Use of cyclopoid copepods for mosquito control

The New Orleans Mosquito Control Board mass produces Mesocyclops longisetus and Macrocyclops albidus for introduction to mosquito breeding sites as a routine part of control operations. Mesocyclops longisetus is used in tires that collect rainwater; M. albidus is used in temporary pools. Field trials in a Spartina marsh, rice fields, and residential roadside ditches in Louisiana suggest that M. longisetus and M. albidus could be of use to control larvae of Anopheles spp. and Culex quinquefasciatus. Mesocyclops longisetus has proved to be effective for Aedes aegypti control in cisterns, 55-gallon drums, and other domestic containers in Honduras.     

The cyclopoid copepods of a wet campo marsh in central Brazil

Eight species of cyclopoid copepods were recorded from 1979–1983 in the complex microhabitats of a wet campo (campo úmido) marsh in central Brazil. Ectocyclops herbsti and Paracyclops fimbriatus occurred most often in areas with water covering the soil; Muscocyclops therasiae n. sp. occurred mainly in soils with no surface water; while Metacyclops campestris n. sp. showed no distinct microhabitat preference. Occurrence of the remaining four species was too sporadic to determine microhabitat preference. Paracyclops carectum n. sp., Metacyclops campestris n. sp., Muscocyclops therasiae n. sp., Muscocyclops bidentatus n. sp. and Ponticyclops boscoi n. g. n. sp. are described. A key to the New World species of Metacyclops s. str. is provided.     

Giselinidae fam. nov., a new monophyletic group of cyclopoid copepods (Copepoda, Crustacea) from the Atlantic deep sea

Four new species of Cyclopoida from deep-sea waters are described and placed in two new genera: Giselina gen. n. and Sensogiselina gen. n. The new genera and species belong to a new monophyletic group within the cyclopinid cyclopoids. A new name, Giselinidae, is proposed for this monophylum. The new family is characterised by the combination of the following characters: (1) tergite of leg 1 fused to cephalosome dorsally, but incompletely fused laterally, (2) absence of aesthetascs on ancestral antennulary segments XVI, XXI and XXV, (3) absence of antennary exopodal setae, (4) presence of only three spines on distal exopodal segment of leg 1, (5) absence of inner setae on first endopodal segments of legs 1–4, (6) outer terminal and distal inner elements of distal endopodal segment of leg 4 transformed into spines, (7) distal outer element of leg 5 exopod transformed into a spine, (8) leg 6 with only one seta, and (9) furcal setae I and III located on dorsal margin. Received in revised form: 16 June 2000 Electronic Publication     

Some evolutionary trends in caligid copepods

The genera Caligus and Lepeophtheirus can be used to illustrate some evolutionary trends. The most striking example of these trends is a gradual reduction of the fourth thoracopod, now largely functionless. All stages of this reduction can be found in Caligidae. Other, apparently correlated, changes are also present. For example, reduction in the armature of the first thoracopod occurs mainly among species in which the fourth exopod has become two-segmented, though still retaining the seta associated with the original three-segmented structure.     

Colonization of the pelagic realm by calanoid copepods

The evolution of calanoid copepods probably extends back into the mid-Paleozoic. Environmental change from the Paleozoic through to the Tertiary is reviewed. Turbidity, water clarity, oxygen, pelagic primary production, and tectonically induced changes in the morphology of the oceans are probably all important drivers of calanoid evolution and their invasion of the pelagic realm. Current views of the phylogeny of the Calanoida are presented as well as a review of some recent work on metabolic potential, female genital system, and nervous system. It is hypothesized that ancestors of the Arietelloidea and Diaptomoidea invaded the water column in the Devonian at a similar time to the Ostracoda and that the ancestors of the Calanoidea–Clausocalanoidea, with their myelinated axons, arose in the Permian during the major deep ventilation of the ocean. Present day distributions of some Diaptomidae, Centropagidae, and Calanidae suggest that these families successfully came through the Jurassic/Cretaceous expansion of the oxygen minimum zone and the K-T boundary event. Some Arietelloidea and Clausocalanoidea became secondarily benthic and may have survived the K-T boundary event in this environment. It is postulated that some Clausocalanoidea reinvaded the water column (e.g. Clausocalanidae, Aetideidae, Phaennidae, Scolecitrichidae) in the Tertiary after finding refuge in deep, low oxygen water away from the sea surface. It is possible that these hypotheses may be testable using genetic information in the near future.     

天南星属的系统发育分析

运用分支分类学方法对天南星属进行了系统发育分析,以天南星属13个组为13个分支分类单位,选择菖蒲属作为外类群,从天南星属植物特征中选取13个性状作为建立数据矩阵的基本资料,并以外类群比较和通行的形态演化规律为依据这些性状进行极化,采用改进后的最大同步法和最小平行进化法进行分类运算,按照最简约的原则,选出演化长度较短的最大同步法谱分支图,作为本文讨论的基础,并在此基础上,探讨了天南星属各组的系统关系。     

Evolutionary implications of swimming behaviour in meiobenthic copepods

Body morphology is said to be the all important factor in determining swimming prowess in copepods. Fusion and differentiation of the body (tagmosis) is coupled with advance into the pelagic realm of the Gymnoplea and is thought, by the provision of a rigid thoracic tagma, to promote swimming efficiency. Thus pelagic copepods are believed to be secondarily derived from bottom dwelling predecessors. Experimental evidence is presented to show that the majority of bottom dwelling harpacticoid families, including the most primitive and the most advanced, have representatives that undergo active sustained swimming movements. Such a widespread occurrence is indicative of a conservative evolutionary trait. This primitive behaviour is linked to precopulatory association which takes place necessarily in the water column; it is a feature retained by representatives of all copepod orders. The implication of cephalic appendage vibration (feeding currents) is the essential feature in the swimming success of the Gymnoplea; planktonic efficiency in these is suggested to have evolved coincident with, rather than because of increased tagmosis.     

CONVERGENT EVOLUTION IN INVERTEBRATES

Resemblance between animal taxa may be due to convergence rather than to recent common ancestry. Constraints on biological materials and adaptation to particular habits or habitats will produce widespread convergence. How may we distinguish the two causes of resemblance? The relationship between convergence and taxonomy is discussed, demonstrating that the choice of taxonomic method will itself determine the extent to which convergence is perceived. In particular, cladistic analysis based on parsimony will tend to minimise and thus conceal convergence: neither the resulting cladogram nor a consistency index derived from it can be used to assess the prevalence of convergence. With any taxonomic system, there can be no substitute for evaluation of the morphological characters used. Complementary use of molecular characters shows promise: we wait further understanding of constraints in genetic evolution and of the possibilities of convergence at this level also. These general principles are illustrated with a range of examples from within and between invertebrate phyla: the phylogeny of Cnidaria and Platyhelminthes cannot be traced with certainty, but where the fossil record allows clear rooting, as for the echinoderms and in particular the echinoids, combination of morphological and molecular methods has made much progress. Sub-groups within a phylum, for example opisthobranch molluscs and the dipteran Phoridae, may show an uncontested phylogeny, and here studies have precisely identified convergence and shown that it may be the commoner cause of resemblance. Adaptation to exacting environments shown by terrestial and freshwater nemertines may also result in a predominance of convergent resemblance. Traditional grouping of phyla breaks down on re-examination of supposedly key characters, such as segmentation, body cavities, germ layers and symmetry, each of which must have had multiple origins: nor are developmental stages (especially not larvae) a reliable guide to relationships. Demarcation of phyla may be difficult, as with arthropods, and location of phyla is even more difficult, due to their early and rapid radiation. Over-simplified definition of characters has bedevilled invertebrate classification and the use of molecular data has not yet resolved the major controversies. The question ‘How common is convergence?’ remains unanswered and may be unanswerable. Our examples indicate that even the minimum detectable levels of convergence are often high, and we conclude that at all levels convergence has been greatly underestimated.     

Origin and evolution of the mitochondrial aminoacyl-tRNA synthetases

Many theories favor a fusion of 2 prokaryotic genomes for the origin of the Eukaryotes, but there are disagreements on the origin, timing, and cellular structures of the cells involved. Equally controversial is the source of the nuclear genes for mitochondrial proteins, although the alpha-proteobacterial contribution to the mitochondrial genome is well established. Phylogenetic inferences show that the nuclearly encoded mitochondrial aminoacyl-tRNA synthetases (aaRSs) occupy a position in the tree that is not close to any of the currently sequenced alpha-proteobacterial genomes, despite cohesive and remarkably well-resolved alpha-proteobacterial clades in 12 of the 20 trees. Two or more alpha-proteobacterial clusters were observed in 8 cases, indicative of differential loss of paralogous genes or horizontal gene transfer. Replacement and retargeting events within the nuclear genomes of the Eukaryotes was indicated in 10 trees, 4 of which also show split alpha-proteobacterial groups. A majority of the mitochondrial aaRSs originate from within the bacterial domain, but none specifically from the alpha-Proteobacteria. For some aaRS, the endosymbiotic origin may have been erased by ongoing gene replacements on the bacterial as well as the eukaryotic side. For others that accurately resolve the alpha-proteobacterial divergence patterns, the lack of affiliation with mitochondria is more surprising. We hypothesize that the ancestral eukaryotic gene pool hosted primordial "bacterial-like" genes, to which a limited set of alpha-proteobacterial genes, mostly coding for components of the respiratory chain complexes, were added and selectively maintained.     

瘿绵蚜科系统发育研究（同翅目：蚜总科）

采用支序分析的方法对瘿绵蚜科的系统发育进行了探讨。研究结果表明,传统的倍蚜族Schlechtendalini、五节根蚜族Fordini和瘿绵蚜族Pemphigini 是单系群,传统的 卷叶绵蚜族Prociphilini 和四脉绵蚜族Tetraneurini是并系群。在瘿绵蚜科的三个亚科中,瘿绵蚜亚科与五节根蚜亚科亲缘关系比与绵蚜亚科更近。另外,根据支序分析结果,建议将丽绵蚜属Formosaphis从瘿绵蚜亚科移入五节根蚜亚科中。     

Biogeographic patterns and the evolution of eureptantic nemerteans

The origin and evolution of the eureptantic nemerteans is discussed from a biogeographic point of view. It is most likely that East Indian Ocean was part of the ancestral distribution of the Eureptantia. The area cladogram estimated by Brooks parsimony analysis (BPA) is to a high degree congruent with a vicariance explanation of the evolution of the Eureptantia and suggests an ancestral distribution concordant with the Tethys Sea. A general area cladogram based on a combined BPA analysis of eureptantic nemerteans and acanthuroid fishes is reconstructed and suggested as a hypothesis of the relationships between east Indian Ocean, west Indian Ocean, west Pacific Ocean, east Adantic Ocean, west Atlantic Ocean, and the Mediterranean. This tree is compared with cladograms from the same areas based on other taxa.     

Origin and evolution of animal life cycles

The ‘origin of larvae’ has been widely discussed over the years, almost invariably with the tacit understanding that larvae are secondary specializations of early stages in a holobenthic life cycle. Considerations of the origin and early radiation of the metazoan phyla have led to the conclusion that the ancestral animal (= metazoan) was a holopelagic organism, and that pelago-benthic life cycles evolved when adult stages of holopelagic ancestors became benthic, thereby changing their life style, including their feeding biology. The literature on the larval development and phylogeny of animal phyla is reviewed in an attempt to infer the ancestral life cycles of the major animal groups. The quite detailed understanding of larval evolution in some echinoderms indicates that ciliary filter-feeding was ancestral within the phylum, and that planktotrophy has been lost in many clades. Similarly, recent studies of the developmental biology of ascidians have demonstrated that a larval structure, such as the tail of the tadpole larva, can easily be lost, viz. through a change in only one gene. Conversely, the evolution of complex structures, such as the ciliary bands of trochophore larvae, must involve numerous genes and numerous adaptations. The following steps of early metazoan evolution have been inferred from the review. The holopelagic ancestor, blastaea, probably consisted mainly of choanocytes, which were the feeding organs of the organism. Sponges may have evolved when blastaea-like organisms settled and became reorganized with the choanocytes in collar chambers. The eumetazoan ancestor was probably the gastraea, as suggested previously by Haeckel. It was holopelagic and digestion of captured particles took place in the archenteron. Cnidarians and ctenophores are living representatives of this type of organization. The cnidarians have become pelago-benthic with the addition of a sessile, adult polyp stage; the pelagic gastraea-like planula larva is retained in almost all major groups, but only anthozoans have feeding larvae. Within the Bilateria, two major lines of evolution can be recognized: Protostomia and Deuterostomia. In protostomes, trochophores or similar types are found in most spiralian phyla; trochophore-like ciliary bands are found in some rotifers, whereas all other aschelminths lack ciliated larvae. It seems probable that the trochophore was the larval type of the ancestral, pelago-benthic spiralian and possible that it was ancestral in all protostomes. Most of the non-chordate deuterostome phyla have ciliary filter-feeding larvae of the dipleurula type, and this strongly indicates that the ancestral deuterostome had this type of larva.     

The evolution of the diatoms (Bacillariophyta). I. Origin of the group and assessment of the monophyly of its major divisions

The diatoms are one of the best characterised algal groups. Despite this, little is known of the evolution of the group from the earliest cell to the myriad of taxa known today. Relationships among taxa at the family or generic level have been recognised in some diatoms. However, relationships at higher taxonomic levels are poorly understood and have often been strongly influenced by the first appearances of key taxa in the fossil record. An independent assessment of relationships among the diatoms at these higher taxonomic levels has been made using rRNA sequence data to infer phylogenetic relationships. In this paper we present an analysis of 18S rRNA data from several chosen centric, araphid and raphid pennate taxa. The phylogenetic inferences from these 18S rRNA sequences are supported by evidence from the fossil record and evidence from ontogenetic data. Ribosomal RNA data indicate that both the centric and araphid pennate lineages may not be monophyletic.     

Emergence and dynamics of cyclopoid copepods in an unpredictable environment

SUMMARY. 1. We studied species composition, abundance and population dynamics of cyclopoid copepods emerging from dormancy from the sediments of a temporary pond in South Carolina in 1985, 1988 and 1989. During a drought in 1988–89, the maximum hydroperiod was 19 days; in 1985 and late 1989-early 1990, the hydroperiods were 57 and 118 days. We also report on species present in 1984 and 1987, two years that had longer hydroperiods, and on abundance of cyclopoids in 1984. 2. Within a day after standing water appeared, fourth-instar copepodids of Diacydops haueri and D. crassicaudis brachycercus became active. These two species appeared every time the pond filled in winter, spring, or autumn. Other species, including Acanthocyclops vernalis, were usually not collected until weeks or months after the pond filled. Because the times and durations of fillings were extremely variable, species composition differed among years, with the most species (eleven) appearing in 1984, the year with the longest hydroperiod. 3. The abundances of emerging Diacydops were much lower in 1988 and 1989 (range of means from seven fillings in spring and autumn: 675–7382 animals m^?2) than 1985 (range of means from three fillings in winter: 26,037–107,418 animals m^?2). Low abundances of emerging animals could have been caused by poor survival of dormant animals, poor production during preceding seasons, or incomplete emergence of the dormant populations. 4. Substrate samples from the dry pond were collected in spring, summer, and autumn 1988 and winter 1989 to measure emergence of the cyclopoids in laboratory incubations. Population densities of emerging animals were much lower in 1988 and 1989 (range of means from seven experiments: 0–120 animals m^?2 over the first 3 days) than in similar experiments in 1984 (Taylor & Mahoney, 1990, means from two experiments: 3630 and 6890 animals m^?2). 5. Despite the low abundance of animals emerging from dormancy in late 1989, the cyclopoid populations in 1990 reached similar densities of copepodids (10^4?-10⁵ animals m^?2) to those reached in 1984 and 1985. These results suggest that short generation time and high reproductive capacity permit rapid recovery from population reductions.     

Scale and squamation character polarity and phyletic assessment in the family Cichlidae

Scale and squamation characters have proved to be useful in investigating phyletic relationships in the family Cichlidae. To provide a sound basis for a cladistic analysis the plesiomorphic states have to be determined. This has been done for the family as a whole as well as for some phyletic lineages. Based on those characters the phylogeny within the family has been investigated.