Niche structure of marine sponges from temperate hard-bottom habitats within Gray's Reef National Marine Sanctuary

2015 ◽  
Vol 96 (2) ◽  
pp. 559-565 ◽  
Author(s):  
Christopher J. Freeman ◽  
Cole G. Easson ◽  
David M. Baker
Keyword(s):  
Sympatric Species ◽  
Marine Sponges ◽  
Latitudinal Gradients ◽  
Isotopic Niche ◽  
Microbial Abundance ◽  
Ecological Benefit ◽  
Relative Placement ◽  
Metabolic Capability ◽  
The Tropics ◽  
Isotopic Space

Many species of marine sponges on tropical reefs host abundant and diverse symbiont communities capable of varied metabolic pathways. While such communities may confer a nutritional benefit to some hosts (termed High Microbial Abundance (HMA) sponges), other sympatric species host only sparse symbiont communities (termed Low Microbial Abundance (LMA) sponges) and obtain a majority of their C and N from local sources. Sponge communities are widespread across large latitudinal gradients, however, and recent evidence suggests that these symbioses may also extend beyond the tropics. We investigated the role that symbionts play in the ecology of sponges from the temperate, hard-bottom reefs of Gray's Reef National Marine Sanctuary by calculating the niche size (as standard ellipse area (SEAc)) and assessing the relative placement of five HMA and four LMA sponge species within bivariate (δ13C and δ15N) isotopic space. Although photosymbiont abundance was low across most of these species, sponges were widespread across isotopic niche space, implying that microbial metabolism confers an ecological benefit to temperate sponges by expanding host metabolic capability. To examine how these associations vary across a latitudinal gradient, we also compared the relative placement of temperate and tropical conspecifics within isotopic space. Surprisingly, shifts in sponge δ13C and δ15N values between these regions suggest a reduced reliance on symbiont-derived nutrients in temperate sponges compared with their tropical conspecifics. Despite this, symbiotic sponges in temperate systems likely have a competitive advantage, allowing them to grow and compete for space within these habitats.

scholarly journals The isotopic niche of Atlantic, biting marine mammals and its relationship to skull morphology and body size

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Massimiliano Drago ◽  
Marco Signaroli ◽  
Meica Valdivia ◽  
Enrique M. González ◽  
Asunción Borrell ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Ocean ◽  
Fisheries Management ◽  
Marine Mammals ◽  
Trophic Position ◽  
Sympatric Species ◽  
Isotopic Niche ◽  
Apex Predators ◽  
Skull Morphology ◽  
Ecosystem Based Fisheries Management

AbstractUnderstanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

scholarly journals Isotopic Niche Segregation among Darwin’s Finches on Santa Cruz Island, Galápagos

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 147
Author(s):  
Mariana Villegas ◽  
Catherine Soos ◽  
Gustavo Jiménez-Uzcátegui ◽  
Shukri Matan ◽  
Keith A. Hobson
Keyword(s):  
Three Dimensional ◽  
Sympatric Species ◽  
Isotopic Niche ◽  
Museum Specimens ◽  
Santa Cruz Island ◽  
Santa Cruz ◽  
Δ13c And Δ15n ◽  
Darwin's Finches ◽  
Darwin’S Finches ◽  
Foraging Guilds

Darwin’s finches are a classic example of adaptive radiation involving differential use of dietary resources among sympatric species. Here, we apply stable isotope (δ13C, δ15N, and δ2H) analyses of feathers to examine ecological segregation among eight Darwin’s finch species in Santa Cruz Island, Galápagos collected from live birds and museum specimens (1962–2019). We found that δ13C values were higher for the granivorous and herbivorous foraging guilds, and lower for the insectivorous finches. Values of δ15N were similar among foraging guilds but values of δ2H were higher for insectivores, followed by granivores, and lowest for herbivores. The herbivorous guild generally occupied the largest isotopic standard ellipse areas for all isotopic combinations and the insectivorous guild the smallest. Values of δ2H provided better trophic discrimination than those of δ15N possibly due to confounding influences of agricultural inputs of nitrogen. Segregation among guilds was enhanced by portraying guilds in three-dimensional isotope (δ13C, δ15N, and δ2H) space. Values of δ13C and δ15N were higher for feathers of museum specimens than for live birds. We provide evidence that Darwin’s finches on Santa Cruz Island tend to be generalists with overlapping isotopic niches and suggest that dietary overlap may also be more considerable than previously thought.

scholarly journals Latitudinal gradients in biotic niche breadth vary across ecosystem types

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151589 ◽  
Author(s):  
Alyssa R. Cirtwill ◽  
Daniel B. Stouffer ◽  
Tamara N. Romanuk
Keyword(s):  
Species Richness ◽  
Food Webs ◽  
Niche Breadth ◽  
The Other ◽  
Latitudinal Gradients ◽  
Food Web Structure ◽  
Scaling Relationships ◽  
Web Structure ◽  
Scaling Relationship ◽  
The Tropics

Several properties of food webs—the networks of feeding links between species—are known to vary systematically with the species richness of the underlying community. Under the ‘latitude–niche breadth hypothesis’, which predicts that species in the tropics will tend to evolve narrower niches, one might expect that these scaling relationships could also be affected by latitude. To test this hypothesis, we analysed the scaling relationships between species richness and average generality, vulnerability and links per species across a set of 196 empirical food webs. In estuarine, marine and terrestrial food webs there was no effect of latitude on any scaling relationship, suggesting constant niche breadth in these habitats. In freshwater communities, on the other hand, there were strong effects of latitude on scaling relationships, supporting the latitude–niche breadth hypothesis. These contrasting findings indicate that it may be more important to account for habitat than latitude when exploring gradients in food-web structure.

Metabolic asymmetry and the global diversity of marine predators

Science ◽  
2019 ◽  
Vol 363 (6425) ◽  
pp. eaat4220 ◽  
Author(s):  
John M. Grady ◽  
Brian S. Maitner ◽  
Ara S. Winter ◽  
Kristin Kaschner ◽  
Derek P. Tittensor ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Patterns ◽  
Marine Mammals ◽  
Phylogenetic Diversity ◽  
Latitudinal Gradient ◽  
Latitudinal Gradients ◽  
Competitive Interactions ◽  
Marine Predators ◽  
Theoretical Predictions ◽  
The Tropics

Species richness of marine mammals and birds is highest in cold, temperate seas—a conspicuous exception to the general latitudinal gradient of decreasing diversity from the tropics to the poles. We compiled a comprehensive dataset for 998 species of sharks, fish, reptiles, mammals, and birds to identify and quantify inverse latitudinal gradients in diversity, and derived a theory to explain these patterns. We found that richness, phylogenetic diversity, and abundance of marine predators diverge systematically with thermoregulatory strategy and water temperature, reflecting metabolic differences between endotherms and ectotherms that drive trophic and competitive interactions. Spatial patterns of foraging support theoretical predictions, with total prey consumption by mammals increasing by a factor of 80 from the equator to the poles after controlling for productivity.

scholarly journals No latitudinal gradients in tempo or mode of morphological evolution in birds

2020 ◽  
Author(s):  
J. Drury ◽  
J. Clavel ◽  
J.A. Tobias ◽  
J. Rolland ◽  
C. Sheard ◽  
...  
Keyword(s):  
Species Interactions ◽  
Morphological Evolution ◽  
Latitudinal Gradients ◽  
Phenotypic Evolution ◽  
Trait Evolution ◽  
Trait Divergence ◽  
Diversity Gradient ◽  
The Tropics ◽  
The Impact ◽  
Phylogenetic Models

AbstractThe latitudinal diversity gradient is one of the most striking patterns in nature yet its implications for morphological evolution are poorly understood. In particular, it has been proposed that an increased intensity of species interactions in tropical biota may either promote or constrain trait evolution, but which of these outcomes predominates remains uncertain. Here, we develop tools for fitting phylogenetic models of phenotypic evolution in which the impact of species interactions can vary across lineages. Deploying these models on a global avian trait dataset to explore differences in trait divergence between tropical and temperate lineages, we find that the effect of latitude on the mode and tempo of morphological evolution is weak and clade- or trait-dependent. Our results indicate that species interactions do not disproportionately impact morphological evolution in tropical bird families and question the validity and universality of previously reported patterns of slower trait evolution in the tropics.

scholarly journals Microbial Diversity and Putative Diazotrophy in High- and Low-Microbial-Abundance Mediterranean Sponges

2015 ◽  
Vol 81 (17) ◽  
pp. 5683-5693 ◽  
Author(s):  
Marta Ribes ◽  
Claudia Dziallas ◽  
Rafel Coma ◽  
Lasse Riemann
Keyword(s):  
Isotopic Ratio ◽  
Horizontal Transmission ◽  
Marine Sponges ◽  
Sponge Tissue ◽  
Microbial Abundance ◽  
Surrounding Water ◽  
Nitrogenase Genes ◽  
Functional Features ◽  
Benthic Pelagic Coupling ◽  
And Function

ABSTRACTMicrobial communities associated with marine sponges carry out nutrient transformations essential for benthic-pelagic coupling; however, knowledge about their composition and function is still sparse. We evaluated the richness and diversity of prokaryotic assemblages associated with three high-microbial-abundance (HMA) and three low-microbial-abundance (LMA) sympatric Mediterranean sponges to address their stability and uniqueness. Moreover, to examine functionality and because an imbalance between nitrogen ingestion and excretion has been observed for some of these species, we sequenced nitrogenase genes (nifH) and measured N2fixation. The prokaryotic communities in the two sponge types did not differ in terms of richness, but the highest diversity was found in HMA sponges. Moreover, the discrete composition of the communities in the two sponge types relative to that in the surrounding seawater indicated that horizontal transmission and vertical transmission affect the microbiomes associated with the two sponge categories.nifHgenes were found in all LMA species and sporadically in one HMA species, and about half of thenifHgene sequences were common between the different sponge species and were also found in the surrounding water, suggesting horizontal transmission.15N2-enriched incubations showed that N2fixation was measurable in the water but was not associated with the sponges. Also, the analysis of the isotopic ratio of15N to14N in sponge tissue indicated that N2fixation is not an important source of nitrogen in these Mediterranean sponges. Overall, our results suggest that compositional and functional features differ between the prokaryotic communities associated with HMA and LMA sponges, which may affect sponge ecology.

scholarly journals Unifying latitudinal gradients in range size and richness across marine and terrestrial systems

2016 ◽  
Vol 283 (1830) ◽  
pp. 20153027 ◽  
Author(s):  
Adam Tomašových ◽  
Jonathan D. Kennedy ◽  
Tristan J. Betzner ◽  
Nicole Bitler Kuehnle ◽  
Stewart Edie ◽  
...  
Keyword(s):  
Species Richness ◽  
Range Size ◽  
Species Range ◽  
Latitudinal Gradients ◽  
Species Diversification ◽  
Marine Bivalves ◽  
The Tropics ◽  
Genus Expansion

Many marine and terrestrial clades show similar latitudinal gradients in species richness, but opposite gradients in range size—on land, ranges are the smallest in the tropics, whereas in the sea, ranges are the largest in the tropics. Therefore, richness gradients in marine and terrestrial systems do not arise from a shared latitudinal arrangement of species range sizes. Comparing terrestrial birds and marine bivalves, we find that gradients in range size are concordant at the level of genera. Here, both groups show a nested pattern in which narrow-ranging genera are confined to the tropics and broad-ranging genera extend across much of the gradient. We find that (i) genus range size and its variation with latitude is closely associated with per-genus species richness and (ii) broad-ranging genera contain more species both within and outside of the tropics when compared with tropical- or temperate-only genera. Within-genus species diversification thus promotes genus expansion to novel latitudes. Despite underlying differences in the species range-size gradients, species-rich genera are more likely to produce a descendant that extends its range relative to the ancestor's range. These results unify species richness gradients with those of genera, implying that birds and bivalves share similar latitudinal dynamics in net species diversification.

Evolution of taxonomic diversity gradients in the marine realm: a comparison of Late Jurassic and Recent bivalve faunas

Paleobiology ◽  
2002 ◽  
Vol 28 (2) ◽  
pp. 184-207 ◽  
Author(s):  
J. Alistair Crame
Keyword(s):  
Food Supply ◽  
Taxonomic Diversity ◽  
Latitudinal Gradients ◽  
Polar Regions ◽  
Extinction Rates ◽  
Diversity Gradients ◽  
Macrobenthic Assemblages ◽  
Marine Realm ◽  
The Tropics ◽  
Extreme Seasonality

We still have much to learn about the evolution of taxonomic diversity gradients through geologic time. For example, have latitudinal gradients always been as steep as they are now, or is this a phenomenon linked to some form of Cenozoic global climatic differentiation? The fossil record offers potential to address this sort of problem, and this study reconstructs latitudinal diversity gradients for the last (Tithonian) stage of the Jurassic period using marine bivalves. At this time of relative global warmth, bivalves were cosmopolitan in their distribution and the commonest element within macrobenthic assemblages.Analysis of 31 regional bivalve faunas demonstrates that Tithonian latitudinal gradients were present in both hemispheres, though on a much smaller magnitude than today. The record of the Northern Hemisphere gradient is more complete and shows a steep fall in values at the tropical/temperate boundary; the Southern Hemisphere gradient exhibits a more regular decline in diversity with increasing latitude.Tithonian latitudinal gradients were underpinned by a tropical bivalve fauna that comprises almost equal numbers of epifaunal and infaunal taxa. The epifaunal component was dominated by three pteriomorph families, the Pectinidae, Limidae and Ostreidae, that may be regarded as a long-term component of tropical bivalve diversity. Of the mixture of older and newer “heteroconch” families that formed the bulk of the infaunal component, the latter radiated spectacularly through the Late Cretaceous and Cenozoic to dominate tropical bivalve faunas at the present day. This pulse of heteroconch diversification, which was a major cause of the steepening of the bivalve latitudinal gradient, provides important evidence that rates of speciation may be negatively correlated with latitude.Nevertheless, we cannot exclude the possibility that elevated extinction rates in the highest latitudes also contributed to the marked steepening of bivalve latitudinal gradients over the last 150 Myr. Rates of extinction within epifaunal bivalve taxa appear to have been higher in these regions through the Cretaceous period, but this was largely before any significant global climatic deterioration. Infaunal bivalve clades have had differential success over this time period in the polar regions. Whereas, in comparison with the Tropics, heteroconchs are very much reduced in numbers today, the anomalodesmatans are much better represented, and the protobranchs have positively thrived. We are beginning to appreciate that low temperature per se may not be a primary cause of elevated rates of extinction. Food supply may be an equally important control on both rates of speciation and extinction; those bivalves that have been able to adapt to the extreme seasonality of food supply have flourished in the polar regions.

scholarly journals Character displacement drives trait divergence in a continental fauna

2021 ◽  
Vol 118 (20) ◽  
pp. e2021209118
Author(s):  
Sean A. S. Anderson ◽  
Jason T. Weir
Keyword(s):  
Evolutionary Theory ◽  
Species Interactions ◽  
New World ◽  
Latitudinal Gradient ◽  
Character Displacement ◽  
Sympatric Species ◽  
Closely Related Species ◽  
Species Sorting ◽  
Trait Divergence ◽  
The Tropics

Coexisting (sympatric) pairs of closely related species are often characterized by exaggerated trait differences. This widespread pattern is consistent with adaptation for reduced similarity due to costly interactions (i.e., “character displacement”)—a classic hypothesis in evolutionary theory. But it is equally consistent with a community assembly bias in which lineages with greater trait differences are more likely to establish overlapping ranges in the first place (i.e., “species sorting”), as well as with null expectations of trait divergence through time. Few comparative analyses have explicitly modeled these alternatives, and it remains unclear whether trait divergence is a general prerequisite for sympatry or a consequence of interactions between sympatric species. Here, we develop statistical models that allow us to distinguish the signature of these processes based on patterns of trait divergence in closely related lineage pairs. We compare support for each model using a dataset of bill shape differences in 207 pairs of New World terrestrial birds representing 30 avian families. We find that character displacement models are overwhelmingly supported over species sorting and null expectations, indicating that exaggerated bill shape differences in sympatric pairs result from enhanced divergent selection in sympatry. We additionally detect a latitudinal gradient in character displacement, which appears strongest in the tropics. Our analysis implicates costly species interactions as powerful drivers of trait divergence in a major vertebrate fauna. These results help substantiate a long-standing but equivocally supported linchpin of evolutionary theory.

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