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1.
Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates), but not for microscopic organisms (e.g. nematodes). Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy) of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica) using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1) nematode communities were unique without even a single common species between the two rainforests, 2) nematode communities were unique among habitats in both rainforests, 3) total species richness was 300% more in the tropical than in the temperate rainforest, 4) 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5) more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats) and large (rainforests) spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota.  相似文献   

2.
Comparisons of nematode communities among ecosystems have indicated that, unlike many organisms, nematode communities have less diversity in the tropics than in temperate ecosystems. There are, however, few studies of tropical nematode diversity on which to base conclusions of global patterns of diversity. This study reports an attempt to estimate nematode diversity in the lowland tropical rainforest of La Selva Biological Research Station in Costa Rica. We suggest one reason that previous estimates of tropical nematode diversity were low is because habitats above the mineral soil are seldom sampled. As much as 62% of the overall genetic diversity, measured by an 18S ribosomal barcode, existed in litter and understorey habitats and not in soil. A maximum-likelihood tree of barcodes from 360 individual nematodes indicated most major terrestrial nematode lineages were represented in the samples. Estimated 'species' richness ranged from 464 to 502 within the four 40 × 40 m plots. Directed sampling of insects and their associated nematodes produced a second set of barcodes that were not recovered by habitat sampling, yet may constitute a major class of tropical nematode diversity. While the generation of novel nematode barcodes proved relatively easy, their identity remains obscure due to deficiencies in existing taxonomic databases. Specimens of Criconematina, a monophyletic group of soil-dwelling plant-parasitic nematodes were examined in detail to assess the steps necessary for associating barcodes with nominal species. Our results highlight the difficulties associated with studying poorly understood organisms in an understudied ecosystem using a destructive (i.e. barcode) sampling method.  相似文献   

3.
We present the results of an intensive sampling program carried out from 2000 to 2007 along both coasts of Costa Rica, Central America. The presence of 44 species of benthic marine algae is reported for the first time for Costa Rica. Most of the new records are Rhodophyta (27 spp.), followed by Chlorophyta (15 spp.), and Heterokontophyta, Phaeophycea (2 spp.). Overall, the currently known marine flora of Costa Rica is comprised of 446 benthic marine algae and 24 Cyanobacteria. This species number is an under estimation, and will increase when species of benthic marine algae from taxonomic groups where only limited information is available (e.g., microfilamentous benthic marine algae, Cyanobacteria) are included. The Caribbean coast harbors considerably more benthic marine algae (318 spp.) than the Pacific coast (190 spp.); such a trend has been observed in all neighboring countries. Compared to other Central American countries, Costa Rica has the highest number of reported benthic marine algae; however, Panama may have a similarly high diversity after unpublished results from a Rhodophyta survey (Wysor, unpublished) are included. Sixty-two species have been found along both the Pacific and Caribbean coasts of Costa Rica; we discuss this result in relation to the emergence of the Central American Isthmus.  相似文献   

4.
The studies on marine copepods of Costa Rica started in the 1990’s and focused on the largest coastal-estuarine systems in the country, particularly along the Pacific coast. Diversity is widely variable among these systems: 40 species have been recorded in the Culebra Bay influenced by upwelling, northern Pacific coast, only 12 in the Gulf of Nicoya estuarine system, and 38 in Golfo Dulce, an anoxic basin in the southern Pacific coast of the country. Freshwater environments of Costa Rica are known to harbor a moderate diversity of continental copepods (25 species), which includes 6 calanoids, 17 cyclopoids and only two harpacticoids. Of the +100 freshwater species recorded in Central America, six are known only from Costa Rica, and one appears to be endemic to this country. The freshwater copepod fauna of Costa Rica is clearly the best known in Central America. Overall, six of the 10 orders of Copepoda are reported from Costa Rica. A previous summary by 2001 of the free-living copepod diversity in the country included 80 marine species (67 pelagic, 13 benthic). By 2009, the number of marine species increased to 209: 164 from the Pacific (49% of the copepod fauna from the Eastern Tropical Pacific) and 45 from the Caribbean coast (8% of species known from the Caribbean Basin). Both the Caribbean and Pacific species lists are growing. Additional collections of copepods at Cocos Island, an oceanic island 530 km away of the Pacific coast, have revealed many new records, including five new marine species from Costa Rica. Currently, the known diversity of marine copepods of Costa Rica is still in development and represents up to 52.6% of the total marine microcrustaceans recorded in the country. Future sampling and taxonomic efforts in the marine habitats should emphasize oceanic environments including deep waters but also littoral communities. Several Costa Rican records of freshwater copepods are likely to represent undescribed species. Also, the biogeographic relevance of the inland copepod fauna of Costa Rica requires more detailed surveys.  相似文献   

5.
Tropical biodiversity is under threat from a wide variety of anthropogenic stressors. Understanding the effect of major stressors—most notably land use change, over‐harvesting, emergence of novel pathogens, and climate change—is a major goal of tropical biology. However, to do so requires baseline data with which to compare present‐day patterns. Unfortunately, the tropics suffer from a lack of basic historical data; the few studies which have published such data have proven invaluable. In 1989, Fauth et al. described their studies of reptile and amphibian diversity and population demographics across tropical elevational gradients in Costa Rica. Since then, Fauth et al.'s basic ecological data have been widely used to document shifting patterns of species composition and abundance. Here, 30 years later, we argue that (a) collecting foundational ecological data remains incredibly important, especially in the tropics, and especially in those taxa which are generally understudied (e.g., reptiles and amphibians), (b) despite being one of the original goals of the 1989 study, the mechanisms driving biogeographical patterns of diversity remain unclear (both in the tropics and globally), and (c) that revisiting sites of historic biodiversity surveys—particularly those along gradients of environmental change—is incredibly important to our understanding of how tropical diversity is currently, and will continue to be, affected by activities in the Anthropocene. In its simplest terms, there has never been a time where the collection of basic data in the tropics has ever been more important.  相似文献   

6.
Tidal flats extend seaward from mangrove forests along many tropicalcoastlines. This contribution compiles the current knowledge on tropicaltidal flats with regard to species richness, abundance, spatial distributionpatterns and ecological roles taken by major organisms. Tidal flatsencompass a variety of soft-sediment habitats which are inhabited by aspecies-rich fauna. Species numbers are generally higher than in temperatetidal flats, but vary widely between tropical sites where they have not yetbeen fully assessed due to lack of research and taxonomic problems. Theassessment of biodiversity is further complicated by a low species frequency,the small size of macroinfaunal organisms and variations in the occurrence ofspecies between sites. Mean abundance ranges from 1000–2000individuals m-2, although figures ten times higher have beenrecorded in a mudflat in Costa Rica, and there are great variations in general.Individual densities of small-sized macrofauna are about ten times higher than for larger macrobenthos. A generalized zonation scheme for intertidaldistribution patterns of tropical tidal flat fauna is presented. The comparisonshows that the occurrence of macrofauna and especially of ecosystemengineers varies between sites, which can in turn explain the great variabilityin species abundance patterns recorded in benthic surveys of tidal flatswithin and between regions. This review revealed similarities as well asdifferences between various tropical tidal flats, which underlines the need for further comparative studies to be done, using the same methodology, before generalizations can be made.  相似文献   

7.
The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12°N to 55°S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies.  相似文献   

8.
Globally, tropical rain forests comprise some of the most diverse and functionally rich ecosystems but are increasingly degraded by human impacts. Protected areas have been shown to conserve species diversity, but their effectiveness at maintaining functional diversity over time is less well known, despite the fact that functional diversity likely reveals more ecological information than taxonomic diversity. By extension, the degree to which species loss decreases functional diversity within protected areas is also unknown; functional redundancy may buffer communities from loss of functional diversity from some local extinctions. Using eight years of camera trap data, we quantified annual functional dispersion of the large mammal community in the Volcán Barva region of Costa Rica and tested for changes in functional dispersion over time in response to environmental and anthropogenic predictors. We quantified functional redundancy based on simulated declines in functional dispersion with species loss. Observed functional dispersion did not change significantly over time and was not associated with measured environmental or anthropogenic predictors. Quantitative modeling of observed functional traits over time did not identify significant changes. We did however find qualitative trends in relative trait proportions, which could be indicative of functional change in the future. We found high functional redundancy, with average simulated functional dispersion declining significantly only after 9 out of 21 large mammal species were lost from the community. We cautiously suggest that protected tropical rain forests can conserve functional diversity over the course of a decade even in heavily fragmented landscapes. Abstract in Spanish is available with online material.  相似文献   

9.
The coffee (Coffea arabica) agro-ecosystem in the Central Valley of Costa Rica was formerly characterized by a high vegetational diversity. This complex system has been undergoing a major transformation to capital-intensive monocultural plantations where all shade trees are eliminated. In this study we examined the pattern of arthropod biodiversity loss associated with this transformation. Canopy arthropods were sampled in three coffee farms: a traditional plantation with many species of shade trees, a moderately shaded plantation with only Erythrina poeppigeana and coffee, and a coffee monoculture. An insecticidal fogging technique was used to sample both canopy and coffee arthropods. Data are presented on three major taxonomic groups: Coleoptera, non-formicid Hymenoptera, and Formicidae. Data demonstrate that the transformation of the coffee agro-ecosystem results in a significant loss of biological diversity of both canopy arthropods as well as arthropods living in coffee bushes. Percentage of species overlap was very small for all comparisons. Furthermore, species' richness on a per tree basis was found to be within the same order of magnitude as that reported for trees in tropical forests. If results presented here are generalizable, this means that conservation efforts to preserve biological diversity should also include traditional agro-ecosystems as conservation units.  相似文献   

10.
Two individual, dicotyledoneous leaves (125 and 98 cm2 in size) and one composed palm leaf (c. 6800 cm2 in size), gathered at La Selva Biological Station, Costa Rica, and Jatun Satcha Biological Station, Amazonian Ecuador, were screened for small-scale foliicolous lichen diversity. On the dicotyledoneous leaf from Costa Rica, 49 lichens and one lichenicolous fungus were found, while a comparable leaf from Ecuador revealed 46 lichens and two lichenicolous fungi. The palm leaf yielded 81 lichens and one lichenicolous fungus. This is the highest alpha-diversity so far reported for foliicolous lichens on individual leaves and invites for comparison with tree diversity in tropical rain forests. Due to the high proportion of species represented by a single thallus, the taxonomic diversity of lichens on individual leaves (or trees in selected plots) cannot be self-supporting, but reflects a high degree of dispersion or entropy within the community of which the individual leaf (or selected plot) is part. Diversity is therefore fractal, showing similar patterns at different scales, each part of a given community reflecting the entire community. Thus, mechanisms that result in high small-scale diversity must be looked for at the community level.  相似文献   

11.
In many tropical lowland rain forests, topographic variation increases environmental heterogeneity, thus contributing to the extraordinary biodiversity of tropical lowland forests. While a growing number of studies have addressed effects of topographic differences on tropical insect communities at regional scales (e.g., along extensive elevational gradients), surprisingly little is known about topographic effects at smaller spatial scales. The present study investigates moth assemblages in a topographically heterogeneous lowland rain forest landscape, at distances of less than a few hundred meters, in the Golfo Dulce region (SW Costa Rica). Three moth lineages—Erebidae–Arctiinae (tiger and lichen moths), the bombycoid complex, and Geometridae (inchworm moths)—were examined by means of automatic light traps in three different forest types: creek forest, slope forest, and ridge forest. Altogether, 6,543 individuals of 419 species were observed. Moth assemblages differed significantly between the three forest types regarding species richness, total abundance, and species composition. Moth richness and abundance increased more than fourfold and eightfold from creek over slope to ridge forest sites. All three taxonomic units showed identical biodiversity patterns, notwithstanding their strong differences in multiple eco-morphological traits. An indicator species analysis revealed that most species identified as characteristic were associated either with the ridge forest alone or with ridge plus slope forests, but very few with the creek forest. Despite their mobility, local moth assemblages are highly differentially filtered from the same regional species pool. Hence, variation in environmental factors significantly affects assemblages of tropical moth species at small spatial scales.  相似文献   

12.
1. Documenting species abundance distributions in natural environments is critical to ecology and conservation biology. Tropical forest insect faunas vary in space and time, and these partitions can differ in their contribution to overall species diversity. 2. In the Neotropics, the Central American butterfly fauna is best known in terms of general natural history, but butterfly community diversity is best documented by studies on South American fruit-feeding butterflies. Here, we present the first long-term study of fruit-feeding nymphalid species diversity from Central America and provide a unique comparison between Central and South American butterfly communities. 3. This study used 60 months of sampling among multiple spatial and temporal partitions to assess species diversity in a Costa Rican rainforest butterfly community. Abundance distributions varied significantly at the species and higher taxonomic group levels, and canopy and understorey samples were found to be composed of distinct species assemblages. 4. Strong similarities in patterns of species diversity were found between this study and one from Ecuador; yet, there was an important difference in how species richness was distributed in vertical space. In contrast to the Ecuadorian site, Costa Rica had significantly higher canopy richness and lower understorey richness. 5. This study affirms that long-term sampling is vital to understanding tropical insect species abundance distributions and points to potential differences in vertical structure among Central and South American forest insect communities that need to be explored.  相似文献   

13.
Aim Central America is a biogeographically interesting area because of its location between the rich and very different biota of North and South America. We aim to assess phytogeographical patterns in the bryophyte floras of oak forests and páramo of the Cordillera de Talamanca, Costa Rica. Location Tropical America, in particular the montane area of Cordillera de Talamanca, Costa Rica. Methods The analysis is based on a new critical inventory of the montane bryophyte flora of Cordillera de Talamanca. All species were assigned to phytogeographical elements on the basis of their currently known distribution. Absolute and percentage similarities were employed to evaluate floristic affinities. Results A total of 401 species [191 hepatics (liverworts), one hornwort, 209 mosses] are recorded; of these, 251 species (128 hepatics, one hornwort, 122 mosses) occur in oak forests. Ninety‐three per cent of all oak forest species are tropical in distribution, the remaining 7% are temperate (4%) and cosmopolitan (3%) species. The neotropical element includes almost 74% of the species, the wide tropical element (pantropical, amphi‐atlantic, amphi‐pacific) only 19%. A significant part of the neotropical species from oak forests are species with tropical Andean‐centred ranges (27%). As compared with bryophyte species, vascular plant genera in the study region are represented by fewer neotropical, more temperate and more amphi‐pacific taxa. Bryophyte floras of different microhabitats within the oak forest and epiphytic bryophyte floras on Quercus copeyensis in primary, early secondary and late secondary oak forest show a similar phytogeographical make‐up to the total oak forest bryophyte flora. Comparison of oak forest and páramo reveals a greater affinity of the páramo bryophyte flora to temperate regions and the great importance of the páramo element in páramo. Surprisingly, oak forests have more Central American endemics than páramo. Main conclusions (1) Providing first insights into the phytogeographical patterns of the bryophyte flora of oak forests and páramo, we are able to confirm general phytogeographical trends recorded from vascular plant genera of the study area although the latter were more rich in temperate taxa. (2) Andean‐centred species are a conspicuous element in the bryophyte flora of Cordillera de Talamanca, reflecting the close historical connection between the montane bryophyte floras of Costa Rica and South America. (3) High percentages of Central American endemics in the bryophyte flora of the oak forests suggest the importance of climatic changes associated with Pleistocene glaciations for allopatric speciation.  相似文献   

14.
Lowland tropical habitats harbour an unexplored genetic diversity of epiphyllous fungi. In the shade of rainforest understoreys, lichenized fungi are specialized to an ephemeral habitat where they produce little vegetative biomass and develop reproductive structures early. In a first population genetic study of epiphyllous lichen fungi, we analysed the intraspecific genetic diversity of five leaf-colonizing lichen mycobiont species. Sampling focused on a lowland perhumid forest plot in Costa Rica, with additional collections from other localities throughout the country. In all species we detected sympatric occurrence of highly diverged haplotypes. Haplotypes belonging to distinct clades in networks were also found on the same leaf, clearly indicating multiple independent colonization events on single leaves. Despite the unusually high genetic diversity of these leaf-colonizing tropical fungi, we did not detect pronounced spatial structure of the haplotype distribution between geographical regions. The observed patterns suggest that the diversity of foliicolous lichens could be much higher than expected, with several cryptic genetic lineages within each morphologically characterized species.  相似文献   

15.
The new basidiolichen Multiclavula ichthyiformis Nelsen, Lücking, Uma?a, Trest & Will-Wolf is described from Costa Rica. The new species differs from other species of Multiclavula in having a basidiocarp with tomentose stipe and flattened lamina with nonamphigenous hymenium. Molecular sequence data (ITS) confirmed its placement within Multiclavula in the Clavulinaceae (Cantharellales, Agaricomycetes). The new lichen was discovered in a Central American paramo remnant, illustrating the importance of biotic inventories of fungi and lichens to increase our knowledge of the diversity of these groups in endangered tropical ecosystems. The new species was found as part of the TICOLICHEN project in Costa Rica.  相似文献   

16.
Conservation of tropical forest birds in countryside habitats   总被引:7,自引:0,他引:7  
The pressing need to increase agricultural production often seems at odds with conserving biodiversity. We find that if managed properly, the tropical countryside may provide a substantial opportunity for tropical bird conservation. We detected 144 bird species from 29 families in agricultural areas outside of extensive native forest in southern Costa Rica. The majority of the species detected were observed foraging, often kilometres from extensive native forest. We estimate that 46% of those native to this region (excluding nocturnal species and waterfowl) are utilizing the countryside in some manner. Forecasts of biodiversity change under various land-use scenarios indicate that policies that affect habitat composition could greatly impact the persistence of these species in the countryside. In particular, if tall trees and edge habitats were removed from this landscape, we predict that bird richness in the countryside would decline by approximately 40%.  相似文献   

17.
18.
By facilitating bioliteracy, DNA barcoding has the potential to improve the way the world relates to wild biodiversity. Here we describe the early stages of the use of cox1 barcoding to supplement and strengthen the taxonomic platform underpinning the inventory of thousands of sympatric species of caterpillars in tropical dry forest, cloud forest and rain forest in northwestern Costa Rica. The results show that barcoding a biologically complex biota unambiguously distinguishes among 97% of more than 1000 species of reared Lepidoptera. Those few species whose barcodes overlap are closely related and not confused with other species. Barcoding also has revealed a substantial number of cryptic species among morphologically defined species, associated sexes, and reinforced identification of species that are difficult to distinguish morphologically. For barcoding to achieve its full potential, (i) ability to rapidly and cheaply barcode older museum specimens is urgent, (ii) museums need to address the opportunity and responsibility for housing large numbers of barcode voucher specimens, (iii) substantial resources need be mustered to support the taxonomic side of the partnership with barcoding, and (iv) hand-held field-friendly barcorder must emerge as a mutualism with the taxasphere and the barcoding initiative, in a manner such that its use generates a resource base for the taxonomic process as well as a tool for the user.  相似文献   

19.
Quick surveys are often used by conservation biologists to assess biodiversity. In tropical forests, fruit-feeding butterflies are a convenient indicator group because they can be readily trapped and are comparatively easy to identify. However, studies carried out in Costa Rica and Ecuador have revealed that long-term sampling is needed to estimate biodiversity accurately. Furthermore, almost half of the biodiversity of fruit-feeding butterflies in the neotropics was found to be in the canopy. Short term sampling in the understory can, therefore, lead to inaccurate estimates of species richness and worse, to poorly informed conservation decisions. Comparable to the studies in South America, we performed a long-term trapping study of the same guild of butterflies in the understory and canopy of Kibale Forest in Uganda, to describe temporal and vertical patterns of biodiversity. We caught 32,308 individuals of 94 species over three years. About 14% of these species could be categorized as canopy specialists and 68% as understory specialists. Temporal variation was extensive and did not follow a clear seasonal pattern. This is the first study in an African forest with continuous sampling of fruit-feeding butterflies over multiple years and in both canopy and understory.  相似文献   

20.
Question: Species diversity is commonly expressed as the number of species present in an area, but this unique value assumes that all species contribute equally to the area's biodiversity. Can taxonomic diversity be used as a complementary measure for species richness in order to assess plant biodiversity in remnants of primary forest and patches of secondary vegetation? Location: Veracruz, Mexico. Methods: Using data from six sampling transects of each vegetation type in an elevation gradient (400‐900 m a.s.l.), we compare the point, mean and cumulative floristic diversity of primary forest and secondary vegetation in a tropical deciduous landscape, using species richness and two measures of taxonomic diversity: average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+). We performed a randomization test to detect differences in the observed taxonomic diversity, from the expected values derived from the species pool of each vegetation type. Results: We found that the species of secondary vegetation are more closely related at low taxonomic levels (lower Δ+ value) than the species of primary forest remnants. Also, in secondary vegetation the distribution of species is uneven among the taxonomic levels and units (high Λ+ value). These patterns are consistent for point, mean and cumulative taxonomic diversity. Families Asteraceae, Euphorbiaceae, Fabaceae and Poaceae are over‐represented, while families Bromeliaceae, Cactaceae, Orchidaceae and Pteridaceae are under‐represented in secondary vegetation. Conclusions: Although in a previous paper we concluded that secondary vegetation is more alpha‐diverse than primary forest (in terms of both cumulative and mean species richness), and beta‐diversity between vegetation types is notoriously high, we now provide a wider view by highlighting the importance of taxonomic diversity in primary forest remnants. Our data indicate that to measure biodiversity accurately, we should seek to capture its different facets. This will allow us to make conservation recommendations based on a broader view, and not on a single dimension.  相似文献   

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