A new look at age and area: the geographic and environmental expansion of genera during the Ordovician Radiation

Paleobiology ◽  
1997 ◽  
Vol 23 (4) ◽  
pp. 410-419 ◽  
Author(s):  
Arnold I. Miller
Keyword(s):  
Species Richness ◽  
Marine Species ◽  
Global Scale ◽  
Direct Link ◽  
Geographic Ranges ◽  
Higher Taxa ◽  
Kinetics Of ◽  
New Look

Although available paleobiological data indicate that the geographic ranges of marine species are maintained throughout their entire observable durations, other evidence suggests, by contrast, that the ranges of higher taxa expand as they age, perhaps in association with increased species richness. Here, I utilize a database of Ordovician genus occurrences collected from the literature for several paleocontinents to demonstrate that a significant aging of the global biota during the Ordovician Radiation was accompanied by a geographic and environmental expansion of genus ranges. The proportion of genera occurring in two or more paleocontinents in the database, and two or more environmental zones within a six-zone onshore-offshore framework, increased significantly in the Caradocian and Ashgillian. Moreover, widespread genera tended to be significantly older than their endemic counterparts, suggesting a direct link between their ages and their environmental and geographic extents. Expansion in association with aging was corroborated further by demonstrating this pattern directly among genera that ranged from the Tremadocian through the Ashgillian. Taken together, these results are significant not only for what they reveal about the kinetics of a major, global-scale diversification, but also for what they suggest about the interpretation of relationships between diversity trends at the α (within-community) and β (between-community) levels.

Diversity of herpetofauna at restored cranberry bogs: A comparative survey of herpetofaunal diversity at a restored wetland in comparison to a retired cranberry bog to assess the restoration success

2022 ◽  
pp. 14-26
Author(s):  
Regina A. Christen
Keyword(s):  
Species Richness ◽  
Relative Abundance ◽  
Survey Methods ◽  
Recovery Phase ◽  
Global Scale ◽  
Early Recovery ◽  
Amphibian Species ◽  
Geographic Ranges ◽  
Restoration Success ◽  
Conservation Concern

Wetlands perform critical ecological functions and provide wildlife habitats. Yet, wetland degradation continues at a global scale. In Massachusetts, USA, wetland restoration has reached remarkable heights, partly promoted by the retirement of cranberry bogs. In this study, to assess the effectiveness of cranberry-farm restoration for conservation of native herpetofauna, we surveyed both retired and restored cranberry bogs in south-eastern Massachusetts. Using both visual encounter surveys and baited aquatic traps, we documented herpetofaunal species and their relative abundance. Both survey methods combined, the cumulative herpetofaunal species richness at the restored bogs (16) exceeded that of the retired bogs (11). Our trap surveys indicated that the amphibian species richness at the retired bog was significantly greater than that of the restored bog. In contrast, reptilian species richness as well as the relative abundance of both amphibians and reptiles were significantly greater at the restored bog compared to the retired bog. Subsequent analyses we performed identified that greater habitat heterogeneity emerging from active restoration intervention was the underlying driver of elevated richness and abundance. Most frequently encountered herpetofauna at the restored versus retired bogs were habitat generalists with broader geographic ranges and are not of conservation concern. Our findings suggest that the restored bog we monitored is still in the early-recovery phase after active intervention. We urge the need for long-term herpetofaunal inventories via systematic, standard surveys to assess restoration success.

scholarly journals Global warming is causing a more pronounced dip in marine species richness around the equator

2021 ◽  
Vol 118 (15) ◽  
pp. e2015094118
Author(s):  
Chhaya Chaudhary ◽  
Anthony J. Richardson ◽  
David S. Schoeman ◽  
Mark J. Costello
Keyword(s):  
Climate Change ◽  
Species Richness ◽  
Animal Species ◽  
Latitudinal Gradient ◽  
Marine Species ◽  
Global Scale ◽  
Marine Biodiversity ◽  
Marine Animal ◽  
Pelagic Species ◽  
The Tropics

The latitudinal gradient in species richness, with more species in the tropics and richness declining with latitude, is widely known and has been assumed to be stable over recent centuries. We analyzed data on 48,661 marine animal species since 1955, accounting for sampling variation, to assess whether the global latitudinal gradient in species richness is being impacted by climate change. We confirm recent studies that show a slight dip in species richness at the equator. Moreover, richness across latitudinal bands was sensitive to temperature, reaching a plateau or declining above a mean annual sea surface temperature of 20 °C for most taxa. In response, since the 1970s, species richness has declined at the equator relative to an increase at midlatitudes and has shifted north in the northern hemisphere, particularly among pelagic species. This pattern is consistent with the hypothesis that climate change is impacting the latitudinal gradient in marine biodiversity at a global scale. The intensification of the dip in species richness at the equator, especially for pelagic species, suggests that it is already too warm there for some species to survive.

Using higher taxa to estimate species richness: birds on New Zealand islands

Ibis ◽  
2001 ◽  
Vol 143 (1) ◽  
pp. 146-148 ◽  
Author(s):  
SIMON HODGE ◽  
CHRIS FRAMPTON
Keyword(s):  
Species Richness ◽  
New Zealand ◽  
Higher Taxa

scholarly journals Species delimitation at a global scale reveals high species richness with complex biogeography and patterns of symbiont association in Peltigera section Peltigera (lichenized Ascomycota: Lecanoromycetes)

Taxon ◽  
2018 ◽  
Vol 67 (5) ◽  
pp. 836-870 ◽  
Author(s):  
Nicolas Magain ◽  
Camille Tniong ◽  
Trevor Goward ◽  
Dongling Niu ◽  
Bernard Goffinet ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Delimitation ◽  
Global Scale ◽  
High Species Richness

scholarly journals Scavenging in the Anthropocene: Human impact drives vertebrate scavenger species richness at a global scale

2020 ◽  
Author(s):  
E Sebastián-González ◽  
JM Barbosa ◽  
JM Pérez-García ◽  
Z Morales-Reyes ◽  
F Botella ◽  
...  
Keyword(s):  
Species Richness ◽  
Human Impact ◽  
Large Scale ◽  
Diversity Index ◽  
Global Scale ◽  
Climatic Conditions ◽  
Ecosystem Functions ◽  
Number Of Species ◽  
Terrestrial Vertebrate ◽  
Latitudinal Patterns

© 2019 John Wiley & Sons Ltd Understanding the distribution of biodiversity across the Earth is one of the most challenging questions in biology. Much research has been directed at explaining the species latitudinal pattern showing that communities are richer in tropical areas; however, despite decades of research, a general consensus has not yet emerged. In addition, global biodiversity patterns are being rapidly altered by human activities. Here, we aim to describe large-scale patterns of species richness and diversity in terrestrial vertebrate scavenger (carrion-consuming) assemblages, which provide key ecosystem functions and services. We used a worldwide dataset comprising 43 sites, where vertebrate scavenger assemblages were identified using 2,485 carcasses monitored between 1991 and 2018. First, we evaluated how scavenger richness (number of species) and diversity (Shannon diversity index) varied among seasons (cold vs. warm, wet vs. dry). Then, we studied the potential effects of human impact and a set of macroecological variables related to climatic conditions on the scavenger assemblages. Vertebrate scavenger richness ranged from species-poor to species rich assemblages (4–30 species). Both scavenger richness and diversity also showed some seasonal variation. However, in general, climatic variables did not drive latitudinal patterns, as scavenger richness and diversity were not affected by temperature or rainfall. Rainfall seasonality slightly increased the number of species in the community, but its effect was weak. Instead, the human impact index included in our study was the main predictor of scavenger richness. Scavenger assemblages in highly human-impacted areas sustained the smallest number of scavenger species, suggesting human activity may be overriding other macroecological processes in shaping scavenger communities. Our results highlight the effect of human impact at a global scale. As species-rich assemblages tend to be more functional, we warn about possible reductions in ecosystem functions and the services provided by scavengers in human-dominated landscapes in the Anthropocene.

scholarly journals Changes of arthropod diversity across an altitudinal ecoregional zonation in Northwestern Argentina

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4117 ◽  
Author(s):  
Andrea X. González-Reyes ◽  
Jose A. Corronca ◽  
Sandra M. Rodriguez-Artigas
Keyword(s):  
Species Richness ◽  
Polynomial Regression ◽  
Species Turnover ◽  
Predictor Variable ◽  
Elevational Gradient ◽  
Pitfall Trap ◽  
Northwestern Argentina ◽  
Higher Taxa ◽  
Total Species Richness ◽  
Wide Range

This study examined arthropod community patterns over an altitudinal ecoregional zonation that extended through three ecoregions (Yungas, Monte de Sierras y Bolsones, and Puna) and two ecotones (Yungas-Monte and Prepuna) of Northwestern Argentina (altitudinal range of 2,500 m), and evaluated the abiotic and biotic factors and the geographical distance that could influence them. Pitfall trap and suction samples were taken seasonally in 15 sampling sites (1,500–4,000 m a.s.l) during one year. In addition to climatic variables, several soil and vegetation variables were measured in the field. Values obtained for species richness between ecoregions and ecotones and by sampling sites were compared statistically and by interpolation–extrapolation analysis based on individuals at the same sample coverage level. Effects of predictor variables and the similarity of arthropods were shown using non-metric multidimensional scaling, and the resulting groups were evaluated using a multi-response permutation procedure. Polynomial regression was used to evaluate the relationship between altitude with total species richness and those of hyperdiverse/abundant higher taxa and the latter taxa with each predictor variable. The species richness pattern displayed a decrease in species diversity as the elevation increased at the bottom wet part (Yungas) of our altitudinal zonation until the Monte, and a unimodal pattern of diversity in the top dry part (Monte, Puna). Each ecoregion and ecotonal zone evidenced a particular species richness and assemblage of arthropods, but the latter ones displayed a high percentage of species shared with the adjacent ecoregions. The arthropod elevational pattern and the changes of the assemblages were explained by the environmental gradient (especially the climate) in addition to a geographic gradient (the distance of decay of similarity), demonstrating that the species turnover is important to explain the beta diversity along the elevational gradient. This suggests that patterns of diversity and distribution of arthropods are regulated by the dissimilarity of ecoregional environments that establish a wide range of geographic and environmental barriers, coupled with a limitation of species dispersal. Therefore, the arthropods of higher taxa respond differently to the altitudinal ecoregional zonation.

Marine species richness

Nature ◽  
1993 ◽  
Vol 361 (6413) ◽  
pp. 597-598 ◽  
Author(s):  
Gary C. B. Poore ◽  
George D. F. Wilson
Keyword(s):  
Species Richness ◽  
Marine Species

scholarly journals Marine species richness

Nature ◽  
1993 ◽  
Vol 361 (6413) ◽  
pp. 598-598 ◽  
Author(s):  
Robert M. May
Keyword(s):  
Species Richness ◽  
Marine Species

scholarly journals Diversification rates and species richness across the Tree of Life

2016 ◽  
Vol 283 (1838) ◽  
pp. 20161334 ◽  
Author(s):  
Joshua P. Scholl ◽  
John J. Wiens
Keyword(s):  
Species Richness ◽  
Positive Relationship ◽  
Tree Of Life ◽  
Diversification Rate ◽  
Substantial Variation ◽  
Diversification Rates ◽  
Higher Taxa ◽  
Over Time

Species richness varies dramatically among clades across the Tree of Life, by over a million-fold in some cases (e.g. placozoans versus arthropods). Two major explanations for differences in richness among clades are the clade-age hypothesis (i.e. species-rich clades are older) and the diversification-rate hypothesis (i.e. species-rich clades diversify more rapidly, where diversification rate is the net balance of speciation and extinction over time). Here, we examine patterns of variation in diversification rates across the Tree of Life. We address how rates vary across higher taxa, whether rates within higher taxa are related to the subclades within them, and how diversification rates of clades are related to their species richness. We find substantial variation in diversification rates, with rates in plants nearly twice as high as in animals, and rates in some eukaryotes approximately 10-fold faster than prokaryotes. Rates for each kingdom-level clade are then significantly related to the subclades within them. Although caution is needed when interpreting relationships between diversification rates and richness, a positive relationship between the two is not inevitable. We find that variation in diversification rates seems to explain most variation in richness among clades across the Tree of Life, in contrast to the conclusions of previous studies.

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