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From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly.

ABSTRACT: Seed dispersal is a key process in plant spatial dynamics. However, consistently applicable generalizations about dispersal across scales are mostly absent because of the constraints on measuring propagule dispersal distances for many species. Here, we focus on fleshy-fruited taxa, specifically taxa with large fleshy fruits and their dispersers across an entire continental rainforest biome. We compare species-level results of whole-chloroplast DNA analyses in sister taxa with large and small fruits, to regional plot-based samples (310 plots), and whole-continent patterns for the distribution of woody species with either large (more than 30 mm) or smaller fleshy fruits (1093 taxa). The pairwise genomic comparison found higher genetic distances between populations and between regions in the large-fruited species (Endiandra globosa), but higher overall diversity within the small-fruited species (Endiandra discolor). Floristic comparisons among plots confirmed lower numbers of large-fruited species in areas where more extreme rainforest contraction occurred, and re-colonization by small-fruited species readily dispersed by the available fauna. Species' distribution patterns showed that larger-fruited species had smaller geographical ranges than smaller-fruited species and locations with stable refugia (and high endemism) aligned with concentrations of large fleshy-fruited taxa, making them a potentially valuable conservation-planning indicator.

SUBMITTER: Rossetto M

PROVIDER: S-EPMC4685777 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly.

Rossetto Maurizio M Kooyman Robert R Yap Jia-Yee S JY Laffan Shawn W SW

Proceedings. Biological sciences 20151201 1820

Seed dispersal is a key process in plant spatial dynamics. However, consistently applicable generalizations about dispersal across scales are mostly absent because of the constraints on measuring propagule dispersal distances for many species. Here, we focus on fleshy-fruited taxa, specifically taxa with large fleshy fruits and their dispersers across an entire continental rainforest biome. We compare species-level results of whole-chloroplast DNA analyses in sister taxa with large and small fru ...[more]

PMID: 26645199

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Project description:OBJECTIVES: Identify patterns of change in species distributions, diversity, concentrations of evolutionary history, and assembly of Australian rainforests. METHODS: We used the distribution records of all known rainforest woody species in Australia across their full continental extent. These were analysed using measures of species richness, phylogenetic diversity (PD), phylogenetic endemism (PE) and phylogenetic structure (net relatedness index; NRI). Phylogenetic structure was assessed using both continental and regional species pools. To test the influence of growth-form, freestanding and climbing plants were analysed independently, and in combination. RESULTS: Species richness decreased along two generally orthogonal continental axes, corresponding with wet to seasonally dry and tropical to temperate habitats. The PE analyses identified four main areas of substantially restricted phylogenetic diversity, including parts of Cape York, Wet Tropics, Border Ranges, and Tasmania. The continental pool NRI results showed evenness (species less related than expected by chance) in groups of grid cells in coastally aligned areas of species rich tropical and sub-tropical rainforest, and in low diversity moist forest areas in the south-east of the Great Dividing Range and in Tasmania. Monsoon and drier vine forests, and moist forests inland from upland refugia showed phylogenetic clustering, reflecting lower diversity and more relatedness. Signals for evenness in Tasmania and clustering in northern monsoon forests weakened in analyses using regional species pools. For climbing plants, values for NRI by grid cell showed strong spatial structuring, with high diversity and PE concentrated in moist tropical and subtropical regions. CONCLUSIONS/SIGNIFICANCE: Concentrations of rainforest evolutionary history (phylo-diversity) were patchily distributed within a continuum of species distributions. Contrasting with previous concepts of rainforest community distribution, our findings of continuous distributions and continental connectivity have significant implications for interpreting rainforest evolutionary history and current day ecological processes, and for managing rainforest diversity in changing circumstances.

Project description:The soluble sugar concentration of fleshy fruit is a key determinant of fleshy fruit quality. It affects directly the sweetness of fresh fruits and indirectly the properties of processed products (e.g., alcohol content in wine). Despite considerable divergence among species, soluble sugar accumulation in a fruit results from the complex interplay of three main processes, namely sugar import, sugar metabolism, and water dilution. Therefore, inter-species comparison would help to identify common and/or species-specific modes of regulation in sugar accumulation. For this purpose, a process-based mathematical framework was used to compare soluble sugar accumulation in three fruits: grape, tomato, and peach. Representative datasets covering the time course of sugar accumulation during fruit development were collected. They encompassed 104 combinations of species (3), genotypes (30), and growing conditions (19 years and 16 nutrient and environmental treatments). At maturity, grape showed the highest soluble sugar concentrations (16.5-26.3 g/100 g FW), followed by peach (2.2 to 20 g/100 g FW) and tomato (1.4 to 5 g/100 g FW). Main processes determining soluble sugar concentration were decomposed into sugar importation, metabolism, and water dilution with the process-based analysis. Different regulation modes of soluble sugar concentration were then identified, showing either import-based, dilution-based, or import and dilution dual-based. Firstly, the higher soluble sugar concentration in grape than in tomato is a result of higher sugar importation. Secondly, the higher soluble sugar concentration in grape than in peach is due to a lower water dilution. The third mode of regulation is more complicated than the first two, with differences both in sugar importation and water dilution (grape vs. cherry tomato; cherry tomato vs. peach; peach vs. tomato). On the other hand, carbon utilization for synthesis of non-soluble sugar compounds (namely metabolism) was conserved among the three fruit species. These distinct modes appear to be quite species-specific, but the intensity of the effect may significantly vary depending on the genotype and management practices. These results provide novel insights into the drivers of differences in soluble sugar concentration among fleshy fruits.

Project description:Background and aimsSugar concentration is a key determinant of fruit quality. Soluble sugars and starch concentrations in fruits vary greatly from one species to another. The aim of this study was to investigate similarities and differences in sugar accumulation strategies across ten contrasting fruit species using a modelling approach.MethodsWe developed a coarse-grained model of primary metabolism based on the description of the main metabolic and hydraulic processes (synthesis of compounds other than sugar and starch, synthesis and hydrolysis of starch, and water dilution) involved in the accumulation of soluble sugars during fruit development.Key resultsStatistical analyses based on metabolic rates separated the species into six groups according to the rate of synthesis of compounds other than sugar and starch. Herbaceous species (cucumber, tomato, eggplant, pepper and strawberry) were characterized by a higher synthesis rate than woody species (apple, nectarine, clementine, grape and kiwifruit). Inspection of the dynamics of the processes involved in sugar accumulation revealed that net sugar importation, metabolism and dilution processes were remarkably synchronous in most herbaceous plants, whereas in kiwifruit, apple and nectarine, processes related to starch metabolism were temporally separated from other processes. Strawberry, clementine and grape showed a distinct dynamic compared with all other species.ConclusionsOverall, these results provide fresh insights into species-specific regulatory strategies and into the role of starch metabolism in the accumulation of soluble sugars in fleshy fruits. In particular, inter-specific differences in development period shape the co-ordination of metabolic processes and affect priorities for carbon allocation across species. The six metabolic groups identified by our analysis do not show a clear separation into climacteric and non-climacteric species, possibly suggesting that the metabolic processes related to sugar concentration are not greatly affected by ethylene-associated events.

Project description:BackgroundTropical rainforests (TRFs) harbour almost half of the world's vascular plant species diversity while covering only about 6-7% of land. However, why species richness varies amongst the Earth's major TRF regions remains poorly understood. Here we investigate the evolutionary processes shaping continental species richness disparities of the pantropical, epiphytic and mostly TRF-dwelling orchid mega-genus Bulbophyllum (c. 1948 spp. in total) using diversification analyses based on a time-calibrated molecular phylogeny (including c. 45-50% spp. each from Madagascar, Africa, Neotropics, and 8.4% from the Asia-Pacific region), coupled with ecological niche modelling (ENM) of geographic distributions under present and past (Last Glacial Maximum; LGM) conditions.ResultsOur results suggest an early-to-late Miocene scenario of 'out-of-Asia-Pacific' origin and progressive, dispersal-mediated diversification in Madagascar, Africa and the Neotropics, respectively. Species richness disparities amongst these four TRF lineages are best explained by a time-for-speciation (i.e. clade age) effect rather than differences in net diversification or diversity-dependent diversification due to present or past spatial-bioclimatic limits. For each well-sampled lineage (Madagascar, Africa, Neotropics), we inferred high rates of speciation and extinction over time (i.e. high species turnover), yet with the origin of most extant species falling into the Quaternary. In contrast to predictions of classical 'glacial refuge' theories, all four lineages experienced dramatic range expansions during the LGM.ConclusionsAs the Madagascan, African and Neotropical lineages display constant-rate evolution since their origin (early-to-mid-Miocene), Quaternary environmental change might be a less important cause of their high species turnover than intrinsic features generally conferring rapid population turnover in tropical orchids (e.g., epiphytism, specialization on pollinators and mycorrhizal fungi, wind dispersal). Nonetheless, climate-induced range fluctuations during the Quaternary could still have played an influential role in the origination and extinction of Bulbophyllum species in those three, if not in all four TRF regions.

Project description:Background:The main aim of the study was to analyse the influence of fleshy fruits (plums) on the post-metamorphic growth and feeding behaviour of the green toad Bufotes viridis. We tested the following two hypotheses: (1) juveniles of the green toad are characterised by faster growth in conditions involving fallen plums Prunus cerasifera due to the associated presence of more varied food such as invertebrates; (2) green toads exhibit more active feeding behaviour in the presence of fleshy fruits. Methods:A total of 120 fresh metamorphs of the green toad were randomly assigned to one of four groups: two experimental groups with fleshy plums and two other groups as controls (without fruits). Each group was kept in an enclosure to which wild invertebrates had free access. Each individual toad was measured for snout-vent length (mm) and body mass (g) every other day for 30 days. In order to determine whether fallen plums influence the feeding behaviour of toads, the number of active and hidden (under an artificial shelter) individuals was also noted. Results:The results showed that green toads from both enclosures with plums were characterised by more rapid growth than individuals from the control treatments. Simultaneously, in the enclosure with fleshy fruits, greater species richness of wild invertebrates was observed. No differences in active feeding behaviour were noted between control groups and groups with plums. Discussion:Fleshy fruits, upon falling, attract many types of invertebrates; thus they may represent good dietary supplements for fresh amphibian metamorphs. Therefore, the presence of fruit trees close to a breeding site might influences the post-metamorphic growth of amphibians, but not their feeding behaviour. The presence of insects associated with fallen fruit seems to favour the occurrence of amphibian populations, which is particularly important, since, due to political and social pressure, numbers of fruit trees are currently being reduced. To our knowledge, no previous study has investigated the potential influence of the presence of fruit trees on the growth and behaviour of anurans.

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From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly.

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From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly.

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