Wagner Insa, Ganzhorn Jörg U, Kalko Elisabeth K V, Tschapka Marco
University of Ulm, Institute of Evolutionary Ecology and Conservation Genomics, Albert-Einstein-Allee 11, Ulm D-89069, Germany
University of Hamburg, Animal Ecology and Conservation, Hamburg, Germany.
J Exp Biol. 2015 Apr;218(Pt 7):1016-21. doi: 10.1242/jeb.114322.
Most frugivorous bats are efficient seed dispersers, as they typically do not damage seeds and transport them over long distances. In contrast, bats of the phyllostomid genus Chiroderma cheat fig trees by acting more as seed predators than as seed dispersers. The bats initially separate seeds from fruit pulp in the mouth. After extracting the juice from the fruit pulp, they thoroughly chew the seeds and spit out small seed fragments in a pellet. Consequently, the faeces contain almost no viable seeds. We compared the nutrient content of intact fig seeds with ejecta and faecal samples from both Chiroderma villosum and the 'conventional' frugivorous bat Artibeus watsoni. We show that C. villosum can extract nutrients from the seeds, especially protein and fat. The processing time of figs showed no significant difference between the two bat species. Food-choice experiments showed that C. villosum preferred fig species with more seeds over those with fewer seeds. This preference, in combination with the specialized seed-chewing behaviour, leads to an increased nutrient intake per fig. This unique strategy enables C. villosum to satisfy its nutritional requirements with a lower number of figs than other species, which decreases the amount of energy necessary for foraging flights as well as the predation risk during foraging.
大多数食果蝙蝠是高效的种子传播者，因为它们通常不会损坏种子，并能将种子远距离传播。相比之下，叶口蝠属的基氏蝠属蝙蝠对无花果树的行为更像是种子捕食者而非种子传播者，它们欺骗了无花果树。这些蝙蝠最初在口中将种子与果肉分离。从果肉中榨出汁液后，它们会彻底咀嚼种子，然后将小的种子碎片以粪丸的形式吐出。因此，粪便中几乎不含有 viable seeds。我们比较了完整无花果树种子与绒毛基氏蝠和“传统”食果蝙蝠沃森犬蝠的排出物及粪便样本的营养成分。我们发现，绒毛基氏蝠能够从种子中提取营养物质，尤其是蛋白质和脂肪。两种蝙蝠处理无花果的时间没有显著差异。食物选择实验表明，绒毛基氏蝠更喜欢种子较多的无花果品种，而不是种子较少的品种。这种偏好，再加上专门的种子咀嚼行为，使得每颗无花果的营养摄入量增加。这种独特的策略使绒毛基氏蝠能够用比其他物种更少的无花果来满足其营养需求，这减少了觅食飞行所需的能量以及觅食过程中的捕食风险。
