Stable isotopes

In 1999 Oecologia published a special issue dedicated to the analysis of stable isotope ratios in ecology. We have previously posted a paper by Cerling et al., in which they used these analyses to identify crop-raider and migrant individuals in an elephant population. Afterwards, Mugino Ozaki and Udayani Weeransinghe have respectively proposed the following papers:

Cerling, T.E. & Harris J.M. 1999. Carbon isotopes between diet and bioapatite in ungulate mammals and implications for ecological and paleontological studies. Oecologia 120, 347-363, and

Cerling, T.E., Harris, J.M. & Leakey, M.G. 1999. Browsing and grazing in elephants: the isotope record of modern and fossil proboscideans. Oecologia 120, 364-374.

The first paper is somewhat arid, but provides very important information on the enrichment factor of 13C for tooth enamel of ungulates and their diet accross a number of world's biomes.

In the second paper, Cerling et al. present an easier to read work in which they use 13C isotope ratios to show how the diet of current elephants is predominantely browse (rather than graze how it has been sometimes inferred from direct observation studies in savannah environs!). Subsequently they show that, however, the diet of proboscideans has been C4-dominated for most of their history until very recently (1 Ma) when they shifted towards C3 food items. Why this change?

Read the beautiful paper!

Photo: young male of Asian elephant grazing at Uda Walawa NP, Sri Lanka (by Oliphas)