scholarly journals Hermaphroditism in fish: incidence, distribution and associations with abiotic environmental factors

Author(s):  
Susanna Pla ◽  
Francesc Maynou ◽  
Francesc Piferrer

AbstractThe distribution of hermaphroditism in fishes has traditionally been mainly explained by its dependence on biotic factors. However, correlates with major abiotic factors have not been investigated on a quantitative basis and at a global scale. Here, we determined the incidence of hermaphroditism in fish at the family and species level, tested the hypothesis that evolutionary relationships account for the poor presence of hermaphroditism in freshwater species, and tested the association of sexual systems with latitude, habitat type and depth. Functional hermaphroditism is reported in 8 orders, 34 families and 370 species of fishes, all teleosts. Sequential hermaphroditism predominates over simultaneous hermaphroditism at a ratio ~ 5:1 and protogyny (female-to-male sex change) predominates ~ 6:1 over protandry (male-to-female). We found 12 hermaphroditic species that can live in freshwater. However, seven of these species are from four primarily marine families while there are only five species from two mostly freshwater families. Protogynous and bi-directional sex changers have a tighter association with reef-associated tropical and subtropical habitats when compared to protandrous species, which tend to be more plastic in terms of distribution requirements. Finally, simultaneous hermaphrodite species live both in the deep sea and shallow waters in similar proportions. This study can be the basis for further research in specific groups for different purposes, including ecological and evolutionary issues as well as conservation and management of exploited species. Understanding the environmental correlates can help to forecast changes in the distribution or phenology of hermaphrodites in a global change scenario.

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Heikki S. Lehtonen ◽  
Jyrki Aakkula ◽  
Stefan Fronzek ◽  
Janne Helin ◽  
Mikael Hildén ◽  
...  

AbstractShared socioeconomic pathways (SSPs), developed at global scale, comprise narrative descriptions and quantifications of future world developments that are intended for climate change scenario analysis. However, their extension to national and regional scales can be challenging. Here, we present SSP narratives co-developed with stakeholders for the agriculture and food sector in Finland. These are derived from intensive discussions at a workshop attended by approximately 39 participants offering a range of sectoral perspectives. Using general background descriptions of the SSPs for Europe, facilitated discussions were held in parallel for each of four SSPs reflecting very different contexts for the development of the sector up to 2050 and beyond. Discussions focused on five themes from the perspectives of consumers, producers and policy-makers, included a joint final session and allowed for post-workshop feedback. Results reflect careful sector-based, national-level interpretations of the global SSPs from which we have constructed consensus narratives. Our results also show important critical remarks and minority viewpoints. Interesting features of the Finnish narratives compared to the global SSP narratives include greater emphasis on environmental quality; significant land abandonment in SSPs with reduced livestock production and increased plant-based diets; continued need for some farm subsidies across all SSPs and opportunities for diversifying domestic production under scenarios of restricted trade. Our results can contribute to the development of more detailed national long-term scenarios for food and agriculture that are both relevant for local stakeholders and researchers as well as being consistent with global scenarios being applied internationally.


Author(s):  
Robert Y. George ◽  
Robert J. Menzies

SynopsisIn this paper the subject of faunal zonation in the ocean floor from the intertidal, and over the continental shelf, slope and rise and to the abyssal plain is examined on the basis of faunal change at the generic and species level. The region investigated over a period of five years aboard R/V Eastward is a Beaufort-Bermuda transect, approximately 75 kilometres wide and 500 kilometres long and bounded between 32° and 36°N latitude and 64° and 79°W longitude. A new method, involving numerical indices reflecting changes in the composition of taxa, endemism and diversity between adjacent depth levels, was developed for defining faunal boundaries. Isotherms and isobaths utilised by earlier authors for characterising deep-sea boundary on a global scale do not coincide with natural faunal boundaries. This study analyses the vertical distribution of 128 species of isopod crustaceans and 28 species of large epibenthic invertebrates. The zonation patterns seem to correspond with correlations in environmental conditions such as currents, topography and sediments.We suggest four major vertical faunal provinces, characterised at the generic level, namely (1) the Intertidal Faunal Province; (2) the Shelf Faunal Province; (3) the Archibenthal Zone of Transition; and (4) the Abyssal Faunal Province and internal zones within these characterised at the species level. The main aspects of interest include the presence of a narrow ‘meso abyssal zone’ with a species maximum, the demonstration of the true transitional nature of the Archibenthal Zone in biotic and abiotic factors and the characteristic low-biomass Red Clay environment showing definite faunal isolation from the continental margin.


2014 ◽  
Vol 72 (3) ◽  
pp. 741-752 ◽  
Author(s):  
Miranda C. Jones ◽  
William W. L. Cheung

Abstract Species distribution models (SDMs) are important tools to explore the effects of future global changes in biodiversity. Previous studies show that variability is introduced into projected distributions through alternative datasets and modelling procedures. However, a multi-model approach to assess biogeographic shifts at the global scale is still rarely applied, particularly in the marine environment. Here, we apply three commonly used SDMs (AquaMaps, Maxent, and the Dynamic Bioclimate Envelope Model) to assess the global patterns of change in species richness, invasion, and extinction intensity in the world oceans. We make species-specific projections of distribution shift using each SDM, subsequently aggregating them to calculate indices of change across a set of 802 species of exploited marine fish and invertebrates. Results indicate an average poleward latitudinal shift across species and SDMs at a rate of 15.5 and 25.6 km decade−1 for a low and high emissions climate change scenario, respectively. Predicted distribution shifts resulted in hotspots of local invasion intensity in high latitude regions, while local extinctions were concentrated near the equator. Specifically, between 10°N and 10°S, we predicted that, on average, 6.5 species would become locally extinct per 0.5° latitude under the climate change emissions scenario Representative Concentration Pathway 8.5. Average invasions were predicted to be 2.0 species per 0.5° latitude in the Arctic Ocean and 1.5 species per 0.5° latitude in the Southern Ocean. These averaged global hotspots of invasion and local extinction intensity are robust to the different SDM used and coincide with high levels of agreement.


2021 ◽  
Author(s):  
Sungeun Lee ◽  
Jackson W Sorensen ◽  
Robin L Walker ◽  
Joanne B Emerson ◽  
Graeme W Nicol ◽  
...  

Viruses shape microbial community structures, impacting metabolic pathways and influencing biogeochemical cycles. Despite their importance, the influence of biotic and abiotic factors on viral community structures across environmental gradients in soil is relatively unknown compared to their prokaryotic hosts. While soil pH strongly influences microbial community structure, it is unclear whether there is a similar influence on soil virus communities. In this study, prokaryotic and viral communities were characterized in soils sampled from the extremes of a long-term pH-manipulated soil gradient (pH 4.5 and 7.5), and viral populations were compared to those in a variety of soil ecosystems ranging in pH (4.0 - 7.5). Prokaryotic and viral community structure were significantly influenced by soil pH at the local scale. Of 1,910 viral operational taxonomic units (vOTUs), 99% were restricted to pH 4.5 or 7.5 soil only. These were compared in gene sharing networks of populations from six other European and North American soil systems. A selection of viral clusters from acidic and neutral pH soils were more associated with those from the local gradient pH 4.5 or 7.5 soils, respectively. Results indicate that as with prokaryotes, soil pH is a factor structuring viral communities at the local and global scale.


2018 ◽  
Author(s):  
Richard A. Boyle ◽  
Carolin R. Löscher

Integrated geological evidence suggests that grounded ice sheets occurred at sea level across all latitudes during two intervals within the Neoproterozoic era; the “snowball Earth” (SBE) events. Glacial events at ~730 and ~650 million years ago (Ma) were probably followed by a less severe but nonetheless global-scale glaciation at ~580Ma, immediately preceding the proliferation of the first fossils exhibiting unambiguous animal-like form. Existing modelling identifies weathering-induced CO2 draw-down as a critical aspect of glacial inception, but ultimately attributes the SBE phenomenon to unusual tectonic boundary conditions. Here we suggest that the evident directional decrease in Earth’s susceptibility to a SBE suggests that such a-directional abiotic factors are an insufficient explanation for the lack of SBE events since ~580 Ma. Instead we hypothesize that the terrestrial biosphere’s capacity to sustain a given level of biotic weathering-enhancement under suboptimal/declining temperatures, itself decreased over time: because lichens (with a relatively robust tolerance of sub-optimal temperatures) were gradually displaced on the land surface by more complex photosynthetic life (with a narrower temperature window for growth). We use a simple modelling exercise to highlight the critical (but neglected) importance of the temperature sensitivity of the biotic weathering enhancement factor and discuss the likely values of key parameters in relation to both experiments and the results of complex climate models. We show how the terrestrial biosphere’s capacity to sustain a given level of silicate-weathering-induced CO2 draw-down is critical to the temperature/greenhouse forcing at which SBE initiation is conceivable. We do not dispute the importance of low degassing rate and other tectonic factors, but propose that the unique feature of the Neoproterozoic was biology’s capacity to tip the system over the edge into a runaway ice-albedo feedback; compensating for the self-limiting decline in weathering rate during the temperature decrease on the approach to glaciation. Such compensation was more significant in the Neoproterozoic than the Phanerozoic due, ultimately, to changes in the species composition of the weathering interface over the course of evolutionary time.


mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Flora Vincent ◽  
Chris Bowler

ABSTRACT Diatoms are a major component of phytoplankton, believed to be responsible for around 20% of the annual primary production on Earth. As abundant and ubiquitous organisms, they are known to establish biotic interactions with many other members of plankton. Through analyses of cooccurrence networks derived from the Tara Oceans expedition that take into account both biotic and abiotic factors in shaping the spatial distributions of species, we show that only 13% of diatom pairwise associations are driven by environmental conditions; the vast majority are independent of abiotic factors. In contrast to most other plankton groups, on a global scale, diatoms display a much higher proportion of negative correlations with other organisms, particularly toward potential predators and parasites, suggesting that their biogeography is constrained by top-down pressure. Genus-level analyses indicate that abundant diatoms are not necessarily the most connected and that species-specific abundance distribution patterns lead to negative associations with other organisms. In order to move forward in the biological interpretation of cooccurrence networks, an open-access extensive literature survey of diatom biotic interactions was compiled, of which 18.5% were recovered in the computed network. This result reveals the extent of what likely remains to be discovered in the field of planktonic biotic interactions, even for one of the best-known organismal groups. IMPORTANCE Diatoms are key phytoplankton in the modern ocean that are involved in numerous biotic interactions, ranging from symbiosis to predation and viral infection, which have considerable effects on global biogeochemical cycles. However, despite recent large-scale studies of plankton, we are still lacking a comprehensive picture of the diversity of diatom biotic interactions in the marine microbial community. Through the ecological interpretation of both inferred microbial association networks and available knowledge on diatom interactions compiled in an open-access database, we propose an ecosystems approach for exploring diatom interactions in the ocean.


2017 ◽  
Vol 74 (8) ◽  
pp. 2180-2190 ◽  
Author(s):  
Bruno Welter Giraldes ◽  
Petrônio Alves Coelho Filho ◽  
David M. Smyth ◽  
Petrônio Alves Coelho

Abstract The relationship between populations of marine organisms and physicochemical gradients directly influence distributions of species within associated seascapes. This study examines the impact that exposure to sunlight and substrate type has on the distribution of decapods in a tropical coastal reef environment. The study was performed at night when the species are at their most active using a visual census methodology to observe the natural nocturnal behaviour. The research revealed the existence of three distinct habitats housing specific decapod assemblages within tropical hard substrate environments; the External-Reef habitat which accommodates colonial benthic host decapods; the Crevicular-Reef habitat which accommodates the reef-stygofauna; and the Interface habitat between the reef and soft substrate which is habituated by transient decapod species. The findings extend the previous zonation patterns for decapods to the subtidal zone using physical parameters as the rationale defining allocation. The study collated and reviewed documented taxonomic and ecological evidence which supports this division of decapods into similar reef seascapes worldwide. It further proposes that this format of subtidal zonation may be applicable on a global scale to species which inhabit a comparable ecological niche within tropical zones.


2021 ◽  
Vol 12 ◽  
Author(s):  
Markus Rienth ◽  
Nicolas Vigneron ◽  
Philippe Darriet ◽  
Crystal Sweetman ◽  
Crista Burbidge ◽  
...  

Temperature, water, solar radiation, and atmospheric CO2 concentration are the main abiotic factors that are changing in the course of global warming. These abiotic factors govern the synthesis and degradation of primary (sugars, amino acids, organic acids, etc.) and secondary (phenolic and volatile flavor compounds and their precursors) metabolites directly, via the regulation of their biosynthetic pathways, or indirectly, via their effects on vine physiology and phenology. Several hundred secondary metabolites have been identified in the grape berry. Their biosynthesis and degradation have been characterized and have been shown to occur during different developmental stages of the berry. The understanding of how the different abiotic factors modulate secondary metabolism and thus berry quality is of crucial importance for breeders and growers to develop plant material and viticultural practices to maintain high-quality fruit and wine production in the context of global warming. Here, we review the main secondary metabolites of the grape berry, their biosynthesis, and how their accumulation and degradation is influenced by abiotic factors. The first part of the review provides an update on structure, biosynthesis, and degradation of phenolic compounds (flavonoids and non-flavonoids) and major aroma compounds (terpenes, thiols, methoxypyrazines, and C13 norisoprenoids). The second part gives an update on the influence of abiotic factors, such as water availability, temperature, radiation, and CO2 concentration, on berry secondary metabolism. At the end of the paper, we raise some critical questions regarding intracluster berry heterogeneity and dilution effects and how the sampling strategy can impact the outcome of studies on the grapevine berry response to abiotic factors.


Author(s):  
Boris Worm ◽  
Derek P. Tittensor

The number of species found at a given point on the planet varies by orders of magnitude, yet large-scale gradients in biodiversity appear to follow some very general patterns. Little mechanistic theory has been formulated to explain the emergence of observed gradients of biodiversity both on land and in the oceans. Based on a comprehensive empirical synthesis of global patterns of species diversity and their drivers, this book develops and applies a new theory that can predict such patterns from few underlying processes. The book shows that global patterns of biodiversity fall into four consistent categories, according to where species live: on land or in coastal, pelagic, and deep ocean habitats. The fact that most species groups, from bacteria to whales, appear to follow similar biogeographic patterns of richness within these habitats points toward some underlying structuring principles. Based on empirical analyses of environmental correlates across these habitats, the book combines aspects of neutral, metabolic, and niche theory into one unifying framework. Applying it to model terrestrial and marine realms, the book demonstrates that a relatively simple theory that incorporates temperature and community size as driving variables is able to explain divergent patterns of species richness at a global scale. Integrating ecological and evolutionary perspectives, the book yields surprising insights into the fundamental mechanisms that shape the distribution of life on our planet.


2021 ◽  
Vol 8 ◽  
Author(s):  
Patricia Pérez Pérez ◽  
Iván Rodríguez-Escolar ◽  
Elena Carretón ◽  
José Ángel Sánchez Agudo ◽  
Jacob Lorenzo-Morales ◽  
...  

Various factors are currently causing an increase in vector-borne parasitic diseases at a global scale; among them, some stand out, such as climatic disturbances derived from global change, the increase in movements of reservoir animals, or changes in land made by human activity. In the European continent, there have been an increasing number of epidemiological studies focused on the detection of these diseases, especially in dogs. In Spain, there are few epidemiological studies focused on the evaluation of the biotic and abiotic factors that may influence the distribution, such as climatic zones, orography, or presence of water reservoirs. The aim of this study was to analyze the prevalence and distribution of several canine vector-borne diseases caused by Dirofilaria immitis, Leishmania infantum, Anaplasma platys, and Ehrlichia canis in the autonomous community of Castilla y León, the largest region of the Iberian Peninsula, providing a geospatial approach based on a geographic information system (GIS) analysis. Blood from a total of 1,475 domestic dogs from the nine provinces of Castilla y León were analyzed. Also, a GIS analysis of the sample locations was carried out, taking into account the most important predictor variables. The prevalence in dogs infected by D. immitis was 7.19%, and the seroprevalence by L. infantum was 4.61 and 1.56% for A. platys and E. canis. Most of the infected animals were located in areas with stagnant water, irrigated agriculture, or riverbanks, always close to forest and woodland vegetation. These results indicate that dogs living in Castilla y León should take prophylactic measures to avoid infections.


Sign in / Sign up

Export Citation Format

Share Document