Increased sea ice cover disrupts food web structure in coastal Antarctica

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Sea ice is a major environmental driver in Antarctica, and changes in sea ice cover are likely to influence benthic food web structure through several processes (modifications of benthic-pelagic coupling, disruption of benthic production and/or modifications of benthic community structure and therefore resource availability for benthic consumers). To date, regions where sea ice cover is decreasing have received more attention than regions where it is increasing. Here, on the other hand, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using time-tested integrative trophic markers (stable isotope ratios of carbon, nitrogen and sulfur) and state-of-the-art data analysis tools (bayesian ecological models), we studied the structure of the food web associated to benthic macroinvertebrates communities. In total, 28 macroinvertebrate taxa spanning most present animal groups (sponges, sea anemones, nemerteans, nematods, sipunculids, sessile and mobile polychaetes, gastropods, bivalves, pycnogonids, crustaceans, sea stars, sea urchins, brittle stars and sea cucumbers) and functional guilds (grazers, deposit feeders, filter feeders, predators, scavengers) were investigated. Our results indicate that the absence of seasonal sea ice breakup deeply influences coastal benthic food webs in Antarctica. We recorded marked differences from literature data, both in terms of horizontal (i.e. primary producers and resources supporting animal populations) and vertical (i.e. trophic level of the studied consumers) structure of the food web. Overall, sympagic (sea-ice associated) algae dominated the diet of many important consumers, and the trophic levels of invertebrates were low, suggesting omnivore consumers relied less on predation and/or scavenging than in normal environmental conditions. Surprisingly, few animals seemed to feed on the extremely abundant benthic biofilm, whose exceptional development was also presumably linked with the peculiar sea ice conditions. Interpretation of data was complicated by the peculiar ecophysiological features of Antarctic invertebrates, whose very low metabolic rates could be associated to low tissue turnover. However, comparison of data obtained in the austral summers of 2013-2014 (first year without seasonal breakup) and 2014-2015 (second year without seasonal breakup) clearly showed that the observed trends were linked with actual temporal changes in invertebrate feeding habits rather than with other potential ecological drivers. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden man-driven changes in environmental conditions and trophic resource availability. They also show that local and/or global trends of sea ice increase in Antarctica could cause strong changes in food web structure and therefore impact zoobenthic communities. This reinforces the view that, no matter their overall direction (i.e. increase or decrease), fluctuations in sea ice cover are likely to influence Antarctic benthic ecosystems' structure and functioning.vERSO (Ecosystem Resilience in the Southern Ocean, BR/132/A1/vERSO

Early fossils illuminate character evolution and interrelationships of Lampridiformes (Teleostei, Acanthomorpha)

Lampridiformes is a peculiar clade of pelagic marine acanthomorph (spiny-rayed) teleosts. Its phylogenetic position remains ambiguous, and varies depending on the type of data (morphological or molecular) used to infer interrelationships. Because the extreme morphological specializations of lampridiforms may have overwritten the ancestral features of the group with a bearing on its relationships, the inclusion of fossils that exhibit primitive character state combinations for the group as a whole is vital in establishing its phylogenetic position. Therefore, we present an osteological data set of extant (ten taxa) and fossil (14 taxa) acanthomorphs, including early Late Cretaceous taxa for which a close relationship with extant Lampridiformes has been suggested: †Aipichthyoidea, †Pharmacichthyidae, and †Pycnosteroididae. We find that all three taxa plus Lampridiformes form a clade that we call Lampridomorpha. Under this hypothesis, †Aipichthyoidea is paraphyletic. The inclusion of fossils in the analysis changes the topology, highlighting their critical importance in phylogenetic studies of morphological characters. When fossils are included, Lampridomorpha is sister to Euacanthomorpha (all other extant acanthomorphs), concurring with most previous anatomical studies, but conflicting with most molecular results. Lampridomorpha as a whole was a major component of the earliest acanthomorph faunas, notably in the Cenomanian

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

New nuclear markers and exploration of the relationships among Serraniformes (Acanthomorpha, Teleostei): The importance of working at multiple scales

International audienceWe explore the relationships within Serraniformes (Li et al., 2009) using a dense taxon sampling and seven nuclear markers. Six had already used been for teleost phylogeny (IRBP, MC1R, MLL4, Pkd1, Rhodopsin, and RNF213) at other scales, and one (MLL2) is new. The results corroborate the composition of Serraniformes described in previous publications (some Gasterosteiformes, Perciformes and Scorpaeniformes). Within the clade, Notothenioidei and Zoarcoidei are each monophyletic. Cottoidei was not monophyletic due to placement of the genus Ebinania (Psychrolutidae). Our independent data confirm the sister-group relationship of Percophidae and Notothenioidei as well as the division of Platycephaloidei in four different groups (Bembridae, Platycephalidae, Hoplichthyidae and Peristediidae with Triglidae). Within Cottoidei, Liparidae and Cyclopteridae formed a clade associated with Cottidae, the genus Cottunculus (Psychrolutidae), and Agonidae. Serranidae and Scorpaenidae are not monophyletic, with the Serranidae divided in two clades (Serraninae and Epinephelinae/Anthiinae) and Scorpaenidae including Caracanthidae and the genus Ebinania (Psychrolutidae). We discuss some morphological characters supporting clades within the Scorpaenidae

The phylogenetic intrarelationships of spiny-rayed fishes (Acanthomorpha, Teleostei, Actinopterygii): fossil taxa increase the congruence of morphology with molecular data

Acanthomorpha (spiny-rayed fishes) is a clade of teleosts that includes more than 15 000 extant species. Their deep phylogenetic intrarelationships, first reconstructed using morphological characters, have been extensively revised with molecular data. Moreover, the deep branches of the acanthomorph tree are still largely unresolved, with strong disagreement between studies. Here, we review the historical propositions for acanthomorph deep intrarelationships and attempt to resolve their earliest branching patterns using a new morphological data matrix compiling and revising characters from previous studies. The taxon sampling we use constitutes a first attempt to test all previous hypotheses (molecular and morphological alike) with morphological data only. Our sampling also includes Late Cretaceous fossil taxa, which yield new character state combinations that are absent in extant taxa. Analysis of the complete morphological data matrix yields a new topology that shows remarkable congruence with the well-supported molecular results. Lampridiformes (oarfishes and allies) are the sister to all other acanthomorphs. Gadiformes (cods and allies) and Zeiformes (dories) form a clade with Percopsiformes (trout-perches) and the enigmatic Polymixia (beardfish) and Stylephorus (tube-eye). Ophidiiformes (cusk-eels and allies) and Batrachoidiformes (toadfishes) are nested within Percomorpha, the clade that includes most of modern acanthomorph diversity. These results provide morphological synapomorphies and independent corroboration of clades previously only recovered from molecular data, thereby suggesting the emergence of a congruent picture of acanthomorph deep intrarelationships. Fossil taxa play a critical role in achieving this congruence, since a very different topology is found when they are excluded from the analysis

The complete nucleotide sequence of the mitochondrial DNA of the dogfish, Scyliorhinus canicula.

We have determined the complete nucleotide sequence of the mitochondrial DNA (mtDNA) of the dogfish, Scyliorhinus canicula. The 16,697-bp-long mtDNA possesses a gene organization identical to that of the Osteichthyes, but different from that of the sea lamprey Petromyzon marinus. The main features of the mtDNA of osteichthyans were thus established in the common ancestor to chondrichthyans and osteichthyans. The phylogenetic analysis confirms that the Chondrichthyes are the sister group of the Osteichthyes

Tracking the elusive monophyly of nototheniid fishes (Teleostei) with multiple mitochondrial and nuclear markers

International audienceSince the first molecular study of the suborder Notothenioidei in 1994, many phylogenetic studies have been published. Among these, those with a sufficient number of taxa have all suggested that the Nototheniidae, as currently defined, is monophyletic only with the inclusion of the Channichthyidae, Artedidraconidae, Bathydraconidae and Harpagiferidae. This is corroborated by more recent studies including more taxa, but in these studies either the number of nuclear markers or the number of taxa included remained low. We obtained sequences for a large sampling covering most nototheniid genera for five markers described previously for other samplings (COI, Rhodopsin retrogene, Pkd1, HECW2, and SSRP1) and one nuclear marker never used before in phylogenetic inference (PPM1d). The topology for the combined analysis of the nuclear coding genes, as well as the topology for SSRP1 (non-coding) and the combined analysis for all markers all support the paraphyly of Nototheniidae, the genus Notothenia (including Paranotothenia) is the sister group of the clade Channichthyidae, Artedidraconidae, Bathydraconidae and Harpagiferidae, and genus Gobionotothen is a sister group to both. As in previous studies, Trematomus, Lepidonotothen and Patagonotothen form a clade that also includes Indonotothenia cyanobrancha. The position of Pleuragramma antarctica, Dissostichus species and Aethotaxis mitopteryx remains unstable and dependant on markers and analyses. We therefore propose the inclusion of the four families of the High Antarctic clade in the Nototheniidae, and their transformation into subfamilies. We transfer Paranotothenia magellanica to the genus Notothenia, as Notothenia magellanica