life, among which would cluster attendant species. (27)
Overall, Elton's writings suggest a broadly educated, imaginative and articulate mind at work. Neither description of this map shows him at his best. 'Immense transport streams' is a peculiar metaphor; why not rivers? Why not highways, bridges or trails of ants, imagery familiar to almost any reader. He could have called attention to the effects of an inexorable succession of loadings and unloadings at major ports. He could have used the whole system to better effect than the cumbersome metaphor of tanks, valves and tubes appearing later in the book. (28) He could have emphasised that in 1936, British-flagged shipping comprised about forty-seven per cent of the global fleet, so the actual number of cargo ships at sea was over twice that pictured, and military ships brought the total even higher. (29) He could have pointed out using then-readily available sources that by 1955 the global commercial fleet included nearly 32,500 registered vessels, over twenty times as many as had been depicted on B. R. 84. (30)
Effectively forgotten except for Elton's remarks, B. R. 84 may have been conceived as the first in a series. A similar plotting undertaken for 24 November 1937, this time using supposedly concurrent commodity data, was published in 1938 as B. R. 135. In 1941 Life Magazine published a heavily redacted version of B. R. 84 (devoid of tables, dates and legend) to illustrate an anonymous article titled 'The Battle for Britain'. (31) According to its accompanying caption, a 'similar' map (thus perhaps a version of either B. R. 84 or the more recent B. R. 135) was also displayed at the 1939 New York World's Fair. There is no evidence that the Admiralty published further maps of the kind during the ensuing war, or that the series was revived after 1945.
In 1949 Harvard geographer Edward L. Ullman displayed a greatly reduced, black-and-white version of B. R. 84 when proposing 'to devise some method of mapping accurately the flow of ocean trade in order to provide (1) an indicator of economic circulation on the earth, and (2) a useful tool for "taking the pulse" of world trade and movement'. (32) An appended editor's note apologised for the 'possible poor reproduction' of 'the large original'. No published responses to Ullman's proposal have come to light, nor did he ever accomplish that particular goal, but mapping commerce interested him for the rest of his career. (33)
A swan song of sorts occurred during a session of the House of Lords on 2 December 1974 when the [sixth] Earl of Harrowby asked whether Her Majesty's Government would 'consider bringing out a modern edition of Chart B. R. 84'. In answer, Lord Winterbottom stated that the cost of publishing such another such chart 'would not be justified in the present circumstances'. (34) Winterbottom did not elaborate, but 'stagflation' exacerbated by the first OPEC oil price shock was crippling the economy, public spending was at an all-time high, and Wilson's Labour government was already cancelling some defence contracts. (35)
In the twenty-first century every registered commercial ship and many private pleasure craft carry Global Positioning System transponders. Such satellite-facilitated communication enables constant contact with their home bases, but also allows online services such as MarineTraffic.com to generate global maps pinpointing nearly 40,000 vessels in something close to real time. In the interwar era such a feat required extensive post-facto data collection and manual drafting. B. R. 84 was published in July 1937, several months after its title date. Why go to the trouble of producing such a document at all? Mainly, perhaps, for its propaganda value. Sorting out all the intended messages and audiences in detail exceeds the scope of this paper. It can be said that British shipping and shipbuilding during the interwar period were complicated by treaty obligations, commercial competition and the ongoing obsolescence of external combustion (coal-fired steam) engines. Failing to keep up in any of these matters would have unwelcome consequences. Maritime historian Greg Kennedy summarised it succinctly: 'For Britain, her merchant marine represented a crucial strategic and economic lifeline over which military reserves and materials were transported to and from the far reaches of the empire. Just as important, this strategic resource transported the vital goods and material Britain required to maintain one of the world's strongest economies and to obtain the raw materials which fed a modern industrial society'. (36) With the Merchant Marine Act of 1936, the United States was embarking on a program of reform and expansion that the British saw as a threat to their traditional (if fading) domination of oceangoing cartage. (37) And as noted, by 1936 the seeds of World War Two had plainly sprouted in Asia and were germinating in Europe. Military and commercial shipping and shipbuilding were intimately linked by subsidies and policies that effectively allowed rapid nationalisation of private fleets for transporting troops and materiel. Perhaps it wasn't coincidental that the title date chosen for B. R. 84, 7 March 1936, was the day Germany abrogated the treaties of Versailles and Locarno by remilitarising the Rhineland. (38) Similarly, B. R. 135 commemorated the date a Brussels conference of the 1922 'Nine Power Treaty' nations, aimed at ending the Sino-Japanese War, adjourned without achieving its purpose. (39)
B. R. 84 was invested with explicit and tacit meanings that enrich our understanding of transportation history. Charles Elton found additional meaning as incidental to the map's original purposes as redistribution of marine biota was to the activity it depicted. Elton, a pioneer of animal ecology and science-based nature conservation, could have made much better use of B. R. 84 even without benefit of hindsight. That he did not is a small, incidental mystery of his career. But like most prior accounts of introduced species, including some written by Elton himself, The Ecology of Invasions itself was an incidental work, a detour from its author's main ecological interests, an itch he finally had to scratch. (40) It was written hurriedly, as if to clear his desk and mind of accumulated debris; and entertainingly, but certainly less coherently and deeply considered than his 1967 magnum opus, The Pattern of Animal Communities. As he confided to an American protege: 'I did the broadcasts I sent you copies of; am now turning that stuff into a 45,000-word heavily illustrated book for Methuens which I shall have written in nine weeks, ten days more to go, mostly about invasions and ecological interspersion, etc'. (41) In that context, perhaps forty-one words were all Elton felt he could spare.
Matthew K. Chew
Arizona State University
(1) The apt term 'ambient biota' is uncommon in the relevant literature but seems to have been introduced in C. Kleinstreuer, Theoretical Analysis and Two-Dimensional Computer Model of Passive Biota Entrainment at Cooling Water Intakes of Power Plants. Doctoral Dissertation (Nashville, Vanderbilt University, 1977).
(2) For the elaborate case of a many-named, pan-Caribbean medicinal and ornamental shrub that might have originated on the tropical American mainland, any of various island groups, or even in Africa, see L. L. Schiebinger, Plants and Empire: Colonial Bioprospecting in the Atlantic World (Harvard University Press, 2004).
(3) M. K. Chew, 'Invasion Biology: Historical Precedents', in D. Simberloff and M. Rejmanek (eds), Encyclopedia of Biological Invasions (Berkeley, University of California Press, 2011), pp. 369-75.
(4) Prominent among these works were F. J. F. Meyen's Grundriss der Pflanzengeographie (Berlin, Hande und Spenersche, 1836); Charles Pickering's The Geographical Distribution of Animals and Plants (Boston, Little-Brown, 1854); Victor Hehn's Kulturpflanzen und Haustiere in ihrem Ubergang aus Asien nach Griechenland und Italien sowie das iibrige Europa (Berlin, G. Borntraeger, 1870); and Alphonse de Candolle's Origine des Plantes Cultivees (Paris, G. Bailliere, 1883).
(5) M. A. Davis, 'Invasion Biology 1958-2005: The pursuit of science and conservation', in M. W. Cadotte, S. M. McMahon and T. Fukami (eds), Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature (Dordrecht, Springer, 2006).
(6) See, e.g. M. H. Williamson and K. C. Brown, 'The Analysis and Modelling of British Invasions', Philosophical Transactions of the Royal Society of London B 314 (1986), 505-22; also M. H. Williamson and A. Fitter, 'The varying success of invaders', Ecology, 77:6 (1996), 1661-6.
(7) D. N. Smith, 'Elton, Oliver (1861-1945)', rev. Rebecca Mills, Oxford Dictionary of National Biography (Oxford University Press, 2004).
(8) K. Paviour-Smith, 'Elton, Charles Sutherland (1900-91)', Oxford Dictionary of National Biography (Oxford University Press, 2004).
(9) P. Anker, Imperial Ecology: Environmental Order in the British Empire (Cambridge, MA, Harvard University Press, 2001); P. Crowcroft, Elton's Ecologists: A History of the Bureau of Animal Population (Chicago, University of Chicago Press, 1991).
(10) R. P. McIntosh, The Background of Ecology: Concept and Theory (Cambridge University Press, 2000), p. 89.
(11) P. Crowcroft, Elton s Ecologists.
(12) D. Chitty, Do Lemmings Commit Suicide? Beautiful Hypotheses and Ugly Facts (Oxford University Press, 1996), p. 19.
(13) M. K. Chew, Ending with Elton: Preludes to Invasion Biology. Doctoral Dissertation (Tempe, Arizona State University, 2006), p. 126.
(14) Ibid., pp.118-20. One of Elton's objectives on the Matamek trip was to meet with New York Zoological Society factotum Madison Grant (remembered for pioneering species conservation but also his notorious racist manifesto The Passing of The Great Race)to discuss a proposal submitted earlier the same year. Grant could not attend the conference, but his lieutenant Reid Blair did, and a deal was struck to underwrite Elton's Bureau of Animal Population at Oxford.
(15) S. Bocking, Ecologists and Environmental Politics: A History of Contemporary Ecology (New Haven, Yale University Press, 1997), pp. 29-30.
(16) Chew, 'Invasion Biology: Historical Precedents'.
(17) Chew, Ending with Elton, p. 255-8.
(18) C. S. Elton, The Ecology of Invasions by Animals and Plants (London, Methuen), p. 29.
(19) 'B. R. 'stands for 'Books of Reference', applied to declassified or unclassified publications.
(20) The 'tabular statement' was not consulted.
(21) Vessel icons were not counted for this article to determine the exact number depicted.
(22) J. T. Carlton. 'The inviolate sea? Charles Elton and biological invasions in the world's oceans', in D. M. Richardson (ed.), Fifty Years of Invasion Ecology: The Legacy of Charles Elton (Chichester, Wiley-Blackwell, 2011), pp. 25-34.
(23) A. N. Cohen and J. T. Carlton, Biological Study: Nonindigenous Aquatic Species in a United States Estuary. A Case Study of the Biological Invasions of the San Francisco Bay and Delta (Washington DC, US Fish and Wildlife Service and National Sea Grant College Program, 1995), p. 210.
(24) Most of the maps reproduced in The Ecology of Invasions were reduced to 114 mm wide to fit between the margins of single pages. Figures 1 and 2 came from V. B. Link, A History of Plague in the United States of America, Public Health Monograph 26 (Washington DC, US Department of Health, Education and Welfare, 1955) pp. 104 and 111. County-level shading density in the originals did not survive the reduction in scale, obscuring the critical distinction between counties with negative and positive plague survey results (only un-surveyed counties were un-shaded). See Chew, Ending with Elton, pp. 259-63.
(25) C. S. Elton, BBC Written Archives, RCont1 Talks File I 1932-62, B/C T.P. 16/3/57. An 'as broadcast' full text transcript published under the title 'When Nature Explodes' in The Listener 57 (1957), 514-15 seems to confirm the deletion.
(26) Chew, Ending with Elton, p. 79. The citing publications were K. A. Wodzicki, Introduced Mammals of New Zealand: An Economic and Ecological Survey (Wellington, DSIR, 1950); and C. S. Elton, 'The Biological Cost of Modern Transport', The Journal of Animal Ecology 13:1 (1944), 87-8.
(27) C. S. Elton, 'The Changing Realms of Animal Life', Polish Science and Learning No.2 (1943), 7-11.
(28) Elton, The Ecology of Invasions, p. 51.
(29) A. H. Haag, 'Ocean-going Tonnage 1914-39: Growth and Development of the Merchant Marine in International Trade', Pacific Marine Review 36:11 (1939), 23-5.
(30) Statistical Abstract of the United States 1956 (Washington, DC, US Department of Commerce, 1956), p. 600.
(31) Anonymous. 'Battle of the Atlantic: America moves in to help Britain as the struggle for the seaways begins', Life Magazine 10:2 (24 March 1941), 27-31.
(32) E. L. Ullman, 'Mapping the World's Ocean Trade: A Research Proposal', The Professional Geographer 1:2 (1949), 19-22.
(33) C. D. Harris, 'Edward Louis Ullman, 1912-76', Annals of the Association of American Geographers 67 (1977), 595-600.
(34) Great Britain, House of Lords Debates, 2 December 1974, Vol. 355, c56WA.
(35) N. Woodward, The Management of the British Economy, 1945-2001 (Manchester University Press, 2004).
(36) G. Kennedy, 'American and British Merchant Shipping: Competition and Preparation 193-39' in G. Kennedy (ed.), The Merchant Marine in International Affairs, 1850-1950 (London, Frank Cass, 2000), p. 107.
(37) E. Gibson, The AbandonedOcean: A History of UnitedStates Maritime Policy (Columbia, University of South Carolina Press, 2000), pp. 126 ff.
(38) J. N. Henderson, 'Hitler and The Rhineland, 1936: A Decisive Turning Point', History Today 42:10 (1992), 15-21.
(39) US Department of State, Peace and War: United States Foreign Policy, 1931-41. Publication 1983 (Washington, DC, US Government Printing Office, 1943), pp. 393-4.
(40) Chew, Ending with Elton, pp. 175-208
(41) Letter, C. S. Elton to R. S. Miller, 26 May 1957. C. S. Elton Papers, Oxford Bodleian Library MS.eng.c.3333.E.28.
Matt Chew is an ecologist and historian of biology, biogeography and nature conservation. He focuses primarily on the development and deployment of ideas regarding biogeographical belongingness and the putatively denaturing effects of human agency on biota and 'natural systems'. His work has previously appeared in the major scientific journals Science and Nature, and various specialist journals and anthologies. This paper elaborates on a vignette from his 2006 doctoral dissertation Ending with Elton: Preludes to Invasion Biology. For further information see http://asu.academia. edu/MattChew.
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|Author:||Chew, Matthew K.|
|Publication:||The Journal of Transport History|
|Date:||Dec 1, 2014|
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