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

• Published in: Ecology and evolution 2015-04, Vol.5 (8), p.1601-1608
• Main Authors: Shiel, Brett P., Sherman, Craig D. H., Elgar, Mark A., Johnson, Tamara L., Symonds, Matthew R. E.
• Format: Article
• Language: English
• Subjects: Allometry; Animal behavior; Animal reproduction; antenna size; Antennae; Breeding success; Butterflies & moths; Coloration; Competition; Correlation; Diurnal; Females; Insects; Investment; Lepidoptera; Males; Original Research; Paternity; Quality; receiver; Reproduction; sexual selection; Signal quality; signaling; Species; Sperm; Sperm competition; Testes; testis size
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.1459

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. Animals may trade‐off investment in costly morphological structures to maximise mating success and survival. We explore trade‐offs in investment in sensory structures, testes and wing colouration in the monandrous diurnal painted apple moth Teia anartoides. We find no trade‐offs but do uncover correlated investment in sensory structures, and between testes size and wing colouration.