Megafruit and megafauna diversity are positively associated, while megafruit traits are related to abiotic factors, in Tropical Asia

Our study area encompassed the Indian subcontinent, north to tropical China and east to the Maluku Islands of Indonesia. We recorded megafruits, megafaunal animals, and other potential consumers of megafruits in these subregions. We use the term “diversity” to refer to the number of species for each of these. For each of these variables we gathered species lists from regional floras and published literature. We used personal experience and floras from across the region to identify megafruits. Our searches were exhaustive, but we could have missed a few species for which fruit trait information was not available. The criteria for inclusion were fruit width ≥40 mm (Guimarães et al., 2008) and having an edible fruit-part other than the seed. For genera with several species of megafruits, where some lacked size information, we used additional resources (internet searches, unpublished data) to obtain fruit descriptions. Sixty-nine of the 496 species of megafruits did not have fruit width information available but were included because the genera had many other megafruit species. Half of these species (N = 30) were in Rafflesia, whose dispersers are almost completely unknown (Hidayati and Walck, 2016). The presence or absence of all the megafruit species in our list was recorded for each of the 16 biogeographic subregions. The following details were recorded for the fruit when available: IUCN status, habitat type, growth form (climber, tree, palm, shrub, herb), tree height, fruit-type (berry, drupe, syncarp, syconium, capsule, pod, follicles) and fruit colour. Fruit colour was simplified to the main colour displayed (see below) and then condensed into two broad groups that reflected consumption by terrestrial, dichromatic mammals (Yokoyama et al., 2005) and megafauna (Bunney et al., 2019). Brown, green, yellow, or orange fruits were grouped as being primarily targeted towards these mammals (“megafauna-coloured”), either because the fruit had not invested resources in colours that are not perceived as distinct by dichromats, or because they had invested in odour instead (Valenta et al., 2018), or possibly because these dull colours allowed fruits to escape predation on the forest floor. The other colour grouping – red, black, purple, pink, white, and blue – were fruits that had invested in colours often associated with tetrachromatic birds and, possibly, also perceived by trichromatic primates. The measured characteristics were fruit length (longest axis) and width (second longest axis), seed length and width, and seed number per fruit. Data were collected from published floras from different subregions, journal publications, and other on-line sources (only when published information was unavailable). The references used are recorded in the database. The nomenclatures and distributions of the 495 species in our database were checked in Plants of the World Online database (POWO). Synonyms were removed and distributions changed to follow POWO in 105 of the 157 discrepancies that we observed. For the other 52 species, we followed recent publications and regional floras that were available on-line. Literature cited Bunney, K., Robertson, M. & Bond, W. (2019). The historical distribution of megaherbivores does not determine the distribution of megafaunal fruit in southern Africa. Biological Journal of the Linnean Society 128, 1039–1051. Guimarães, P. R., Galetti, M. & Jordano, P. (2008). Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate. PLoS ONE 3, e1745 (2008). Hidayati, S. N. & Walck, J. L. (2016). A review of the biology of Rafflesia: what do we know and what’s next? Bulletin Kebun Raya 9, 67–78. POWO. (2020). Plants of the World Online | Kew Science. Plants of the World Online http://www.plantsoftheworldonline.org/. Valenta, K., Kalbitzer, U., Razafimandimby, D., Omeja, P., Ayasse, M., Chapman, C. A., Nevo, O. (2018). The evolution of fruit colour: phylogeny, abiotic factors and the role of mutualists. Scientific Reports 8, 14302. Yokoyama, S., Takenaka, N., Agnew, D. W. & Shoshani, J. (2005). Elephants and Human Color-Blind Deuteranopes Have Identical Sets of Visual Pigments. Genetics 170, 335–344.

本研究的研究区域涵盖印度次大陆，北至热带中国区域，东至印度尼西亚马鲁古群岛。我们在这些子区域内记录了大型果实（megafruits）、巨型动物（megafaunal animals）以及其他潜在的大型果实取食者。本研究中，“多样性”一词指代上述各分类单元的物种数量。针对上述各变量，我们从区域植物志及已发表文献中收集了物种名录。我们结合个人研究经验与区域内各植物志，对大型果实进行了鉴定。尽管我们已开展穷尽式检索，但仍可能遗漏了部分缺乏果实性状信息的物种。
纳入标准为：果实宽度≥40mm（Guimarães等，2008），且具有除种子外可食用的果部组织。对于包含多种大型果实物种的属，若其中部分物种缺乏尺寸信息，我们会通过额外资源（网络检索、未发表数据）获取其果实描述信息。在496种大型果实物种中，有69种未提供果实宽度信息，但因对应属内存在大量其他大型果实物种而被纳入本研究。其中30种（N=30）属于大王花属（Rafflesia），其传播媒介几乎完全未知（Hidayati & Walck，2016）。
我们针对16个生物地理子区域，分别记录了本研究名录中所有大型果实物种的存在与否。若可获取相关信息，我们会记录果实的以下细节：国际自然保护联盟（IUCN）保护等级、生境类型、生长型（藤本、乔木、棕榈类、灌木、草本）、树高、果实类型（浆果、核果、聚合果、榕果、蒴果、荚果、蓇葖果）以及果实颜色。我们将果实颜色简化为其呈现的主色调（详见下文），并进一步归纳为两大类别，以对应陆生二色视觉哺乳动物（Yokoyama等，2005）及巨型动物的取食偏好（Bunney等，2019）。
棕色、绿色、黄色或橙色的果实被归为“巨型动物适配色”类，即主要针对上述哺乳动物类群：这可能是因为这类果实未演化出二色视觉者无法分辨的色彩，或是转而通过气味信号吸引传播者（Valenta等，2018），也有可能是这类暗沉色彩可帮助果实避免在林床被捕食。另一类颜色组合包括红色、黑色、紫色、粉色、白色及蓝色，这类果实的色彩通常与四色视觉鸟类相关，且可能也可被三色视觉灵长类分辨。
我们测量的性状包括：果实长度（最长轴）、果实宽度（第二长轴）、种子长度、种子宽度以及单果种子数。数据来源于不同子区域的已出版植物志、期刊文献，以及其他在线资源（仅在已发表信息不可得时使用）。本研究使用的参考文献均已收录于数据库中。
我们通过世界植物在线（Plants of the World Online, POWO）数据库，核查了本数据库中495个物种的命名与分布范围。在我们发现的157处差异中，有105处已按照POWO的标准移除了异名并修正了分布信息。剩余52个物种则参考了已公开的近期文献与区域植物志进行修正。
参考文献：
1. Bunney, K., Robertson, M. & Bond, W. (2019). 巨型草食动物的历史分布未决定南非巨型动物果实的分布. 《林奈学会生物学杂志》128, 1039–1051.
2. Guimarães, P. R., Galetti, M. & Jordano, P. (2008). 种子扩散滞后效应：重新审视已灭绝巨型动物取食的果实. 《公共科学图书馆·综合》3, e1745.
3. Hidayati, S. N. & Walck, J. L. (2016). 大王花属生物学研究综述：已知与未知. 《茂物植物园公报》9, 67–78.
4. POWO. (2020). 世界植物在线 | 邱园科学. 世界植物在线 http://www.plantsoftheworldonline.org/.
5. Valenta, K., Kalbitzer, U., Razafimandimby, D., Omeja, P., Ayasse, M., Chapman, C. A., Nevo, O. (2018). 果实颜色的演化：系统发育、非生物因子与互利共生者的作用. 《科学报告》8, 14302.
6. Yokoyama, S., Takenaka, N., Agnew, D. W. & Shoshani, J. (2005). 大象与人类红色盲二色视觉者拥有相同的视觉色素组. 《遗传学》170, 335–344.