Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan.
Department of Biology, Keio University, 4-1-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8521, Japan.
Sci Rep. 2022 Jun 15;12(1):9981. doi: 10.1038/s41598-022-13887-7.
Some diopsid flies have sexually dimorphic eye stalks that are assumed to require considerable nutrition for growth but are advantageous in competition and courtship. According to the handicap theory, the eye span in some dimorphic species serves as a reliable signal of individual quality to an opponent. However, it is not well understood how well eye span represents energy source storage. In this study, we focused on two species: Sphyracephala detrahens, which has weak dimorphism, and Cyrtodiopsis dalmanni, which has moderate dimorphism. We found that the eye stalks of the former species contained more fat bodies than those of the latter species. When the flies were starved, the fat body cells in the eye stalks underwent autophagy. A strong positive correlation was consistently found between eye span and starvation tolerance for S. detrahens, while a weak correlation was found for C. dalmanni. Furthermore, starvation decreased the contest winning rate between S. detrahens pairs with similar eye spans. These findings suggest that the presentation of resource holding potential may be larger than the actual storage ability and that the fidelity of nutritional storage signaling varies; the signal presented by S. detrahens is more reliable than that presented by C. dalmanni.
有些斜眼蝇的眼柄具有性别二态性，这些眼柄被认为在生长过程中需要大量的营养物质，但在竞争和求偶中具有优势。根据 handicap 理论，一些二态性物种的眼柄跨度可以作为个体质量的可靠信号传递给对手。然而，眼柄跨度在多大程度上代表能量储存源还不是很清楚。在这项研究中，我们关注了两个物种：具有较弱二态性的 Sphyracephala detrahens 和具有中等二态性的 Cyrtodiopsis dalmanni。我们发现前者的眼柄中含有比后者更多的脂肪体。当苍蝇被饥饿时，眼柄中的脂肪体细胞会发生自噬。我们发现，对于 S. detrahens，眼柄跨度与饥饿耐受性之间存在强烈的正相关关系，而对于 C. dalmanni，相关性较弱。此外，饥饿会降低具有相似眼柄跨度的 S. detrahens 对之间的比赛获胜率。这些发现表明，资源持有潜力的表现可能大于实际储存能力，并且营养储存信号的保真度不同；S. detrahens 呈现的信号比 C. dalmanni 呈现的信号更可靠。
