Differential seed predation on two species of Arctostaphylos (Ericaceae)

Summary The fire-prone California chaparral contains two sympatric species of shrubs: Arctostaphylos glauca and A. glandulosa. A previous study showed that in a stand where both species had similar amounts of coverage, A. glauca had fewer seeds in the soil. We attempt to answer the questions: 1) Could ground-foraging seed predators produce the lower population of A. glauca seeds in the soil? 2) Do predators select fruits randomly with respect to fruit size? 3) Do the fruits of the two species differ in the proportions of fruit components (i.e. seeds, endocarp, mesocarp, and exocarp) in ways that could be important to seed predators? Predation was measured on artificial caches of fruits, for 17 weeks. Selection by predators was examined by comparing weights of fruits recovered from soil samples with newlymatured fruits on the shrubs. Fruits components were characterized by dividing fruits into 3 fractions and weighing. More fruits of A. glauca were removed from the caches. Fruits of both species recovered from the soil were lighter than those on the shrubs. The weights of seeds, stony and fleshy fruit layers were all larger in A. glauca. Within fruits of A. glandulosa, the weights of the three components, various combinations, and ratios were all significantly correlated, while in A. glauca no other component, combination of components, or ratio examined was significantly correlated with the weights of the seeds.     

Fruit Mineral Contents of Six Wild Species of the North Andean Patagonia, Argentina

The fruit mineral contents (K, Ca, Ba, Br, Zn, Co, Cr, Fe, Na, Rb, Cs, and Sr) of four native and two exotic naturalized shrubs growing in different areas of the Andean Patagonian region of Argentina were investigated. Native species Berberis darwinii, Berberis microphylla (Berberidaceae), Aristotelia chilensis (Elaeocarpaceae) and Ribes magellanicum (Saxifragaceae) produce small berries while the fruits of the exotic species Rosa rubiginosa and Rosa canina (Rosaceae) are aggregates of aquenes. They are used to prepare jams, tea, liquors, and ice creams. Native shrub fruits had higher content of Br, Zn, Co, Cr, Fe, Mo, and Na than those of the exotic naturalized species. Rosa species showed the highest contents of Ca and Ba in their fruits (the mean content doubled those of the native plant fruits). The fruit nutrient content found in the studied species was similar or higher than other values reported for fruits of temperate and tropical species in the world.     

The roles of adult and larval specialisations in limiting the occurrence of five species of Dacus (Diptera: tephritidae) in cultivated fruits

Summary The relative importance of adult preferences or specialisations of larval physiology in restricting the host range of five species of Dacine fruit flies (Diptera: Tephritidae) was examined, with particular emphasis on their utilization of cultivated fruits. The species; D. tryoni, D. jarvisi, D. cucumis, D. musae and D. cacuminatus differ widely in host range with D. tryoni being highly polyphagous while D. cacuminatus is virtually monophagous. Laboratory experiments showed that larvae of all species survived and developed in many cultivated fruits in which the specialists never occur in the field. By contrast the oviposition preferences and specificity of adult females differed widely between species. Female D. tryoni oviposited in most species of fruit. The specialised species; D. cucumis, D. musae and D. cacuminatus strongly preferred their usual hosts and would not oviposit in novel fruits even in the absence of the preferred host. In contrast, D. jarvisi consistently preferred its main native host but when this was not offered readily accepted cultivated fruits. These differences in preference are consistent with the pattern of infestation displayed by each species in the field. The study indicate that, in general, the occurrence of these species of Dacus in cultivated fruits is constrained more by the behavioural preferences of adult females than by larval specialisations. A genetic change in some aspect of host recognition or acceptance would be necessary for the specialised species to regularly infest cultivated fruits though no change in larval characteristics may be needed. As the types and concentrations of defensive secondary compounds may differ between native and cultivated fruits this conclusion cannot be extended to host shifts among native fruits.     

A field test of the directed deterrence hypothesis in two species of wild chili

The directed deterrence hypothesis posits that secondary metabolites in ripe fruit function to deter fruit consumption by vertebrates that do not disperse seeds, while not impacting consumption by those that do. We tested this hypothesis in two species of wild chilies (Capsicum spp.). Both produce fruits that contain capsaicinoids, the compounds responsible for the pungency of chilies. Previous work suggests seed-dispersing birds but not seed-destroying rodents consume chili fruits, presumably because rodents are deterred by capsaicin. However, fruit removal from chili plants by rodents and other mammals has not been previously explored. Because laboratory rodents can develop a preference for capsaicin, it is quite possible that wild rodents are natural consumers of chili fruits. We monitored the fate of 125 marked fruits of Capsicum chacoense and 291 fruits of Capsicum annuum. For both species, essentially all fruit removal occurred during the day, when rodents are inactive. Video monitoring revealed fruit removal only by birds, mostly by species known to disperse chili seeds in viable condition. Furthermore, these species are from taxonomic groups that tend to specialize on lipid-rich fruits. Both species of chili produce fruits that are unusually high in lipids (35% in C. chacoense, 24% in C. annuum). These results support the directed deterrence hypothesis and suggest that fruiting plants distinguish between seed predators and seed dispersers by producing fruits that repel the former and attract the latter.     

Two new endemic species of Myrtaceae and an anatomical novelty from the Highlands of Brazil

Campomanesia cavalcantina Soares-Silva & Proen?a and Psidium ratterianum Proen?a & Soares-Silva (Myrtaceae), two new species from the Brazilian highlands are described and illustrated. Campomanesia cavalcantina is similar to Campomanesia eugenioides (Cambess.) D. Legrand var. eugenioides, but differs from this species in being an hemixyle, by the narrow to broadly elliptic-falcate leaves 1.7 – 4.6 times as long as wide with 8 – 15 lateral veins, by the less densely glandular leaves and flowers, and by the lanceolate, c. 7 mm long bracteoles which are persistent to young fruit stage. Psidium ratterianum appears to be most closely allied to P. australe Cambess. Both species share the hemixyle habit, similar leaf shape, leaf ratio and floral morphology. P. ratterianum differs from that species by its narrow, ascendant, strongly bullate leaves, bracteoles which are persistent in the fruit, expanded, funnel-shaped stigma and smaller, elliptic fruits. Anatomically, Psidium ratterianum differs from other species of Psidium, and from other new-world Myrtaceae (Tribe Myrteae), in that the leaves are amphistomatic, a character known to occur in the Australian genus Leptospermum.     

Alyssum kaynakiae sp. nov. (sect. Gamosepalum,Brassicaceae) from southwest Anatolia,Turkey

A new species, Alyssum kaynakiae Y?lmaz, is described from southwest Anatolia, Turkey. The new species belongs to Alyssum sect. Gamosepalum (Hausskn.) T. R. Dudley. Alyssum kaynakiae is closely related to A. niveum T. R. Dudley, but differs by its biennial life form, longer ascendent stems, not imbricated linear cauline leaves and equally inflated fruits.     

Oviposition behaviour of two tephritid fruit flies,Dacus tryoni and Dacus jarvisi,as influenced by the presence of larvae in the host fruit

Summary When offered a choice, females of the fruit flies Dacus tryoni (Frogg.) and D. jarvisi (Tryon) strongly preferred to lay in fruits without larvae rather than fruits which already contained larvae. Fruits which contained even low densities of larvae, including newly hatched ones, received many fewer eggs than control fruits. This preference was not influenced by the species of larvae present in the fruits nor by the distance to uninfested fruits. Discrimination occurred when fruits with and without larvae were close together (10 cm apart) and also when they were separated by distances of about one metre. Laboratory assays suggested that the flies detect chemical changes in the fruit associated with the decomposition which accompanies larval feeding, but they do not seem to detect the larvae Perse. This behaviour may be significant when these two species utilise the same host since the species which is able to infest fruits first will reduce the availability of hosts for the other species. In contrast to many other Tephritids (e.g. Rhagoletis, Anastrepha and Ceratitis) female Dacus don't discriminate against fruits which contain eggs nor do they deposit a pheromone to deter oviposition by females that subsequently visit the fruit. An hypothesis is proposed to explain the absence of oviposition-deterring pheromones in Dacus, and their presence in many other species of Tephritidae, on the basis of differences in life history and population structure.     

Spatial distributions and clutch sizes of Drosophila species ovipositing on cherry fruits of different stages

In the aggregation theory, aggregation of eggs is one of important conditions for the coexistence of species. However, aggregation of eggs by clutch laying does not always promote coexistence, whereas aggregation of eggs by aggregated distributions of ovipositing females always has a significant contribution to the coexistence. In this study, spatial distributions of three Drosophila species across naturally occurring cherry fruits were studied with relation to their clutch sizes. Drosophila suzukii oviposited eggs mainly on fresh fruits on trees, and its eggs were randomly distributed across cherry fruits. The emergence data also indicated random spatial distributions of this species. Random egg distributions of this species are explained by random visits of females to fruits and the production of clutches of mostly single eggs. On the other hand, D. lutescens and D. rufa oviposited on fallen fruits, showed aggregated distributions in the emergence data, and frequently produced clutches of a few eggs. In these species, the degree of aggregation was usually significantly lower than the expectation based on random visits of females to fruits and their clutch sizes observed in the present experiments, indicating that their aggregation is unlikely to arise from aggregated distributions of ovipositing females. Thus, the spatial aggregation of these species does not necessarily lead to their coexistence.     

Asymmetrical Dependence Between a Neotropical Mistletoe and its Avian Seed Disperser

The degree of interdependence among interacting species has major implications for our understanding of the coevolutionary process and biodiversity maintenance. However, the mutualism strength among fruiting plants and their seed dispersers remains poorly understood in tropical ecosystems. We evaluated simultaneously the effectiveness of the avian seed dispersers of the mistletoe Struthanthus flexicaulis (Loranthaceae) and the contribution of its fruits to their diets in a highland rocky savanna in southeastern Brazil. The mistletoe fruits are small lipid‐rich pseudoberries available throughout the year. Four passerine birds fed on fruits, but Elaenia cristata (Tyrannidae) was the most effective disperser, responsible for more than 96 percent of the dispersed seeds. This bird swallowed fruits whole, expelling and depositing undamaged seeds by regurgitation and bill wiping on perches. From 646 dispersed seeds, 56 percent were deposited on safe sites, thin live twigs of 38 susceptible host species. Elaenia cristata were predominantly frugivorous, feeding on typically ornithocoric fruits of at least 12 species, but also on arthropods. Although fruits represented 75 percent of the feeding bouts along the year, S. flexicaulis fruits represented only 34 percent of the E. cristata diet. Our results highlight the asymmetrical nature of this mutualistic interaction, with the mistletoe life cycle locally linked to one highly effective seed disperser that is more weakly dependent on mistletoes fruits as a food source. We suggest that merging the seed dispersal effectiveness framework with diet assessment of seed dispersers is needed to clarify the asymmetries in mutualistic pairwise interactions involving plants and their animal partners.     

Petals may act as a reward: myrmecochory in shrubby Darwinia species of south‐eastern Australia

The removal rates of fruits (the diaspore) were assessed in exclusion experiments in three shrubby species of Darwinia, endemic to the Sydney Basin of south‐eastern Australia. There was a clear pattern of fruit removal in just a few days by small species of ants from the genera Iridomyrmex, Crematogaster and Pheidole. When only ants had access to fruits an average of 41% of fruits were removed, whereas when only vertebrates had access an average of 13% of fruits were removed. There was some variation in the number of fruits removed both between species and within species across study sites or annual seed crops. When ants had access to seeds this variation in removal amounted to 10–80% over 1–4 days. Uniquely in Darwinia, it is the old petals (which remain attached to the fruit) that are attractive to the ants, rather than a specific lipid body. This likely represents a case of successful ecological fitting by Darwinia to take advantage of the widespread presence of myrmecochory in the Australian flora.     

Infestation of fruit by conspecific and heterospecific females deters oviposition in two Tephritidae fruit fly species

Tephritidae fruit fly larvae develop entirely in the host chosen by the females. To improve the fitness of their progeny, females would benefit from rejecting previously exploited hosts. Anastrepha fraterculus and Ceratitis capitata are two species of fruit flies having similar nutritional requirements and overlapping in their distribution. Previous studies found that competition between the larvae of these species might reach high levels, suggesting that cross-recognition would be an adaptive trait. In this work, we tested the ability of A. fraterculus and C. capitata females to recognize and avoid fruits previously infested by both conspecific and heterospecific females. In laboratory behavioural arenas, females were presented with fruits that had been previously exposed to either conspecific or heterospecific females. Then, we conducted choice and non-choice assays to compare the response of A. fraterculus and C. capitata females to infested and non-infested fruits. In non-choice tests, the females from both species rejected fruits previously infested by conspecific and heterospecific individuals. However, the rejection occurred at different steps of the sequence leading to oviposition: A. fraterculus showed a lower rate of visits to infested fruits, whereas C. capitata visited both infested and non-infested fruits, but the latency to visit a fruit and the rejection frequency were higher and the duration of the visit to infested fruit was lower. In choice assays, the rejection of heterospecific infested fruit was higher than that of conspecific infested fruits, for both species. Our results suggest that, regardless of the sensory mechanism used by females, the recognition of previous infestation is bidirectional and females of both species, belonging to different genera, recognize fruit infested by heterospecifics. These responses indicate that cross-recognition, supposedly a highly beneficial trait, could be occurring in nature, thus reducing interspecific competition and contributing to the coexistence of these species.     

Are introduced rats (<Emphasis Type="Italic">Rattus rattus</Emphasis>) both seed predators and dispersers in Hawaii?

Invasive rodents are among the most ubiquitous and problematic species introduced to islands; more than 80% of the world’s island groups have been invaded. Introduced rats (black rat, Rattus rattus; Norway rat, R. norvegicus; Pacific rat, R. exulans) are well known as seed predators but are often overlooked as potential seed dispersers despite their common habit of transporting fruits and seeds prior to consumption. The relative likelihood of seed predation and dispersal by the black rat, which is the most common rat in Hawaiian forest, was tested with field and laboratory experiments. In the field, fruits of eight native and four non-native common woody plant species were arranged individually on the forest floor in four treatments that excluded vertebrates of different sizes. Eleven species had a portion (3–100%) of their fruits removed from vertebrate-accessible treatments, and automated cameras photographed only black rats removing fruit. In the laboratory, black rats were offered fruits of all 12 species to assess consumption and seed fate. Seeds of two species (non-native Clidemia hirta and native Kadua affinis) passed intact through the digestive tracts of rats. Most of the remaining larger-seeded species had their seeds chewed and destroyed, but for several of these, some partly damaged or undamaged seeds survived rat exposure. The combined field and laboratory findings indicate that many interactions between black rats and seeds of native and non-native plants may result in dispersal. Rats are likely to be affecting plant communities through both seed predation and dispersal.     

Digestion of fruit of invasive alien plants by three southern African avian frugivores

Many highly invasive plants are fleshy‐fruited and owe their invasiveness largely to mutualisms formed with local dispersers. The energetic benefits gained by frugivores from ingestion of fruits of invasive alien plants remain poorly documented. We assess whether avian frugivores process fruits of invasive alien plants effectively to meet their daily energetic requirements. Four fleshy‐fruited plant species that are invasive in southern Africa were considered –Solanum mauritianum, Cinnamomum camphora, Lantana camara and Psidium guajava. Their fruits were fed to three common generalist frugivores – Red‐winged Starling Onychognathus morio, Speckled Mousebird Colius striatus and Dark‐capped Bulbul Pycnonotus tricolor– to determine the efficiency of digestion. Energetic parameters calculated for all fruit diets varied significantly between frugivore species. Speckled Mousebirds and Dark‐capped Bulbuls maintained body mass and efficiently processed all four fruit types, whereas Red‐winged Starlings only did so on C. camphora and S. mauritianum diets. These results explain why these fruits are attractive to local avian frugivores. Furthermore, these avian frugivores processed large quantities of invasive fruits, thereby serving as potentially efficient dispersers.     

FOSSIL CERATOPHYLLUM (CERATOPHYLLACEAE) FROM THE TERTIARY OF NORTH AMERICA

Fossil fruits and a vegetative axis assignable to the extant genus Ceratophyllum are described from four North American Tertiary localities. Fossil fruits assignable to the extant species C. muricatum and C. echinatum are reported from the Eocene Green River and Claiborne formations, and the Miocene Esmerelda Formation, respectively. An extinct species, C. furcatispinum, is described from the Paleocene Fort Union Formation and represents the oldest published report of Ceratophyllum in the fossil record. The existence of extant angiosperm species in the Eocene is very unusual and may be attributable in this case to slow evolutionary rates and unusual evolutionary properties associated with hydrophily in the genus Ceratophyllum.     

Olfactory response of three parasitoid species (Hymenoptera: Braconidae) to volatiles of guavas infested or not with fruit fly larvae (Diptera: Tephritidae)

The olfactory responses of the native parasitoids Doryctobracon areolatus (Szépligeti) and Asobara anastrephae (Muesebeck) and of the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) to guava (Psidium guajava L.) infested or not with fruit fly larvae were evaluated. D. areolatus and D. longicaudata females responded to the odors of uninfested rotting guavas, although D. areolatus was also attracted to fruits at the initial maturation (turning) stage. The females of these species recognized the volatiles of guavas containing Ceratitis capitata (Wied.) larvae. However, in bioassays involving fruits with larvae of different instars, D. longicaudata females were not able to separate between fruits containing C. capitata larvae at the initial instars and larvae at the third instar. In the evaluations of volatiles released by guavas containing C. capitata and Anastrepha fraterculus (Wied.) larvae, the D. longicaudata females were oriented toward the volatiles of fruits containing both host species, but differed significantly from volatiles of guavas containing C. capitata larvae. The D. areolatus females also showed responses to both species, although with a preference for volatiles of fruits containing A. fraterculus larvae. The A. anastrephae females were oriented toward the odors of fruits infested with both fruit fly species. In the shade house, D. longicaudata females were oriented to volatiles of rotting fruits containing larvae or not, but could not significantly differentiate between hosts. D. areolatus females were not attracted toward fruits on the ground in the shade house, regardless of host, suggesting that this parasitoid does not forage on fallen fruits.     

Breeding site specificity in the domestic species of Drosophila

Summary The emergences of domestic Drosophila species from fruits and vegetables in a market are analysed by partitioning the species diversity. Confidence limits are determined for the components of diversity.Despite some coexistence of different species within the same breeding site, ecological differences between them are revealed. Partitioning of the breeding sites is more important than partitioning of the season. D. melanogaster, D. simulans, and D. subobscura are specialised on fruits and D. busckii on vegetables. D. immigrans and D. hydei are less specialised. The coexistence is explained by reference to ecological theory.     

Survival of serotinous seedbanks during bushfires: Comparative studies of Hakea species from southeastern Australia

Abstract The study assessed the survival, during bushfires, of seedbanks of six serotinous Hakea species found in the Sydney region of southeastern Australia. The survival of seeds was examined when fruits were heated in a muffle furnace at ambient temperatures ranging from 200–800°C for 1 min. For each species, fruit weight and dimensions of fruit walls were measured to characterize insulation. A field experiment was performed to examine the survival of the serotinous seedbank of Hakea dactyloides in a bushfire. Ambient and internal fruit temperatures were recorded during the fire. The viability of seeds from fruits exposed to the fire was tested and compared with an unburnt sample. Viability of seeds within fruits exposed in the furnace varied according to species. Seeds of large fruited species such as Hakea constablei and Hakea propinqua survived, whereas those of the small fruited species Hakea teretifolia and H. dactyloides suffered significant mortality. The threshold temperature for death in four species was linearly related to the thickness of lower and lateral fruit walls, and to dry weight of fruits. Internal and external temperatures of fruits decreased with increasing height on experimental H. dactyloides plants in the field. High levels of mortality (relative to the unburnt control) corresponded with fire temperature maxima greater than 400°C (external) and greater than 60°C (internal). In general, these temperatures occur when shrub crowns burn. A high risk of death for H. dactyloides, H. teretifolia and H. sericea seeds will result because fruits of these species have thin walls.     

Fruit choice by red howler monkeys (Alouatta seniculus) in a tropical rain forest

This paper presents and discusses aspects of fruit selectivity by red howler monkeys (Alouatta seniculus) in relation with morphological characteristics of fruits. These data are used to provide an answer to the following questions: which are the fruit characteristics that lead fruit choice of howler monkeys and to what extent fruit characteristics play a role in seed dispersal by monkeys? The frugivorous diet of a troop of red howler monkeys was determined during a 2-year field study in French Guiana. The selection of fruit by howler monkeys was analyzed in relation to the fruit availability. Results showed that, although consumption followed availability, fruit species could be classified in three categories according to their selection ratio (percentage of consumption/percentage of abundance) as “high ranking,” “middle ranking,” and “low ranking” species. Also, the 97 species of fruit eaten by the monkeys were grouped according to the morphological characteristics thought to influence the monkeys' choice. This showed that howler monkeys consumed essentially fruits with juicy pulp, bright color, and a small number of well-protected seeds. Most of high ranking species had medium-sized fruits with yellow color, and low ranking species often had small fruits. However, howler monkeys are associated with the dispersal of seeds from fruit with a hard and indehiscent pericarp and/or large seeds, like those of the Sapotaceae family. Consequently, they can be considered as “specialized” frugivores for this fruit syndrome. © l996 Wiley-Liss, Inc.     

云南鸡脚连(小檗科)的变异式样

小檗属鸡脚连(Berberis paraspecta Ahrendt)自1961 年发表以来,已有分类学文献对该种的描述一直模糊不清。通过在云南省玉龙县玉龙雪山野外调查与居群取样,结合模式标本核查,对鸡脚连重要分类学性状特征进行了补充和订正。鸡脚连果实1~5 个簇生,平均为(2.23±1.18)个;幼果或子房内胚珠1~3 个,平均为(2.07±0.29)个;成熟果实紫黑色,无粉霜,种子1~3 个,平均为(1.77±0.44)个。研究结果表明,有关文献关于鸡脚连果实单生,且仅含1 粒种子等关键的特征描述,在鸡脚连野生居群及模式标本上都不存在, 同时分析了鸡脚连果实、种子及胚珠数目、叶片及叶刺等分类学性状特征的变异系数,并补充了活植物及模式标本的图片资料。     

Sucrose phosphate synthase and other sucrose metabolizing enzymes in fruits of various species

Recent reports have suggested that sucrose phosphate synthase (EC 2.4.1.14), a key enzyme in sucrose biosynthesis in photosynthetic “source” tissues, may also be important in some sucrose accumulating “sink” tissues. These experiments were conducted to determine if sucrose phosphate synthase is involved in sucrose accumulation in fruits of several species. Peach (Prunus persica NCT 516) and strawberry (Fragaria x ananassa cv. Chandler) fruits were harvested directly from the plant at various stages of fruit development. Kiwi (Actinidia chinensis), papaya (Carica papaya), pineapple (Ananas comosus) and mango (Mangifera indica) were sampled in postharvest storage over a period of several days. Carbohydrate concentrations and activities of sucrose phosphate synthase, sucrose synthase (EC 2.4.1.13), and acid and neutral invertases (EC 3.2.1.26) were measured. All fruits contained significant activities of sucrose phosphate synthase. Moreover, in fruits from all species except pineapple and papaya, there was an increase in sucrose phosphate synthase activity associated with the accumulation of sucrose in situ. The increase in sucrose concentration in peaches was also associated with an increase in sucrose synthase activity and, in strawberries, with increased activity of both sucrose synthase and neutral invertase. The hexose pools in all fruits were comprised of equimolar concentrations of fructose and glucose, except in the mango. In mango, the fructose to glucose ratio increased from 2 to 41 during ripening as sucrose concentration more than doubled. The results of this study indicate that activities of the sucrose metabolizing enzymes, including sucrose phosphate synthase, within the fruit itself, are important in determining the soluble sugar content of fruits of many species. This appears to be true for fruits which sweeten from a starch reserve and in fruits from sorbitol translocating species, raffinose saccharide translocating species, and sucrose translocating species.