scholarly journals Habitat fragmentation and the species-area relationship: a focus on total species richness obscures the impact of habitat loss on habitat specialists

2014 ◽  
Vol 20 (10) ◽  
pp. 1136-1146 ◽  
Author(s):  
Thomas J. Matthews ◽  
H. Eden Cottee-Jones ◽  
Robert J. Whittaker
Keyword(s):  
Species Richness ◽  
Habitat Fragmentation ◽  
Habitat Loss ◽  
Total Species Richness ◽  
Species Area ◽  
Habitat Specialists ◽  
Species Area Relationship ◽  
The Impact ◽  
Total Species

scholarly journals Inferring global species richness from megatransect data and undetected species estimates

2019 ◽  
Vol 88 (1) ◽  
pp. 42-53 ◽  
Author(s):  
Bernhard A. Huber ◽  
Anne Chao
Keyword(s):  
Species Richness ◽  
New Species ◽  
Confidence Interval ◽  
Incidence Data ◽  
Total Species Richness ◽  
Species Incidence ◽  
Biogeographic Regions ◽  
Global Patterns ◽  
The Impact ◽  
Total Species

Ratio-like approaches for estimating global species richness have been criticised for their unjustified extrapolation from regional to global patterns. Here we explore the use of cumulative percentages of ‘new’ (i.e., not formally described) species over large geographic areas (‘megatransects’) as a means to overcome this problem. In addition, we take into account undetected species and illustrate these combined methods by applying them to a family of spiders (Pholcidae) that currently contains some 1,700 described species. The raw global cumulative percentage of new species (‘new’ as of the end of 2008, when 1,001 species were formally described) is 75.1%, and is relatively constant across large biogeographic regions. Undetected species are estimated using the Chao2 estimator based on species incidence data (date by species and locality by species matrices). The estimated percentage of new species based on the date by species matrices is 76.0% with an estimated standard error (s.e.) of 2.6%. This leads to an estimated global species richness of about 4,200 with a 95% confidence interval of (3,300, 5,000). The corresponding values based on locality by species matrices are 84.2% (s.e. 3.0%) and 6,300 with a 95% confidence interval of (4,000, 8,600). Our results suggest that the currently known 1,700 species of Pholcidae may represent no more than about 25–40% of the total species richness. The impact of further biasing factors like geography, species size and distribution, cryptic species, and model assumptions needs to be explored.

Species richness in the Phanerozoic: an investigation of sampling effects

Paleobiology ◽  
1978 ◽  
Vol 4 (4) ◽  
pp. 394-406 ◽  
Author(s):  
Philip W. Signor
Keyword(s):  
Species Richness ◽  
Species Abundance ◽  
Strongly Correlated ◽  
Species Abundance Distribution ◽  
Sediment Volume ◽  
Total Species Richness ◽  
Cenozoic Sediments ◽  
The Impact ◽  
The Relationship ◽  
Total Species

Given estimates of the variation in total standing species richness through the periods of the Phanerozoic, mean species duration, and the relative intensity of the sampling of the fauna from each of the periods, the expected number of described species can be predicted for each period of the Phanerozoic using an analytic sampling model. This model is based on the assumption that the relative abundances of species in any geologic period can be approximated by the canonical (lognormal) species-abundance distribution.Three commonly cited models of standing species richness (Valentine, 1973; Gould et al., 1977; Bambach, 1977) each suggest different patterns of species richness in the Phanerozoic. By assuming that sampling of the fossil record is proportionate to sediment volume, it can be shown with the sampling model that the Empirical, Equilibrium, and Species-Richness Models each predict that the number of described species will be strongly correlated with sediment volume. Equally high correlations are predicted if it is assumed that sampling is proportionate to sediment area or to paleontological interest. The correlations predicted for each of the three models are remarkably similar. The impact of sampling effects is so strong that the variations in species richness postulated by these three models are almost completely obscured. Preservational biases will probably only further obscure the relationship between the number of described species and total species richness. Therefore, it seems likely that analysis of trends in the total number of described species will be of little use in determining trends in worldwide species richness in the Phanerozoic.Comparison of the actual patterns of variation in the number of described species and the expected numbers of described species predicted by the sampling model reveals that more species are known from the Cenozoic than would be predicted from the abundance of Cenozoic sediments or from the amount of paleontological interest in the Cenozoic. This might have resulted from the Cenozoic sediments remaining relatively free of diagenetic effects which might have destroyed the fossils entombed in the sediments.

scholarly journals Island species-area relationships in the Andaman islands emerge because rarer species are disproportionately favored on larger islands

2019 ◽  
Author(s):  
Leana D. Gooriah ◽  
Priya Davidar ◽  
Jonathan M. Chase
Keyword(s):  
Species Richness ◽  
Random Sampling ◽  
Common Species ◽  
Sampling Effort ◽  
Island Species ◽  
Total Species Richness ◽  
Species Area ◽  
Using Data ◽  
Species Richness And Abundance ◽  
Total Species

AbstractThe Island Species-Area relationship (ISAR) describes how the number of species increases with increasing size of an island (or island-like habitat), and is of fundamental importance in island biogeography and conservation. Here, we use a framework based on individual-based rarefactions to infer whether ISARs result from random sampling, or whether some process are acting beyond sampling (e.g., disproportionate effects and/or habitat heterogeneity). Using data on total and relative abundances of four taxa (birds, butterflies, amphibians and reptiles) across the Andamans and Nicobar archipelago, we examine how different metrics of biodiversity (total species richness, rarefied species richness, and abundance-weighted effective numbers of species emphasizing common species) vary with island area. Total species richness increased for all taxa, as did rarefied species richness for a given sampling effort. This indicates that the ISAR did not result because of random sampling, but that instead, species were disproportionately favored on larger islands. This disproportionate effect was primarily due to changes in the abundance of rarer species, because there was no effect on the abundance-weighted diversity measure for all taxa except butterflies. Furthermore, for the two taxa for which we had plot-level data (lizards and frogs), within-island β -diversity did not increase with island size, suggesting that heterogeneity effects were unlikely to be driving these ISARS. Overall, our results indicate that the ISAR of these taxa is most likely because rarer species are more likely to survive and persist beyond that which would have been expected by random sampling alone, and emphasizes the role of these larger islands in the preservation and conservation of species.

Partial cutting reduces species richness of fungi on woody debris in oak-rich forests

2008 ◽  
Vol 38 (7) ◽  
pp. 1807-1816 ◽  
Author(s):  
Björn Nordén ◽  
Frank Götmark ◽  
Martin Ryberg ◽  
Heidi Paltto ◽  
Johan Allmér
Keyword(s):  
Species Richness ◽  
Woody Debris ◽  
Basal Area ◽  
Fruiting Bodies ◽  
Partial Cutting ◽  
Total Species Richness ◽  
Before And After ◽  
Closed Canopy ◽  
And Control ◽  
Total Species

Partial cutting is increasingly applied in European temperate oak-dominated forests for biofuel harvesting, and to counteract succession in protected stands. Effects on biodiversity of these measures need to be carefully evaluated, and species-rich but neglected taxa such as fungi should be considered. We studied the effects of partial cutting on fungal fruiting bodies on woody debris. In 21 closed canopy forests rich in large oaks in Sweden, on average 25%–30% of the basal area was cut. Fruiting bodies were counted and some were collected in treated and control plots before and after treatment. We found 334 basidiomycete and 47 ascomycete species. Species richness of basidiomycetes declined significantly more in treated plots (on average 26%) than in control plots (on average 13%) between seasons. Species richness of ascomycetes increased by 17% in control plots and decreased by 2% in treated plots. Total species richness was significantly reduced on fine woody debris (1–10 cm in diameter), but not on coarse woody debris (>10 cm). Overall species composition did not change significantly as a result of partial cutting, but red-listed species tended to decrease more in treated plots. We suggest that approximately 30% of the stands should not be thinned, and dead stems and fallen branches should not be removed, to favor saproxylic fungi and their associated fauna.

scholarly journals Fish species diversity in headwaters streams of Paraguay and Paraná Basins

2007 ◽  
Vol 50 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Yzel Rondon Súarez ◽  
Sabrina Bigatão Valério ◽  
Karina Keyla Tondado ◽  
Alexandro Cezar Florentino ◽  
Thiago Rota Alves Felipe ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Environmental Factors ◽  
Fish Species ◽  
Total Species Richness ◽  
Paraná Basin ◽  
Parana Basin ◽  
Number Of Individuals ◽  
Total Species ◽  
Fish Species Diversity

The influence of spatial, temporal and environmental factors on fish species diversity in headwater streams in Paraguay and Paraná basins, Brazil was examined. A total of 4,605 individuals were sampled, distributed in 60 species. The sampled streams in Paraná basin presented a larger total species richness (42) than Paraguay streams (40). However the estimated richness was larger in Paraguay basin (53) than Paraná streams (50). The streams of Paraná basin had a greater mean species richness and evenness, while more individuals per sample were found in the Paraguay basin. Difference between the sub-basins were found in the Paraguay basin, while for the basin of Paraná, richness and evenness vary significantly between the sub-basins, but the number of individuals varied seasonally. The most important environmental factors to species diversity and abundance were altitude, water temperature, stream width and stream depth for both the basins.

scholarly journals Increased mosquito abundance and species richness in Connecticut, United States 2001–2019

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tanya A. Petruff ◽  
Joseph R. McMillan ◽  
John J. Shepard ◽  
Theodore G. Andreadis ◽  
Philip M. Armstrong
Keyword(s):  
United States ◽  
Species Richness ◽  
Community Composition ◽  
Pathogen Transmission ◽  
Public Health Importance ◽  
Data Set ◽  
Mosquito Abundance ◽  
Total Species Richness ◽  
Multiple Species ◽  
Total Species

Abstract Historical declines in multiple insect taxa have been documented across the globe in relation to landscape-level changes in land use and climate. However, declines have either not been universally observed in all regions or examined for all species. Because mosquitoes are insects of public health importance, we analyzed a longitudinal mosquito surveillance data set from Connecticut (CT), United States (U.S.) from 2001 to 2019 to identify changes in mosquito community composition over time. We first analyzed annual site-level collections and metrics of mosquito community composition with generalized linear/additive mixed effects models; we also examined annual species-level collections using the same tools. We then examined correlations between statewide collections and weather variables as well as site-level collections and land cover classifications. We found evidence that the average trap night collection of mosquitoes has increased by ~ 60% and statewide species richness has increased by ~ 10% since 2001. Total species richness was highest in the southern portion of CT, likely due to the northward range expansion of multiple species within the Aedes, Anopheles, Culex, and Psorophora genera. How the expansion of mosquito populations in the northeast U.S. will alter mosquito-borne pathogen transmission in the region will require further investigation.

The Westphalian–Stephanian macrofloral record from the South Wales Coalfield, UK

2007 ◽  
Vol 144 (3) ◽  
pp. 465-486 ◽  
Author(s):  
CHRISTOPHER J. CLEAL
Keyword(s):  
Species Richness ◽  
Detailed Comparison ◽  
The South ◽  
Significant Drop ◽  
South Wales ◽  
Total Species Richness ◽  
Total Species

The South Wales Coalfield has the most complete Westphalian macrofloral record anywhere on the Variscan Foreland or adjacent basins, with 135 biodiversity-meaningful morphospecies having been recognized. All of the standard macrofloral biozones of the Westphalian Stage have been recognized, although a detailed comparison with the Central Pennines Coalfields has indicated some discrepancies in the relative positions of the biozonal boundaries. Total Species Richness progressively increases through the Langsettian Substage, and then remains relatively stable through most of the Duckmantian and Bolsovian substages. There is a distinct reduction in Total Species Richness towards the top of the Bolsovian Substage, but this partially recovers in the middle Asturian Substage with the appearance of a range of marattialean ferns, and medullosalean and callistophytaleans pteridosperms. There is no evidence of any significant drop in Total Species Richness towards the top of the succession, indicating that conditions at this time were relatively stable. The change from coastal floodplain to alluvial braidplain conditions in middle Bolsovian times correlates with a marked increase in the proportion of medullosalean remains being preserved in the adpression record, reflecting an expansion of the clastic-substrate habitats.

Hot-Spot Facts and Artifacts-Questioning Israel's Great Biodiversity

2009 ◽  
Vol 55 (3) ◽  
pp. 263-279 ◽  
Author(s):  
Uri Roll ◽  
Lewi Stone ◽  
Shai Meiri
Keyword(s):  
Species Richness ◽  
Biological Diversity ◽  
Hot Spot ◽  
Flowering Plants ◽  
Prediction Intervals ◽  
Predicting Factors ◽  
Mediterranean Countries ◽  
Species Area ◽  
Expected Values ◽  
Species Area Relationship

Israel's biological diversity has been praised as being particularly rich in relation to its size; however this assumption was never tested when taking into account the empirical form of the species-area relationship. Here we compared the species richness of different countries to see if the Israeli diversity is exceptionally rich when area is accurately accounted for. We compared richness of amphibians, birds, mammals, reptiles, flowering plants, conifers and cycads, and ferns in all the world's countries. We further tested the effects of mean latitude, altitude span, and insularity on species richness both for all world countries and just for Mediterranean countries. For all taxa and in all tests, Israel lies within the prediction intervals of the models. Out of 42 tests, Israel's residuals lie in the upper decile of positive residuals once: for reptiles, when compared to all world countries, taking all predicting factors into account. Using only countries larger than 1000 km2, Israel was placed as top residual when compared to other Mediterranean countries for mammals and reptiles. We therefore conclude that Israel's species richness does not significantly exceed the expected values for a country its size. This is true when comparing it to either world or just Mediterranean countries. Adding more predicting factors does not change this fact.

scholarly journals The Impact of the Species–Area Relationship on Estimates of Paleodiversity

PLoS Biology ◽  
2005 ◽  
Vol 3 (8) ◽  
pp. e266 ◽  
Author(s):  
Anthony D Barnosky ◽  
Marc A Carrasco ◽  
Edward B Davis
Keyword(s):  
Species Area ◽  
Species Area Relationship ◽  
The Impact
Sign in / Sign up

Export Citation Format

Share Document