Interactive effects between diet and genotypes of host and pathogen define the severity of infection

Host resistance and parasite virulence are influenced by multiple interacting factors in complex natural communities. Yet, these interactive effects are seldom studied concurrently, resulting in poor understanding of host‐pathogen‐environment dynamics. Here, we investigated how the level of opportunist pathogen virulence, strength of host immunity and the host condition manipulated via diet affect the survival of wood tiger moth Parasemia plantaginis (Arctidae). Larvae from “low cuticular melanin” and “high cuticular melanin” (considered as low and high pathogen resistance, respectively) selection lines were infected with moderately and highly virulent bacteria strains of Serratia marcescens, while simultaneously manipulating host diet (with or without antibacterial compounds). We measured host survival and food preference before and after infection to test whether the larvae “self‐medicate” by choosing an anti‐infection diet (Plantago major, i.e., plantain leaf) over lettuce (Lactuca sativa). “High melanin” larvae were more resistant than “low melanin” larvae to the less virulent strain that had slower growth and colonization rate compared with the more virulent strain. Cuticular melanin did not enhance survival when the larvae were infected with the highly virulent strain. Anti‐infection diet enhanced survival of the “high melanin” but not the “low melanin” hosts. Survival was dependent on family origin even within the melanin selection lines. Despite the intrinsic preference for lettuce, no evidence of self‐medication was found. These results demonstrate that the relative benefit of host cuticular melanin depends on both diet and pathogen virulence: plantain diet only boosted the immunity of already resistant “high melanin” hosts, and cuticular melanin increased host survival only when infected with moderately virulent pathogen. Moreover, there was considerable variation in host survival between families within both melanin lines suggesting genetic basis for resistance. These results indicate that although melanin is an important predictor of insect immunity, its effect on disease outcomes greatly depends on other interacting factors.     

Agroforestry systems conserve species-rich but modified assemblages of tropical birds and bats

Although an increasing number of studies have shown that diverse, multi-strata agroforestry systems can contribute to the conservation of tropical biodiversity, there is still debate about how the biodiversity within agroforestry systems compares to that of intact forest and alternative land uses. In order to assess the relative importance of agroforestry systems for biodiversity conservation, we characterized bat and bird assemblages occurring in forests, two types of agroforestry systems (cacao and banana) and plantain monocultures in the indigenous reserves of Talamanca, Costa Rica. A total of 2,678 bats of 45 species were captured, and 3,056 birds of 224 species were observed. Agroforestry systems maintained bat assemblages that were as (or more) species-rich, abundant and diverse as forests, had the same basic suite of dominant species, but contained more nectarivorous bats than forests. Agroforestry systems also contained bird assemblages that were as abundant, species-rich and diverse as forests; however the species composition of these assemblages was highly modified, with fewer forest dependent species, more open area species and different dominant species. The plantain monocultures had highly modified and depauperate assemblages of both birds and bats. Across land uses, bird diversity and species richness were more closely correlated with the structural and floristic characteristics than were bats, suggesting potential taxon-specific responses to different land uses. Our results indicate that diverse cacao and banana agroforestry systems contribute to conservation efforts by serving as habitats to high numbers of bird and bat species, including some, but not all, forest-dependent species and species of known conservation concern. However, because the animal assemblages in agroforestry systems differ from those in forests, the maintenance of forests within the agricultural landscape is critical for conserving intact assemblages at the landscape level.     

The status of cacao (Theobroma cacao,sterculiaceae) in the western hemisphere

There are, at the present time, effectively no long-range, ongoing programs in any tropical country of the western hemisphere dedicated to the improvement of cacao (Theobroma cacao, Sterculiaceae). While some effort is currently made to obtain new acquisitions of cacao cultivars exhibiting desirable characteristics and to maintain genepools of these trees, there are few data from field trials to prove and substantiate these qualities. In addition, there is a growing concern regarding the disparities between predicted yields of cacao trees through the use of “hybrid” seed and from actual production under field conditions. This has stimulated an awareness of the current inadequate understanding of the genetics of cacao and the lack of comprehension as to which cultivars, under distinct ecological conditions, are precocious, resistant to disease, or heavy bearing, or indeed demonstrate those traits vital to the success of farming programs adapted to today’s market conditions. This paper examines the events that have led to the current status of selection, development, and breeding of cacao. Alternative approaches are suggested.     

Impact of the invasion of the imported fire ant

The impact of the imported fire ant (IFA) is complex, in large part, because several very different species of “Fire Ants” have invaded and one of these has two forms, all of which are hard to separate by the public, as well as, some investigators not focused on the ant. Each of these different “IFA” species and forms differ in their impact. Further, these ants impact a number of “things” ranging from the environment and wildlife (plants and animals) as well as people, their environment and infrastructure. In addition, they can not only lead to death of living things (including people), but they can destroy many aspects of our environment and infrastructure at the cost of millions of dollars. But there are some beneficial aspects and some people can make many thousands of dollars due to their presence. This is an attempt to look at these issues.     

Genes Acquired by Horizontal Transfer Are Potentially Involved in the Evolution of Phytopathogenicity in Moniliophthora perniciosa and Moniliophthora roreri, Two of the Major Pathogens of Cacao

Moniliophthora perniciosa and Moniliophthora roreri are phytopathogenic basidiomycete species that infect cacao causing two important diseases in this crop: “Witches’ Broom” and “Frosty Pod Rot”, respectively. The ability of species from this genus (Moniliophthora) to cause disease is exceptional in the family Marasmiaceae. Species in closely related genera including, Marasmius, Crinipellis, and Chaetocalathus, are mainly saprotrophs and are not known to cause disease. In this study, the possibility that this phytopathogenic lifestyle has been acquired by horizontal gene transfer (HGT) was investigated. A stringent genome comparison pipeline was used to identify potential genes that have been obtained by Moniliophthora through HGT. This search led to the identification of three genes: a metallo-dependent hydrolase (MDH), a mannitol phosphate dehydrogenase (MPDH), and a family of necrosis-inducing proteins (NEPs). Phylogenetic analysis of these genes suggests that Moniliophthora acquired NEPs from oomycetes, MDH from actinobacteria and MPDH from firmicutes. Based on the known gene functions and on previous studies of M. perniciosa infection and development, a correlation between gene acquisition and the evolution of the phytopathogenic genus Moniliophthora can be postulated.     

Establishing macroecological trait datasets: digitalization,extrapolation, and validation of diet preferences in terrestrial mammals worldwide

Ecological trait data are essential for understanding the broad‐scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species’ evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (“MammalDIET”). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill‐in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack‐knife approach applied to the compiled species‐level diet data) and externally (using independent species‐level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species‐level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus‐level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (“Animal”, “Mammal”, “Invertebrate”, “Plant”, “Seed”, “Fruit”, and “Leaf”) had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad‐scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa.     

Honeybee navigation: linear perception of short distances travelled

Recent evidence indicates that honeybees measure distance flown to a food source by integrating, over time, the apparent visual motion of the environment that they experience en route to the goal. Is the bee's perception of distance travelled a linear function of distance, or is it some other function? This question was investigated by training bees to fly into a tunnel and receive a food reward. The walls and floor of the tunnel were lined with a random texture, and the reward was placed at one of two fixed distances, “near” or “far”, from the tunnel entrance. The feeder containing the reward was placed in a box which could be accessed through one of two openings, one on the left side of the box, and the other on the right. When the box was at the “near” position, the reward could only be accessed through the left-hand opening; when the box was at the “far” position, the reward could only be accessed through the right-hand opening. When the trained bees were tested individually in an identical, fresh tunnel with the reward removed from the box, they showed a strong preference for the left-hand opening when tested at the “near” distance, and for the right-hand opening when tested at the “far” distance. At intermediate positions, the bees' preference for the two openings varies linearly with distance. These findings suggest that the honeybee's perception of distance travelled is linear, at least over the distances and range of image motions experienced in our experiments. The implications for navigation and for the encoding of distance information in the dance are discussed.     

No species is an island: testing the effects of biotic interactions on models of avian niche occupation

Traditionally, the niche of a species is described as a hypothetical 3D space, constituted by well‐known biotic interactions (e.g. predation, competition, trophic relationships, resource–consumer interactions, etc.) and various abiotic environmental factors. Species distribution models (SDMs), also called “niche models” and often used to predict wildlife distribution at landscape scale, are typically constructed using abiotic factors with biotic interactions generally been ignored. Here, we compared the goodness of fit of SDMs for red‐backed shrike Lanius collurio in farmlands of Western Poland, using both the classical approach (modeled only on environmental variables) and the approach which included also other potentially associated bird species. The potential associations among species were derived from the relevant ecological literature and by a correlation matrix of occurrences. Our findings highlight the importance of including heterospecific interactions in improving our understanding of niche occupation for bird species. We suggest that suite of measures currently used to quantify realized species niches could be improved by also considering the occurrence of certain associated species. Then, an hypothetical “species 1” can use the occurrence of a successfully established individual of “species 2” as indicator or “trace” of the location of available suitable habitat to breed. We hypothesize this kind of biotic interaction as the “heterospecific trace effect” (HTE): an interaction based on the availability and use of “public information” provided by individuals from different species. Finally, we discuss about the incomes of biotic interactions for enhancing the predictive capacities on species distribution models.     

Infection of non‐host model plant species with the narrow‐host‐range Cacao swollen shoot virus

Cacao swollen shoot virus (CSSV) is a major pathogen of cacao (Theobroma cacao) in Africa, and long‐standing efforts to limit its spread by the culling of infected trees have had very limited success. CSSV is a particularly difficult virus to study, as it has a very narrow host range, limited to several tropical tree species. Furthermore, the virus is not mechanically transmissible, and its insect vector can only be used with difficulty. Thus, the only efficient means to infect cacao plants that have been experimentally described so far are by particle bombardment or the agroinoculation of cacao plants with an infectious clone. We have genetically transformed three non‐host species with an infectious form of the CSSV genome: two experimental hosts widely used in plant virology (Nicotiana tabacum and N. benthamiana) and the model species Arabidopsis thaliana. In transformed plants of all three species, the CSSV genome was able to replicate, and, in tobacco, CSSV particles could be observed by immunosorbent electron microscopy, demonstrating that the complete virus cycle could be completed in a non‐host plant. These results will greatly facilitate the preliminary testing of CSSV control strategies using plants that are easy to raise and to transform genetically.     

Behavior of males in a reproductive aggregation of the banded demoiselle Calopteryx splendens (Insecta, Odonata)

The view according to which damselfly males practice two alternative reproductive tactics of access to females is critically discussed. It is widely accepted that some males (“territorial” ones) have priority as potential female partners, while others (“sneakers” or “wanderers”) are incapable of retaining an individual territory. They have a chance of mating only by intruding briefly into the area defended by a “territorial” male when a female is present there. Thus, the tactics of a “territorial” male consists in waiting for a female in its territory and copulating with it “by agreement,” whereas non-territorial males resort to forced copulations. By observation of individually marked males (48 out of 118) it was shown that every male could be regarded as “territorial” during a certain period and as a “wanderer” before and after it. Thus, no correlation between the modes of space use by a male (residence/mobility) and the characters of its external morphology and/or signal behavior appears to be possible in principle. According to the data obtained, a more plausible explanation is that the female chooses not the male but the best area for oviposition. In addition, it was ascertained that adherence to forced copulations cannot constitute successful “tactics” since they rarely result in insemination, neither by “territorial” nor “non-territorial” males. In other words, we are dealing not with certain alternative tactics (i.e., specialized adaptive mechanisms that have evolved in the species) but simply with the results of different sets of circumstances at a given moment.     

Molecular diet analysis finds an insectivorous desert bat community dominated by resource sharing despite diverse echolocation and foraging strategies

Interspecific differences in traits can alter the relative niche use of species within the same environment. Bats provide an excellent model to study niche use because they use a wide variety of behavioral, acoustic, and morphological traits that may lead to multi‐species, functional groups. Predatory bats have been classified by their foraging location (edge, clutter, open space), ability to use aerial hawking or substrate gleaning and echolocation call design and flexibility, all of which may dictate their prey use. For example, high frequency, broadband calls do not travel far but offer high object resolution while high intensity, low frequency calls travel further but provide lower resolution. Because these behaviors can be flexible, four behavioral categories have been proposed: (a) gleaning, (b) behaviorally flexible (gleaning and hawking), (c) clutter‐tolerant hawking, and (d) open space hawking. Many recent studies of diet in bats use molecular tools to identify prey but mainly focus on one or two species in isolation; few studies provide evidence for substantial differences in prey use despite the many behavioral, acoustic, and morphological differences. Here, we analyze the diet of 17 sympatric species in the Chihuahuan desert and test the hypothesis that peak echolocation frequency and behavioral categories are linked to differences in diet. We find no significant correlation between dietary richness and echolocation peak frequency though it spanned close to 100 kHz across species. Our data, however, suggest that bats which use both gleaning and hawking strategies have the broadest diets and are most differentiated from clutter‐tolerant aerial hawking species.     

A Composite Linkage Map from Three Crosses Between Commercial Clones of Cacao, Theobroma cacao L.

In this paper, we report the construction of the first composite map of cacao from linkage data of one F₂ and two F₁ mapping populations with a high number of codominant markers in common. The combination of linkage information from all three maps results in the currently most precise estimates of marker locations and distances between markers, especially in densely marked areas. JoinMap®V4 software was used for all marker quality assessment and mapping. Individual (sub-composite) maps and the composite map contained 10 major linkage groups, corresponding to the number of cacao chromosomes. Homogeneity of marker placement was very high among sub-composite maps, the composite map, and the designated “reference” map. Care was exercised in the re-creation of sub-composite maps and the composite map to include only markers with acceptable mapping quality parameters. The composite map places more markers with higher precision than any individual map. This research clearly demonstrates for the first time a very high level of marker homogeneity among commercial cacao clones compared to other species. The observed homogeneity between different maps, including the composite one, is probably due to a narrow genetic base of commercial cacao clones. Markers linked to identified quantitative trait loci (QTLs) are more likely to retain linkage in other commercial clones, rendering the QTLs in cacao potentially more stable than in other species.     

Dispersal of a Human-Cultivated Crop by Wild Chimpanzees (<Emphasis Type="Italic">Pan troglodytes verus</Emphasis>) in a Forest–Farm Matrix

With the conversion of natural habitats to farmland, nonhuman primates (hereafter primates) are increasingly exposed to agricultural crops. Although frugivorous primates are important seed dispersers that sometimes feed on agricultural fruits, evidence for dispersal of crops by primates is lacking. Here, we examine flexible feeding on cacao (Theobroma cacao) fruit and seed dispersal patterns by chimpanzees (Pan troglodytes verus) at Bossou in Guinea, and consequent cacao germination and survival. From direct observations, we confirm that cacao fruit is not an important food to chimpanzees, representing 0.23 % of focal animal feeding time. Chimpanzees ingest cacao pulp and either spit out the large seeds intact from unripe cacao fruit or swallow the seeds from ripe cacao fruits, which are consequently deposited in feces. From ecological surveys we show that chimpanzees distributed cacao extensively throughout their home range, at a mean distance of 407 m?±?SE 0.6 (N?=?90 clusters, range: 4–1130 m) from cacao plantations. As distance from the cacao plantation increased, cacao plants were more likely to survive. Other factors, including number of cacao plants in a cluster, plant height, and openness of the understory did not predict short-term cacao survival. Cacao plants within the forest did not produce fruit. By contrast, when chimpanzees deposited seeds in a plantation, cacao plants produced fruits as a result of farmers’ maintenance of the area. Our local-scale findings emphasize the complex behavioral and ecological interconnections between coexisting humans and primates in agricultural landscapes and generate interesting questions regarding primate niche construction and crop “ownership” related to who “plants” the crop.     

Spirometra species from Asia: Genetic diversity and taxonomic challenges

Despite considerable controversy concerning the taxonomy of species within the genus Spirometra, human sparganosis and spirometrosis mainly in Asia and Europe has long been confidently ascribed to Spirometra erinaceieuropaei. Recently, the mitochondrial genomes of purported “S. erinaceieuropaei”, “Spirometra decipiens” and “Spirometra ranarum” from Asia have been determined. However, it has been pointed out that the morphological criteria used for identifying these species are unsuitable and thus these identifications are questionable. In the present study, therefore, Spirometra samples from Asia were re-examined based on mitochondrial cytochrome c oxidase subunit 1 gene sequences and the identification of these species was discussed. Haplotype network and phylogenetic analyses revealed that: i) two distinct Spirometra species, Type I and Type II, are present in Asia and neither of which is close to likely European “S. erinaceieuropaei”; ii) Type I is genetically diverse and widely distributed, however Type II is known so far from Japan and Korea; iii) “S. decipiens” and “S. ranarum” reported from Asia are conspecific with Type I; iv) Type I is probably conspecific with Spirometra mansoni, and Type II may represent an undescribed species.     

Bird diversity in cacao farms and forest fragments of western Panama

Theobroma cacao plantings, when managed under the shade of rainforest trees, provide habitat for many resident and migratory bird species. We compared the bird diversity and community structure in organic cacao farms and nearby forest fragments throughout mainland Bocas del Toro, Panama. We used this dataset to ask the following questions: (1) How do bird communities using cacao habitat compare to communities of nearby forest fragments? (2) To what extent do Northern migratory birds use shaded cacao farms, and do communities of resident birds shift their abundances in cacao farms seasonally? (3) Do small scale changes in shade management of cacao farms affect bird diversity? Using fixed radius point counts and additional observations, we recorded 234 landbird species, with 102 species that were observed in both cacao and forest fragments, 86 species that were only observed in cacao farms, and 46 species that were restricted to forest fragments. Cacao farms were rich in canopy and edge species such as tanagers, flycatchers and migratory warblers, but understory insectivores were nearly absent from cacao farms. We observed 27 migratory species, with 18 species in cacao farms only, two species in forest only, and seven species that occurred in both habitats. In cacao farms, the diversity of birds was significantly greater where there was less intensive management of the canopy shade trees. Shade tree species richness was most important for explaining variance in bird diversity. Our study shows that shaded cacao farms in western Panama provide habitat for a wide variety of resident and migratory bird species. Considering current land use trends in the region, we suggest that action must be taken to prevent conversion away from shaded cacao farms to land uses with lower biodiversity conservation value.     

Effect of plant age and turfgrass competition on the efficacy of the Sclerotinia minor granular bioherbicide on broadleaf plantain and prostrate knotweed

Broadleaf plantain and prostrate knotweed are important weeds of turfgrass systems. The fungus Sclerotinia minor Jagger (IMI 344141) has been registered as a biological herbicide (Sarritor?) for dandelion (Taraxacum officinale) in Canadian turfgrass habitats. The objective of this study was to evaluate the effect of plant age and turfgrass environment on the efficacy of S. minor against two additional weeds; broadleaf plantain and prostrate knotweed. The turfgrass environment alone exerted significant reduction of above and below ground biomass of broadleaf plantain, to the same magnitude as the S. minor treatment in a grass-free environment. Prostrate knotweed biomass, however, was not reduced to this extent by competition with turfgrass. In the presence of grass, S. minor caused a significant biocontrol effect on all studied variables with more than 90% above ground damage on both weed species. Severe damage occurred on 3–6-week-old plantains with 100% above and below ground reduction, although smaller dry weight reductions were observed on older plantains. Treatment with S. minor reduced the dry matter of 3–5-week-old prostrate knotweed by 65–85%, but less damage occurred on older prostrate knotweed. The bioherbicide fungus is destructive for both species, but variation in area of contact due to different growth forms, growth rates and resource allocation patterns due to different life forms resulted in different biocontrol efficacy on the two species. Control of broadleaf plantain was effective – similar to that previously reported for dandelion – but control of prostrate knotweed was only partial.     

The Role of Parieto-Occipital Junction in the Interaction between Dorsal and Ventral Streams in Disparity-Defined Near and Far Space Processing

Neuropsychological and functional MRI data suggest that two functionally and anatomically dissociable streams of visual processing exist: a ventral perception-related stream and a dorsal action-related stream. However, relatively little is known about how the two streams interact in the intact brain during the production of adaptive behavior. Using functional MRI and a virtual three-dimensional paradigm, we aimed at examining whether the parieto-occipital junction (POJ) acts as an interface for the integration and processing of information between the dorsal and ventral streams in the near and far space processing. Virtual reality three-dimensional near and far space was defined by manipulating binocular disparity, with -68.76 arcmin crossed disparity for near space and +68.76 arcmin uncrossed disparity for near space. Our results showed that the POJ and bilateral superior occipital gyrus (SOG) showed relative increased activity when responded to targets presented in the near space than in the far space, which was independent of the retinotopic and perceived sizes of target. Furthermore, the POJ showed the enhanced functional connectivity with both the dorsal and ventral streams during the far space processing irrespective of target sizes, supporting that the POJ acts as an interface between the dorsal and ventral streams in disparity-defined near and far space processing. In contrast, the bilateral SOG showed the enhanced functional connectivity only with the ventral stream if retinotopic sizes of targets in the near and far spaces were matched, which suggested there was a functional dissociation between the POJ and bilateral SOG.     

Colletotrichum gloeosporioides s.l. associated with Theobroma cacao and other plants in Panama: multilocus phylogenies distinguish host-associated pathogens from asymptomatic endophytes

Colletotrichum interacts with numerous plant species overtly as symptomatic pathogens and cryptically as asymptomatic endophytes. It is not known whether these contrasting ecological modes are optional strategies expressed by individual Colletotrichum species or whether a species' ecology is explicitly pathogenic or endophytic. We explored this question by inferring relationships among 77 C. gloeosporioides s.l. strains isolated from asymptomatic leaves and from anthracnose lesions on leaves and fruits of Theobroma cacao (cacao) and other plants from Panamá. ITS and 5'-tef1 were used to assess diversity and to delineate operational taxonomic units for multilocus phylogenetic analysis. The ITS and 5'-tef1 screens concordantly resolved four strongly supported lineages, clades A-D: Clade A includes the ex type of C. gloeosporioides, clade B includes the ex type ITS sequence of C. boninense, and clades C and D are unidentified. The ITS yielded limited resolution and support within all clades, in particular the C. gloeosporioides clade (A), the focal lineage dealt with in this study. In contrast the 5'-tef1 screen differentiated nine distinctive haplotype subgroups within the C. gloeosporioides clade that were concordant with phylogenetic terminals resolved in a five-locus nuclear phylogeny. Among these were two phylogenetic species associated with symptomatic infections specific to either cacao or mango and five phylogenetic species isolated principally as asymptomatic infections from cacao and other plant hosts. We formally describe two new species, C. tropicale and C. ignotum, that are frequent asymptomatic associates of cacao and other Neotropical plant species, and epitypify C. theobromicola, which is associated with foliar and fruit anthracnose lesions of cacao. Asymptomatic Colletotrichum strains isolated from cacao plants grown in China included six distinct C. gloeosporioides clade taxa, only one of which is known to occur in the Neotropics.     

Genetic Structure and Molecular Diversity of Cacao Plants Established as Local Varieties for More than Two Centuries: The Genetic History of Cacao Plantations in Bahia,Brazil

Bahia is the most important cacao-producing state in Brazil, which is currently the sixth-largest country worldwide to produce cacao seeds. In the eighteenth century, the Comum, Pará and Maranhão varieties of cacao were introduced into southern Bahia, and their descendants, which are called ‘Bahian cacao’ or local Bahian varieties, have been cultivated for over 200 years. Comum plants have been used to start plantations in African countries and extended as far as countries in South Asia and Oceania. In Brazil, two sets of clones selected from Bahian varieties and their mutants, the Agronomic Institute of East (SIAL) and Bahian Cacao Institute (SIC) series, represent the diversity of Bahian cacao in germplasm banks. Because the genetic diversity of Bahian varieties, which is essential for breeding programs, remains unknown, the objective of this work was to assess the genetic structure and diversity of local Bahian varieties collected from farms and germplasm banks. To this end, 30 simple sequence repeat (SSR) markers were used to genotype 279 cacao plants from germplasm and local farms. The results facilitated the identification of 219 cacao plants of Bahian origin, and 51 of these were SIAL or SIC clones. Bahian cacao showed low genetic diversity. It could be verified that SIC and SIAL clones do not represent the true diversity of Bahian cacao, with the greatest amount of diversity found in cacao trees on the farms. Thus, a core collection to aid in prioritizing the plants to be sampled for Bahian cacao diversity is suggested. These results provide information that can be used to conserve Bahian cacao plants and applied in breeding programs to obtain more productive Bahian cacao with superior quality and tolerance to major diseases in tropical cacao plantations worldwide.     

Results of a food addition experiment in a north-central Chile small mammal assemblage: evidence for the role of "bottom-up" factors

Since 1989, effects of biotic interactions including predation and herbivory have been examined in a replicated experimental study in a north‐central Chilean semiarid thorn scrub community. Strong responses of small mammals and plants to El Niño Southern Oscillations (ENSO) have also been documented suggesting that “bottom‐up” factors related to high rainfall are important. To simulate increased primary productivity effects on small mammals, ad lib rabbit pellet additions were initiated in mid‐1997 on unfenced grids near the experimental complex. Following the 1997 El Niño event with three times normal precipitation, numbers of small mammals during pre‐addition months and the first treatment year were similar on control and food addition grids. During the second year (1998–1999), a period of severe drought, food additions had significant positive effects on numbers of two predominantly herbivorous “core” (resident) species, Octodon degus and Phyllotis darwini, and an omnivorous “quasi‐core” (resident but highly fluctuating) species, Akodon olivaceus; however, all three species declined towards the end of the second treatment year. Two “opportunistic” (temporarily resident) species, Abrothrix longipilis (an insectivore) and Oligoryzomys longicaudatus (a granivore), showed no responses to food additions. An insectivorous marsupial, Thylamys elegans (also a “core species”), had significantly lower numbers on food addition grids. Changes in body weight distributions and proportions of reproductive individuals particularly in O. degus indicate in situ responses. Whereas no differences in residency, numbers of stations visited, and trappability were observed, energy compensation ratios greater than one suggest significant immigration in the second year. Thus, food additions elicited strong responses by herbivorous/omnivorous “core” and “quasi‐core species” whereas they had no effects on “opportunistic species”. These results reinforce the view that “bottom‐up” factors influencing food availability exert prevailing control on numerically important small mammal species by temporarily increasing carrying capacity, and that “top‐down” factors (i.e., biotic interactions) become important when small mammal numbers are at or near their carrying capacity. Spatial dynamics may be important in explaining declines of species populations exhibiting initially positive responses to food additions.