590 Tiere (Zoologie)
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Highlights
• Three ecological groups were identified based on distributional patterns.
• Old assessments were confirmed with the latest occurrence data.
• For each group, we derived different population trends in times of global change.
• Global change elevates importance of vector-borne diseases.
• Our results serve as base for effective Simuliidae monitoring.
Abstract
The black fly genus Simulium includes medically and ecologically important species, characterized by a wide variation of ecological niches largely determining their distributional patterns. In a rapidly changing environment, species-specific niche characteristics determine whether a species benefits or not. With aquatic egg, larval and pupal stages followed by a terrestrial adult phase, their spatial arrangements depend upon the interplay of aquatic conditions and climatic-landscape parameters in the terrestrial realm. The aim of this study was to enhance the understanding of the distributional patterns among Simulium species and their ecological drivers. In an ecological niche modelling approach, we focused on 12 common black fly species with different ecological requirements. Our modelling was based on available distribution data along with five stream variables describing the climatic, land-cover, and topographic conditions of river catchments. The modelled freshwater habitat suitability was spatially interpolated to derive an estimate of the adult black flies' probability of occurrence. Based on similarities in the spatial patterns of modelled habitat suitability we were able to identify three biogeographical groups, which allows us to confirm old assessments with current occurrence data: (A) montane species, (B) broad range species and (C) lowland species. The five veterinary and human medical relevant species Simulium equinum, S. erythrocephalum, S. lineatum, S. ornatum and S. reptans are mainly classified in the lowland species group. In the course of climatic changes, it is expected that biocoenosis will slightly shift towards upstream regions, so that the lowland group will presumably emerge as the winner. This is mainly explained by wider ecological niches, including a higher temperature tolerance and tolerance to various pollutants. In conclusion, these findings have significant implications for human and animal health. As exposure to relevant Simulium species increases, it becomes imperative to remain vigilant, particularly in investigating the potential transmission of pathogens.
Though recent investigations have contributed substantially to our understanding of the Alpine-Dinaric radiation of the genus Zospeum Bourguignat, 1856, its southernmost member, Zospeum troglobalcanicum Absolon, 1916, has remained a taxonomic ghost. The assumed absence of type material, the insufficient original description, and the lack of new samples from its Western Balkan type locality have stymied further clarification. The recent discovery of a single syntype shell housed at the Natural History Museum Vienna now enables the first morphological assessment via 3D X-ray and SEM imaging. Based on this image data, different characters for assessing the southernmost members of the genus are determined and a lectotype is designated. Eleven allied species from 15 Western Balkan populations are described from museum material and recent sampling efforts: Z. amplioscutum Jochum & Ruthensteiner sp. nov., Z. biokovoense Jochum & Ruthensteiner sp. nov., Z. constrictum Jochum & Ruthensteiner sp. nov., Z. dubokidoense Jochum & Ruthensteiner sp. nov., Z. intermedium Jochum & Ruthensteiner sp. nov., Z. kolbae Jochum, Inäbnit, Kneubühler & Ruthensteiner sp. nov., Z. neuberti Jochum & Ruthensteiner sp. nov., Z. njegusiense Jochum & Ruthensteiner sp. nov., Z. njunjicae Jochum, Schilthuizen & Ruthensteiner sp. nov., Z. tortuosum Jochum & Ruthensteiner sp. nov. and Z. tumidum Jochum, Schilthuizen & Ruthensteiner sp. nov. One species, Z. kolbae, is described using DNA sequence data and one species, Z. simplex Inäbnit, Jochum & Neubert, 2021 for which DNA sequence data is already available, is supported by morphological data presented in this study. The DNA sequence dataset (COI, 16S and H3) is included here and implemented in the most recent phylogenetic reconstruction of the genus. A translation of Karel Absolon’s notes from the Balkan scientific expeditions is provided.
In the vast abyssal plains northwest of Iceland, white glass sponges of the genus Caulophacus Schulze, 1886 were inhabited by reddish Bythocaris G.O. Sars, 1870 shrimps and pinkish amphipods. After in situ observations at 3700 m depth, in -1°C waters by a remotely operated vehicle, members of this assemblage were collected and preserved for molecular studies. Based on integrative taxonomic analyses, the amphipods were identified as a new species of the genus Halirages Boeck, 1871 – Halirages spongiae sp. nov. Lörz, Nack & Tandberg –, as described in detail below. Part of our integrative approach was to establish reference DNA barcodes for known species of Halirages. However, our investigation of material of Calliopiidae G.O. Sars, 1895 collected around Iceland and Norway revealed slight morphological discrepancies in all the described species of Halirages. Except for Halirages fulvocinctus (M. Sars, 1858), none of the encountered specimens of Calliopiidae fully matched a current species description. We illuminate the morphological characteristics of nine operational taxonomic units, which also represented clades in COI and 28S. We set the Icelandic samples in the context of Halirages from Canada and Norway. A key to the world species of Halirages is provided.
The genus Plateosaurus is one of the most challenging aspects of early-diverging sauropodomorph taxonomy, with a total of 29 names and a century of revisions. As a result, nomina dubia have been treated as synonyms of Plateosaurus trossingensis, adding to the confusion about the extent of morphological variability. Here, we provide a thorough revision of the taxonomy proposed by von Huene as well as the subsequent taxonomic interpretations of Plateosaurus through a complete inventory of the specimens stored in the Palaeontological Collection of Tübingen. We reassess the status of the specimens in the collection and propose that the sauropodomorph-bearing layers are not necessarily monospecific. Most of the original fieldwork documentation has been lost, but we use the taxonomy established by von Huene as a historical reference point to reconstruct what was known at the time. This revised taxonomy of Plateosaurus narrows the genus to three species: Pl. trossingensis, Pl. longiceps, and Pl. gracilis (as a metataxon), and restricts the genera Gresslyosaurus and Pachysaurus to large and robust individuals, as pragmatic decisions aimed to test their affinities to other Late Triassic sauropodomorphs. Future studies should consider not only morphological variability, but also stratigraphy, palaeogeography, and environmental data when delineating species within and outside the Plateosaurus plexus.
Background: In the speciation continuum, the strength of reproductive isolation varies, and species boundaries are blurred by gene flow. Interbreeding among giraffe (Giraffa spp.) in captivity is known, and anecdotal reports of natural hybrids exist. In Kenya, Nubian (G. camelopardalis camelopardalis), reticulated (G. reticulata), and Masai giraffe sensu stricto (G. tippelskirchi tippelskirchi) are parapatric, and thus, the country might be a melting pot for these taxa. We analyzed 128 genomes of wild giraffe, 113 newly sequenced, representing these three taxa.
Results: We found varying levels of Nubian ancestry in 13 reticulated giraffe sampled across the Laikipia Plateau most likely reflecting historical gene flow between these two lineages. Although comparatively weaker signs of ancestral gene flow and potential mitochondrial introgression from reticulated into Masai giraffe were also detected, estimated admixture levels between these two lineages are minimal. Importantly, contemporary gene flow between East African giraffe lineages was not statistically significant. Effective population sizes have declined since the Late Pleistocene, more severely for Nubian and reticulated giraffe.
Conclusions: Despite historically hybridizing, these three giraffe lineages have maintained their overall genomic integrity suggesting effective reproductive isolation, consistent with the previous classification of giraffe into four species.
Background: In the speciation continuum the strength of reproductive isolation varies, and species boundaries are blurred by gene flow. Interbreeding among giraffe (Giraffa spp.) in captivity is known and anecdotal reports of natural hybrids exist. In Kenya, Nubian (G. camelopardalis camelopardalis), reticulated (G. reticulata), and Masai giraffe sensu stricto (G. tippelskirchi tippelskirchi) are parapatric, and thus the country might be a melting pot for these taxa. We analyzed 128 genomes of wild giraffe, 113 newly sequenced, representing these three taxa.
Results: We found varying levels of Nubian ancestry in 13 reticulated giraffe sampled across the Laikipia Plateau most likely reflecting historical gene flow between these two lineages. Although comparatively weaker signs of ancestral gene flow and potential mitochondrial introgression from reticulated into Masai giraffe were also detected, estimated admixture levels between these two lineages are minimal. Importantly, contemporary gene flow between East African giraffe lineages was not statistically significant. Effective population sizes have declined since the Late Pleistocene, more severely for Nubian and reticulated giraffe.
Conclusions: Despite historically hybridizing, these three giraffe lineages have maintained their overall genomic integrity suggesting effective reproductive isolation, consistent with the previous classification of giraffe into four species.
The snake pipefish, Entelurus aequoreus (Linnaeus, 1758), is a slender, up to 60 cm long, northern Atlantic fish that dwells in open seagrass habitats and has recently expanded its distribution range. The snake pipefish is part of the family Syngnathidae (seahorses and pipefish) that has undergone several characteristic morphological changes, such as loss of pelvic fins and elongated snout. Here, we present a highly contiguous, near chromosome-scale genome of the snake pipefish assembled as part of a university master’s course. The final assembly has a length of 1.6 Gbp in 7,391 scaffolds, a scaffold and contig N50 of 62.3 Mbp and 45.0 Mbp and L50 of 12 and 14, respectively. The largest 28 scaffolds (>21 Mbp) span 89.7% of the assembly length. A BUSCO completeness score of 94.1% and a mapping rate above 98% suggest a high assembly completeness. Repetitive elements cover 74.93% of the genome, one of the highest proportions so far identified in vertebrate genomes. Demographic modeling using the PSMC framework indicates a peak in effective population size (50 – 100 kya) during the last interglacial period and suggests that the species might largely benefit from warmer water conditions, as seen today. Our updated snake pipefish assembly forms an important foundation for further analysis of the morphological and molecular changes unique to the family Syngnathidae.
Highlights
• Genomes for all five Natrix species, two represented by two distinct subspecies each, were sequenced.
• Two genomes were de-novo assembled to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp.
• Evidence for interspecific hybridization, both between allopatric and widely sympatric species.
• Fossil-calibrated molecular clock using genomes indicates that species are ancient several million-year-old lineages.
• Our findings imply that speciation took place despite continued gene flow.
Abstract
Understanding speciation is one of the cornerstones of biological diversity research. Currently, speciation is often understood as a continuous process of divergence that continues until genetic or other incompatibilities minimize or prevent interbreeding. The Palearctic snake genus Natrix is an ideal group to study speciation, as it comprises taxa representing distinct stages of the speciation process, ranging from widely interbreeding parapatric taxa through parapatric species with very limited gene flow in narrow hybrid zones to widely sympatric species. To understand the evolution of reproductive isolation through time, we have sequenced the genomes of all five species within this genus and two additional subspecies. We used both long-read and short-read methods to sequence and de-novo-assemble two high-quality genomes (Natrix h. helvetica, Natrix n. natrix) to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp, respectively, and used these as references to assemble the remaining short-read-based genomes. Our phylogenomic analyses yielded a well-supported dated phylogeny and evidence for a surprisingly complex history of interspecific gene flow, including between widely sympatric species. Furthermore, evidence for gene flow was also found for currently allopatric species pairs. Genetic exchange among these well-defined, distinct, and several million-year-old reptile species emphasizes that speciation and maintenance of species distinctness can occur despite continued genetic exchange.
The finding of Breviconia andrei sp. nov. in the Russian Bering Sea enabled the clear-cut phylogenetic characterization of the former monotypic genus Breviconia Conroy-Dalton & Huys, 2000 as a monophylum. Comparison of the new species with B. australis (George, 1998) and other members of the subfamily Ancorabolinae Sars, 1909 yielded four autapomorphies that unambiguously support the monophyletic state of Breviconia: (1) an elongated and approximately 90°-curved mandibular gnathobase, (2) reduction of the maxillar endopod, (3) maxillar endites carrying 2 instead of 3 setae, and (4) loss of the minute seta on the maxillipedal claw. For B. andrei sp. nov., two autapomorphies could be detected, namely, (1) the development of dorsal tubercles on the P5-bearing body somite and (2) the remarkable elongation of the first endopodal segment of the first swimming leg that is twice as long as the whole exopod. Of particular interest is the presence of a 3-segmented endopod in the third swimming leg of the male of B. andrei sp. nov. It disproves the current assumption that the Ancorabolinae are characterized by (among others) the derived presence of an only 2-segmented endopod in the male’s third swimming leg.
The most basic behavioural states of animals can be described as active or passive. However, while high-resolution observations of activity patterns can provide insights into the ecology of animal species, few methods are able to measure the activity of individuals of small taxa in their natural environment. We present a novel approach in which the automated VHF radio-tracking of small vertebrates fitted with lightweight transmitters (< 0.2 g) is used to distinguish between active and passive behavioural states.
A dataset containing > 3 million VHF signals was used to train and test a random forest model in the assignment of either active or passive behaviour to individuals from two forest-dwelling bat species (Myotis bechsteinii (n = 50) and Nyctalus leisleri (n = 20)). The applicability of the model to other taxonomic groups was demonstrated by recording and classifying the behaviour of a tagged bird and by simulating the effect of different types of vertebrate activity with the help of humans carrying transmitters. The random forest model successfully classified the activity states of bats as well as those of birds and humans, although the latter were not included in model training (F-score 0.96–0.98).
The utility of the model in tackling ecologically relevant questions was demonstrated in a study of the differences in the daily activity patterns of the two bat species. The analysis showed a pronounced bimodal activity distribution of N. leisleri over the course of the night while the night-time activity of M. bechsteinii was relatively constant. These results show that significant differences in the timing of species activity according to ecological preferences or seasonality can be distinguished using our method.
Our approach enables the assignment of VHF signal patterns to fundamental behavioural states with high precision and is applicable to different terrestrial and flying vertebrates. To encourage the broader use of our radio-tracking method, we provide the trained random forest models together with an R-package that includes all necessary data-processing functionalities. In combination with state-of-the-art open-source automated radio-tracking, this toolset can be used by the scientific community to investigate the activity patterns of small vertebrates with high temporal resolution, even in dense vegetation.