Meristics
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BACKGROUND: Species delineation is particularly challenging in taxa with substantial intra-specific variation. In systematic studies of fishes, meristics and linear measurements that describe shape are often used to delineate species. Yet, little is known about the taxonomic value of these two types of morphological characteristics. Here, we used Tropheus (Teleostei, Cichlidae) from the southern subbasin of Lake Tanganyika to test which of these types of characters best matched genetic lineages that could represent species in this group of stenotypic rock-dwelling cichlids. We further investigated intra-population variation in morphology. By linking this to a proxy of a population's age, we could assess the evolutionary stability of different kinds of morphological markers. RESULTS: Morphological data was collected from 570 specimens originating from 86 localities. An AFLP approach revealed the presence of five lineages in the southern subbasin: T. moorii, T. brichardi, T. sp. 'maculatus', T. sp. 'Mpimbwe' and T. sp. 'red', which we consider to represent distinct species. Although both types of morphological data supported this classification, a comparison of PST-values that describe inter-population morphological differentiation, revealed a better correspondence between the taxon delineation based on AFLP data and the patterns revealed by an analysis of meristics than between the AFLP-based taxon delineation and the patterns revealed by an analysis of shape. However, classifying southern populations of Tropheus was inherently difficult as they contained a large amount of clinal variation, both in genetic and in morphological data, and both within and among species. A scenario is put forward to explain the current-day distribution of the species and colour varieties and the observed clinal variation across the subbasin's shoreline. Additionally, we observed that variation in shape was larger in populations from shallow shores whereas populations from steep shores were more variable in meristics. This difference is explained in terms of the different timescales at which small and large scale lake level fluctuations affected populations of littoral cichlids at steep and shallow shores. CONCLUSIONS: Our results showed meristics to be more evolutionary stable, and of higher taxonomic value for species delimitation in Tropheus, than linear measurements that describe shape. These results should be taken into account when interpreting morphological differences between populations of highly stenotypic species, such as littoral cichlids from the Great East African Lakes.
- Klíčová slova
- AFLP, Africa, Body shape, Clinal variation, Evolution, Meristics, Morphology, PST, Population differentiation, Species delimitation,
- Publikační typ
- časopisecké články MeSH
Morphological (meristic and morphometric traits), karyological and molecular (microsatellites, cytochrome b) analyses were performed to characterize a hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus. Meristic and morphometric traits were different between hybrid and both parental species. The number of chromosomes found in hybrid specimen indicated that this individual represents the post-F(1) generation of hybrids and the microsatellite analysis of the hybrid showed the presence of variants typical for R. rutilus and C. nasus.
- MeSH
- chiméra anatomie a histologie klasifikace genetika MeSH
- Cyprinidae anatomie a histologie klasifikace genetika MeSH
- cytochromy b genetika MeSH
- karyotypizace MeSH
- mikrosatelitní repetice MeSH
- mitochondriální DNA genetika MeSH
- řeky MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- cytochromy b MeSH
- mitochondriální DNA MeSH
BACKGROUND: Legless lizards, the slow worms of the genus Anguis, are forming secondary contact zones within their Europe-wide distribution. METHODS: We examined 35 populations of A. fragilis and A. colchica to identify the level of morphological and genetic divergence in Poland. We applied a conventional study approach using metric, meristic, and categorial (coloration) features for a phenotype analysis, and two standard molecular markers, a mitochondrial (NADH-ubiquinone oxidoreductase chain 2; ND2) and a nuclear (V(D)J recombination-activating protein 1; RAG1) one. RESULTS: We found clear differences between A. fragilis and A. colchica in molecular markers and phenotype-in meristic features, e.g., ear opening, number of scales rows around the body, and higher than so far known diversity in ND2 and RAG1 haplotypes. The presence of five hybrids was detected in three populations in the Polish part of the European contact zone. In all hybrids, homozygous alleles of RAG1 were detected, which suggests a back-crossing within the genus. CONCLUSIONS: The ability to produce fertile offspring by A. fragilis x A. colchica hybrids shows inefficient mechanisms of reproductive isolation of the two legless lizards. The hybrids were indistinguishable from parental species in head proportions (principal components and discriminant analyses) but more resembling A. colchica in meristic traits.
- Klíčová slova
- Anguidae, Biogeography, Hybridization, Morphometrics, Speciation, Taxonomy,
- MeSH
- fenotyp MeSH
- genetická variace MeSH
- haplotypy genetika MeSH
- homeodoménové proteiny MeSH
- ještěři * genetika anatomie a histologie MeSH
- reprodukční izolace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Polsko MeSH
- Názvy látek
- homeodoménové proteiny MeSH
- RAG-1 protein MeSH Prohlížeč
The lectotype and paralectotype of Synodontisvictoriae Boulenger, 1906, designated by Poll (1971), were examined. Inconsistencies between data presented for the designated lectotype and the illustrated individual raise the question of whether lectotypification by Poll is valid. This case is not formally regulated by the International Code of Zoological Nomenclature, but based on Article 74.5, the lectotypification for S.victoriae should be considered invalid because it cannot unambiguously indicate a single name-bearing specimen. Thus, we designate a new lectotype for S.victoriae (BMNH 1906.5.30.191, Entebbe, standard length 188.2 mm) out of two syntypes and provide illustrations and new morphometric and meristic data for both specimens.
- Klíčová slova
- Catfish, East Africa, ICZN, freshwater fish, taxonomy,
- Publikační typ
- časopisecké články MeSH
The 'Cichlasoma' facetum group is part of the taxonomically complex group of Neotropical cichlid fishes of the tribe Heroini. Many species groups and unplaced species of heroines are still left without a generic name following the revision of the genus Cichlasoma. We describe here the 'Cichlasoma' facetum group as a new genus, Australoheros, and provide evidence for its monophyly based on phylogenetic analyses of morphological and mtDNA characters. Australoheros is morphologically characterized by the lowest values in meristic characters among heroines and by three apomorphic characters in coloration pattern. In addition to the three described species of Australoheros, our results of species delimitation based on a combination of tree- and character-based approaches identify seven putatively new species of Australoheros. Several coding schemes of morphological characters are used to recover the intrageneric relationships within the genus, resulting in very similar topologies. Discovery of additional species within the genus is expected once material from the whole distribution area is studied.
Die ‘Cichlasoma’ facetum Gruppe ist eine der zahlreichen Artengruppen von Amerikanischen Buntbarschen der taxonomisch komplizierten Gruppe der Heroini. Viele Artengruppen der Heroinen haben keinen stabilen Gattungsnamen nach der Revision der Gattung Cichlasoma. Wir beschreiben diese Artengruppe als neue Gattung, Australoheros, und demonstrieren ihre Monophylie anhand einer phylogenetischen Analyse von morphologischen und mtDNA Merkmalen. Morphologisch ist Australoheros durch die niedrigsten meristischen Werte innerhalb der Heroini sowie durch drei apomorphe Merkmale gekennzeichnet. Die Kombination verschiedener Verfahren der Merkmalsanalyse ermöglicht die Identifikation von sieben weiteren Arten neben den drei bereits beschriebenen dieser Artengruppe. Durch verschiedene Kodierungsschemata der morphologischen Merkmale entwickeln wir eine phylogenetische Hypothese der Verwandtschaftsverhältnisse der Arten innerhalb von Australoheros und zeigen, dass verschiedene Kodierungen zu sehr ähnlichen Topologien führen.
- Klíčová slova
- Australoheros new genus, Cichlidae, South America, phylogeny, species delimitation, ‘Cichlasoma’ facetum group,
- Publikační typ
- časopisecké články MeSH
Parthenogenetic species are usually considered to be short-lived due to the accumulation of adverse mutations, lack of genetic variability, and inability to adapt to changing environment. If so, one may expect that the phenotype of clonal organisms may reflect such genetic and/or environmental stress. To test this hypothesis, we compared the developmental stability of bisexual and parthenogenetic lizards of the genus Darevskia. We assessed asymmetries in three meristic traits: ventral, preanal, and supratemporal scales. Our results suggest that the amount of ventral and preanal asymmetries is significantly higher in clones compared with their maternal, but not paternal, progenitor species. However, it is questionable, whether this is a consequence of clonality, as it may be considered a mild form of outbreeding depression as well. Moreover, most ventral asymmetries were found in the bisexual species Darevskia valentini. We suggest that greater differences in asymmetry levels among bisexuals may be, for instance, a consequence of the population size: the smaller the population, the higher the inbreeding and the developmental instability. On the basis of the traits examined in this study, the parthenogens do not seem to be of significantly poorer quality.
- Klíčová slova
- developmental stability, fluctuating asymmetry, lizards, morphology, parthenogenesis,
- MeSH
- druhová specificita MeSH
- ještěři genetika růst a vývoj MeSH
- partenogeneze MeSH
- pohlavní dimorfismus MeSH
- rozvržení tělního plánu MeSH
- zvířata MeSH
- zvířecí šupiny MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This study describes a case of polytrauma of the axial skeleton accompanied by a spinal anatomical variation of an early medieval old female skeleton (dated to the 8th-9th century AD), with the purpose of clarifying the origin of the condition and to understand its impact on the life quality of the individual. The skeleton was subjected to macroscopic and X-ray examination. An anthropological analysis discovered the skeleton is well preserved, gracile, and with significant traces of physical activity. A detailed survey of the spine revealed there are six cervical, 12 thoracic, and six lumbar vertebrae. The examination of the pathological changes discovered a severe chest polytrauma (a compressive fracture of the 9th thoracic vertebra and multiple rib fractures), associated with pleural rind ossification, severe osteoarthritis, and ankylosis of both intervertebral and costovertebral joints. The irregularity in the number of vertebrae was determined as a double meristic vertebral variation probably caused by a presomitic mesoderm segmentation disorder. The pathological changes examined were assumed to be of traumatic aetiology with a possible osteoporotic background, and were compared with similar changes caused by tuberculosis and ankylosing spondylitis. The woman had to have been suffering from severe back pain, her back was deformed to a dowager's hump, but she managed to survive for many years after the traumatic event.
- Publikační typ
- časopisecké články MeSH
Three species of small-sized rheophilic Barbus fishes are endemic to and widely distributed throughout the mountain regions in the Danube River basin. In Hungary, barbels referred to as B. petenyi occur in streams in the foothills of the Carpathians near the borders with Slovakia, Ukraine and Romania. However, up to now, no genetic investigations were carried out on rheophilic barbels in this region. This study aims to clarify the taxonomic identity and distribution of the rheophilic barbels in the Hungarian plain based on molecular and morphological analyses. Two mitochondrial genes (cytochrome b, ATPase 6/8) and one nuclear gene (beta-actin intron 2) were sequenced and several morphometric and meristic characters were recorded. Phylogenetic and morphological analyses revealed that there are four genetically distinct lineages among the rheophilic barbels in the Carpathian Basin. The results demonstrated that North-Hungarian Barbus populations belong to B. carpathicus and that B. petenyi presumably does not occur in Hungary. As expected, B. balcanicus was only recorded in samples from the Balkans analyzed for reference. A distinct species, new to science, was discovered to be present in Sebes-Körös River (Crişul Repede) in eastern Hungary and western Romania and is formally described here as B. biharicus Antal, László, Kotlík - sp. nov.
- Klíčová slova
- ATPase 6/8, Act-2, Barbus biharicus, Biharian barbel, Cyprinidae, Cyt b,
- MeSH
- buněčné jádro genetika MeSH
- Cyprinidae anatomie a histologie klasifikace genetika MeSH
- druhová specificita MeSH
- fylogeneze * MeSH
- mitochondriální geny genetika MeSH
- řeky * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Balkánský poloostrov MeSH
- Maďarsko MeSH
- Rumunsko MeSH
PREMISE: Apomixis and hybridization are two essential and complementary factors in the evolution of plants, including ferns. Hybridization combines characteristics from different species, while apomixis conserves features within a lineage. When combined, these two processes result in apo-sex hybrids. The conditions leading to the formation of these hybrids are poorly understood in ferns. METHODS: We cultivated spores from 66 fern samples (43 apomicts, 7 apo-sex hybrids, and 16 sexuals), and measured their development in vitro over 16 weeks. We evaluated germination, lateral meristem formation rates, sexual expression, and production of sporophytes and then compared ontogenetic patterns among the three groups. RESULTS: The three examined groups formed antheridia (male gametangia) but differed in overall gametophyte development. Sexual species created archegonia (female, 86% of viable samples), but no sporophytes. Apomicts rarely created nonfunctional archegonia (8%) but usually produced apogamous sporophytes (75%). Surprisingly, apomictic and sexual species showed similar development speed. The sexually reproducing parents of viable studied hybrids formed about twice as many meristic gametophytes as the apomictic parents (39% vs. 20%, respectively). CONCLUSIONS: We present the most thorough comparison of gametangial development of sexual and apomictic ferns, to date. Despite expectations, apomictic reproduction might not lead to earlier sporophyte formation. Apomicts produce functional sperm and thus can contribute this type of gamete to their hybrids. The development patterns found in the parents of hybrids indicate a possible increase of hybridization rates by antheridiogens. The apo-sex hybrids always inherit the apomictic reproductive strategy and are thus capable of self-perpetuation.
- Klíčová slova
- Dryopteris, agamospory, antheridia, apo-sex hybrid, apogamy, archegonia, gametes, hybridization, pteridophytes, wood fern,
- MeSH
- apomixie * genetika MeSH
- kapradiny * genetika MeSH
- lidé MeSH
- otcové MeSH
- rozmnožování MeSH
- zárodečné buňky rostlin MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Host specificity varies among parasite species. Some parasites are strictly host-specific, others show a specificity for congeneric or non-congeneric phylogenetically related host species, whilst some others are non-specific (generalists). Two cyprinids, Cyprinus carpio and Carassius gibelio, plus their respective hybrids were investigated for metazoan parasites. The aim of this study was to analyze whether interspecies hybridization affects host specificity. The different degrees of host specificity within a phylogenetic framework were taken into consideration (i.e. strict specialist, intermediate specialist, and intermediate generalist). METHODS: Fish were collected during harvesting the pond and identified using meristic traits and molecular markers. Metazoan parasite species were collected. Host specificity of parasites was determined using the following classification: strict specialist, intermediate specialist, intermediate generalist and generalist. Parasite species richness was compared between parental species and their hybrids. The effect of host species on abundance of parasites differing in host specificity was tested. RESULTS: Hybrids harbored more different parasite species but their total parasite abundance was lower in comparison with parental species. Interspecies hybridization affected the host specificity of ecto- and endoparasites. Parasite species exhibiting different degrees of host specificity for C. carpio and C. gibelio were also present in hybrids. The abundance of strict specialists of C. carpio was significantly higher in parental species than in hybrids. Intermediate generalists parasitizing C. carpio and C. gibelio as two phylogenetically closely related host species preferentially infected C. gibelio when compared to C. carpio, based on prevalence and maximum intensity of infection. Hybrids were less infected by intermediate generalists when compared to C. gibelio. CONCLUSIONS: This finding does not support strict co-adaptation between host and parasite genotypes resulting in narrow host specificity, and showed that hybrid genotypes are susceptible to parasites exhibiting host specificity. The immune mechanisms specific to parental species might represent potential mechanisms explaining the low abundance of parasites in C. gibelio x C. carpio hybrids.
