Is the positive relationship between species richness and shoot morphological plasticity mediated by ramet density or is there a direct link?

Oecologia ◽  
2015 ◽  
Vol 178 (3) ◽  
pp. 867-873 ◽  
Author(s):  
Mari Lepik ◽  
Kristjan Zobel
Keyword(s):  
Species Richness ◽  
Positive Relationship ◽  
Morphological Plasticity ◽  
Direct Link ◽  
Ramet Density

scholarly journals Recent increases in assemblage rarity are linked to increasing local immigration

2020 ◽  
Vol 7 (7) ◽  
pp. 192045
Author(s):  
Faith A. M. Jones ◽  
Maria Dornelas ◽  
Anne E. Magurran
Keyword(s):  
Species Richness ◽  
Rare Species ◽  
Positive Relationship ◽  
Recent Past ◽  
Additional Species ◽  
Species Lists ◽  
Biodiversity Change

As pressures on biodiversity increase, a better understanding of how assemblages are responding is needed. Because rare species, defined here as those that have locally low abundances, make up a high proportion of assemblage species lists, understanding how the number of rare species within assemblages is changing will help elucidate patterns of recent biodiversity change. Here, we show that the number of rare species within assemblages is increasing, on average, across systems. This increase could arise in two ways: species already present in the assemblage decreasing in abundance but with no increase in extinctions, or additional species entering the assemblage in low numbers associated with an increase in immigration. The positive relationship between change in rarity and change in species richness provides evidence for the second explanation, i.e. higher net immigration than extinction among the rare species. These measurable changes in the structure of assemblages in the recent past underline the need to use multiple biodiversity metrics to understand biodiversity change.

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.

scholarly journals Thirty-six years of legal and illegal wildlife trade entering the USA

Oryx ◽  
2019 ◽  
pp. 1-10 ◽  
Author(s):  
Maria Therese Bager Olsen ◽  
Jonas Geldmann ◽  
Mike Harfoot ◽  
Derek P. Tittensor ◽  
Becky Price ◽  
...  
Keyword(s):  
Decision Making ◽  
Species Richness ◽  
Positive Relationship ◽  
Species Conservation ◽  
Wildlife Trade ◽  
Country Size ◽  
The Usa ◽  
Taxonomic Groups ◽  
Over Time ◽  
Main Region

AbstractThe USA is the largest consumer of legally, internationally-traded wildlife. A proportion of this trade consists of species listed in the Appendices of CITES, and recorded in the CITES Trade Database. Using this resource, we quantified wildlife entering the USA for 82 of the most frequently recorded wildlife products and a range of taxonomic groups during 1979–2014. We examined trends in legal trade and seizures of illegally traded items over time, and relationships between trade and four national measures of biodiversity. We found that: (1) there is an overall positive relationship between legal imports and seizures; (2) Asia was the main region exporting CITES-listed wildlife products to the USA; (3) bears, crocodilians and other mammals (i.e. other than Ursidae, Felidae, Cetacea, Proboscidea, Primates or Rhinocerotidae) increased in both reported legal trade and seizures over time; (4) legal trade in live specimens was reported to be primarily from captive-produced, artificially-propagated or ranched sources, whereas traded meat was primarily wild sourced; (5) both seizures and legally traded items of felids and elephants decreased over time; and (6) volumes of both legally traded and seized species were correlated with four attributes of exporting countries: species endemism, species richness, number of IUCN threatened species, and country size. The goal of our analysis was to inform CITES decision-making and species conservation efforts.

The positive relationship between relief and species richness in mesophotic communities on offshore banks, including geographic patterns

2016 ◽  
Vol 23 (4) ◽  
pp. 195-207 ◽  
Author(s):  
Paul W. Sammarco ◽  
Marissa F. Nuttall ◽  
Daniel Beltz ◽  
L. Horn ◽  
G. Taylor ◽  
...  
Keyword(s):  
Species Richness ◽  
Positive Relationship ◽  
Geographic Patterns

scholarly journals More individuals but fewer species: testing the ‘more individuals hypothesis’ in a diverse tropical fauna

2010 ◽  
Vol 6 (4) ◽  
pp. 490-493 ◽  
Author(s):  
Terrence P. McGlynn ◽  
Michael D. Weiser ◽  
Robert R. Dunn
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Large Scale ◽  
Positive Relationship ◽  
Tropical Rainforest ◽  
Net Primary Productivity ◽  
Resource Abundance ◽  
Monotonic Increase ◽  
Ant Diversity ◽  
Unimodal Relationship

A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the ‘more individuals hypothesis’ (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.

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.

scholarly journals DEDEYOLU GÖLETİ (ELAZIĞ–TÜRKİYE) ZOOPLANKTONU

2020 ◽  
Vol 15 (4) ◽  
pp. 143-154
Author(s):  
Serap Saler
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Dominant Species ◽  
Positive Relationship ◽  
Ph Value ◽  
Strong Positive Correlation ◽  
Keratella Cochlearis ◽  
Index Value ◽  
Richness Index ◽  
Number Of Individuals

In this study, it is aimed to determine the zooplankton and species diversity of Dedeyolu Pond. Zooplankton samples were taken from 3 stations in monthly periods between May 2011 and April 2012. In the research, 17 species belonging to Rotifera, 6 species belonging to Cladocera and 2 species belonging to Copepoda were identified in Dedeyolu Pond. Among all zooplankton, it was represented Rotifera with 81%, Cladocera with 14% and Copepoda with 5%. Species diversity reached its highest value in April (H'=2.34) in the 3rd station, and the Margalef species richness index value reached its highest value in the first station (D=3.84) in October. There were a strong positive correlation between the number of individuals and the temperature in Dedeyolu Pond (r=0.674), a weak positive relationship between the number of individuals and the pH value (r=0.370), and a weak positive relationship between the number of individuals and the dissolved oxygen value (r=0.290). Keratella cochlearis species was recorded as the dominant species in all seasons in the pond.

Non-indigenous marine macroalgae in native communities: a case study in the British Isles

2008 ◽  
Vol 88 (4) ◽  
pp. 693-698 ◽  
Author(s):  
Frederic Mineur ◽  
Mark P. Johnson ◽  
Christine A. Maggs
Keyword(s):  
Species Richness ◽  
Northern Ireland ◽  
Community Composition ◽  
Native Species ◽  
Positive Relationship ◽  
Marine Macroalgae ◽  
Indigenous Species ◽  
Species Introduction ◽  
Southern England ◽  
Non Indigenous Species

It has traditionally been considered that areas with high natural species richness are likely to be more resistant to non-indigenous species than those with lower numbers of species. However, this theory has been the subject of a debate over the last decade, since some studies have shown the opposite trend. In the present study, a macroalgal survey was carried out at 24 localities in Northern Ireland and southern England, using a quadrat approach in the lower littoral. The two opposing hypotheses were tested (negative versus positive relationship between native and non-indigenous species richness) in this marine environment. The effect of the presence of ‘impacts’, potential sources of disturbance and species introduction (e.g. marina, harbour or aquaculture), was also tested. A positive relationship was found between the number of non-indigenous species and the native species richness at the three different scales tested (quadrats, sites and localities). At no scale did a richer native assemblage appear to restrict the establishment of introduced species. The analyses revealed greater species richness and different community composition, as well as more non-indigenous species, in southern England relative to Northern Ireland. The presence of the considered impacts had an effect on the community composition and species richness in southern England but not in Northern Ireland. Such impacts had no effect on the non-indigenous species richness in either area.

scholarly journals How do plant communities and flower visitors relate? A case study of semi-natural xerothermic grasslands

2013 ◽  
Vol 82 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Damian Chmura ◽  
Paweł Adamski ◽  
Zygmunt Denisiuk
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Plant Communities ◽  
Correspondence Analysis ◽  
Positive Relationship ◽  
Detrended Correspondence Analysis ◽  
Permanent Plots ◽  
Moisture Index ◽  
Rarefaction Analysis ◽  
Flower Visitors

<p>The paper examines the relationships between the species composition of flower visitors and plants in the semi-natural xerothermic grasslands in southern and central Poland. Thirty 10 × 10 m permanent plots were laid out in total, mainly in nature reserves. The vegetation units studied were classified according to the Braun-Blanquet system; these were phytocoenoses of the <em>Festuco-Brometea</em> classes <em>Inuletum ensifoliae</em>, <em>Adonido-Brachypodietum pinnati</em> and the transitional plant community. Entomological research was performed using the Pollard method within the same plots. A particular site was visited only once and different sites were studied between April and August 2008. We applied, among others, co-correspondence-analysis Co-CA, detrended correspondence analysis (DCA) and redundancy analysis (RDA) to investigate the co-occurrence patterns of plants and flower visitors and their biotopic requirements. We found that the species composition of flower visitors cannot be predicted by floristic composition when the duration of the study is restricted to one day (but under similar weather conditions); however, there is a positive relationship between the species richness of insects and plants and a positive relationship between the number of plant species and the abundance of flower visitors. The Ellenberg moisture index and the cover of meadow species significantly explained the species composition of insects. The three various vegetation units and five dominant xerothermic species, i.e. <em>Adonis vernalis</em>, <em>Anemone sylvestris</em>, <em>Inula ensifolia</em>, <em>Linum hirsutum</em> and <em>Carlina onopordifolia</em> that were studied across time differed in the species richness of insects. Our results demonstrate that possible patterns in the species composition and the assembly rules of flower visitors are not apparent when the Pollard method is applied. Based on the data obtained using this method, the flower visiting assemblages seem not to be driven by competition and they primarily show a tendency to co-occur which can be an artifact. A plant-focused method that included a rarefaction analysis yielded more insightful results and shed more light on the differences between the dominant plants that shape the physiognomy of plant communities in a possible pollination specialization.</p>

scholarly journals Correlation/causation in ecology: towards mechanistic explanations for the Species-Area Relationship

2016 ◽  
Author(s):  
Andersonn Prestes
Keyword(s):  
Species Richness ◽  
Positive Relationship ◽  
Abiotic Factors ◽  
Causal Explanations ◽  
Biotic And Abiotic Factors ◽  
Mechanistic Explanations ◽  
Species Area ◽  
Species Area Relationship ◽  
Per Se ◽  
Recurrent Patterns

There is a common intuition in biology that strict laws are very difficult to be found. Still, there are recurrent patterns in nature, suggesting broad generalizations and understanding of phenomena. The problem is that many generalizations in biology, especially in the form of correlations, might be decoupled from causality, weakening their power of explanation. Here, I bring an example on the Species-Area Relationship (SAR). The SAR is a well-known generalization in biology. The recurrent pattern states a positive relationship between area size and species richness. Understanding the mechanisms why there is a correlation between area and diversity remains a major challenge. I suggest an explicitly focus on mechanistic explanations for the SAR. I propose to use the integration, comparison and interpretation of other (associated or secondary) natural patterns in the searching for causal explanations. Area per se might not account for causality in species diversification or absolute species richness in larger regions. Biotic and abiotic factors of a given area might be studied in order to discover the causal underpinnings of the SAR.

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