Archive for June, 2007

Our latest paper has now been accepted for publication by the French ecological journal View et Milieu. It is the latest in a series of three that uses the Chowdhury Ecosystem Model (see Appendix 1) to examine an important problem in evolutionary ecology, i.e., the niche breadth-latitude hypothesis, according to which greater species numbers in the tropics are correlated with narrower niches. The Chowdhury Ecosystem Model permits simulations over evolutionary (millions of years) and much shorter ecological time scales. It is agent based, i.e., each individual is treated separately with its own random birth and death, instead of by a differential equation describing how the total number of individuals changes with time. Sometimes, differential equations can give qualitatively wrong results compared to the more realistic individual treatment. In physics, such agent-based simulations have been used for half a century as “Molecular Dynamics” or “Monte Carlo”. Monte Carlo simulations are also important tools in biology.

The Abstract of the paper follows.

Habitat width along a latitudinal gradient
D. Stauffer, C. Schulze, K. Rohde

Abstract
We use the Chowdhury ecosystem model, one of the most complex agentbased ecological models, to test the latitude-niche breadth hypothesis, with regard to habitat width, i.e., whether tropical species generally have narrower habitats than high latitude ones. In two previous studies using the Chowdhury Model, we have shown that simulations result in faster speciation in the tropics and in latitudinal diversity gradients, that the complexity of foodwebs increases with time and at higher rates in the tropics (Rohde & Stauffer 2005), and that latitudinal ranges of species are greater in the tropics, contradicting Rapoport’s rule (Stauffer & Rohde 2006). In this paper we show that the Chowdhury Model does not support the latitude-niche breadth hypothesis for the niche dimension habitat width: habitats, measured by comparing species numbers in small and large areas at a particular locality, are generally wider and not narrower in the tropics. This hypothesis cannot, therefore, give a causal explanation of latitudinal gradients in species diversity

One reads quite frequently in the press that Muslim women who committed adultery are stoned to death etc. etc. I always thought that such instances in some backward countries were more a tribal than a religious tradition.

The following two reports, one referring to Sunni, the other to Shiite customs, are of interest in this context.

1) Sunni Islam. According to the German news magazine Der Spiegel, 26.2.07, the Grand Mufti of Egypt, Ali Gumaa, the highest religious authority in Egypt, issued a fatwa on one of the most important TV shows, according to which a woman who had lost her hymen before marriage, can be restored to virginity surgically. However, the woman should keep quiet about it to her future husband: “ If God had wished that we know everything about each other, he would have made as all clairvoyants”. And if a woman commits adultery, but regrets her deed and asks God for forgiveness, she shall keep quiet it about it to her husband, in order to preserve peace in the family. This led to a heated controversy in the conservative Egyptian society, but the Mufti’s position was supported by Mohammed Schama, Professor for Islamic sciences at the Azhar University (the most important Sunni University): “These rules are not new, it is all written in the books”; and the Mufti had supported his fatwa with sayings of the Prophet. The Mufti stressed that “bawdy” (unzüchtige) girls had a right to a second chance.

2) Shiite Islam. According to a BBC News report (2.6.07, extracts):

“Iran’s Interior Minister, Mostafa Pour-Mohammadi (a cleric), has started promoting temporary marriage as a solution to the country’s social problems. Shia Islam allows a man and woman to marry for a fixed period of time, ranging from an hour to a century. A man can also have any number of temporary marriages - or sigheh, as they are known.

However, Iranian society still looks down on temporary marriage as a cover for prostitution. He said there needed to be a cultural change to allow this.

Iran first started promoting temporary marriage as an alternative to living in sin 15 years ago. The then President, Hashemi Rafsanjani, said it was a way for men and women to satisfy their sexual needs.

He even said there was no need for a cleric: the couple could read out an oath in private in order to marry. These days, some girls who want to travel with their boyfriends and be allowed to stay in the same hotel room or avoid arrest by the moral police might have a temporary marriage.”