A growing body of evidence suggests that plants alter their chemical composition in relation to the amount of incoming solar radiation (“insolation“) they are exposed to during life. Chemical changes are induced in order to provide protection against the deleterious effects of ultraviolet (UV) radiation; a relatively small, but important component of the total solar spectrum. UV radiation is linked with a range of detrimental biological effects, primarily stemming from damaged DNA. As sessile organisms, plants need to employ various mitigation mechanisms to prevent/reduce damage induced by UV radiation. Such mechanisms include effective DNA repair pathways, physiological adaptations, and UV-absorbing compounds. It is this last mechanism, UV-absorbing compounds (UACs), that is discussed here.
Lycopodium spore chemistry can be divided into two distinct groups; aliphatic components and phenolic components.
The course provided an introduction to the methods, guidance as to when to use the techniques and then outlined the assumptions, limitations and strengths of the various methods. The need to fully understand the techniques applied before attempting to critically evaluate the results was also strongly emphasised.
The course consisted of lectures covering measures of dispersion, cluster analysis, dendrograms, regression analysis, tree models, gradient analysis, transfer functions, time series and hypothesis testing. Afternoon practical computer classes involved using R, C2 and CANOCO to implement the various techniques covered in the lectures.
Overall the course was a great introduction to statistical analysis which I would certainly recommend for anybody working with complex and noisy datasets. In the next few days I will be using my newly learnt R skills to run indirect gradient analysis such as PCA, CA, DCA and NMDSCAL to search for environmental gradients within my data.
Numerical Analysis of Biological and Environmental Data training couse is an annual event and was held at UCL, on 14-25th May 2012. For more information about the course see Gavin’s website or read his blog From the bottom of the heap.
COMMENT ON THE USE OF NITROGEN ISOTOPES IN PALAEOLIMOLOGICAL STUDIES As a component of my doctoral research, I am examining nitrogen (N) isotopes within sediments obtained from Lake Bosumtwi (West Africa). Below I review and comment on the key uses and limitations of using N isotopes to interpret past environmental change with particular reference to lake sediments. Discussion is based on the key text by Talbot (2001).
Talbot, M.R. 2001. Nitrogen isotopes in palaeolimnology. Tracking environmental change using lake sediments. Volume 2. Physical and geochemical methods (ed. by W.M. Last and J.P. Smol), pp. 401-439. Kluwer Academic Press, Dordrecht.