ResearchPad - biodiversity https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Molecular clocks, biogeography and species diversity in <i>Herichthys</i> with evaluation of the role of Punta del Morro as a vicariant brake along the Mexican Transition Zone in the context of local and global time frame of cichlid diversification]]> https://www.researchpad.co/article/elastic_article_12834 Using molecular dated phylogenies and biogeographic reconstructions, the species diversity, biogeography and time frame of evolution of the genus Herichthys were evaluated. In particular, we test the role of Punta del Morro (PdM) as a vicariant brake along the Mexican Transition Zone in the context of local and global time frame of cichlid diversification using several sets of calibrations. Species diversity in Herichthys is complex and the here employed dating methods suggest young age and rapid divergence for many species while species delimitation methods did not resolve these young species including both sympatric species pairs. Based on our molecular clock dating analyses, Herichthys has colonized its present distribution area significantly prior to the suggested vicariance by PdM (10–17.1 Ma vs. 5 to 7.5 Ma). The PdM constraint is in conflict with all other paleogeographic and fossil constraints including novel ones introduced in this study that are, however, congruent among each other. Our study demonstrates that any cichlid datings significantly older or younger than the bounds presented by our analyses and discussion have to be taken as highly questionable from the point of view of Middle American paleogeography and cichlid biogeography unless we allow the option that cichlid biogeography is completely independent from ecological and geological constraints.

]]>
<![CDATA[Drivers of beta diversity in modern and ancient reef-associated soft-bottom environments]]> https://www.researchpad.co/article/elastic_article_8320 Beta diversity, the compositional variation among communities, is often associated with environmental gradients. Other drivers of beta diversity include stochastic processes, priority effects, predation, or competitive exclusion. Temporal turnover may also explain differences in faunal composition between fossil assemblages. To assess the drivers of beta diversity in reef-associated soft-bottom environments, we investigate community patterns in a Middle to Late Triassic reef basin assemblage from the Cassian Formation in the Dolomites, Northern Italy, and compare results with a Recent reef basin assemblage from the Northern Bay of Safaga, Red Sea, Egypt. We evaluate beta diversity with regard to age, water depth, and spatial distance, and compare the results with a null model to evaluate the stochasticity of these differences. Using pairwise proportional dissimilarity, we find very high beta diversity for the Cassian Formation (0.91 ± 0.02) and slightly lower beta diversity for the Bay of Safaga (0.89 ± 0.04). Null models show that stochasticity only plays a minor role in determining faunal differences. Spatial distance is also irrelevant. Contrary to expectations, there is no tendency of beta diversity to decrease with water depth. Although water depth has frequently been found to be a key factor in determining beta diversity, we find that it is not the major driver in these reef-associated soft-bottom environments. We postulate that priority effects and the biotic structuring of the sediment may be key determinants of beta diversity.

]]>
<![CDATA[A database of functional traits for spiders from native forests of the Iberian Peninsula and Macaronesia]]> https://www.researchpad.co/article/N63d31772-8edc-4bfb-82df-69546f8dc392 There is an increasing demand for databases including species trait information for biodiversity and community ecology studies. The existence of trait databases is useful for comparative studies within taxa or geographical regions, but there is low availability of databases for certain organisms. Here we present an open access functional trait database for spiders from Macaronesia and the Iberian Peninsula, recording several morphological and ecological traits related to the species life histories, microhabitat and trophic preferences.New informationWe present a database that includes 12 biological traits for 506 spider species present in natural forests of the Iberian Peninsula (Spain) and three Macaronesian archipelagoes (Azores, Madeira and Canary Islands). The functional trait database consists of two sections:individual-level data for six morphological traits (total body size, prosoma length, prosoma width, prosoma height, tibia I length and fang length), based on direct measurements of 2844 specimens of all spider species; andspecies-level aggregate data for 12 traits (same 6 morphological traits as in the previous section plus dispersal ability, vertical stratification, circadian activity, foraging strategy, trophic specialization and colonization status), based on either the average of the direct measurements or bibliographic searches.This functional trait database will serve as a data standard for currently ongoing analyses that require trait and functional diversity statistics. ]]> <![CDATA[Conservation of terrestrial invertebrates: a review of IUCN and regional Red Lists for ]]> https://www.researchpad.co/article/Ne05b9250-c0fe-4d47-98c6-0075a3f0204d Red Listing of Threatened species is recognized as the most objective approach for evaluating extinction risk of living organisms which can be applied at global or national scales. Invertebrates account for nearly 97% of all animals on the planet but are insufficiently represented in the IUCN Red Lists at both scales. To analyze the occurrence of species present in regional Red Lists, accounts of 48 different countries and regions all over the world were consulted and all data about myriapods () ever assessed in Red Lists at any level assembled. Myriapod species assessments were found in eleven regional Red Lists; however, no overlap between the species included in the global IUCN Red List and the regional ones was established. This means that myriapod species considered threatened at regional level may not be eligible for international funding specific for protection of native threatened species (more than US$ 25 million were available in the last decade) as most financial instruments tend to support only threatened species included in the IUCN Red List. As the lack of financial resources may limit protection for species in risk of extinction, it is urgent to increase the possibilities of getting financial support for implementation of measures for their protection. A Red List of all species recorded in Red Lists at national or local (596) and global (210) scales totaling 806 species is presented. This list shows for the first time an overview of the current conservation status of species. Here, the urgent need of establishing a Specialist Group in the Species Survival Commission of IUCN is also stressed.

]]>
<![CDATA[Ooctonus vulgatus (Hymenoptera, Mymaridae), a potential biocontrol agent to reduce populations of Philaenus spumarius (Hemiptera, Aphrophoridae) the main vector of Xylella fastidiosa in Europe]]> https://www.researchpad.co/article/N503c34c3-73c7-4316-aa36-d8ecad427c59

As a vector of Xylella fastidiosa (Wells, 1987) in Europe, the meadow spittlebug Philaenus spumarius (Linnaeus, 1758) (Hemiptera, Aphrophoridae) is a species of major concern. Therefore, tools and agents to control this ubiquitous insect that develops and feeds on hundreds of plant species are wanted. We conducted a field survey of P. spumarius eggs in Corsica and provide a first report of Ooctonus vulgatus Haliday, 1833 (Hymenoptera, Mymaridae) as a potential biocontrol agent of P. spumarius in Europe. To allow species identification, we summarized the main characters distinguishing O. vulgatus from other European species of Ooctonus and generated COI DNA barcodes. Parasitism rates were variable in the four localities included in the survey but could reach 69% (for an average number of eggs that hatched per locality of 109). Based on the geographic occurrences of O. vulgatus obtained from the literature, we calibrated an ecological niche model to assess its potential distribution in the Holarctic. Obviously, several questions need to be addressed to determine whether O. vulgatus could become an effective biocontrol agent of P. spumarius in Europe. So far, O. vulgatus has been reared only from P. spumarius eggs, but its exact host-range should be evaluated to ensure efficiency and avoid non-target effect. The top-down impact of the parasitoid on vector populations should also be assessed on large data sets. Finally, the feasibility of mass rearing should be tested. We hope this report serves as a starting point to initiate research on this parasitoid wasp to assess whether it could contribute to reduce the spread and impact of X. fastidiosa in Europe.

]]>
<![CDATA[Substrate rugosity and temperature matters: patterns of benthic diversity at tropical intertidal reefs in the SW Atlantic]]> https://www.researchpad.co/article/N7c59bde4-0dbb-4a33-a228-9eb85bb49e49

Modeling and forecasting ocean ecosystems in a changing world will require advances in observational efforts to monitor marine biodiversity. One of the observational challenges in coastal reef ecosystems is to quantify benthic and climate interactions which are key to community dynamics across habitats. Habitat complexity (i.e., substrate rugosity) on intertidal reefs can be an important variable explaining benthic diversity and taxa composition, but the association between substrate and seasonal variability is poorly understood on lateritic reefs in the South Atlantic. We asked if benthic assemblages on intertidal reefs with distinct substrate rugosity would follow similar seasonal patterns of succession following meteo-oceanographic variability in a tropical coastal area of Brazil. We combined an innovative 3D imaging for measuring substrate rugosity with satellite monitoring to monitor spatio-temporal patterns of benthic assemblages. The dataset included monthly in situ surveys of substrate cover and taxon diversity and richness, temporal variability in meteo-oceanographic conditions, and reef structural complexity from four sites on the Eastern Marine Ecoregion of Brazil. Additionally, correlation coefficients between temperature and both benthic diversity and community composition from one year of monitoring were used to project biodiversity trends under future warming scenarios. Our results revealed that benthic diversity and composition on intertidal reefs are strongly regulated by surface rugosity and sea surface temperatures, which control the dominance of macroalgae or corals. Intertidal reef biodiversity was positively correlated with reef rugosity which supports previous assertions of higher regional intertidal diversity on lateritic reefs that offer increased substrate complexity. Predicted warming temperatures in the Eastern Marine Ecoregion of Brazil will likely lead to a dominance of macroalgae taxa over the lateritic reefs and lower overall benthic diversity. Our findings indicate that rugosity is not only a useful tool for biodiversity mapping in reef intertidal ecosystems but also that spatial differences in rugosity would lead to very distinct biogeographic and temporal patterns. This study offers a unique baseline of benthic biodiversity on coastal marine habitats that is complementary to worldwide efforts to improve monitoring and management of coastal reefs.

]]>
<![CDATA[Till Death (Or an Intruder) Do Us Part: Intrasexual-Competition in a Monogamous Primate]]> https://www.researchpad.co/article/5989daaaab0ee8fa60ba8f45

Polygynous animals are often highly dimorphic, and show large sex-differences in the degree of intra-sexual competition and aggression, which is associated with biased operational sex ratios (OSR). For socially monogamous, sexually monomorphic species, this relationship is less clear. Among mammals, pair-living has sometimes been assumed to imply equal OSR and low frequency, low intensity intra-sexual competition; even when high rates of intra-sexual competition and selection, in both sexes, have been theoretically predicted and described for various taxa. Owl monkeys are one of a few socially monogamous primates. Using long-term demographic and morphological data from 18 groups, we show that male and female owl monkeys experience intense intra-sexual competition and aggression from solitary floaters. Pair-mates are regularly replaced by intruding floaters (27 female and 23 male replacements in 149 group-years), with negative effects on the reproductive success of both partners. Individuals with only one partner during their life produced 25% more offspring per decade of tenure than those with two or more partners. The termination of the pair-bond is initiated by the floater, and sometimes has fatal consequences for the expelled adult. The existence of floaters and the sporadic, but intense aggression between them and residents suggest that it can be misleading to assume an equal OSR in socially monogamous species based solely on group composition. Instead, we suggest that sexual selection models must assume not equal, but flexible, context-specific, OSR in monogamous species.

]]>
<![CDATA[Twenty-six additional new combinations in the Magnolia (Magnoliaceae) of China and Vietnam]]> https://www.researchpad.co/article/N5202c181-3dfd-40bd-a433-1d24ad15de87

Abstract

In accordance with the previous reduction of the remaining genera of subfamily Magnolioideae (Magnoliaceae) into the genus Magnolia, twenty-six new nomenclatural combinations are formally made by transferring to Magnolia some additional Chinese and Vietnamese taxa from the segregate genera of Manglietia, Michelia and Yulania. The following nine new combinations are created from Manglietia, namely Magnolia admirabilis, M. albistaminea, M. guangnanica, M. jinggangshanensis, M. maguanica, M. pubipedunculata, M. pubipetala, M. rufisyncarpa and M. sinoconifera. Also, twelve new combinations are created from Michelia, namely Magnolia caloptila, M. caudata, M. fallax, M. gelida, M. hunanensis, M. maudiae var. rubicunda, M. multitepala, M. platypetala, M. rubriflora, M. septipetala, M. sonlaensis, M. xinningia. Finally, five new combinations are created from Yulania, namely Magnolia baotaina, M. pendula, M. pilocarpa var. ellipticifolia, M. puberula and M. urceolata.

]]>
<![CDATA[Two new species of Rhaphium from Qinghai Province, China (Diptera, Dolichopodidae, Rhaphiinae)]]> https://www.researchpad.co/article/Ne91d2f67-b158-4ad4-8416-c17aaf2186a0

Abstract

At present, there are 31 species of Rhaphium Meigen recorded in China. In this paper, two species from Qinghai Province of China are described as new to science: Rhaphium huzhuensesp. nov., Rhaphium minhensesp. nov. A key to the Chinese species of Rhaphium is provided.

]]>
<![CDATA[Geographic boundaries and natural history notes of the microendemic endangered frog Eupsophus migueli Formas, 1977 (Alsodidae) in the Mahuidanche Range, southern Chile]]> https://www.researchpad.co/article/N613a9e27-4da3-4d48-b522-8b29066698b9

Abstract

Eupsophus migueli is considered a microendemic endangered species inhabiting the temperate Nothofagus forests of the Mahuidanche Range of southern Chile. However, this categorization is based on scarce data about its distribution and natural history. In order to assess these parameters, this article reports new geographic records obtained through intensive fieldwork between 2011 and 2016. Considering this, an updated distribution map for E. migueli is proposed, and new data about natural history traits and habitat use are provided. The information obtained in this study is discussed considering the zoogeographical importance of E. migueli, and confirms the species IUCN conservation status.

]]>
<![CDATA[The mitochondrial phylogeny of land plants shows support for Setaphyta under composition-heterogeneous substitution models]]> https://www.researchpad.co/article/N8f14fcc2-0524-4065-b708-e2a60b264d8d

Congruence among analyses of plant genomic data partitions (nuclear, chloroplast and mitochondrial) is a strong indicator of accuracy in plant molecular phylogenetics. Recent analyses of both nuclear and chloroplast genome data of land plants (embryophytes) have, controversially, been shown to support monophyly of both bryophytes (mosses, liverworts, and hornworts) and tracheophytes (lycopods, ferns, and seed plants), with mosses and liverworts forming the clade Setaphyta. However, relationships inferred from mitochondria are incongruent with these results, and typically indicate paraphyly of bryophytes with liverworts alone resolved as the earliest-branching land plant group. Here, we reconstruct the mitochondrial land plant phylogeny from a newly compiled data set. When among-lineage composition heterogeneity is accounted for in analyses of codon-degenerate nucleotide and amino acid data, the clade Setaphyta is recovered with high support, and hornworts are supported as the earliest-branching lineage of land plants. These new mitochondrial analyses demonstrate partial congruence with current hypotheses based on nuclear and chloroplast genome data, and provide further incentive for revision of how plants arose on land.

]]>
<![CDATA[Discovery of a new species of the Hypoxylon rubiginosum complex from Iran and antagonistic activities of Hypoxylon spp. against the Ash Dieback pathogen, Hymenoscyphus fraxineus, in dual culture]]> https://www.researchpad.co/article/N42b420df-f01d-4492-b8d8-193894490051

Abstract

During a survey of xylarialean fungi in Northern Iran, several specimens that showed affinities to the Hypoxylon rubiginosum complex were collected and cultured. A comparison of their morphological characters, combined with a chemotaxonomic study based on high performance liquid chromatography, coupled with diode array detection and mass spectrometry (HPLC-DAD/MS) and a multi-locus phylogeny based on ITS, LSU, rbp2 and tub2 DNA sequences, revealed a new species here described as Hypoxylon guilanense. In addition, Hypoxylon rubiginosumsensu stricto was also encountered. Concurrently, an endophytic isolate of the latter species showed strong antagonistic activities against the Ash Dieback pathogen, Hymenoscyphus fraxineus, in a dual culture assay in our laboratory. Therefore, we decided to test the new Iranian fungi for antagonistic activities against the pathogen, along with several cultures of other Hypoxylon species that are related to H. rubiginosum. Our results suggest that the antagonistic effects of Hypoxylon spp. against Hym. fraxineus are widespread and that they are due to the production of antifungal phomopsidin derivatives in the presence of the pathogen.

]]>
<![CDATA[Description of six new large species of Argentinomyia Lynch-Arribálzaga, 1891 and redescription of Talahua fervida (Fluke, 1945) (Diptera, Syrphidae, Syrphinae)]]> https://www.researchpad.co/article/Nb19af340-0fde-4b2f-a9fe-ac31a54fbaca

Abstract

The morphological similarities between five new large Argentinomyia species and Talahua fervida Fluke are characterized and presented. Six new species of Argentinomyia (10–12 mm long) are described: Argentinomyia andina Montoya & Wolff, sp. nov. (Colombia), Argentinomyia choachi Montoya, sp. nov. (Colombia), Argentinomyia quimbaya Montoya & Wolff, sp. nov. (Colombia), Argentinomyia huitepecensis Montoya, sp. nov. (México), Argentinomyia puntarena Montoya, sp. nov. (Costa Rica), and Argentinomyia talamanca Thompson, sp. nov. (Costa Rica). The genus Talahua Fluke is re-diagnosed and, Talahua fervida redescribed. A taxonomic key and a comparison of diagnostic characters are presented. Photographs of head, abdominal and wing maculae patterns, as well as illustrations of male genitalia are provided for species identification.

]]>
<![CDATA[Two species of Thoracostomopsidae (Nematoda: Enoplida) from Jeju Island, South Korea]]> https://www.researchpad.co/article/Nd6f075e6-61c4-4ffd-9fc5-9d3a90d27b8d

During a survey of intertidal zones at beaches on Jeju Island, two species belonging to the family Thoracostomopsidae were discovered. One new species, Enoploides koreanus sp. nov. and one known species, Epacanthion hirsutum Shi & Xu, 2016 are reported. Along with morphological analysis, mitochondrial cytochrome oxidase c subunit 1 (mtCOI) sequences and 18S rRNA sequences of the species were also obtained and used to check relative p-distance and phylogenetic positions. While most species of Enoploides have long spicules, the new species belongs to a group of Enoploides with short spicules < 150 µm). Of the seven species with short spicules, the new species is most closely related to E. disparilis Sergeeva, 1974. They both have similar body length, fairly similar sized and shaped spicules with small gubernaculum running parallel to distal end of spicule, and an index value of b. The new species can be distinguished from E. disparilis by having pre-anal supplementary organ with short conical tail, while E. disparilis lacks pre-anal supplementary organ and has a long conico-cylindrical tail. Along with the description of the new species, the genus Enoploides Ssaweljev, 1912 is bibliographically reviewed and revised. Of 45 species described to date, 27 are now considered valid, 16 species inquirendae due to inadequate descriptions and ambiguity of the material examined, along with two cases of nomen nudum. With this review, we provide an updated diagnosis and list of valid species, a tabular key comparing diagnostic characters of all valid species, and a new complete key to species. One known species, Epacanthion hirsutum Shi & Xu, 2016, is reported in Korea for the first time. The morphology agrees well with the original description provided by Shi & Xu, 2016. As they had already reviewed the genus at the time of reporting four Epacanthion species, we provide only a description, depiction, and measurements for comparison purposes.

]]>
<![CDATA[Long-term continuously monocropped peanut significantly changed the abundance and composition of soil bacterial communities]]> https://www.researchpad.co/article/N2b441e4b-bf77-472a-8f83-cfd091e8da1e

Soil sickness is the progressive loss of soil quality due to continuous monocropping. The bacterial populations are critical to sustaining agroecosystems, but their responses to long-term peanut monocropping have not been determined. In this study, based on a previously constructed gradient of continuous monocropped plots, we tracked the detailed feedback responses of soil bacteria to short- and long-term continuous monocropping of four different peanut varieties using high-throughput sequencing techniques. The analyses showed that soil samples from 1- and 2-year monocropped plots were grouped into one class, and samples from the 11- and 12-year plots were grouped into another. Long-term consecutive monocropping could lead to a general loss in bacterial diversity and remarkable changes in bacterial abundance and composition. At the genera level, the dominant genus Bacillus changed in average abundance from 1.49% in short-term monocropping libraries to 2.96% in the long-term libraries. The dominant species Bacillus aryabhattai and Bacillus funiculus and the relatively abundant species Bacillus luciferensis and Bacillus decolorationis all showed increased abundance with long-term monocropping. Additionally, several other taxa at the genus and species level also presented increased abundance with long-term peanut monocropping; however, several taxa showed decreased abundance. Comparing analyses of predicted bacterial community functions showed significant changes at different KEGG pathway levels with long-term peanut monocropping. Combined with our previous study, this study indicated that bacterial communities were obviously influenced by the monocropping period, but less influenced by peanut variety and growth stage. Some bacterial taxa with increased abundance have functions of promoting plant growth or degrading potential soil allelochemicals, and should be closely related with soil remediation and may have potential application to relieve peanut soil sickness. A decrease in diversity and abundance of bacterial communities, especially beneficial communities, and simplification of bacterial community function with long-term peanut monocropping could be the main cause of peanut soil sickness.

]]>
<![CDATA[A new species of cryptic Bush frog (Anura, Rhacophoridae, Raorchestes) from northeastern Bangladesh]]> https://www.researchpad.co/article/Nf2a02021-be73-445a-a052-4f13cefefcce

Abstract

Raorchestes is a speciose genus of bush frogs with high diversity occurring in the Western Ghats of India. Relatively fewer species have been recorded across India, through Bangladesh, southern China, into Vietnam and Peninsular Malaysia. Many bush frogs are morphologically cryptic and therefore remain undescribed. Here, a new species, Raorchestes rezakhanisp. nov., is described from northeastern Bangladesh based on morphological characters, genetics, and bioacoustics. The 16S rRNA gene distinguished this species from 48 known species of this genus. Bayesian Inference and Maximum Likelihood analyses indicated that the new species was most similar to R. tuberohumerus, a species found in the Western Ghats, and to R. gryllus, a species found in Vietnam. Bioacoustics indicated that their calls were similar in pattern to most Raorchestes species, although number of pulses, duration of pulses, pulse intervals and amplitude differentiated it from a few other species. It is suggested that northeastern India, Bangladesh, northern Myanmar, and southern China represent important, relatively unexplored areas that could yield additional species of Raorchestes. Since many remaining habitat patches in Bangladesh are under severe threat from deforestation, efforts should be made to protect these last patches from further degradation.

]]>
<![CDATA[Catalyzing rapid discovery of gold-precipitating bacterial lineages with university students]]> https://www.researchpad.co/article/N1a44b6bf-58da-4441-b695-6e6e3f9e006c

Intriguing and potentially commercially useful microorganisms are found in our surroundings and new tools allow us to learn about their genetic potential and evolutionary history. Engaging students from different disciplines and courses in the search for microbes requires an exciting project with innovative but straightforward procedures and goals. Here we describe an interdisciplinary program to engage students from different courses in the sampling, identification and analysis of the DNA sequences of a unique yet common microbe, Delftia spp. A campus-wide challenge was created to identify the prevalence of this genus, able to precipitate gold, involving introductory level environmental and life science courses, upper-level advanced laboratory modules taken by undergraduate students (juniors and seniors), graduate students and staff from the campus. The number of participants involved allowed for extensive sampling while undergraduate researchers and students in lab-based courses participated in the sample processing and analyses, helping contextualize and solidify their learning of the molecular biology techniques. The results were shared at each step through publicly accessible websites and workshops. This model allows for the rapid discovery of Delftia presence and prevalence and is adaptable to different campuses and experimental questions.

]]>
<![CDATA[Perceived socio-economic impacts of the marbled crayfish invasion in Madagascar]]> https://www.researchpad.co/article/N7a6c5db8-4016-4d26-87a6-87422e70e8c1

The negative environmental and economic impacts of many invasive species are well known. However, given the increased homogenization of global biota, and the difficulty of eradicating species once established, a balanced approach to considering the impacts of invasive species is needed. The marbled crayfish (Procambarus virginalis) is a parthenogenetic freshwater crayfish that was first observed in Madagascar around 2005 and has spread rapidly. We present the results of a socio-economic survey (n = 385) in three regions of Madagascar that vary in terms of when the marbled crayfish first arrived. Respondents generally considered marbled crayfish to have a negative impact on rice agriculture and fishing, however the animals were seen as making a positive contribution to household economy and food security. Regression modeling showed that respondents in regions with longer experience of marbled crayfish have more positive perceptions. Unsurprisingly, considering the perception that crayfish negatively impact rice agriculture, those not involved in crayfish harvesting and trading had more negative views towards the crayfish than those involved in crayfish-related activities. Food preference ranking and market surveys revealed the acceptance of marbled crayfish as a cheap source of animal protein; a clear positive in a country with widespread malnutrition. While data on biodiversity impacts of the marbled crayfish invasion in Madagascar are still completely lacking, this study provides insight into the socio-economic impacts of the dramatic spread of this unique invasive species. Biby kely tsy fantam-piaviana, mahavelona fianakaviana” (a small animal coming from who knows where which supports the needs of the family). Government worker Analamanga, Madagascar.

]]>
<![CDATA[Lake-depth related pattern of genetic and morphological diatom diversity in boreal Lake Bolshoe Toko, Eastern Siberia]]> https://www.researchpad.co/article/N3e538c26-938b-46fc-81d6-ffac689cc377

Large, old and heterogenous lake systems are valuable sources of biodiversity. The analysis of current spatial variability within such lakes increases our understanding of the origin and establishment of biodiversity. The environmental sensitivity and the high taxonomic richness of diatoms make them ideal organisms to investigate intra-lake variability. We investigated modern intra-lake diatom diversity in the large and old sub-arctic Lake Bolshoe Toko in Siberia. Our study uses diatom-specific metabarcoding, applying a short rbcL marker combined with next-generation sequencing and morphological identification to analyse the diatom diversity in modern sediment samples of 17 intra-lake sites. We analysed abundance-based compositional taxonomic diversity and generic phylogenetic diversity to investigate the relationship of diatom diversity changes with water depth. The two approaches show differences in taxonomic identification and alpha diversity, revealing a generally higher diversity with the genetic approach. With respect to beta diversity and ordination analyses, both approaches result in similar patterns. Water depth or related lake environmental conditions are significant factors influencing intra-lake diatom patterns, showing many significant negative correlations between alpha and beta diversity and water depth. Further, one near-shore and two lagoon lake sites characterized by low (0-10m) and medium (10-30m) water depth are unusual with unique taxonomic compositions. At deeper (>30m) water sites we identified strongest phylogenetic clustering in Aulacoseira, but generally much less in Staurosira, which supports that water depth is a strong environmental filter on the Aulacoseira communities. Our study demonstrates the utility of combining analyses of genetic and morphological as well as phylogenetic diversity to decipher compositional and generic phylogenetic patterns, which are relevant in understanding intra-lake heterogeneity as a source of biodiversity in the sub-arctic glacial Lake Bolshoe Toko.

]]>
<![CDATA[First records and new information on the associations of echinoderms with other phyla in the rocky reefs of northern Chocó, Colombian Pacific]]> https://www.researchpad.co/article/N25d10b9c-f85f-4f90-9f59-a08870695aae

Abstract

Rocky reefs of the northern Colombian Pacific (Chocó) are diverse ecosystems that are poorly studied. Echinoderms are one of the principal groups in these ecosystems with associations to different species, including benthic organisms in which they live and other species that use them as hosts. These relationships include fishes, sponges, seaweeds, cnidarians, polychaetes, bryozoans, crustaceans, mollusks, and other echinoderms. For this area, 22 associations were registered, including commensalism, epibionts and parasitism. This work constitutes the first report for the associations of Eucidaris thouarsii with Suberites aff. ficus, E. thouarsii with Ophiothela mirabilis, and Holothuria (Thymiosicia) impatiens with Encheliophis vermicularis. Associations of Pentaceraster cumingi with Zenopontonia soror, and Ophionereis annulata with Malmgreniella cf. variegata are new records for Colombia. This work also expands the range of hosts previously described for Ophiothela mirabilis and expands the distribution of the association between Diadema mexicanum and Echineulima cf. robusta.

]]>