The influence of pulp lipids on fruit preference by birds

Use patterns of lipid-rich, fleshy fruits were examined for frugivorous birds. Approximately 20% of fleshy-fruited species within plant communities bear fruit with >10% dry weight lipids. These fruits are fed upon by the most heavily frugivorous bird species in those communities studied and are the focus of highly specialized relationships among birds and fruits. In aviary tests some temperate frugivores show preference for higher lipid native fruits and prefer higher-lipid artificial fruits with as little as 3% wet weight difference in lipid content. The importance of lipids in fruit preference by birds, and the possible effects of differing digestive physiologies in birds are discussed.     

Phenology of fleshy fruits in a wet sclerophyll forest in southeastern Australia: are birds an important influence?

Summary The hypothesis that seasonality in the production of fleshy fruits in temperate regions is the result of selection by avian seed dispersal agents or avian seed predators was tested in a temperate wet sclerophyll forest in south-eastern Australia. I determined whether ten common fleshy-fruited species produced fruits when potential avian seed dispersers were most abundant or avian seed predators were least abundant. The season of fruit production was not correlated with avian disperser abundance nor with seasonal changes in avian seed predators. Peak fruiting occurred during autumn but fruit-eating birds were equally abundant from spring through to autumn. Avian seed predators (parrots) did not show any seasonal variation in abundance. If dispersers are influencing fruiting seasonality in wet sclerophyll forest, it is likely that changes in social behaviour and feeding patterns of dispersers during autumn, rather than increases in abundance, will be an important influence on fruiting patterns in wet sclerophyll forest. However, environmental and life history factors may also influence phenology.     

A botanical inventory of a tropical seasonal forest in Khao Yai National Park,Thailand: implications for fruit–frugivore interactions

The diversity of plants in tropical forests makes dietary studies of frugivores difficult. This paper provides a botanical inventory of a tropical seasonal forest community in Khao Yai National Park, Thailand. The forest is valuable from a conservation perspective because it is one of the last remaining intact forests in northeastern Thailand, and is an important refuge for many animal and plant species. A 4-ha inventory plot measuring 200 × 200 m was established and all plants greater than or equal to 10 cm in diameter at breast height (dbh) were measured and permanently labeled. We found 1610 stems belonging to 105 species, 76 genera and 35 families, with a combined basal area of 142.5 m². The community was dominated by species of Lauraceae, Cornaceae, Euphorbiaceae, Meliaceae, and Elaeocarpaceae. About one-third of the plant species (40 spp.) identified in this study were vulnerable to extinction because they were mostly dispersed by large frugivores, which were intolerant of human impact. If they disappear, these forests may become dominated by plant species that are dispersed by abiotic means and species with small-seeded fruits.     

Diets of fruit-eating birds: what are the causes of interspecific differences?

Differences in fruit choice among the bird species of a Spanish shrubland were related to the size of fruits and to the lipid content of pulp. Lipid-rich fruits were selected by the bird species with slower food passage rates through the digestive tract. These bird species also fed frequently on insects and seeds. Bird species with faster food passage rates fed less on insects and seeds, and ate mainly fruits with pulp poor in lipids (rich in sugars and water). Studies of digestion in birds indicate that lipids require slower food passage rates for efficient digestion and intestinal transport than simple sugars. The available evidence indicates that the European bird species that show stronger preferences for lipid-rich fruits are no better as seed dispersers, from the point of view of the plants, than species choosing lipidpoor fruits. Thus, the degree of frugivory of birds, their fruit choice patterns and their effects on seed dispersal do not seem to be related to each other in the ways expected by the early models of the evolution of fleshy fruits.     

Spatial dynamics of <Emphasis Type="Italic">Ilex aquifolium</Emphasis> populations seed dispersal and seed bank: understanding the first steps of regeneration

The objective of this study was to analyse quantitatively the spatial distribution of holly (Ilex aquifolium L.) seed rain and seed bank, and to detect the relationships between these consecutive processes. We measured seed dispersal by birds and fallen fruits, and also density and viability of seed bank in two Ilex populations in central Spain. Analysis was made distinguishing the following microhabitats: holly woodland, edge of holly woodland, open grassland 10 m and 100 m from the woodland, fleshy fruit shrubs, dry fruit shrubs, and adjacent non-holly woodland. Spatial distribution of dispersed and in-soil seeds was measured by the clumping index. Seed rain and seed bank under holly woodlands were significantly higher than in the other microhabitats. Forest edges and fleshy fruit shrubs were the next microhabitats with the highest seed rain and seed bank density. Interannual and interlocality variations were not significant. The relative importance of the different dispersal methods varied between microhabitats, with a similar support of bird dispersed seeds and fallen fruits within the woodland and a greater influence of cattle dispersal in open areas. Seed spatial aggregation was significant in both dispersed seeds and soil seeds from holly woodlands and the edge of the forest. Aggregation under shrubs, grasslands and the adjacent forests evidenced a general random distribution of holly seeds (only in some cases clumping index was significant). Quantitative differences between seed rain and seed bank are important. Post-dispersal seed predation did not modify seed rain distribution, which was mirrored in the seed bank pattern. These two phases of holly regeneration had a heavy spatial influence, determined by the landscape structure and activity of the dispersal agents, that reflects a differential recruitment potential. Comparisons between both populations suggest that in the southern locality (Robregordo) holly has a weaker capacity to colonize open areas, and a stronger recruitment limitation due to propagule availability.     

Barcoding Queensland Fruit Flies (Bactrocera tryoni): impediments and improvements

Identification of adult fruit flies primarily involves microscopic examination of diagnostic morphological characters, while immature stages, such as larvae, can be more problematic. One of the Australia’s most serious horticultural pests, the Queensland Fruit Fly (Bactrocera tryoni: Tephritidae), is of particular biosecurity/quarantine concern as the immature life stages occur within food produce and can be difficult to identify using morphological characteristics. DNA barcoding of the mitochondrial Cytochrome Oxidase I (COI) gene could be employed to increase the accuracy of fruit fly species identifications. In our study, we tested the utility of standard DNA barcoding techniques and found them to be problematic for Queensland Fruit Flies, which (i) possess a nuclear copy (a numt pseudogene) of the barcoding region of COI that can be co‐amplified; and (ii) as in previous COI phylogenetic analyses closely related B. tryoni complex species appear polyphyletic. We found that the presence of a large deletion in the numt copy of COI allowed an alternative primer to be designed to only amplify the mitochondrial COI locus in tephritid fruit flies. Comparisons of alternative commonly utilized mitochondrial genes, Cytochrome Oxidase II and Cytochrome b, revealed a similar level of variation to COI; however, COI is the most informative for DNA barcoding, given the large number of sequences from other tephritid fruit fly species available for comparison. Adopting DNA barcoding for the identification of problematic fly specimens provides a powerful tool to distinguish serious quarantine fruit fly pests (Tephritidae) from endemic fly species of lesser concern.     

The effect of unripe fruits on ripe fruit removal by birds in Pistacia terebinthus: flag or handicap?

The shrub Pistacia terebinthus produces crowded infructescences with up to several hundred fruits, which are bright red when unripe and turn green when ripe. Most fruits contain an empty seed and never reach maturity. More ripe fruits were removed by birds from experimental bicolored fruit displays (consisting of infructescences with ten ripe fruits and stripped of unripe fruits, paired with infructescences with only unripe fruits) than from monocolored ones (single infructescences with ten ripe fruits and stripped of unripe fruits). Thus, the presence of unripe fruits seems to increase the conspicuousness or attractiveness of fruit displays to fruit-eating birds. A second experiment compared ripe fruit removal from experimental infructescences having only ripe fruits, with that from control infructescences containing both ripe fruits and natural numbers of unripe fruits, all on P. terebinthus plants. Unlike the first experiment, each bicolored display in this case consisted of a single infructescence with both unripe and ripe fruits. A higher proportion of ripe fruits was removed by birds from infructescences free of unripe fruits. This result suggests that the presence of unripe fruits reduces the accessibility of ripe fruits for fruit-eating birds. This is further supported by field observations of bird foraging behavior.     

油茶肉质果和肉质叶营养成分分析与评价

采用常规生化分析方法,测定了油茶（Camellia oleifera Abel.）肉质果、肉质叶基本营养成分,用原子吸收光谱法测定微量元素含量,用高效液相色谱仪测定维生素C的含量,用氨基酸全自动分析仪测定氨基酸的种类,应用模糊识别法和氨基酸比值系数法对油茶肉质果、肉质叶蛋白质营养价值进行了全面评价,并与12种常见热带、亚热带水果进行对照比较。结果表明油茶肉质果、肉质叶富含糖、酸、蛋白质、氨基酸、脂肪。其微量元素和维生素C含量高于一些常见水果。油茶肉质果、肉质叶的必需氨基酸（EAA）占氨基酸总量（TAA）的37%和35%,其蛋白营养价值要优于12种水果。因此,油茶肉质果、肉质叶的营养价值优于一些常见水果,是一种值得开发利用的优质水果。     

DNA barcoding of stylommatophoran land snails: a test of existing sequences

DNA barcoding has attracted attention because it is a potentially simple and universal method for taxonomic assignment. One anticipated problem in applying the method to stylommatophoran land snails is that they frequently exhibit extreme divergence of mitochondrial DNA sequences, sometimes reaching 30% within species. We therefore trialled the utility of barcodes in identifying land snails, by analysing the stylommatophoran cytochrome oxidase subunit I sequences from GenBank. Two alignments of 381 and 228 base pairs were used to determine potential error rates among a test data set of 97 or 127 species, respectively. Identification success rates using neighbour‐joining phylogenies were 92% for the longer sequence and 82% for the shorter sequence, indicating that a high degree of mitochondrial variation may actually be an advantage when using phylogeny‐based methods for barcoding. There was, however, a large overlap between intra‐ and interspecific variation, with assignment failure (per cent of samples not placed with correct species) particularly associated with a low degree of mitochondrial variation (Kimura 2‐parameter distance < 0.05) and a small GenBank sample size (< 25 per species). Thus, while the optimum intra/interspecific threshold value was 4%, this was associated with an overall error of 32% for the longer sequences and 44% for the shorter sequences. The high error rate necessitates that barcoding of land snails is a potentially useful method to discriminate species of land snail, but only when a baseline has first been established using conventional taxonomy and sample DNA sequences. There is no evidence for a barcoding gap, ruling out species discovery based on a threshold value alone.     

DNA metabarcoding and the cytochrome c oxidase subunit I marker: not a perfect match

DNA metabarcoding enables efficient characterization of species composition in environmental DNA or bulk biodiversity samples, and this approach is making significant and unique contributions in the field of ecology. In metabarcoding of animals, the cytochrome c oxidase subunit I (COI) gene is frequently used as the marker of choice because no other genetic region can be found in taxonomically verified databases with sequences covering so many taxa. However, the accuracy of metabarcoding datasets is dependent on recovery of the targeted taxa using conserved amplification primers. We argue that COI does not contain suitably conserved regions for most amplicon-based metabarcoding applications. Marker selection deserves increased scrutiny and available marker choices should be broadened in order to maximize potential in this exciting field of research.     

DNA条形码技术在植物中的研究现状

DNA条形码技术（DNA barcoding）是用短的DNA片段对物种进行识别和鉴定的分子生物学技术。在动物研究中该技术已经成功应用于利用线粒体细胞色素c氧化酶亚基I（COI）进行物种鉴定和发现隐种或新物种。相对于动物, COI基因在高等植物中进化速率较慢, 因此植物条形码研究以叶绿体基因组作为重点, 但目前还处于寻找合适的基因片段阶段。许多学者对此进行了积极的探索, 报道了多种植物条形码的候选片段或组合, 但还没有获得满足所有标准的特征位点片段。该文介绍了DNA条形码的标准、优点、工作流程及数据分析方法, 总结了DNA条形码在植物中的研究现状。