352 research outputs found
Global patterns in seagrass herbivory: Why, despite existing evidence, there are solid arguments in favor of latitudinal gradients in seagrass herbivory
© 2020, Coastal and Estuarine Research Federation. The ecological paradigm that biological interactions are more intense in the tropics than in temperate or polar regions has existed since the mid-twentieth century, but several recent meta-analyses have provided scant evidence for latitudinal gradients in the intensity of herbivory. This contradictory evidence led us to carefully review the data and results of several of those papers that failed to find latitudinal gradients in rates of seagrass herbivory. To re-evaluate the arguments around the presence or absence of latitudinal gradients in herbivory in seagrass, we began by expanding the selection criteria to include more studies to compare the published latitudinal range of seagrass occurrences with the latitudes in which seagrass herbivory has been studied. We also compared the latitudinal range of known seagrass herbivores with the distribution of studies on seagrass herbivory. Finally, we investigated studies that provided seasonal data on net primary production and standing stock of seagrasses, which allowed an assessment of the relative amounts of production that could enter the seagrass grazing food web among latitudes and climatic regimes. Consistent with recent meta-analyses, we found little latitudinal effect on grazing rates. However, we argue that the following factors are likely to confound these findings and potentially mask latitudinal trends in seagrass herbivory: (1) the paucity of data available to test latitudinal trends in grazing rates at high latitudes; (2) the mismatch between the geographic distribution of important grazers and studies on seagrass herbivory; (3) the paucity of experimental studies from areas with little or no herbivory because few researchers would initiate a study on something not observed to be occurring; (4) the high level of seasonality in seagrass production in high latitudes, where seagrass production is very low or nonexistent in winter months; (5) the fact that temperate areas with Mediterranean climates behave very differently than temperate areas at similar latitudes with much greater seasonality, thereby making latitude a much less informative independent variable than annual range in temperature; and (6) anthropogenic disturbances, including the overharvesting to functional extinction of large seagrass herbivores in both temperate and tropical regions. Thus, while we currently cannot discount the lack of a latitudinal gradient in grazing intensity, we argue that the intensity of grazing is likely to be greater in the tropics than high-latitude regions where the carrying capacity of seagrass meadows is far less stable. Either way, there are clear gaps in our knowledge and ability to evaluate the role of grazing in seagrass ecosystems and inform future efforts to conserve and restore these extraordinarily valuable ecosystems
Chapman-Enskog method and synchronization of globally coupled oscillators
The Chapman-Enskog method of kinetic theory is applied to two problems of
synchronization of globally coupled phase oscillators. First, a modified
Kuramoto model is obtained in the limit of small inertia from a more general
model which includes ``inertial'' effects. Second, a modified Chapman-Enskog
method is used to derive the amplitude equation for an O(2) Takens-Bogdanov
bifurcation corresponding to the tricritical point of the Kuramoto model with a
bimodal distribution of oscillator natural frequencies. This latter calculation
shows that the Chapman-Enskog method is a convenient alternative to normal form
calculations.Comment: 7 pages, 2-column Revtex, no figures, minor change
Catalogue of squat lobsters of the world (Crustacea: Decapoda: Anomura-families Chirostylidae, Galatheidae and Kiwaidae)
220 páginas, 5 figuras, 1 tabla.[EN] This adaptation text reproduces Anexo I of the dissertation “Results”: Sistemática e historia evolutiva de la Familia Galatheidae (Crustacea: Anomura) en el Pacífico Sur, of Patricia Cabezas (2010) http://hdl.handle.net/10261/134771[ES] Este artículo es una adaptación del Anexo I de la tesis doctoral: Sistemática e historia evolutiva de la Familia Galatheidae (Crustacea: Anomura) en el Pacífico Sur, of Patricia Cabezas (2010) http://hdl.handle.net/10261/134771Taxonomic and ecological interest in squat lobsters has grown considerably over the last two decades. A checklist of the
870 current valid species of squat lobsters of the world (families Chirostylidae, Galatheidae and Kiwaidae) is presented.
The compilation includes the complete taxonomic synonymy and geographical distribution of each species plus type
information (type locality, repository and registration number). The numbers of described species in the world’s major
ocean basins are summarised.Peer reviewe
Marine Biodiversity in the Australian Region
The entire Australian marine jurisdictional area, including offshore and sub-Antarctic islands, is considered in this paper. Most records, however, come from the Exclusive Economic Zone (EEZ) around the continent of Australia itself. The counts of species have been obtained from four primary databases (the Australian Faunal Directory, Codes for Australian Aquatic Biota, Online Zoological Collections of Australian Museums, and the Australian node of the Ocean Biogeographic Information System), but even these are an underestimate of described species. In addition, some partially completed databases for particular taxonomic groups, and specialized databases (for introduced and threatened species) have been used. Experts also provided estimates of the number of known species not yet in the major databases. For only some groups could we obtain an (expert opinion) estimate of undiscovered species. The databases provide patchy information about endemism, levels of threat, and introductions. We conclude that there are about 33,000 marine species (mainly animals) in the major databases, of which 130 are introduced, 58 listed as threatened and an unknown percentage endemic. An estimated 17,000 more named species are either known from the Australian EEZ but not in the present databases, or potentially occur there. It is crudely estimated that there may be as many as 250,000 species (known and yet to be discovered) in the Australian EEZ. For 17 higher taxa, there is sufficient detail for subdivision by Large Marine Domains, for comparison with other National and Regional Implementation Committees of the Census of Marine Life. Taxonomic expertise in Australia is unevenly distributed across taxa, and declining. Comments are given briefly on biodiversity management measures in Australia, including but not limited to marine protected areas
How Many Species Are There on Earth and in the Ocean?
The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed
A Noncoding Point Mutation of Zeb1 Causes Multiple Developmental Malformations and Obesity in Twirler Mice
Heterozygous Twirler (Tw) mice develop obesity and circling behavior associated with malformations of the inner ear, whereas homozygous Tw mice have cleft palate and die shortly after birth. Zeb1 is a zinc finger protein that contributes to mesenchymal cell fate by repression of genes whose expression defines epithelial cell identity. This developmental pathway is disrupted in inner ears of Tw/Tw mice. The purpose of our study was to comprehensively characterize the Twirler phenotype and to identify the causative mutation. The Tw/+ inner ear phenotype includes irregularities of the semicircular canals, abnormal utricular otoconia, a shortened cochlear duct, and hearing loss, whereas Tw/Tw ears are severely malformed with barely recognizable anatomy. Tw/+ mice have obesity associated with insulin-resistance and have lymphoid organ hypoplasia. We identified a noncoding nucleotide substitution, c.58+181G>A, in the first intron of the Tw allele of Zeb1 (Zeb1Tw). A knockin mouse model of c.58+181G>A recapitulated the Tw phenotype, whereas a wild-type knockin control did not, confirming the mutation as pathogenic. c.58+181G>A does not affect splicing but disrupts a predicted site for Myb protein binding, which we confirmed in vitro. In comparison, homozygosity for a targeted deletion of exon 1 of mouse Zeb1, Zeb1ΔEx1, is associated with a subtle abnormality of the lateral semicircular canal that is different than those in Tw mice. Expression analyses of E13.5 Twirler and Zeb1ΔEx1 ears confirm that Zeb1ΔEx1 is a null allele, whereas Zeb1Tw RNA is expressed at increased levels in comparison to wild-type Zeb1. We conclude that a noncoding point mutation of Zeb1 acts via a gain-of-function to disrupt regulation of Zeb1Tw expression, epithelial-mesenchymal cell fate or interactions, and structural development of the inner ear in Twirler mice. This is a novel mechanism underlying disorders of hearing or balance
Climate drives the geography of marine consumption by changing predator communities
Este artículo contiene 7 páginas, 3 figuras, 1 tabla.The global distribution of primary production and consumption by
humans (fisheries) is well-documented, but we have no map linking
the central ecological process of consumption within food
webs to temperature and other ecological drivers. Using standardized
assays that span 105° of latitude on four continents, we show
that rates of bait consumption by generalist predators in shallow
marine ecosystems are tightly linked to both temperature and the
composition of consumer assemblages. Unexpectedly, rates of
consumption peaked at midlatitudes (25 to 35°) in both Northern
and Southern Hemispheres across both seagrass and unvegetated
sediment habitats. This pattern contrasts with terrestrial systems,
where biotic interactions reportedly weaken away from the equator,
but it parallels an emerging pattern of a subtropical peak in
marine biodiversity. The higher consumption at midlatitudes was
closely related to the type of consumers present, which explained
rates of consumption better than consumer density, biomass, species
diversity, or habitat. Indeed, the apparent effect of temperature
on consumption was mostly driven by temperature-associated turnover
in consumer community composition. Our findings reinforce
the key influence of climate warming on altered species composition
and highlight its implications for the functioning of Earth’s
ecosystems.We acknowledge funding from the Smithsonian
Institution and the Tula Foundation.Peer reviewe
Sustainable drainage system site assessment method using urban ecosystem services
The United Kingdom's recently updated approach to sustainable drainage enhanced biodiversity and amenity objectives by incorporating the ecosystem approach and the
ecosystem services concept. However, cost-effective and reliable methods to appraise the biodiversity and amenity values of potential sustainable drainage system (SuDS)sites and their surrounding areas are still lacking, as is a method to enable designers to distinguish and link the amenity and biodiversity benefits that SuDS schemes can offer. In this paper, therefore, the authors propose two ecosystem services- and disservices-based methods (i.e. vegetation structure cover-abundance examination and cultural ecosystem services and disservices variables appraisal) to aid SuDS designers to distinguish and link amenity and biodiversity benefits, and allow initial site
assessments to be performed in a cost-effective and reliable fashion. Forty-nine representative sites within Greater Manchester were selected to test the two methods.
Amenity and biodiversity were successfully assessed and habitat for species, carbon sequestration, recreation and education ecosystem services scores were produced,which will support SuDS retrofit design decision-making. Large vegetated SuDS sites with permanent aquatic features were found to be most capable of enhancing biodiversity- and amenity-related ecosystem services. Habitat for species and
recreation ecosystem services were also found to be positively linked to each other. Finally, waste bins on site were found to help reduce dog faeces and litter coverage. Overall, the findings presented here enable future SuDS retrofit designs to be more wildlife friendly and socially inclusive
Biodiversity of the Deep-Sea Continental Margin Bordering the Gulf of Maine (NW Atlantic): Relationships among Sub-Regions and to Shelf Systems
Background: In contrast to the well-studied continental shelf region of the Gulf of Maine, fundamental questions regarding
the diversity, distribution, and abundance of species living in deep-sea habitats along the adjacent continental margin
remain unanswered. Lack of such knowledge precludes a greater understanding of the Gulf of Maine ecosystem and limits
development of alternatives for conservation and management.
Methodology/Principal Findings: We use data from the published literature, unpublished studies, museum records and
online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf
of Maine (39–43uN, 63–71uW, 150–3000 m depth); (2) compare patterns of taxonomic diversity and distribution of
megafaunal and macrofaunal species among six distinct sub-regions and to the continental shelf; and (3) estimate the
amount of unknown diversity in the region. Known diversity for the deep-sea region is 1,671 species; most are narrowly
distributed and known to occur within only one sub-region. The number of species varies by sub-region and is directly
related to sampling effort occurring within each. Fishes, corals, decapod crustaceans, molluscs, and echinoderms are
relatively well known, while most other taxonomic groups are poorly known. Taxonomic diversity decreases with increasing
distance from the continental shelf and with changes in benthic topography. Low similarity in faunal composition suggests
the deep-sea region harbours faunal communities distinct from those of the continental shelf. Non-parametric estimators of
species richness suggest a minimum of 50% of the deep-sea species inventory remains to be discovered.
Conclusions/Significance: The current state of knowledge of biodiversity in this deep-sea region is rudimentary. Our ability
to answer questions is hampered by a lack of sufficient data for many taxonomic groups, which is constrained by sampling
biases, life-history characteristics of target species, and the lack of trained taxonomists
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