Nutmeg-Vertebrate Interactions in the Asia-Pacific Region: Importance of Frugivores for Seed Dispersal in Myristicaceae

Abstract

In tropical forests, large frugivores are assumed to be important seed dispersers for many large-seeded trees such as the Myristicaceae, a widespread and common family. However, not all frugivores are effective seed dispersers, and understanding which frugivores are effective is vital for conservation biology. Here, we summarize the available data on fruit characteristics and frugivores for a large number of Myristicaceae species in the Asia-Pacific region and suggest future directions for evaluating the effects of disperser loss for these trees. Studies of fruit characteristics of Myristicaceae were highly biased toward morphological information, and few studies examined reproductive phenology or fruit chemistry. We identified 338 instances of nutmeg-frugivore interactions that included 129 species of Myristicaceae and 109 species of frugivores, including 40 bird, 68 mammal, and one reptile species. Large birds were major seed dispersers for this tree family. These bird species, such as hornbills and pigeons, consumed a variety of nutmeg species, remained briefly at fruiting trees, and dispersed intact seeds far from the parent trees in the forest. Although most seeds dispersed by birds subsequently suffered high seed predation by rodents, some germinated and established as seedlings, indicating the qualitative effectiveness of large birds as seed dispersers for Myristicaceae. Mammals were also major consumers of Myristicaceae. Gibbons, macaques, and civets potentially acted as long-distance dispersers for some nutmeg species. Orangutans, leaf monkeys, squirrels, and rodents consumed a variety of nutmeg species, but their roles as seed dispersers for Myristicaceae remain unclear. Studies of nutmeg-vertebrate interactions have typically focused on frugivory, whereas few studies have specifically quantified the effectiveness of frugivores as seed dispersers; thus, it remains difficult to evaluate the effect of frugivore loss on the populations of most nutmeg species in this region. Further studies of nutmeg-frugivore interactions are of great ecological importance, and the results of such studies will contribute to a general understanding of which evolutionary forces may have shaped current nutmeg-frugivore interactions in tropical forests worldwide.

Forest cover, hunting pressure, and fruit availability influence seed dispersal in a forest‐savanna mosaic in the Congo Basin

“…Generally speaking, the lack of direct observations and data on actual seed removal events leaves uncertain the respective role of frugivore species, limiting the robustness of our conclusions. Despite these shortcomings, the studied large‐seeded tree species appears to have a highly specialized dispersal strategy, as confirmed by other studies on Myristicaceae species in Asia (Kitamura & Poonswad ), Central America (Howe & Vande Kerckhove , ), and South America (Holbrook & Loiselle , Queenborough et al . , Ratiarison & Forget , Boissier et al .…”

“…Generally speaking, the lack of direct observations and data on actual seed removal events leaves uncertain the respective role of frugivore species, limiting the robustness of our conclusions. Despite these shortcomings, the studied large-seeded tree species appears to have a highly specialized dispersal strategy, as confirmed by other studies on Myristicaceae species in Asia (Kitamura & Poonswad 2013), Central America (Howe & Vande Kerckhove 1980, 1981, and South America (Holbrook & Loiselle 2009, Queenborough et al 2013, Ratiarison & Forget 2013, Boissier et al 2014. Plants with a restricted seed disperser assemblage are known to be particularly sensitive to human disturbances (Howe et al 1985, Cordeiro & Howe 2003, Holbrook & Loiselle 2009, Uriarte et al 2011, Ratiarison & Forget 2013, especially when they have large seeds that only larger vertebrates can ingest and disseminate (Vanthomme et al 2010, Markl et al 2012.…”

Predicting Climate Change Impacts on the Rare and Endangered Horsfieldia tetratepala in China

“…The distribution area of H. tetratepala is mainly affected by the tropical monsoon climate, in which the average annual temperature is 20~25 • C and the average annual rainfall is 1500~3500 m [49]. Research has shown that the seeds of this species are mainly dispersed by frugivorous birds, mammals, some reptiles and gravity dispersal [50,51]. During a field survey in 2018, the species was found to be disappearing due to the expansion of banana and rubber cultivation and tourism development.…”

Spatial genetic structure in four understoryPsychotriaspecies (Rubiaceae) and implications for tropical forest diversity

“…Vertebrate frugivores are often presumed to carry seeds long distances (e.g., Jordano et al, 2007 ;Lees and Peres, 2009 ;Lenz et al, 2011 ), but the shape of the dispersal kernel can vary with the disperser and ecological context. Long-distance seed dispersal of hundreds to thousands of meters by birds and bats has been documented many times, especially for canopy trees (e.g., Hardesty et al, 2006 ;Seidler and Plotkin, 2006 ;Kays et al, 2011 ;Kitamura et al, 2011 ;Kitamura and Poonswad, 2013 ;Seltzer et al, 2013 ). But birds of closed-canopy understories are relatively sedentary and loath to cross water and habitat barriers ( Diamond et al, 1976 ;Moore et al, 2008 ).…”