Frugivory by three species of lizards in Madagascar: Implication for their ecological roles as seed dispersers

Animal-mediated seed dispersal, particularly endozoochory, is an important ecological process for numerous plant species. While most research on endozoochory has focused on birds and mammals, some lizards are also known to consume fruits and play a significant role in seed dispersal. However, lizards remain overlooked as frugivores and seed dispersers. To clarify the role of lizards as seed dispersers in forest ecosystems, we conducted behavioral observations and fecal analyses on three diurnal lizard species: Furcifer oustaleti, Oplurus cuvieri, and Zonosaurus laticaudatus in a tropical dry forest in Ankarafantsika National Park, northwestern Madagascar, during the wet seasons from 2022 to 2024 (two years). We also conducted germination trials on seeds defecated by F. oustaleti and O. cuvieri. We captured 89, 254, and 38 individuals of the three lizard species, and 15.8%, 20.1%, and 24.7% of the individuals had seeds in their feces, respectively. Behavioral observations and fecal analyses revealed that F. oustaleti, O. cuvieri, and Z. laticaudatus consumed fruits from 8, 18, and 8 plant species. For individuals with seeds in their feces, the mean number of defecated seeds per individual was 27.2 (range: 1–300), and we confirmed that some of these species had substantial germination rates (> 50%). Moreover, lizards tended to consume different plant species compared to the Common Brown Lemur (Eulemur fulvus), a principal seed disperser in this forest. These lizards may therefore play important roles as seed dispersers, and their contribution to forest regeneration in Madagascar should be considered.

动物介导的种子传播，尤其是内食性传播（endozoochory），是诸多植物物种不可或缺的重要生态过程。当前针对内食性传播的研究多聚焦于鸟类与哺乳类类群，尽管已有研究证实部分蜥蜴会取食果实并在种子传播中发挥关键作用，但蜥蜴作为食果动物与种子传播者的生态角色长期被学界忽视。为明确蜥蜴在森林生态系统中的种子传播功能，我们于2022年至2024年的湿季（共计两年），在马达加斯加西北部的安卡拉凡兹卡国家公园热带旱林中，对三种日行性蜥蜴——奥氏变色龙（Furcifer oustaleti）、库氏鬣蜥（Oplurus cuvieri）与宽尾带蜥（Zonosaurus laticaudatus）——开展了行为观察与粪便分析。此外，我们还对奥氏变色龙与库氏鬣蜥粪便中排出的种子开展了发芽试验。本次研究共捕获三种蜥蜴个体各89只、254只与38只，其中粪便携带种子的个体占比依次为15.8%、20.1%与24.7%。行为观察与粪便分析结果显示，奥氏变色龙、库氏鬣蜥与宽尾带蜥分别取食了8种、18种与8种植物的果实。在粪便携带种子的个体中，单只个体平均排出的种子数量为27.2粒（范围：1~300粒），且我们证实部分受试植物种子的发芽率超过50%。进一步分析发现，相较于该森林的主要种子传播者——褐狐猴（Eulemur fulvus），蜥蜴所取食的植物物种组成存在显著差异。综上，蜥蜴或可作为重要的种子传播者类群，其在马达加斯加森林植被更新中的生态贡献理应得到更多关注与考量。