recent papers
This is a test run, i.e., my first blog. I am using it to draw your attention to some recent papers on ecological/evolutionary modelling done jointly with Dietrich Stauffer of the Institute of Theoretical Physics, Universität Köln, Germany. Dietrich Stauffer is one of the leading computational physicists in the world. His “Introduction to Percolation Theory” has been cited around 4000 times. His many papers include applications of models to physics, chemistry, genetics, immunology, language evolution, geology and biology. His most recent book, published jointly with some colleagues, is on “Biology, Sociology, Geology by Computational physicists” (Elsevier 2006).
Our papers are:
Rohde, K. and Stauffer, D. 2005. Simulation of geographical trends in the Chowdhury ecosystem model. Advances in Complex Systems 8, 451-464. http://arxiv.org/q-bio/0505016
Stauffer, D and. Rohde, K. 2006. Simulation of Rapoport’s rule for latitudinal species spread. Theory in Biosciences 125, 55-65. http://arxiv.org/q-bio/0507033
Stauffer, D., Schulze C., Rohde K. submitted. Habitat width along a latitudinal gradient. View et Milieu http://arxiv.org/q-bio/0612012
In the first of these papers, we use the Chowdhury ecosystem model to analyse latitudinal gradients in species diversity. We found that complexity of foodwebs increases with time and at a higher rate at low latitudes. Keeping many niches empty makes the results correspond more closely to natural gradients.
In the second paper, we use the Chowdhury ecosystem model to test Rapoport’s rule, according to which latitudinal ranges of species are greater at high latitudes. We did not find support for the rule, in agreement with empirical studies.
In the third paper, we use the Chowdhury ecosystem model to test the latitude-niche breadth hypothesis, which explains the higher species diversity in the tropics by narrower niches there. We did not find support for the hypothesis, in agreement with some empirical studies.
I have examined the same ecological/evolutionary problems in a number of earlier papers using empirical data. References can be found at http://www-personal.une.edu.au/~krohde/
February 13th, 2007 at 9:25 am
Wow, its all so very interesting, especially to someone like myself who is NOT a science student. I probably won’t sound as academic as most but here’s my idea for what its worth! It seems that while there is so much focus on exactly what effects global warming will have and exactly where and when these disatrous events will occur that some things have not been fully considered by politicians or the general public. For example, whether human beings have created or contributed to global warming is indifferent in realising and addressing it. Politicians seem to be quibbling over the economic cost of addressing global warming, so here are some of my questions on the subject: Since we agree that global warming is real and that the conseqences will be environmentally and economically damaging, how much will tanks of breathable air/water cost in the future? Who will be able to afford it? Who will decide who distributes it? Will governments subsidise air for the poor? I have a sneaking suspicion that they will “let the market forces do their work” - a very unsettling thought if you have studied the history of market forces and the havoc they have wreaked upon millions of starving people around the world! Maybe these economists have adopted and bastardized Darwin’s thoery of evolution to include the thoughts that economics is a natural progression of evolution …”only the wealthy survive”. Strength, speed, agililty and therefore genetics, may no longer play a part in the “survival of the fittest” way of thinking. If scientists and economists and politicians are able to step outside the narrow confines of their specific research or policies, they may find that the broader picture is able to give more perspective and generally, a very useful view of what is to come down the road. I’m glad that as a scientist you are making the effort to saty in touch with “ordinary” people, it will help you stay in touch with your “humanity” and remind you why you research and work on the things you do!
February 13th, 2007 at 6:04 pm
Hello Professor, I like your posts, even though I drift across to your marine ecology work in symbiotic fashion from an arts pathway. “Latitudinal gradients in species diversity” seems to infer productivity due to heat, to these untrained eyes.
In consideration of languages analogous to species, and indigenous human cultures or communities retreating to highlands and islands, or remote desert oasis trails, can you explain for us general readers the implication/s of your critiques and other contributions to species diversity in relation to remoteness of access to predators or predatorial incursion. By the way, topographical studies in forested regions would probably indicate similar species survival rates as early human occupations of similar geographic bases. I refer to highland mammals like tree kangaroos in PNG/West Papua and Pademelons in the misty highlands (higher than 700m-750m above sea level) Border Ranges NAtional Park.
The idea here being a level of protection based on cultural laws, eg. no hunting, of that species, in a certain region. Therefore they proliferate, apparently stronger and more aware of the safety zone over time, as long as that totem protection or Conservation Zone law remains in place.
February 24th, 2007 at 12:18 pm
Helen. I appreciate your comments and sympathize with them. In any scientific statement there always is a certain margin of error. Applied to the causes of global warming, which now can be considered a certainty, humans are very likely responsible for all or most of it, although we cannot be 100% sure. Shall we wait until we are 100 % sure, that is, until the earth is devastated? It is bad enough already. And global warming must be addressed whether we are responsible for it or not. Unfortunately, many politicians are “programmed” to consider only what is good for winning the next election. And, importantly, the most influential politicians are from the wealthier countries and what happens to the billions of poorer people interests them only marginally, although there are of course exceptions.
Baz. Thanks for your comments. Latitudinal gradients in diversity are indeed also found in languages and cultural diversity in general. Just consider the hundreds of languages in Papua New Guinea and other tropical areas. I shall post my ideas on the causes of latitudinal gradients on my blog over the next week or so (”effective evolutionary time”). Just look out for it.
February 27th, 2007 at 3:33 pm
Professor, thank-you for your reply and I look forward to following the “causes of latitudinal gradients” discussion/elaboration as it unfolds for us here. I did scan through and read up some of the background material you provide on this field. I have some interest in cellular biology where growth ratios might be regulated by distinct and ongoing proportions. This interest comes out of observations of (giant?) Nautilus shells and their amazing propensity to manifest in a standard “Phi” pattern. You would know this to refer to the simple square within a rectangle in accord with the Fibonacci adding series, such that a single group of proportions 0.618034… : 1.0 : 1.618034…. and its reverse, determine involution or growth parameters.
I enjoy as a hobby observing similar growth patterns in palms, pines, other conifers, other shell-fish and such examples.
Perhaps you could indulge me, and any interested passersby, in revealing examples of this sort of ratio standardisation in the microscopic world you and your colleagues observe and analyse.
PS, in response to Helen’s post, I am reminded of the under-resourced Air Quality monitoring in regions like SE Qld with regard to air-born pollutants like Sulphur Dioxide (bad for asthma sufferers, and emitted most often by diesel-burning power stations, as happens/use to happen in factories in Brisbane). Nitrates, heavy particulates (from diesel vehicle exhausts mostly) and various chlorine-based pollutants need to be monitored more than they are in air-quality catchments. CO 2 we might recall is a big problem from the Point of View of global warming reversal or mitigation, but persistent organo-chlorine, heavy metal and other chemical pollutants in air (briefly), on land or in water bodies makes a significant contribution to the negative impacts and ecological challenges we still face, as well as potential sea-level and temperature rises. By the way, is not the replacement of disarmament with gradual rearmament (with nuclear and other globally threatening weaponry) currently a threat on a par with the unrestrained proliferation of released fossil-fuel carbons? I suggest a multi-approach and broad-spectrum awareness of global threats demanding global/regional solutions.
February 27th, 2007 at 4:17 pm
Baz. You might be interested in looking at Stephen Wolfram: A New Kind of Science 2001. On pages 421ff he describes pigmentation patterns of cone shells, which correspond almost exactly to patterns generated by cellular automata (on computers) following very simple rules. In other parts of the book he describes shapes of snail shells generated by such automata. All this means that single mutations may be responsible for differences in patterns and shapes. - Shapes and patterns of leaves also can be generated in such a way.
Concerning your comment: “….is not the replacement of disarmament with gradual rearmament (with nuclear and other globally threatening weaponry) currently a threat on a par with the unrestrained proliferation of released fossil-fuel carbons? I suggest a multi-approach and broad-spectrum awareness of global threats demanding global/regional solutions.” I totally agree. Criminal war mongering and development of “tactical” nuclear warheads, to mention only one example, may lead the earth down a path from which it will be difficult to escape. In my opinion, the way out is a gradual and general disarmament of all states. Imagine the enormous savings which could be used for eliminating poverty and social inequality, and for saving the environment. However, given who is in power and what they believe in, this sounds very much like wishful thinking.
June 22nd, 2008 at 11:10 am
National Institute Of Immunology Complex
Please keep these excellent posts coming.