High-resolution geophysical imaging of reptile burrows (San Salvador rock iguana, The Bahamas): implications for ichnology and conservation ecology

Neoichnological research of terrestrial tracemakers in coastal settings provides important palaeoenvironmental information about their context within the subaerial facies. Here we present the first geophysical dataset of reptile burrows in a carbonate substrate and use it to help visualize parts of the burrows of the Bahamian (San Salvador) rock iguana (Cyclura rileyi). High-resolution 800 MHz ground-penetrating radar (GPR) images within an enclosure on San Salvador Island were employed to discriminate between the electromagnetic signal response from subsurface anomalies related to air-dominated voids or live animals within burrows. The dielectric contrast between the carbonate substrate and open burrows was sufficient to identify the majority of 15-20-cm-wide subsurface extensions of the inclined tunnels in the upper 30-40 cm. Whereas limestone clasts induced some interference, it is possible to differentiate their high-amplitude diffractions from those produced by the iguana burrows. Our research indicates that GPR imaging is a viable, rapid, non-invasive method of visualizing animal burrows, with implications to neoichnology, paleoichnology, and conservation ecology of semi-fossorial species. Furthermore, the critically endangered status of Bahamian land iguanas, as well as ongoing threats from natural and introduced pressures, highlights the need for research into their ichnological record.

Environmental Economics of Pollination

The pollination of crops by domesticated bees and wild pollinators is easily and often imagined as an accidental but essential process in agriculture. The notion that pollinators are overlooked despite their essential role in food production is widespread among the general public, as well as in policy debates concerning all issues related to pollinators, ranging from regulation of pesticides to conservation of habitat for wild bees, to support of beekeeping as an industry or as a hobby. Meade was the first to formalize this notion by making pollination a canonical example of beneficial externality in economics and arguing that subsidies should be established to ensure that honeybees are provided in optimal numbers to pollinate crops. In the first two decades of the 21st century, the same argument, but this time focusing on wild pollinators, has been proposed and supported by a large and growing literature in conservation ecology. However, a thorough review of contributions on the economics of pollination reveals several misconceptions behind the appealing fable of pollination externalities. The most striking rebuttal of Meade’s argument comes from the study of pollination markets, where beekeepers and crop growers engage in voluntary transactions called pollination contracts. A small economics literature formalizes the issue of incentives solved by these transactions and provides a detailed empirical analysis of many complex aspects, such as the establishment of standards for the monitoring of bee densities or the impact of seasonality of blooms and bee population dynamics on pollination prices. Outside pollination markets, economists have made rather sparse and partial contributions to several other important issues related to pollination in agriculture, such as valuation of pollination services, conservation of wild pollinators, and regulation of pesticides that impact pollinators. On these topics, studies have largely been published in non-economics journals and economists stand to make valuable contributions by applying and popularizing the concepts of incentive design, information costs, and other key insights of environmental economics in the study of pollination.

Sixty Years with the Chrysobalanaceae

A review is given of the studies of Ghillean Prance and associates on the Chrysobalanaceae over the past sixty years. This has focussed on defining the generic boundaries in the family and on monographic work with a worldwide approach to this pantropical family. The importance of field studies for work on monographs and Floras is emphasized. Monographs are still the basis for much work on conservation, ecology and economic botany and are needed as a foundation for molecular studies. The importance of being open to experimenting with new techniques and as a result being willing to change the taxonomy in accordance with new findings is demonstrated and emphasized. The twelve genera of the Chrysobalanaceae at the beginning of this career-long study have now increased to twenty-eight in order to present a much better monophyletic and evolutionary arrangement based on recent molecular evidence. In particular it was necessary to divide and rearrange the originally large genera Parinari and Licania into a number of smaller segregate genera. All known species were included in a worldwide monograph published in 2003. A brief review of the economic use for the family is given.