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Species Accumulation Curves (species + accumulation_curve)

Distribution by Scientific Domains

Life Sciences	83%

Selected Abstracts

Estimating the Species Accumulation Curve Using Mixtures

BIOMETRICS, Issue 2 2005
Chang Xuan Mao
Summary As a significant tool in ecological studies, the species accumulation curve or the collector's curve is the graph of the expected number of detected species as a function of sampling effort. The problem of estimating the species accumulation curve based on an empirical data set arising from quadrat sampling is studied in a nonparametric binomial mixture model. It will be shown that estimating the species accumulation curve not only is independent of the unknown number of species but also includes estimating the number of species as a limiting case. For the purpose of interpolation, moment-based estimators, associated with asymptotic confidence intervals, are developed from several points of view. A likelihood-based procedure is developed for the purpose of extrapolation, associated with bootstrap confidence intervals. The proposed methods are illustrated by ecological data sets. [source]

Elevational Patterns of Diversity and Abundance of Eusocial Paper Wasps (Vespidae) in Costa Rica

BIOTROPICA, Issue 3 2009
Anjali Kumar
ABSTRACT We used a standard sampling protocol to measure elevational patterns of species richness and abundance of eusocial paper wasps (Hymenoptera: Vespidae) in Costa Rica. The sample transect of six sites spanned approximately 2000 m in elevation from lowland to montane forest. Species accumulation curves and species richness estimates both document a low elevation peak in paper wasp species richness at 50 and 300 m asl, with a decline in species richness at higher elevations. Comparison of species composition among elevations revealed strong species turnover from a rich lowland fauna to a depauperate, but distinct, montane fauna. We also observed a general trend toward a greater abundance of paper wasps at higher elevations, a pattern not usually observed in eusocial insects. Army ant species that prey on paper wasps declined in abundance with elevation across the sample transect, a pattern that has been observed at other sites. We discuss the possibility that elevational changes in predation pressure affect variation in paper wasp abundance and species richness. Eusocial paper wasp species employ one of two modes of colony founding, independent and swarm founding. We found that the total abundance of individual swarm-founding wasps was higher at all elevations than the abundance of independent-founding wasps, supporting previous suggestions that Neotropical swarm founders are more successful ecologically. [source]

Effect of species richness and relative abundance on the shape of the species accumulation curve

AUSTRAL ECOLOGY, Issue 4 2003
Graham G. Thompson
Abstract We explain how species accumulation curves are influenced by species richness (total number of species), relative abundance and diversity using computer-generated simulations. Species richness defines the boundary of the horizontal asymptote value for a species accumulation curve, and the shape of the curve is influenced by both relative abundance and diversity. Simulations with a high proportion of rare species and a few abundant species have a species accumulation curve with a low ,shoulder' (inflection point on the ordinate axis) and a long upward slope to the asymptote. Simulations with a high proportion of relatively abundant species have a steeply rising initial slope to the species accumulation curve and plateau early. Diversity (as measured by Simpson's and Shannon,Weaver indices) for simulations is positively correlated with the initial slope of the species accumulation curve. Species accumulation curves cross when one simulation has a high proportion of both rare and abundant species compared with another that has a more even distribution of abundance among species. [source]

Estimating the Species Accumulation Curve Using Mixtures

Spatial and temporal variation of abundance, biomass and diversity within marine reserves in the Philippines

DIVERSITY AND DISTRIBUTIONS, Issue 4 2010
Jonathan A. Anticamara
Abstract Aim, The objective of this study was to investigate the influence of protection duration (years of fishing closure) and location (distance from shore) on reef fish diversity. Location, Danajon Double Barrier Reef, Bohol, Philippines. Methods, Reef fish abundance and size structure, by species, were obtained monthly using replicated underwater visual belt transects (n = 8; 70 × 5-m belt transects) over 3 years (2002,2005) at eight sites that included six marine reserves and two unprotected reef areas. We analysed species accumulation curves, diversity indices and abundance,biomass comparison (ABC) curves within and across the study sites to assess the influence of protection duration and location. Results, Analyses showed that longer protection duration impacted reef fish diversity at both inshore and offshore sites by shifting ABC curves from higher abundance than biomass curves at fished sites to higher biomass than abundance curves at most of the protected sites. Protection duration did not significantly influence either the rate of species accumulation within sites or the 12 diversity indices measured across the study sites. The offshore sites consistently showed higher rates of species accumulation and diversity indices values than inshore sites with similar protection duration. One protected offshore young marine reserve site that has been assessed as the least well-managed showed patterns more consistent with the fished sites. Main conclusions, Analyses showed that protection duration mainly impacted diversity by increasing the dominance of large-bodied species and enhancing total biomass. Besides protection duration, reserve location influenced species accumulation curves and diversity indices. [source]

Integrating highly diverse invertebrates into broad-scale analyses of cross-taxon congruence across the Palaearctic

ECOGRAPHY, Issue 6 2009
Andreas Schuldt
Our knowledge on broad-scale patterns of biodiversity, as a basis for biogeographical models and conservation planning, largely rests upon studies on the spatial distribution of vertebrates and plants, neglecting large parts of the world's biodiversity. To reassess the generality of these patterns and better understand spatial diversity distributions of invertebrates, we analyzed patterns of species richness and endemism of a hyperdiverse insect taxon, carabid beetles (ca 11 000 Palaearctic species known), and its cross-taxon congruence with well-studied vertebrates (amphibians, reptiles) and plants across 107,units of the Palaearctic. Based on species accumulation curves, we accounted for completeness of the carabid data by separately examining the western (well-sampled) and eastern (partly less well-sampled) Palaearctic and China (deficient data). For the western Palaearctic, we highlight overall centers of invertebrate, vertebrate and plant diversity. Species richness and endemism of carabids were highly correlated with patterns of especially plant and amphibian diversity across large parts of the Palaearctic. For the well-sampled western Palaearctic, hotspots of diversity integrating invertebrates were located in Italy, Spain and Greece. Only analysis of Chinese provinces yielded low congruence between carabids and plants/vertebrates. However, Chinese carabid diversity is only insufficiently known and China features the highest numbers of annual new descriptions of carabids in the Palaearctic. Even based on the incomplete data, China harbors at least 25% of all Palaearctic carabid species. Our study shows that richness and endemism patterns of highly diverse insects can exhibit high congruence with general large scale patterns of diversity inferred from plants/vertebrates and that hotspots derived from the latter can also include a high diversity of invertebrates. In this regard, China qualifies as an outstanding multi-taxon hotspot of diversity, requiring intense biodiversity research and conservation effort. Our findings extend the limited knowledge on broad-scale invertebrate distributions and allow for a better understanding of diversity patterns across a larger range of the world's biodiversity than usually considered. [source]

On the estimation of species richness based on the accumulation of previously unrecorded species

ECOGRAPHY, Issue 1 2002
Emmanuelle Cam
Estimation of species richness of local communities has become an important topic in community ecology and monitoring. Investigators can seldom enumerate all the species present in the area of interest during sampling sessions. If the location of interest is sampled repeatedly within a short time period, the number of new species recorded is typically largest in the initial sample and decreases as sampling proceeds, but new species may be detected if sampling sessions are added. The question is how to estimate the total number of species. The data collected by sampling the area of interest repeatedly can be used to build species accumulation curves: the cumulative number of species recorded as a function of the number of sampling sessions (which we refer to as "species accumulation data"). A classic approach used to compute total species richness is to fit curves to the data on species accumulation with sampling effort. This approach does not rest on direct estimation of the probability of detecting species during sampling sessions and has no underlying basis regarding the sampling process that gave rise to the data. Here we recommend a probabilistic, nonparametric estimator for species richness for use with species accumulation data. We use estimators of population size that were developed for capture-recapture data, but that can be used to estimate the size of species assemblages using species accumulation data. Models of detection probability account for the underlying sampling process. They permit variation in detection probability among species. We illustrate this approach using data from the North American Breeding Bird Survey (BBS). We describe other situations where species accumulation data are collected under different designs (e.g., over longer periods of time, or over spatial replicates) and that lend themselves to of use capture-recapture models for estimating the size of the community of interest. We discuss the assumptions and interpretations corresponding to each situation. [source]

The value of georeferenced collection records for predicting patterns of mosquito species richness and endemism in the Neotropics

ECOLOGICAL ENTOMOLOGY, Issue 1 2008
DESMOND H. FOLEY
Abstract 1.,Determining large-scale distribution patterns for mosquitoes could advance knowledge of global mosquito biogeography and inform decisions about where mosquito inventory needs are greatest. 2.,Over 43 000 georeferenced records are presented of identified and vouchered mosquitoes from collections undertaken between 1899 and 1982, from 1853 locations in 42 countries throughout the Neotropics. Of 492 species in the data set, 23% were only recorded from one location, and Anopheles albimanus Wiedemann is the most common species. 3.,A linear log,log species,area relationship was found for mosquito species number and country area. Chile had the lowest relative density of species and Trinidad-Tobago the highest, followed by Panama and French Guiana. 4.,The potential distribution of species was predicted using an Ecological Niche Modelling (ENM) approach. Anopheles species had the largest predicted species ranges, whereas species of Deinocerites and Wyeomyia had the smallest. 5.,Species richness was estimated for 1° grids and by summing predicted presence of species from ENM. These methods both showed areas of high species richness in French Guiana, Panama, Trinidad-Tobago, and Colombia. Potential hotspots in endemicity included unsampled areas in Panama, French Guiana, Colombia, Belize, Venezuela, and Brazil. 6.,Argentina, The Bahamas, Bermuda, Bolivia, Cuba, and Peru were the most under-represented countries in the database compared with known country species occurrence data. Analysis of species accumulation curves suggested patchiness in the distribution of data points, which may affect estimates of species richness. 7.,The data set is a first step towards the development of a global-scale repository of georeferenced mosquito collection records. [source]

Determining woodpecker diversity in the sub-Himalayan forests of northern India using call playbacks

JOURNAL OF FIELD ORNITHOLOGY, Issue 2 2010
Raman Kumar
ABSTRACT Tropical forests have exceptional woodpecker diversity, but little is known about the abundance and diversity of woodpeckers in the Indian subcontinent, particularly for the Shorea robusta -dominated moist deciduous forests of northern India. Our objective was to compare the number of woodpecker species and number of individuals detected using playback surveys and visual/aural transect surveys at five sites. Each site was surveyed 5,6 times along a 2000-m transect, with woodpeckers detected using two methods: (1) visual and aural cues, and (2) playing back calls of 13 species at 400-m intervals. Both methods involved similar effort per survey (100,110 min). During surveys, we detected 11 species of woodpeckers. More species and more than twice as many individuals were detected during playback surveys than during visual/aural surveys. In addition, species accumulation curves showed that we detected the species known to be present based on previous work faster with playback surveys than with visual/aural surveys at four of the five sites. During field trials, 97% of targeted individuals (N= 269) of 12 species responded to playback, and 83% of the responses occurred within 1 min of broadcast. The number of species of woodpeckers in our study area (11 species) was typical for a structurally diverse, tropical/subtropical moist broad-leaved forest. Our results demonstrate that playback surveys are more efficient and accurate than visual/aural surveys, and that playback surveys can be useful for assessing and monitoring woodpecker diversity in tropical forests. RESUMEN Los bosques tropicales tienen una diversidad excepcional de pájaros carpinteros, pero se conoce muy poco sobre la abundancia y diversidad de estas aves en la parte norte del sub-continente de la India, particularmente en el bosque deciduo húmedo dominado por Shorea robusta. Nuestro objetivo fue comparar el número de especies y de individuos de carpinteros utilizando grabaciones para censarlos y transectos visuales/auditivos en cinco lugares. Cada lugar fue censado 5,6 veces, cada 400m, a lo largo de un transecto de 2000 m, utilizando pistas visuales y auditivas y grabaciones de 13 especies. Ambos métodos incluyeron un esfuerzo similar por censo (100,110 minutos). Durante los censos, detectamos 11 especies de pájaros carpinteros. Una cantidad mayor de especies y más del doble de los individuos fueron detectados utilizando grabaciones que en los censos visuales/auditivos. Además, las curvas de acumulación de especies mostraron que detectamos las especies que sabíamos estaban presentes (basados en trabajos previos) de forma más rápida utilizando grabaciones que con el método visual/auditivo en cuatro de las cinco localidades. Durante las pruebas de campo el 97% (N= 269) de 12 especies respondieron a las grabaciones, y el 83% de las respuestas se obtuvieron un minuto después de exponerlos a la grabación. El número de especies de pájaros carpinteros en nuestra área de estudio (11) fue el típico para un bosque tropical/subtropical húmedo de hoja ancha y estructura diversificada. Nuestros resultados demuestran que los censos en donde se usan grabaciones son más eficientes y precisos que los censos visuales/auditivos. Además que los censos en donde se usan grabaciones pueden ser útiles para determinar y monitorear la diversidad de carpinteros en bosques tropicales. [source]

Effect of species richness and relative abundance on the shape of the species accumulation curve

Survey-gap analysis in expeditionary research: where do we go from here?

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2005
V. A. FUNK
Research expeditions into remote areas to collect biological specimens provide vital information for understanding biodiversity. However, major expeditions to little-known areas are expensive and time consuming, time is short, and well-trained people are difficult to find. In addition, processing the collections and obtaining accurate identifications takes time and money. In order to get the maximum return for the investment, we need to determine the location of the collecting expeditions carefully. In this study we used environmental variables and information on existing collecting localities to help determine the sites of future expeditions. Results from other studies were used to aid in the selection of the environmental variables, including variables relating to temperature, rainfall, lithology and distance between sites. A survey gap analysis tool based on ,ED complementarity' was employed to select the sites that would most likely contribute the most new taxa. The tool does not evaluate how well collected a previously visited site survey site might be; however, collecting effort was estimated based on species accumulation curves. We used the number of collections and/or number of species at each collecting site to eliminate those we deemed poorly collected. Plants, birds, and insects from Guyana were examined using the survey gap analysis tool, and sites for future collecting expeditions were determined. The south-east section of Guyana had virtually no collecting information available. It has been inaccessible for many years for political reasons and as a result, eight of the first ten sites selected were in that area. In order to evaluate the remainder of the country, and because there are no immediate plans by the Government of Guyana to open that area to exploration, that section of the country was not included in the remainder of the study. The range of the ED complementarity values dropped sharply after the first ten sites were selected. For plants, the group for which we had the most records, areas selected included several localities in the Pakaraima Mountains, the border with the south-east, and one site in the north-west. For birds, a moderately collected group, the strongest need was in the north-west followed by the east. Insects had the smallest data set and the largest range of ED complementarity values; the results gave strong emphasis to the southern parts of the country, but most of the locations appeared to be equidistant from one another, most likely because of insufficient data. Results demonstrate that the use of a survey gap analysis tool designed to solve a locational problem using continuous environmental data can help maximize our resources for gathering new information on biodiversity. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 549,567. [source]