Investment in sensory structures, testis size, and wing coloration in males of a diurnal moth species: trade-offs or correlated growth?

For dioecious animals, reproductive success typically involves an exchange between the sexes of signals that provide information about mate location and quality. Typically, the elaborate, secondary sexual ornaments of males signal their quality, while females may signal their location and receptivity. In theory, the receptor structures that receive the latter signals may also become elaborate or enlarged in a way that ultimately functions to enhance mating success through improved mate location. The large, elaborate antennae of many male moths are one such sensory structure, and eye size may also be important in diurnal moths. Investment in these traits may be costly, resulting in trade-offs among different traits associated with mate location. For polyandrous species, such trade-offs may also include traits associated with paternity success, such as larger testes. Conversely, we would not expect this to be the case for monandrous species, where sperm competition is unlikely. We investigated these ideas by evaluating the relationship between investment in sensory structures (antennae, eye), testis, and a putative warning signal (orange hindwing patch) in field-caught males of the monandrous diurnal painted apple moth Teia anartoides (Lepidoptera: Lymantriidae) in southeastern Australia. As predicted for a monandrous species, we found no evidence that male moths with larger sensory structures had reduced investment in testis size. However, contrary to expectation, investment in sensory structures was correlated: males with relatively larger antennae also had relatively larger eyes. Intriguingly, also, the size of male orange hindwing patches was positively correlated with testis size.

The weak natural law thesis and the common good

The weak natural law thesis asserts that any instance of law is either a rational standard for conduct or defective. At first glance, the thesis seems compatible with the proposition that the validity of a law within a legal system depends upon its sources rather than its merits. Mark C. Murphy has nonetheless argued that the weak natural law thesis can challenge this core commitment of legal positivism via an appeal to law’s function and defectiveness conditions. My contention in the current paper is that in order to make good on the challenge, the defender of the weak natural law thesis should appeal explicitly to the common good, understood as the principal normative reason in the political domain. In section I I outline the main implications of the weak natural law thesis and clarify a common misunderstanding regarding its explanatory role. Section II then argues for the indispensability of the common good to the natural law jurisprudential thesis on the grounds that it has an essential role to play in a natural law account of law’s defectiveness conditions and the presumptive moral obligatoriness of legal norms. Finally, in section III I examine the compatibility of a strengthened version of the weak natural law thesis with legal positivism in light of the centrality of the common good to the natural law jurisprudential position.

Book review: Hannah Murphy, The Making of International Trade Policy: NGOs, Agenda-setting and the WTO (Cheltenham, UK: Edward Elgar, 2010), 240 pp., £65.00, ISBN 978 18498 00181 (hbk).

The nexus between states,non-state actors and intergovernmental organisations is an increasingly important area in both the study and practice of global governance. Hannah Murphy makes a meaningful contribution to this area in examining the informal role of non-governmental organisations (NGOs) in relation to agenda-setting within the World Trade Organization (WTO). © Dean Coldicott, Deakin University 2012.

Empirical essays on international trade.

The thesis comprises four essays on the effects of free trade agreements and regional economic cooperation on trade flows in Africa, comparison of the effects of migration on trade in Africa and Asia, and the causal effects of service trade on service income at the cross-country level.