Interaction network between frugivorous birds and zoochorous plants in cloud forest riparian strips immersed in anthropic landscapes

Worldwide,tropical montane cloud forest is one of the most important and biodiverse ecosystems;however,it is also one of those most threatened by anthropic activities.These activities lead to a fragmented,deforested landscape with narrow riparian forest strips immersed in an agricultural matrix dominated by pastures.Here,we characterize the interaction network between frugivorous birds and zoochorous plants in riparian strips of cloud forest in deforested landscapes of Central Veracruz,Mexico.To characterize the network of this mutualistic interaction,we estimated network-and species-level metrics using the Bipartite R package.Nestedness,modularity and robustness were used to describe network structure.Centrality measures of degree,closeness,betweenness centrality and their relative contribution to nestedness were used to determine the importance of each bird/plant species to the network’s structure.This interaction network has 24 species of birds and 30 species of plants,with low connectance(0.11),low nestedness(11.53),and intermediate but not significant modularity(0.49).The bird species most important to network stability were Chlorospingus flavopectus,Myadestes occidentalis,and Catharus mexicanus.The most important plants were Conostegia xalapensis,C.arborea,and Rubus ulmifolius.Network robustness varied from 0.36 to 0.86 and its stability is compromised when species of birds or plants with the highest values of centrality are removed,with plant removal more detrimental.Riparian strips of cloud forest crossing deforested areas maintain a relatively rich set of birds that disperse the seeds of many forest plants,thus they are crucial to the preservation of this mutualistic network in anthropic landscapes.Network stability is severely undermined by the loss of any of the few species—whether birds or plants—with high centrality values.The most important plants for this stability are pioneer tree and shrub species that provide food for several bird species,and they are also crucial to cloud forest regeneration.A worrisome finding is that some of the bird species most important to network stability are also among the most sought-after as ornamental birds by illegal collectors in the region.

An edible fruit from the Jurassic of China

Frugivory is an important ecological tie between animals and angiosperms.It plays an important role in the evolution of food webs and energy flow networks in the ecosystem.However,little is known about how old this relationship can be due to lack of relevant fossil evidence.Here,the authors report a fossil fruit,Jurafructus gen.nov.,a putative angiosperm from the Middle-Late Jurassic(>164 Ma)of Daohugou Village,Inner Mongolia,China,which provides the currently earliest evidence of frugivory.The fossil is a more or less three-dimensionally preserved coalified drupe that has been damaged by animals in two different ways.The pericarp,in addition to the seed coat surrounding parenchyma seed contents,is suggestive of an angiospermous affinity,as such a 3+3 structure is distinct from a three-layered seed coat in gymnosperms.The seed possesses a distal micropyle,attached on the base of the pericarp,suggestive of a former orthotropous ovule in the gynoecium.The damaged pericarp of Jurafructus suggests that firugivory can be dated back to the Middle-Late Jurassic.Apparently,the ecological relationship between angiosperms and animals extends deep into the fossil record.

Host compatibility interacts with seed dispersal to determine smallscale distribution of a mistletoe in Xishuangbanna,Southwest China

Aims Mistletoe infection between intra- and interspecific hosts can be restricted by seed dispersal, host–mistletoe compatibility and other factors, yet few studies have linked seed dispersal and seedling establishment together for understanding mistletoe plant distribution and demography together in different anthropogenic disturbance forest types at a local scale. The objectives of this study were to examine how three factors—seed disperser behavior, post-dispersal host compatibility and canopy cover—affect the spatial distribution of a generalist mistletoe Dendrophthoe pentandra (Loranthaceae) in plantation and rainforest within Xishuangbanna, Southwest China.MethodsWe observed mistletoe D. pentandra infection patterns at the scale of individual trees and sixteen 400-m2 forest plots in adjacent plantation and rainforest within Xishuangbanna. To elucidate what determines infection patterns at different scales and in different forest types, we observed the behavior of major avian seed dispersers and carried out a seed inoculation experiment to examine how post-dispersal compatibility and light incidence affect the infection of different hosts.Important FindingsDendrophthoe pentandra displayed an aggregated distribution and infected 10 species in our study site, with a significantly higher infection prevalence and intensity in the plantation than in the tropical forest. Different seed dispersers provided contrasting initial mistletoe templates: the specialist frugivore Dicaeum concolor (plain flowerpecker) preferred to fly between mistletoes in infected trees in the plantation and likely intensified existing infections. In contrast, the dietary generalist Pycnonotus jocosus(red-whiskered bulbul) was more likely to visit uninfected trees, thereby establishing new infections. Thus, seed dispersal appears to be an important determinant of the mistletoes distribution, with deposition patterns providing an initial distribution template and determining small-scale patterns. However, post-dispersal and abiotic factors revealed that different host compatibilities and levels of light incidence in different habitats affected the survival of D. pentandra seedlings. Hence, our findings suggest that seed dispersal interacts with host compatibility and canopy cover to determine establishment success, survival and the observed distribution patterns.

Bird-plant interactions and vulnerability to biological invasions

Aims Species interactions regulate the invasiveness of non-native species and as declines of native tree species escalate,exotic tree species that offer supplementary resources to animal seed-dispersers should expand their distributions as they fill ecological roles.Our primary objective was to forecast impacts from an imminent biological invasion(laurel wilt disease)by quantifying resources provided by native(threatened)and exotic fruits(disease-resistant)and associated bird foraging preferences.Methods In the southeastern USA,we tested for redundancy among the resources provided by native and exotic fruits to overwintering birds.Comparisons between abundant subcanopy species Persea borbonia(native)and Cinnamomum camphora(exotic)were paramount considering the widespread disease-induced decline of P.borbonia,and the biological and phylogenetic similarities between these species.Across two winter survey periods,we quantified fruit removal and documented bird species using motion-activated cameras in the field.Physical and chemical fruit characteristics were also quantified.Important Findings Foraging bouts on both P.borbonia and C.camphora fruits were documented for four native bird species.There was no difference in selectivity between fruit types during Year 1 of our survey,but there was a significant preference for C.camphora fruit in Year 2;the change in preference was correlated with significantly lower temperatures in Year 2.While the pulp/seed ratio and moisture content differed,the nutritional content of fruit pulp(g/100 g)was similar between fruit types.Given the apparent redundancy among these native and exotic fruit resources,we forecast increases in the consumption and dispersal of exotic propagules following the widespread laurel wilt disease-induced decline of P.borbonia and other native fruit bearing members of Lauraceae.This empirically based prediction is among the first to document exotic forest pathogens as indirect threats to native bird-plant interactions and potential facilitators of exotic plant invasion.

Florivory by the occupants of phytotelmata in flower parts can decrease host plant fecundity

Some types of plant accumulate liquid in their inflorescences creating phytotelmata.These environments protect the flowers against florivory,although they may be colonized by aquatic or semiaquatic florivorous insect larvae,whose effects on the fitness of the plants remain unclear.We tested the hypothesis of floral antagonism by the occupants of phytotelmata,which predicts that florivory by the occupants of the phytotelmata represents a cost to the female fitness of the plant,reducing its fecundity.We manipulated experimentally the infestation by 3 florivores larvae species occupants of phytotelmata in inflorescences of Heliconia spathocircinata(Heliconiaceae)to test for negative direct trophic effects on the fecundity of the flowering and fruiting bracts.We found that the foraging of the hoverfly(Syrphidae)and moth(Lepidoptera)larvae in the inflorescences contributed to a decline in the fecundity of the plant.While the lepidopteran impacted fecundity when foraging in both flowering and fruiting bracts,the syrphid only affected the fruiting bracts,which indicates that the nectar and floral tissue are the principal resource exploited by the hoverfly.By contrast,soldier fly(Stratiomyidae)had a neutral effect on fecundity,while foraging in flowering or fruiting bracts.These findings corroborate our hypothesis,that herbivory by the larval occupants represents cost to the host plant having phytotelmata.The negative influence of this foraging on plant fecundity will nevertheless depend on the consequences of the exploitation of resources,which vary considerably in ephemeral habitats such as the phytotalmanta of flower parts.

Geometric morphometrics of mandibles for dietary differentiation of Bovidae(Mammalia:Artiodactyla)

The mammalian family Bovidae has been widely studied in ecomorphological research,with important applications to paleoecological and paleohabitat reconstructions.Most studies of bovid craniomandibular features in relation to diet have used linear measurements.In this study,we conduct landmark-based geometric-morphometric analyses to evaluate whether different dietary groups can be distinguished by mandibular morphology.Our analysis includes data for 100 species of extant bovids,covering all bovid tribes and 2 dietary classifications.For the first classification with 3 feeding categories,we found that browsers(including frugivores),mixed feeders,and grazers are moderately well separated using mandibular shape.A finer dietary classification(frugivore,browser,browser-grazer intermediate,generalist,variable grazer,and obligate grazer)proved to be more useful for differentiating dietary extremes(frugivores and obligate grazers)but performed equally or less well for other groups.Notably,frugivorous bovids,which belong in tribe Cephalophini,have a distinct mandibular shape that is readily distinguished from all other dietary groups,yielding a 100%correct classification rate from jackknife cross-validation.The main differences in mandibular shape found among dietary groups are related to the functional needs of species during forage prehension and mastication.Compared with browsers,both frugivores and grazers have mandibles that are adapted for higher biomechanical demand of chewing.Additionally,frugivore mandibles are adapted for selective cropping.Our results call for more work on the feeding ecology and functional morphology of frugivores and offer an approach for reconstructing the diet of extinct bovids.

Seed dispersal in Hong Kong,China:past,present and possible futures

In the present article,published and unpublished information regarding seed dispersal in the degraded landscape of Hong Kong,China,is reviewed.Information was available for 1681 native plant species,of which 1165 were assigned to probable seed dispersal modes.Endozoochory accounted for one-third(34.4%)of all species evaluated,half(54.4%)of those from forests,and more than two-thirds(69.2%)of all trees and tall shrubs.Wind dispersal(25.9%)and dispersal by an unknown agent(30.7%)accounted for most of the rest,with the unknown species mostly small-seeded herbs.Although the frugivore fauna of the Hong Kong region has been truncated since the late Pleistocene,there are few clear examples of failed mutualisms.The most striking is the absence of scatter-hoarding rodents from Hong Kong,despite the presence of forest trees that appear to require them for effective dispersal.There are also some large Lauraceae fruits that appear to be targeted at larger-gaped birds than currently present.Most endozoochorous species are dispersed by 3 small passerine birds(Pycnonotus jocosus,P.sinensis,and Zosterops japonicus),with larger birds,fruit bats(Cynopterus sphinx,Rousettus leschenaulti),rhesus macaques(Macaca mulatta),civets(Paguma larvata,Viverricula indica),and muntjacs(Muntiacus muntjac)accounting for the remainder.The low plant diversity in frugivore droppings,seed traps,and secondary vegetation suggests plant succession may be dispersal limited,although this has not been investigated experimentally.Planting underdispersed species is the simplest solution but,in the longer term,the(re)introduction of a scatter-hoarding rodent should be considered as well as that of other locally and regionally extinct frugivores.

Bats and their vital ecosystem services:a global review

Bats play crucial ecosystem services as seed dispersers,pollinators,controllers of insects,and nutrient recyclers.However,there has not been a thorough global review evaluating these roles in bats across all biogeographical regions of the world.We reviewed the literature published during the last two decades and identified 283 relevant studies:78 dealt with the control of potential insect pests by bats,80 related to the suppression of other arthropods,60 on the dispersal of native or endemic seeds,11 dealt with the dispersal of seeds of introduced plants,29 on the pollination of native or endemic plants,1 study on pollination of introduced plants,and 24 on the use of guano as fertilizer.Our literature search showed that queries combining the terms“seed dispersal,”“insectivorous bats,”“nectarivorous bats,”“use of guano,”and“ecosystem services”returned 577 studies,but half were experimental in nature.We found that the evaluation of ecosystem services by bats has been mostly conducted in the Neotropical and Palearctic regions.To detect differences across relevant studies,and to explain trends in the study of ecosystem services provided by bats,we performed generalized linear mixed models(GLMM)fitted with a Poisson distribution to analyze potential differences among sampling methods.We identified 409 bat species that provide ecosystem services,752 insect species consumed by bats and 549 plant species either dispersed or pollinated by bats.Our review summarizes the importance of conserving bat populations and the ecological services they provide,which is especially important during the current pandemic.

Internal dispersal of seed-inhabiting insects by vertebrate frugivores:a review and prospects

The finding that some seed-inhabiting insects can survive passage through the entire digestive tract of seed-dispersing vertebrates is relatively recent,but evidence suggests that it does occur.Here,I document this phenomenon,discuss its qualitative and quantitative dimensions,and offer suggestions for further research.The few documented cases that I review include plant species belonging to different families,with varied fleshy fruit types,number of seeds per fruit and seed size.The vertebrate frugivores involved include passerines that feed on relatively small fruits,and galliforms,and perissodactyls and primates that feed on larger fruits.The seed-inhabiting insects in-volved are the larvae of seed-infesting wasps,parasitoid wasps and seed-infesting beetles.The phenomenon has been verified in open,rural ecosystems in North America and Southern Europe,and in tropical and subtropical forests in South America.These varied scenarios suggest that the qualitative dimension of the phenomenon is considerably greater than known thus far.A simple method for detecting new events is proposed.However,re-search must also focus on the identity and biology of seed-feeding insects of wild fleshy fruits and their parasitoids.High survival rates of seed-inhabiting insects after vertebrate gut passage are predominant.This phenomenon generally appears to favor insect dispersal.

Food supplementation by an invasive fleshy-fruited shrub sustains body condition of a native frugivorous bird during winter

Birds tend to adjust their behavior and physiology to changes in food availability in their environment.Season­al fluctuation of food resources may act as an energetic challenge,augmenting hypothalamus-pituitary-adre­nal axis(HPA axis)activity,leading to an increase in corticosterone concentrations and promoting the metab­olism of energy stores.Plant invasions may alter seasonal food fluctuations by providing a food supply during scarce seasons.This could attenuate the energetic challenge,reducing HPA axis activity and the metabolism of reserves.Using a system with seasonal fluctuation in food availability,we tested if fruit supplementation by the invasive fleshy-fruited Pyracantha angustifolia during the season of native fruit scarcity decreases the con­sumption of energy stores through activity attenuation of the HPA axis.We measured changes in body condition and circulating corticosterone(CORT)concentration in Turdus chiguanco occurring at sites both invaded and not invaded by P.angustifolia over 3 time periods that correspond to the periods prior to,during and after high­est fruit production of the plant.Fruit scarcity in the ecosystem appears as an energetic challenge for T.chiguan­co,given that body mass,fat score and residuals of body mass/tarsus length decreased during winter in a site not invaded by the exotic shrub.Conversely,the presence of the invasive plant seemed to attenuate the metab­olism of energetic reserves,as we did not record changes in body condition in birds inhabiting the invaded site.Unexpectedly,plasma CORT concentration did not vary between sites or periods.Further evaluation is required to elucidate how enhanced body condition,resulting from the consumption of a fleshy-fruited invasive plant,af­fects survivorship and reproductive performance in T.chiguanco.