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1.
Hitoshi Miyasaka Motomi Genkai-Kato Yo Miyake Daisuke Kishi Izumi Katano Hideyuki Doi Shin-ya Ohba Naotoshi Kuhara 《Limnology》2008,9(1):75-80
Relationships between weight (W; dry weight) and length (L; head capsule width, total body length or head carapace length) were examined in 31 Japanese freshwater macroinvertebrate
taxa, using the form W = aL
b
. The relationships were expressed as data of the lowest taxonomic level and data of higher taxonomic levels. The length–weight
relationships obtained in this study were similar to those obtained in North America and Europe at the lowest taxonomic level,
whereas they could be different from those obtained in North America and Europe at the higher taxonomic levels. We suggest
that researchers should make their own regressions for a target taxon or use the regression for the same taxon as possible
lower taxonomic level in the local area. 相似文献
2.
T. Tyler 《Plant Systematics and Evolution》2005,250(3-4):133-145
Patterns of allozyme variation have been investigated in 101 clones representing most of the morphological variation (and taxa) found in the amphi-apomictic genus Pilosella Hill. in the Nordic countries. Levels of variation were very high, both within narrowly defined taxa and within the whole data-set, but the correlation between a morphology-based taxonomy and patterns of allozyme variation was very weak. Almost all enzyme bands were found in more than one taxon and the differences between broadly defined species in terms of the frequency of bands were generally small. Cluster analyses did not perfectly recover any taxon but there were some tendencies for samples of some broadly defined taxa (e.g. P. officinarum s. l., and P. cymosa ssp. cymosa) to cluster together. It is concluded that there is considerable gene-flow among virtually all Nordic morpho-types of Pilosella and this is considered an argument for applying a very broad species concept in this genus.Financial support for the present study has been recieved from Stiftelsen Harald E. Johanssons minnesfond at the Royal Swedish Academy of Sciences. 相似文献
3.
Daniel E. Terlizzi M. Drew Ferrier Erin A. Armbrester Kara A. Anlauf 《Journal of applied phycology》2002,14(4):275-280
Growth of dinoflagellates representing three orders, the Gymnodiniales,Peridiniales, and the Prorocentrales was examined following treatment withbarley straw extract. Selected dinoflagellate taxa showed growth responsessimilar to those reported for freshwater algae including: inhibition(Gyrodinium galatheanum, Gymnodiniumsanguineum, Heterocapsa triquetra andH. pygmaea); stimulation (Gyrodinium instriatum,Prorocentrum minimum and P. micans); and no effect(Gyrodinium estuariale, G. uncatenum,Ceratium furca, Peridinium sp.).Although barley straw extracts do not appear to have value as a universalmanagement tool for dinoflagellates, they may have potential in management ofspecific taxa and possibly taxonomic groups. 相似文献
4.
Aquatic macroinvertebrates are commonly used biological indicators for assessing the health of freshwater ecosystems. However,
counting all the invertebrates in the large samples that are usually collected for rapid site assessment is time-consuming
and costly. Therefore, sub-sampling is often done with fixed time or fixed count live-sorting in the field or with preserved
material using sample splitters in the laboratory. We investigate the differences between site assessments provided when the
two sub-sampling approaches (Live-sort and Lab-sort) were used in conjunction with predictive bioassessment models. The samples
showed a method bias. The Live-sort sub-samples tended to have more large, conspicuous invertebrates and often fewer small
and, or cryptic animals that were more likely to be found in Lab-sort samples where a microscope was used. The Live-sort method
recovered 4–6 more taxa than Lab-sorting in spring, but not in autumn. The magnitude of the significant differences between
Live-sort and Lab-sort predictive model outputs, observed to expected (O/E) taxa scores, for the same sites ranged from 0.12 to 0.53. These differences in the methods resulted in different assessments
of some sites only and the number of sites that were assessed differently depended on the season, with spring samples showing
most disparity. The samples may differ most in spring because many of the invertebrates are larger at that time (and thus
are more conspicuous targets for live-sorters). The Live-sort data cannot be run through a predictive model created from Lab-sort
data (and vice versa) because of the taxonomic differences in sub-sample composition and the sub-sampling methods must be standardized within
and among studies if biological assessment is to provide valid comparisons of site condition. Assessments that rely on the
Live-sorting method may indicate that sites are ‘less impaired’ in spring compared to autumn because more taxa are retrieved
in spring when they are larger and more visible. Laboratory sub-sampling may return fewer taxa in spring, which may affect
assessments relying on taxonomic richness. 相似文献
5.
6.
Amplified fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) were employed to examine the genetic
relationship between Guizotia taxa, to suggest the taxonomic status of some of these taxa, and to identify their diagnostic markers. Results from AFLPs
and RAPDs share some features in common, both revealing G. scabra ssp. schimperi as the most closely related taxon to G. abyssinica, and indicating that G. arborescens and G. zavattarii are the most divergent taxa. Most of the diagnostic markers revealed in this study were specific to G. arborescens and G. zavattarii. Our analysis suggests that G. scabra ssp. scabra, G. scabra ssp. schimperi, Chelelu and Ketcha are separate species. In this study, AFLP was found to be superior to RAPD in detecting genetic variation,
in internal consistency of the data and in the fitness of its clusters to genetic similarity data. AFLPs revealed genetic
relationship between Guizotia taxa that is more inline with the cytogenetic and hybridization studies than that revealed by RAPDs. 相似文献
7.
Alison R. Sherwood Morgan L. Vis Timothy J. Entwisle Orlando Necchi Jr Gernot G. Presting 《Phycological Research》2008,56(4):269-279
Sixty‐five accessions of the species‐rich freshwater red algal order Batrachospermales were characterized through DNA sequencing of two regions: the mitochondrial cox1 gene (664 bp), which is proposed as the DNA barcode for red algae, and the UPA (universal plastid amplicon) marker (370 bp), which has been recently identified as a universally amplifying region of the plastid genome. upgma phenograms of both markers were consistent in their species‐level relationships, although levels of sequence divergence were very different. Intraspecific variation of morphologically identified accessions for the cox1 gene ranged from 0 to 67 bp (divergences were highest for the two taxa with the greatest number of accessions; Batrachospermum helminthosum and Batrachospermum macrosporum); while in contrast, the more conserved universal plastid amplicon exhibited much lower intraspecific variation (generally 0–3 bp). Comparisons to previously published mitochondrial cox2–3 spacer sequences for B. helminthosum indicated that the cox1 gene and cox2–3 spacer were characterized by similar levels of sequence divergence, and phylogeographic patterns based on these two markers were consistent. The two taxa represented by the largest numbers of specimens (B. helminthosum and B. macrosporum) have cox1 intraspecific divergence values that are substantially higher than previously reported, but no morphological differences can be discerned at this time among the intraspecific groups revealed in the analyses. DNA barcode data, which are based on a short fragment of an organellar genome, need to be interpreted in conjunction with other taxonomic characters, and additional batrachospermalean taxa need to be analyzed in detail to be able to draw generalities regarding intraspecific variation in this order. Nevertheless, these analyses reveal a number of batrachospermalean taxa worthy of more detailed DNA barcode study, and it is predicted that such research will have a substantial effect on the taxonomy of species within the Batrachospermales in the future. 相似文献
8.
9.
Seed protein profiles of 40 cultivated and wild taxa of Chenopodium have been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The relative similarity between various taxa, estimated by Jaccard’s similarity index and clustered in UPGMA dendrogram, is generally in accordance with taxonomic position, crossability relationships and other biochemical characters. Eight accessions of C. quinoa studied are clustered together and show genetic similarity with closely related C. bushianum and C. berlandieri subsp. nuttalliae. The taxa included under C. album complex are clustered in two groups which show that these taxa are a heterogenous assemblage and their taxonomic affinities need a reassessment. Other wild species studied are placed in the dendrogram more or less according to their taxonomic position. 相似文献
10.
11.
G. C. French P. M. Hollingsworth A. J. Silverside R. A. Ennos 《Conservation Genetics》2008,9(6):1547-1562
In Britain the genus Euphrasia comprises ca 20 diploid and tetraploid plant species, including several endemics. However, their conservation is impeded by taxonomic
uncertainty. Analysis of cpDNA and AFLP variation was used to assess their taxonomic status and establish the extent of barriers
to gene exchange among them. Differences in ploidy level constitute a very strong barrier to genetic exchange, although this
is not absolute. The diploid endemics E. vigursii and E. rivularis form morphologically and genetically definable units which show some level of reproductive isolation. Within tetraploid Euphrasia, the species showed varying degrees of distinctness. Analysis of geographically paired samples from two widespread outcrossing
taxa E. arctica and E. nemorosa provides evidence for extensive genetic exchange between them. However AFLP data indicate that this outbreeding species complex
possesses a gene pool distinct from that of the widespread inbreeding tetraploids. The widespread and endemic inbreeding tetraploids
contain examples of morphologically and genetically definable taxa, but also species whose distinctness is more equivocal.
The conservation implications of this study are that species-based action plans are potentially suitable for conservation
of the diploid endemics E. vigursii and E. rivularis. In contrast we contend that a species-based conservation framework, developed with reproductively isolated and genetically
distinct groups in mind, requires modification for conservation of the complex and dynamic diversity found within the tetraploids.
The adoption of ‘taxonomic’ action plans, designed to protect the evolutionary processes generating Euphrasia diversity, may provide a supplementary solution for conserving this type of variation. 相似文献
12.
Beyond Masses and Blooms: The Indicative Value of Oligochaetes 总被引:2,自引:2,他引:0
Piet F. M. Verdonschot 《Hydrobiologia》2006,564(1):127-142
The European Water Framework Directive (WFD) defines a framework for assessing water bodies in Europe in the future. The conditions
in the Directive impose a strong demand for “new” assessment systems. The AQEM project developed an assessment system for
European streams using macroinvertebrates. Almost 900 samples were taken in about 400 streams covering 29 stream types distributed
over eight countries. The role of the Oligochaeta within this European database was analysed. Almost half a million specimens
of oligochaetes were collected in 772 samples. Eight families, 41 genera and 69 species were recorded, although identification
emphasised the families Tubificidae and Naididae. Three countries identified oligochaetes to species level, most others restricted
their identifications to easy identifiable taxa. Numbers of specimens, species, genera and families differed strongly between
the countries due to method, although standardised, and taxonomic knowledge. About 50% of all collected oligochaete taxa had
assigned biological and ecological indicator values for metric calculation in the AQEM assessment system. A further refinement
of this indication list as well as increased coverage of oligochaete taxa was advised. Weighted averaging was used to evaluate
the relation between oligochaete distribution and ecological quality class. It was concluded that when higher taxonomic levels
are used in assessment, the quality evaluation results become biased. Furthermore, oligochaetes can tell us much more about
the ecological status of streams than is commonly assumed. Differences in ecological optima among Limnodrilus udekemianus, Ilyodrilus templetoni, Aulodrilus pluriseta, Nais communis, and Spirosperma ferox are shown. 相似文献
13.
Aqueous calcium (Ca) concentrations are declining in softwater lakes of the Canadian Shield largely because of decades of
acid deposition and afforestation following timber harvesting. Populations of pelagic cladoceran taxa with high Ca requirements,
especially Daphnia spp., are declining in response to reduced aqueous Ca availability. However, the Ca content, and thus the requirements of
littoral cladoceran taxa are unknown; therefore, the potential vulnerability of this major component of lake ecosystems to
ongoing regional Ca decline remains uncertain. Here, we identify the body Ca concentration of nine littoral cladoceran taxa
collected from three lakes in the Muskoka-Haliburton region of Ontario, Canada. Ca content differed among taxonomic groups,
ranging from 3.6 mg g−1 for Acroperus harpae to 23.2 mg g−1 for Disparalona spp. Perhaps surprisingly, some littoral microcrustacean taxa have Ca burdens comparable to the Ca-rich daphniids. Therefore,
there may be differential responses to ongoing lake water Ca declines among taxa within littoral communities as has been observed
among open-water taxa, with potential ecological repercussions for near-shore food webs. 相似文献
14.
15.
Teucrium montanum L. and T. polium L. are the two closest Teucrium L. species from sect. Polium (Mill.) Schreb in Turkey. In addition, they are sympatric for some part of their range in Turkey. In this study, comparative
anatomical and micromorphological studies of the two species are carried out. They have been investigated by their leaf and
stem anatomical features, as well as nutlet micromorphological characteristics. The results of anatomical studies show that
the anatomical characters of both taxa are observed to be similar to the general features of the family Lamiaceae anatomy,
except for lacking rich collenchyma at the corners. Both taxa are similar in stem anatomy and their leaves exhibit xeromorphy.
However, trichome morphology on the stems and the leaves appear to have a taxonomic value in segregation of the two taxa.
Light and scanning electron microscope studies on the nutlets also show that nutlet shapes, measures and surface micromorphologies
are different in the two species. Whereas nutlet surfaces are bireticulate in both species, the nutlets are larger and primary
sculpturing is more distinct in T. polium than in T. montanum. Moreover, the nutlets are oblong to oblong-ovoid and larger in T. polium, but ovoid and smaller in T. montanum. 相似文献
16.
Fifteen cranial measurements were taken from wild caught specimens ofAlouatta seniculus seniculus, A. s. stramineus andA. s. macconnelli. A morphological analysis showed sex dimorphism in these three groups. A multivariate analysis discriminated among these
taxa; males being more clearly discriminated than females. Our data showed that these taxa can be separated on the basis of
quantitative cranial traits, biogeographic distribution, karyological differences, and biochemical characters. We therefore
propose a new taxonomic arrangement, changing their taxonomic status to the species level (Alouatta seniculus, A. macconnelli, andA. stramineus). 相似文献
17.
The Beothukis/Culmofrons problem and its bearing on Ediacaran macrofossil taxonomy: evidence from an exceptional new fossil locality
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The late Ediacaran siliciclastic successions of eastern Newfoundland, Canada, are renowned for their fossils of soft‐bodied macro‐organisms, which may include some of the earliest animals. Despite the potential importance of such fossils for evolutionary understanding, the taxonomic framework within which Ediacaran macrofossils are described is not clearly defined. Rangeomorphs from a newly discovered fossil surface on the Bonavista Peninsula, Newfoundland, require us to reconsider contemporary use of morphological characters to distinguish between genera and species within Ediacaran taxa. The new surface exhibits remarkable preservational fidelity, resolving features smaller than 0.1 mm in dimension in both frondose and non‐frondose taxa. Such preservation permits the recognition of rarely observed fourth‐ and fifth‐order rangeomorph branching, offering unparalleled opportunities to investigate the fine‐scale construction of rangeomorph taxa including Culmofrons plumosa Laflamme et al., 2012. Our observations enable resolution of taxonomic issues relating to rangeomorphs, specifically overlap between the diagnoses of the frondose genera Beothukis Brasier and Antcliffe, 2009 and Culmofrons. We propose a taxonomic framework for all Ediacaran macrofossils whereby gross architecture, the presence/absence of discrete morphological characters and consideration of growth programme are used to distinguish genera, whereas morphometric or continuous characters define taxa at the species level. On the basis of its morphological characters, Culmofrons plumosa is herein synonymized to a species (Beothukis plumosa comb. nov.) within the genus Beothukis. This discussion emphasizes the need to standardize the taxonomic approach used to describe Ediacaran macrofossil taxa at both the genus and species levels, and raises important considerations for future formulation of higher‐level taxonomic groups. 相似文献
18.
Diverse metatherian and eutherian tarsal remains from the Late Cretaceous (middle-late Turonian) Bissekty Formation, Kyzylkum
Desert, Uzbekistan (ca 90 MYA) are described. Their functional and taxonomic properties, along with those of other tarsal
evidence, led to a reassessment of polarity hypotheses of therian, metatherian, and eutherian cruropedal attributes, and the
consequences of this for phylogeny of taxa. There are calcaneal remains of several types of marsupials, and a single astragalus
that probably belongs to one of these. This represents greater taxonomic diversity than the dental record suggests. Exceptionally
large and distally extending peroneal processes, and small and steeply angled calcaneocuboid articulations facing mediodistally,
as seen in the Early Cretaceous Sinodelphys and other Cretaceous and Paleogene taxa, attest not only to the metatherian status of these specimens, but also to the retention
of many ancestral therian features, even more so than in both the Tiupampa and Itaboraí marsupials of the South American Paleocene
(both the calcanea and the astragalus suggest therian traits that are decidedly unlike those of symmetrodonts). Calcanea allocated
to the deltatherioid species at Bissekty testify unequivocally to their metatherian affinity. The morphology of the best represented
sample of eutherian calcanea from Bissekty, presumably of a number of zhelestid species, appears to be more derived than that
of the Late Cretaceous/Paleocene Protungulatum in having a much more reduced peroneal process and a calcaneocuboid articulation that faces distally, oriented nearly at
a 90° angle to the long axis of the calcaneus. In fact, this distally facing facet, common in later eutherians (except for
lineages in the Paleogene record, and various Carnivora), may not be diagnostic of either the protoeutherian, or even of the
protoplacentalian, in spite of its presence in Eomaia. Many putatively “basal” lineages have derived characters, hence such outgroups should not be considered the unequivocal
repositories of only ancestral character states. 相似文献
19.
Abstract: The two odontocete taxa Squalodon grateloupii and Patriocetus ehrlichii, both the type species of their respective genera, have been at the centre of a great deal of taxonomic confusion. Originally regarded to be conspecific, these two taxa have been the subject of a bewildering taxonomic debate lasting for more than a century, which recently led to the suggestion to abandon these widely used names and replace S. grateloupii with the similar, yet independently and later proposed name S. gratelupi as the type species of Squalodon. Here, we attempt to summarise the events leading to the current confused situation in the hope of resolving this issue once and for all and argue that the name Squalodon grateloupii, as originally proposed, should be reinstated. 相似文献
20.
Julia P. G. Jones Jeanne R. Rasamy Andrew Harvey Alicia Toon Birgit Oidtmann Michele H. Randrianarison Noromalala Raminosoa Olga R. Ravoahangimalala 《Biological invasions》2009,11(6):1475-1482
In 2007 an unusual crayfish found in food markets in the capital of Madagascar was preliminarily identified as Procambarus ‘Marmorkrebs’: a new world taxa and the only decapod known to reproduce by parthenogenesis. We present information on the
identity, distribution and ecology of this recent invader and attempt to evaluate the threat it poses to Madagascar’s biodiversity
and to livelihoods. The species appears to be currently limited to the area close to Antananarivo, but is being sold alive
on major transport routes. We present molecular evidence of its taxonomic relationships and confirm that the Procambarus present in Madagascar is indeed the parthenogenic taxa. We investigate its reproductive ecology and find Procambarus ‘Marmorkrebs’ to have an extremely high fecundity; more than six times that of the native crayfish Astacoides. The limited evidence we have suggests that this species poses a serious threat to freshwater biodiversity and that it is
likely to damage human livelihoods (through its impact on fishing and possibly rice agriculture). More research is urgently
needed but in the meantime action is needed to reduce the rate of spread before it is too late. 相似文献