scholarly journals Marine macroinvertebrate species-area relationships, assemblage structure and their environmental drivers on submarine banks

2020 ◽  
Vol 641 ◽  
pp. 25-47
Author(s):  
CH Stortini ◽  
B Petrie ◽  
KT Frank ◽  
WC Leggett
Keyword(s):  
Cold Water ◽  
Chlorophyll Concentration ◽  
Alpha Diversity ◽  
Assemblage Structure ◽  
Environmental Drivers ◽  
Ecological Communities ◽  
Dispersal Capacity ◽  
Theory Of Island Biogeography ◽  
Species Area ◽  
Habitat Properties

Modern extensions of the theory of island biogeography (TIB) posit that the slope of the species-area relationship (SAR) reflects the insularity of ecological communities and is strongly influenced by species’ motility. We explore the relative insularity of crustacean, echinoderm and mollusk/Cirripedia assemblages in terms of both alpha diversity (species richness) and assemblage structure (relative biomass of species). These taxa/groups differ in adult motility and larval dispersal capacity. The habitats of interest were 10 offshore banks on the Scotian Shelf, northwest Atlantic Ocean, a region dominated by the NE- to SW-flowing Nova Scotia Current (NSC). Banks in the NE tended to be larger, more heterogeneous, cooler, less saline, more retentive and more productive (higher chlorophyll a) than those in the SW. Only mollusks/Cirripedia, the least motile and dispersive group, had a significant SAR slope, supporting TIB. For crustaceans and echinoderms, temperature/salinity properties and habitat heterogeneity, respectively, were important predictors of alpha diversity. Inter-bank variation in crustacean assemblage structure was accounted for largely by bank location relative to the NSC; the leading variables accounting for echinoderm and mollusk/Cirripedia assemblage structure were retention time and mean annual chlorophyll concentration, respectively. Along the NE to SW axis of the NSC, there was a substantial loss of species (7 crustacean, 9 echinoderm and 13 mollusk/Cirripedia species) and decreases in the biomass of common cold-water species. A complex interplay of species motility/dispersal capacity, local oceanography and habitat properties determine the extent to which (1) TIB applies to submarine macroinvertebrate assemblages and (2) upstream and downstream assemblages are interconnected.

scholarly journals Lizards along an agricultural land abandonment gradient in Pindos Mountains, Greece

2015 ◽  
Vol 36 (3) ◽  
pp. 253-264 ◽  
Author(s):  
Sylvia Zakkak ◽  
John Maxwell Halley ◽  
Triantafyllos Akriotis ◽  
Vasiliki Kati
Keyword(s):  
Agricultural Land ◽  
Land Use Changes ◽  
Land Abandonment ◽  
Environmental Drivers ◽  
Line Transect ◽  
Mountainous Area ◽  
Ecological Communities ◽  
Dispersal Capacity ◽  
Podarcis Muralis ◽  
Forest Encroachment

Agricultural land abandonment is recognized as one of the main environmental drivers in Southern Europe, affecting ecological communities. Lizards, as ectothermic species with low dispersal capacity, are particularly prone to the threats associated with land use changes. We investigated the effect of land abandonment on lizards in a remote mountainous area in Greece, using line transect sampling, in 20 randomly selected sites [1 km × 1 km], along a four grade abandonment gradient in terms of forest encroachment. We recorded four species: Algyroides nigropunctatus, Lacerta viridis/trilineata, Podarcis tauricus and Podarcis muralis, the latter being the most abundant. Our results did not provide evidence for a significant effect of forest encroachment or grazing on lizard diversity, given the dominance of P. muralis, the availability of all microhabitat types along the gradient and the low grazing intensity in the study area. Environmental parameters at the macrohabitat scale did not prove determinant for habitat variance, but microhabitat analysis showed a clear preference of P. muralis to bare ground. Despite the non-significant effects of land abandonment on lizard diversity, the dominance of P. muralis tends to indicate a lizard community shift towards species inhabiting forested habitats. The preservation of open microhabitats, such as bare land, is considered of great importance for promoting high levels of lizard diversity, as their loss would affect even species currently widespread in forested ecosystems. Low intensity grazing, as well as the enhancement of wild ungulate populations in abandoned areas, can contribute to halting forest encroachment and maintaining the required habitat heterogeneity.

scholarly journals Relation between stability and resilience determines the performance of early warning signals under different environmental drivers

2015 ◽  
Vol 112 (32) ◽  
pp. 10056-10061 ◽  
Author(s):  
Lei Dai ◽  
Kirill S. Korolev ◽  
Jeff Gore
Keyword(s):  
Early Warning ◽  
Alternative Stable States ◽  
Basin Of Attraction ◽  
Environmental Drivers ◽  
Ecological Communities ◽  
Stable States ◽  
Warning Signals ◽  
Early Warning Signals ◽  
The Stability ◽  
Stability And Resilience

Shifting patterns of temporal fluctuations have been found to signal critical transitions in a variety of systems, from ecological communities to human physiology. However, failure of these early warning signals in some systems calls for a better understanding of their limitations. In particular, little is known about the generality of early warning signals in different deteriorating environments. In this study, we characterized how multiple environmental drivers influence the dynamics of laboratory yeast populations, which was previously shown to display alternative stable states [Dai et al., Science, 2012]. We observed that both the coefficient of variation and autocorrelation increased before population collapse in two slowly deteriorating environments, one with a rising death rate and the other one with decreasing nutrient availability. We compared the performance of early warning signals across multiple environments as “indicators for loss of resilience.” We find that the varying performance is determined by how a system responds to changes in a specific driver, which can be captured by a relation between stability (recovery rate) and resilience (size of the basin of attraction). Furthermore, we demonstrate that the positive correlation between stability and resilience, as the essential assumption of indicators based on critical slowing down, can break down in this system when multiple environmental drivers are changed simultaneously. Our results suggest that the stability–resilience relation needs to be better understood for the application of early warning signals in different scenarios.

scholarly journals Maintenance of biodiversity on islands

2016 ◽  
Vol 283 (1829) ◽  
pp. 20160102 ◽  
Author(s):  
Ryan A. Chisholm ◽  
Tak Fung ◽  
Deepthi Chimalakonda ◽  
James P. O'Dwyer
Keyword(s):  
Species Richness ◽  
Island Biogeography ◽  
Mechanistic Model ◽  
Neutral Theory ◽  
Small Island ◽  
Small Islands ◽  
Island Area ◽  
Island Species ◽  
Theory Of Island Biogeography ◽  
Species Area

MacArthur and Wilson's theory of island biogeography predicts that island species richness should increase with island area. This prediction generally holds among large islands, but among small islands species richness often varies independently of island area, producing the so-called ‘small-island effect’ and an overall biphasic species–area relationship (SAR). Here, we develop a unified theory that explains the biphasic island SAR. Our theory's key postulate is that as island area increases, the total number of immigrants increases faster than niche diversity. A parsimonious mechanistic model approximating these processes reproduces a biphasic SAR and provides excellent fits to 100 archipelago datasets. In the light of our theory, the biphasic island SAR can be interpreted as arising from a transition from a niche-structured regime on small islands to a colonization–extinction balance regime on large islands. The first regime is characteristic of classic deterministic niche theories; the second regime is characteristic of stochastic theories including the theory of island biogeography and neutral theory. The data furthermore confirm our theory's key prediction that the transition between the two SAR regimes should occur at smaller areas, where immigration is stronger (i.e. for taxa that are better dispersers and for archipelagos that are less isolated).

scholarly journals Bacterial and archaeal spatial distribution and its environmental drivers in an extremely haloalkaline soil at the landscape scale

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6127 ◽  
Author(s):  
Martha Adriana Martínez-Olivas ◽  
Norma G. Jiménez-Bueno ◽  
Juan Alfredo Hernández-García ◽  
Carmine Fusaro ◽  
Marco Luna-Guido ◽  
...  
Keyword(s):  
Community Structure ◽  
Spatial Patterns ◽  
Environmental Gradients ◽  
Alpha Diversity ◽  
Archaeal Community ◽  
Physicochemical Characteristics ◽  
Soil Characteristics ◽  
Environmental Drivers ◽  
Bacterial Phyla ◽  
Geostatistical Techniques

Background A great number of studies have shown that the distribution of microorganisms in the soil is not random, but that their abundance changes along environmental gradients (spatial patterns). The present study examined the spatial variability of the physicochemical characteristics of an extreme alkaline saline soil and how they controlled the archaeal and bacterial communities so as to determine the main spatial community drivers. Methods The archaeal and bacterial community structure, and soil characteristics were determined at 13 points along a 211 m transect in the former lake Texcoco. Geostatistical techniques were used to describe spatial patterns of the microbial community and soil characteristics and determine soil properties that defined the prokaryotic community structure. Results A high variability in electrolytic conductivity (EC) and water content (WC) was found. Euryarchaeota dominated Archaea, except when the EC was low. Proteobacteria, Bacteroidetes and Actinobacteria were the dominant bacterial phyla independent of large variations in certain soil characteristics. Multivariate analysis showed that soil WC affected the archaeal community structure and a geostatistical analysis found that variation in the relative abundance of Euryarchaeota was controlled by EC. The bacterial alpha diversity was less controlled by soil characteristics at the scale of this study than the archaeal alpha diversity. Discussion Results indicated that WC and EC played a major role in driving the microbial communities distribution and scale and sampling strategies were important to define spatial patterns.

scholarly journals The Dynamic Hypercube as a Niche Community Model

2021 ◽  
Vol 9 ◽  
Author(s):  
John M. Halley ◽  
Stuart L. Pimm
Keyword(s):  
Community Dynamics ◽  
Neutral Theory ◽  
Species Abundance ◽  
Ecological Communities ◽  
Evolutionary Time ◽  
Community Model ◽  
Theory Of Island Biogeography ◽  
Species Abundance Distributions ◽  
Hypercube Model ◽  
Zero Sum

Different models of community dynamics, such as the MacArthur–Wilson theory of island biogeography and Hubbell’s neutral theory, have given us useful insights into the workings of ecological communities. Here, we develop the niche-hypervolume concept of the community into a powerful model of community dynamics. We describe the community’s size through the volume of the hypercube and the dynamics of the populations in it through the fluctuations of the axes of the niche hypercube on different timescales. While the community’s size remains constant, the relative volumes of the niches within it change continuously, thus allowing the populations of different species to rise and fall in a zero-sum fashion. This dynamic hypercube model reproduces several key patterns in communities: lognormal species abundance distributions, 1/f-noise population abundance, multiscale patterns of extinction debt and logarithmic species-time curves. It also provides a powerful framework to explore significant ideas in ecology, such as the drift of ecological communities into evolutionary time.

scholarly journals Synchrony matters more than species richness in plant community stability at a global scale

2020 ◽  
Vol 117 (39) ◽  
pp. 24345-24351 ◽  
Author(s):  
Enrique Valencia ◽  
Francesco de Bello ◽  
Thomas Galland ◽  
Peter B. Adler ◽  
Jan Lepš ◽  
...  
Keyword(s):  
Species Richness ◽  
Global Scale ◽  
Environmental Drivers ◽  
Ecological Communities ◽  
Community Stability ◽  
Forage Production ◽  
The Stability ◽  
Random Fluctuations ◽  
Weak Influence ◽  
Analysis Of Time Series

The stability of ecological communities is critical for the stable provisioning of ecosystem services, such as food and forage production, carbon sequestration, and soil fertility. Greater biodiversity is expected to enhance stability across years by decreasing synchrony among species, but the drivers of stability in nature remain poorly resolved. Our analysis of time series from 79 datasets across the world showed that stability was associated more strongly with the degree of synchrony among dominant species than with species richness. The relatively weak influence of species richness is consistent with theory predicting that the effect of richness on stability weakens when synchrony is higher than expected under random fluctuations, which was the case in most communities. Land management, nutrient addition, and climate change treatments had relatively weak and varying effects on stability, modifying how species richness, synchrony, and stability interact. Our results demonstrate the prevalence of biotic drivers on ecosystem stability, with the potential for environmental drivers to alter the intricate relationship among richness, synchrony, and stability.

Environmental determinism of community structure across trophic levels: moth assemblages and substrate type in the rain forests of south-western China

2014 ◽  
Vol 31 (1) ◽  
pp. 81-89 ◽  
Author(s):  
R. L. Kitching ◽  
A. Nakamura ◽  
M. Yasuda ◽  
A. C. Hughes ◽  
Cao Min
Keyword(s):  
Soil Type ◽  
Alpha Diversity ◽  
Diversity Indices ◽  
Assemblage Structure ◽  
Trophic Levels ◽  
Western China ◽  
Composition Analysis ◽  
Forest Fragments ◽  
Dominant Group ◽  
Plant Assemblage

Abstract:Soil type may drive vegetation structure. In turn, the richness, identity and diversity of arthropod herbivores may be related to plant diversity through specific host plant relationships in a location. We test the hypothesis that the soil type (calcicolous vs alluvial soils) will drive the assemblage structure of a dominant group of arthropod herbivores: the moths. We used sampling sites in rain-forest fragments in south-western China around the Xishuangbanna Tropical Botanical Gardens (21°41′N, 101°25′E) to test this hypothesis. We used Pennsylvania style light traps to take point samples of macromoths and pyraloids from four sampling sites in forest remnants on a limestone geological base and four from alluvial-based forest. A total of 3165 moths (1739 from limestone-based and 1255 from alluvium-based forests) was collected representing 1255 species. The limestone-based sites showed statistically similar levels of species richness and other alpha diversity indices to the four alluvium-based site. Nevertheless the sites were clearly significantly different in terms of species composition. Analysis of contrasting similarity (‘beta’ diversity) indices suggested that there was ‘leakage’ between the two classes of sites when ‘rare’ species were emphasized in the calculations. We used an indicator value procedure to select species that most characterized this separation. We expect that these differences reflect associated changes in plant assemblage structure acting through the herbivorous habits of larval moths. Accordingly, in any assessment of landscape level diversity the nature of the substrate and its associated vegetation is clearly of great importance. This observation also has consequences for the design of conservation programmes.

The long-horned beetles of south Florida (Cerambycidae: Coleoptera): biogeography and relationships with the Bahama Islands and Cuba

1996 ◽  
Vol 74 (12) ◽  
pp. 2154-2169 ◽  
Author(s):  
Jonathan Browne ◽  
Stewart B. Peck
Keyword(s):  
Sea Level ◽  
Distance Effect ◽  
Florida Keys ◽  
Neotropical Region ◽  
South Florida ◽  
The West ◽  
The Past ◽  
South Central ◽  
Theory Of Island Biogeography ◽  
Species Area

South Florida is a floral and faunal transition zone between the Nearctic region and the West Indian part of the Neotropical region. Ninety-one species of Cerambycidae are known from the south Florida mainland and 53 species of Cerambycidae from the Florida Keys. The cerambycid fauna of south Florida is about equally of Neotropical (53%) and Nearctic origin (47%). Since the Florida Keys were entirely submerged several times in the Pliocene and Pleistocene epochs, the present cerambycid fauna is predominantly the result of late Pleistocene – Holocene overland dispersal from south-central Florida and overwater dispersal from the West Indies (Bahama Islands and Cuba). Species–area and species–distance relationships for the islands form significant regression lines as predicted by the equilibrium theory of island biogeography. 'The presence of a "distance effect" is surprising, since it is usually considered that only during the past 10 000 years has the southern tip of the Florida peninsula been fragmented into the present-day islands of the Keys by a rising sea level. An alternative geological scenario, supported by this study, suggests that the present islands of the Keys have appeared as the sea level fell only within the past 6000 years, and the fauna is a more recently derived one.

scholarly journals Marine diversity patterns in Australia are filtered through biogeography

2021 ◽  
Vol 288 (1962) ◽  
Author(s):  
Matthew R. Kerr ◽  
John Alroy
Keyword(s):  
Environmental Variability ◽  
Large Body ◽  
Environmental Drivers ◽  
Small Scale ◽  
Diversity Pattern ◽  
Diversity Patterns ◽  
Environmental Controls ◽  
Marine Diversity ◽  
Species Area ◽  
Future Work

Latitudinal diversity gradients are among the most striking patterns in nature. Despite a large body of work investigating both geographic and environmental drivers, biogeographical provinces have not been included in statistical models of diversity patterns. Instead, spatial studies tend to focus on species–area and local–regional relationships. Here, we investigate correlates of a latitudinal diversity pattern in Australian coastal molluscs. We use an online database of greater than 300 000 specimens and quantify diversity using four methods to account for sampling variation. Additionally, we present a biogeographic scheme using factor analysis that allows for both gradients and sharp boundaries between clusters. The factors are defined on the basis of species composition and are independent of diversity. Regardless of the measure used, diversity is not directly explained by combinations of abiotic variables. Instead, transitions between regions better explain the observed patterns. Biogeographic gradients can in turn be explained by environmental variables, suggesting that environmental controls on diversity may be indirect. Faunas within provinces are homogeneous regardless of environmental variability. Thus, transitions between provinces explain most of the variation in diversity because small-scale factors are dampened. This explanation contrasts with the species-energy hypothesis. Future work should more carefully consider biogeographic gradients when investigating diversity patterns.

scholarly journals Fine-Scale Heterogeneity of a Cold-Water Coral Reef and Its Influence on the Distribution of Associated Taxa

2021 ◽  
Vol 8 ◽  
Author(s):  
David M. Price ◽  
Aaron Lim ◽  
Alexander Callaway ◽  
Markus P. Eichhorn ◽  
Andrew J. Wheeler ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Deep Sea ◽  
Cold Water ◽  
Biological Effects ◽  
Pair Correlation ◽  
Growth Patterns ◽  
Environmental Drivers ◽  
Point Pattern ◽  
Fine Scale ◽  
Water Coral

Benthic fauna form spatial patterns which are the result of both biotic and abiotic processes, which can be quantified with a range of landscape ecology descriptors. Fine- to medium-scale spatial patterns (<1–10 m) have seldom been quantified in deep-sea habitats, but can provide fundamental ecological insights into species’ niches and interactions. Cold-water coral reefs formed by Desmophyllum pertusum (syn. Lophelia pertusa) and Madrepora oculata are traditionally mapped and surveyed with multibeam echosounders and video transects, which limit the ability to achieve the resolution and/or coverage to undertake fine-scale, centimetric quantification of spatial patterns. However, photomosaics constructed from imagery collected with remotely operated vehicles (ROVs) are becoming a prevalent research tool and can reveal novel information at the scale of individual coral colonies. A survey using a downward facing camera mounted on a ROV traversed the Piddington Mound (Belgica Mound Province, NE Atlantic) in a lawnmower pattern in order to create 3D reconstructions of the reef with Structure-from-Motion techniques. Three high resolution orthorectified photomosaics and digital elevation models (DEM) >200 m2 were created and all organisms were geotagged in order to illustrate their point pattern. The pair correlation function was used to establish whether organisms demonstrated a clustered pattern (CP) at various scales. We further applied a point pattern modelling approach to identify four potential point patterns: complete spatial randomness (CSR), an inhomogeneous pattern influenced by environmental drivers, random clustered point pattern indicating biologically driven clustering and an inhomogeneous clustered point pattern driven by a combination of environmental drivers and biological effects. Reef framework presence and structural complexity determined inhabitant distribution with most organisms showing a departure from CSR. These CPs are likely caused by an affinity to local environmental drivers, growth patterns and restricted dispersion reproductive strategies within the habitat across a range of fine to medium scales. These data provide novel and detailed insights into fine-scale habitat heterogeneity, showing that non-random distributions are apparent and detectable at these fine scales in deep-sea habitats.

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