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31.
Gengo Tanaka 《Hydrobiologia》2005,538(1-3):231-242
The naupliar eye of podocopid ostracods is a useful character for considering evolution in photic environments. Based on external
morphologies and histological observations, naupliar eyes are here categorized into six types. The fossil record demonstrates
that the major evolutionary changes in podocopid naupliar eyes occured after the Ordovician. Eye types 1 and 2 are not joined
to the carapace by the hypodermal cells, and these two types are found in Palaeozoic ostracods. Eye type 3, 4, 5 and 6 are
extended on eye stalks, tightly joined to the carapace by the hypodermal cells, and use the carapace as the refractive cuticle
lens. Eye type 3 appeared in the Permian, and eye types 4, 5 and 6 appeared in the Early Jurassic. The design of the podocopid
naupliar eye diversified in the Early Jurassic. 相似文献
32.
After more than two centuries of research, more than 65,000 living and fossil ostracod species have been described and studied,
yet much remains to be learned about this ancient, widespread and diverse group of bivalved arthropods. Their higher classification
and phylogeny are subjects of vigorous debate, as is their position in the broader picture of crustacean phylogeny. At the
same time, major advances in our understanding of ostracod lineages and their relationships are resulting from the application
of innovative approaches and techniques. This preface provides a contextual overview of the 15 contributions to this volume,
which resulted from the 14th International Symposium on Ostracoda (ISO2001) held in 2001at Shizuoka, Japan. As such it provides
a cross-section of topics at the forefront of research on the evolution and diversity of Ostracoda, and indicates directions
for future work. 相似文献
33.
Alexander Liebau 《Hydrobiologia》2005,538(1-3):115-137
Focusing on palaeontological data from the literature of the last four decades, a new classification of the Ostracoda is outlined. The superorder Podocopomorpha is accepted as a mantle term for the ‘P-orders’ Palaeocopida, Punciocopida, Platycopida and Podocopida; its counterpart are the Myodocopomorpha (Cypridinida, Halocypridida and ? Leperditicopida). The Podocopida comprise the suborders Bairdiocopina, Cytherocopina, Sigilliocopina, Cypridocopina, Darwinulocopina and Healdiocopina (n.;=Metacopina s.s.). The non-calcifying ostracodomorph arthropods (Archaeocopida and Phosphatocopida) of the Early Palaeozoic, now excluded from the Ostracoda by many authors, are also considered briefly. 相似文献
34.
Carmen Arias 《Geobios》2009,42(1):1
This paper discusses the extinction pattern of the Pliensbachian-Toarcian boundary (PTB) ostracod assemblages at the Almonacid de la Cuba section (Cordillera Ibérica, NE Spain), which has been recently proposed as auxiliary boundary stratotype for the PTB. The ostracod record shows that the main Early Jurassic ostracod extinction event occurred not at the end of the Pliensbachian, but near the top of the Mirabile ammonite Subzone, Tenuicostatum ammonite Zone (Early Toarcian). On the basis of the evaluation of PTB ostracod record, a new causal explanation for the Early Toarcian ostracod turnover is proposed. This paper suggests that a reorganization of surface and deep-water circulations caused by the opening of the Hispanic Corridor could have generated a mild cooling episode, finally affecting the survival of healdioid ostracods. 相似文献
35.
1. Delineation of protected areas for rare subterranean species is a key problem for groundwater biodiversity conservation, because of practical difficulties in implementation. Criteria for site selection are presented that are derived from studies on two remarkable Ostracoda, Dolekiella europaea Gidó, Artheau, Colin, Danielopol & Marmonier (Limnocytheridae) and Vestalenula carveli Artheau (Darwinulidae) discovered in south-western France.
2. Arguments for natural heritage value and protection of subterranean species are proposed and illustrated by using information on these two ostracod species. The proposed criteria are: (i) local and/or regional endemism; (ii) known occurrence of the species at a few localities only; (iii) representativeness for ancient phylogenetic lineages with wider geographical distributions in the past; and (iv) suitability for scientific study because of unique morphological or biological traits.
3. It is also proposed to prioritise the protection of subsurface sites using the following criteria: (i) type locality for newly described species; (ii) presence of other rare stygobiotic taxa; and (iii) high population densities of the primary target species.
4. Development and implementation of protection strategies at local scale are likely to benefit from collaboration between scientists, policy makers and stakeholders. The measures taken should complement existing national and/or international attempts at large-scale protection of groundwater biodiversity. 相似文献
2. Arguments for natural heritage value and protection of subterranean species are proposed and illustrated by using information on these two ostracod species. The proposed criteria are: (i) local and/or regional endemism; (ii) known occurrence of the species at a few localities only; (iii) representativeness for ancient phylogenetic lineages with wider geographical distributions in the past; and (iv) suitability for scientific study because of unique morphological or biological traits.
3. It is also proposed to prioritise the protection of subsurface sites using the following criteria: (i) type locality for newly described species; (ii) presence of other rare stygobiotic taxa; and (iii) high population densities of the primary target species.
4. Development and implementation of protection strategies at local scale are likely to benefit from collaboration between scientists, policy makers and stakeholders. The measures taken should complement existing national and/or international attempts at large-scale protection of groundwater biodiversity. 相似文献
36.
根据对北部湾生态环境综合调查所采集的浮游动物样品,对北部湾秋、冬季浮游介形类组成及群落结构进行了多元分析.结果表明,测区内浮游介形类种类为11种,分属于低盐暖水类群、广温广盐类群和高温高盐类群3个生态类群;海区内的平均丰度较低,其中针刺真浮萤数量最多,为海区的绝对优势种,左右着整个北部湾浮游介形类的数量.聚类分析和MDS分析表明,北部湾浮游介形类为一个结构相对稳定的群落,秋、冬季可看成是一个群落的2个亚群;对各聚类组的丰度与水温、盐度相关分析表明,水温、盐度对浮游介形类群落结构变化所产生的作用较小,但存在一定的规律性;在冬季,底层温盐对群落Ⅱ产生显著影响. 相似文献
37.
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40.
Baltanás Angel Otero Marina Arqueros Laura Rossetti Giampaolo Rossi Valeria 《Hydrobiologia》2000,419(1):65-72
Developmental changes in carapace form (size+shape) during ontogeny have been explored in Eucypris virens (Crustacea, Ostracoda) using elliptic Fourier analysis. Clones from different geographic localities raised under controlled constant conditions (temperature and photoperiod) were used to characterize developmental pathways in the species. A larger data set including field populations and laboratory populations cultured under a range of environmental conditions were used to infer influence of environmental factors on carapace shape changes during ontogeny. Size changes between consecutive juvenile stages support empirical laws describing the doubling of ostracod volume at each moult. Ontogenetic changes point out the remarkable influence of environmental conditions on carapace shape. 相似文献