Pandora’s box in the deep sea –intraspecific diversity patterns and distribution of two congeneric scavenging amphipods

Paralicella tenuipes Chevreux, 1908 and Paralicella Shulenberger and Barnard, 1976 are known as widely distributed deep-sea scavenging amphipods. Some recent studies based on genetic data indicated the presence of high intraspecificvariationofP.caperescasuggestingitisaspeciescomplex.Basedon published molecular data from the Pacific and Indian oceans and new material obtained from the North and South Atlantic, we integrated the knowledge on the intraspecific variation and species distribution of the two nominal taxa. The study included analysis of three genes (COI, 16S rRNA, 28S rRNA) and revealed the existence of a single Molecular Operational Taxonomic Unit (MOTU) within P. tenuipes and six different MOTUs forming P. caperesca. The distribution pattern of the recognized lineages varied with three (P. tenuipes, MOTU 1 and MOTU 5 of P. caperesca) being widely distributed. There was evidence of contemporary population connectivity expressed by the share of the same COI haplotypes by individuals from very distant localities. At the same time no signal of recent demographic changes was observed within the studied taxa. The time-calibrated phylogeny suggested the emergence of species to be at the time of Mesozoic/Cenozoic transition that may be associated with global changes of the ocean circulation and deep sea water cooling

A genetic fingerprint of Amphipoda from Icelandic waters – the baseline for further biodiversity and biogeography studies

Source at https://doi.org/10.3897/zookeys.731.19931.Amphipods constitute an abundant part of Icelandic deep-sea zoobenthos yet knowledge of the diversity of this fauna, particularly at the molecular level, is scarce. The present work aims to use molecular methods to investigate genetic variation of the Amphipoda sampled during two IceAGE collecting expeditions. The mitochondrial cytochrome oxidase subunit 1 (COI) of 167 individuals originally assigned to 75 morphospecies was analysed. These targeted morhospecies were readily identifiable by experts using light microscopy and representative of families where there is current ongoing taxonomic research. The study resulted in 81 Barcode Identity Numbers (BINs) (of which >90% were published for the first time), while Automatic Barcode Gap Discovery revealed the existence of 78 to 83 Molecular Operational Taxonomic Units (MOTUs). Six nominal species (Rhachotropis helleri, Arrhis phyllonyx, Deflexilodes tenuirostratus, Paroediceros propinquus, Metopa boeckii, Astyra abyssi) appeared to have a molecular variation higher than the 0.03 threshold of both p-distance and K2P usually used for amphipod species delineation. Conversely, two Oedicerotidae regarded as separate morphospecies clustered together with divergences in the order of intraspecific variation. The incongruence between the BINs associated with presently identified species and the publicly available data of the same taxa was observed in case of Paramphithoe hystrix and Amphilochus manudens. The findings from this research project highlight the necessity of supporting molecular studies with thorough morphology species analyses

Multi-ocean distribution of a brooding predator in the abyssal benthos

Abstract How far are species distributed on the abyssal plains? Spanning from 3000 to 6000 m below sea level, abyssal plains cover three-quarters of the ocean floor and are the largest but also least explored habitat on Earth. The question of vertical and horizontal distribution is central to understanding biogeographic and population genetic processes within species inhabiting the deep-sea benthos. Amphipod crustaceans are an important and dominant taxon in this ecosystem. As they are brooders, their dispersal capacities are more limited compared to species with free-swimming larvae, and with the exception of a few scavenging species deep-sea amphipods are restricted to a single ocean. Based on an integrative taxonomic approach (morphology, COI, 16S and 18S) we demonstrate the occurrence of a predatory amphipod species, Rhachotropis abyssalis, in three oceans: the Antarctic Ross Sea, the Northwest Pacific and the North Atlantic; regions more than 20,000 km apart. Although such extensive geographic distributions may represent a rare exception for brooding predators, these findings might also be no exception at all, but a reflection of the rare sampling and rare taxonomic investigation of invertebrate predators in the deep-sea. Our findings highlight our abysmal state of knowledge regarding biodiversity and biogeography on abyssal plains

Depth zonation of Northwest Pacific deep-sea macrofauna

Areas of the Northwest (NW) Pacific have been investigated in the last century from board of the Russian RV Vityaz. During the past decade intensive collaboration between German and Russian scientists has yielded a wealth of precious material partly from unknown areas. The samples are comparable and were retrieved using comparative epibenthic sledge (EBS) deployments following a standardized sampling approach. In the present paper we investigate a large number of EBS samples (76) from a widespread geographic area. Macrofaunal high-taxonomic-level taxa composition is analysed based on four joint expeditions performed between 2010 and 2016, led by German and Russian teams in the NW Pacific, the Sea of Japan, the Sea of Okhotsk, and the Kuril-Kamchatka Trench and adjacent abyssal plain. In total, 410,279 invertebrates were sampled with an epibenthic sledge and more than half of all animals were collected in the Sea of Japan (240,803 individuals). Arthropods, represented by crustaceans, were dominant throughout all geographic areas (199,044 ind.), followed by Annelida (84,751 ind.), Echinodermata (46,317 ind.), and Mollusca (43,391 ind.). Within these phyla, eleven taxa occurred with more than 10,000 individuals in the samples from all geographic areas. The most numerous were the Peracarida (104,139 ind., represented by Isopoda [42,511 ind.], Amphipoda [29,375 ind.], Cumacea [16,364 ind.], Tanaidacea [15,889 ind.]), followed by Polychaeta (84,751 ind.), Copepoda 76,496 ind., Bivalvia (36,286 ind.), Ophiuroidea (34,818 ind.), Nematoda (24,968 ind.), Ostracoda (11,304 ind.), and Holothuroidea (10,772 ind.). The pattern of occurrence per taxon varied between geographic areas. In general, Bivalvia and Holothuroidea were more frequently recorded from hadal stations, but no significant differences could be observed between geographic areas (Sea of Japan, Sea of Okhotsk, and open NW Pacific) at high level taxa (classes, subclasses, superorders) when community composition is compared and depth differences are taken into account. However, significant differences between all depth zones (p < 0.05) were revealed for both PERMANOVA and non-parametric pairwise t-tests

Are rare species useful species? Obstacles to the conservation of tree diversity in the dry forest zone agro-ecosystems of Mesoamerica

Aim To test the potential to conserve rare dry forest tree and shrub species circa situm.Location Oaxaca, Mexico and Southern Honduras.Methods Local uses (timber, posts and firewood) of species were determined principally through semistructured interviews with 20 rural householders in each of four communities in Honduras and four in Oaxaca. Tree and shrub diversity inventories were carried out in a total of 227 forest patches and parcels of farmland in those eight communities. Species’ conservation priorities were determined using the star system of Hawthorne (1996) and IUCN listings.Results Despite a large number of useful species, remarkably few were also conservation priorities. Useful species were found to be substitutable as is illustrated by Bombacopsis quinata, Cordia alliodora, Guaiacum sanctum and G. coulteri.Conclusions In these areas, circa situm conservation is inhibited by the lack of species that are both rare and useful. Usefulness must be interpreted as a function of substitutability. Natural regeneration provides an abundance of diversity, farmers are unlikely to invest in the management of a species when suitable substitutes are freely available. The key to conserving rare species may be in maintaining or enhancing the value of the landscape elements in which they are found