EGRU-blog

In basketball, height gives a distinctive advantage: the big boys can play ball high up without being interfered by the ones sprattling closer to ground zero. Naturally, the height comes with the cost to maneuverability and acceleration. Besides, driving a testosterone elevating sports car is a luxury reserved for boys who never quite grew up – at least physically. And how does this all relate to science?

Well, scanning through recent literature I came across something that tickled my curiosity, probably because of my predisposition and interest on classical biogeographical rules (e.g. Bergmann’s rule, Gloger’s rule and Allen’s rule). In the pages of Fisheries Science, Japanese researchers report about a study testing assumptions critical for ‘Jordan’s Rule’ (Ando et al. 2008. Estimation of heritability and genetic correlation of number of abdominal and caudal vertebrae in masu salmon. Fisheries Science 74:293-298). I admit, this was the first time I heard about this particular rule, despite the fact that it has apparently been around for a while. Namely, the rule was formulated by D.S. Jordan already in 1892 (Jordan DS 1892. Relations of temperature to vertebrae among fishes. Proc. US Nat. Mus. 1892; 14: 107–120). According to Jordan’s rule, the vertebral number in fishes increases with latitude, and this would attributable to ambient temperatures during ontogeny of individual fishes. 

In a recent review of the topic, McDowall (2008. Jordan’s and other ecogeographical rules, and the vertebral number in fishes. J. Biogeography 35: 501-508) concludes that causes underlying Jordan’s rule remain unclear, and that ‘the question needs to be addressed at the population/species/species group scale; moreover, the lack of discrimination between environmental and inherited causes of variation adds to the complexity’. I was left wondering whether Jordan rules also among sticklebacks? He certainly ruled NBA scenes for decades.