摘要:

Morphological characteristics of the terrestrial (Acteonemertes, Antiponemertes, Argonemertes, Katechonemertes, Leptonemertes) and freshwater (Campbellonemertes, Potamonemertes) paramonostiliferous nemerteans, all of which are at present unplaced at the family level, are compared and contrasted with those of the marine generaPlectonemertes(Plectonemertidae),Cratene‐mertes, KorolkevilschiaandNippormemertes(Cratenemertidae). It is concluded that whilstActeonemertes, Antiponemertes, Argonemertes, CampbellonemertesandPotamonemertescan with certainty be placed in the family Plectonemertidae, the unspecialized and geographically isolated generaKatechonemertesandLeptonemertes,although lacking positive grounds for their exclusion, are only questionably included in this taxon. The possible evolutionary relationships of the plectonemertid genera are discussed and a diagnosis of the family is provide

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02410.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Principal component analysis (PCA) is a one‐group method. Its purpose is to transform correlated variables into uncorrelated ones and to find linear combinations accounting for a relatively large amount of the total variability, thus reducing the number of original variables to a few components only.In the simultaneous analysis of different groups, similarities between the principal component structures can often be modelled by the methods of common principal components (CPCs) or partial CPCs. These methods assume that either all components or only some of them are common to all groups, the discrepancies being due mainly to sampling error.Previous authors have dealt with the k‐group situation either by pooling the data of all groups, or by pooling the within‐group variance‐covariance matrices before performing a PCA. The latter technique is known as multiple group principal component analysis or MGPCA (Thorpe, 1983a). We argue that CPC‐ or partial CPC‐analysis is often more appropriate than these previous methods.A morphometrical example using males and females ofMicrotus californicusandM. ochrogasteris presented, comparing PCA, CPC and partial CPC analyses. It is shown that the new methods yield estimated components having smaller standard errors than when groupwise analyses are performed. Formulas are given for estimating standard errors of the eigenvalues and eigenvectors, as well as for computing the likelihood ratio statistic used to test the appropriateness of the CPC‐ or part

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02411.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

This paper explores the requirements and advantages of multiple group principal component analysis (MGPCA) when it is used to investigate population differentiation. A distinction is drawn between equality of orientation of the within‐group axes and equality of variance along these axes. Several examples of the use of MGPCA are discussed and it is shown that MGPCAper sedoes not require equality of variance along the axes although it may be a requirement of some of the techniques subsequently used to analyse the component scores. MGPCA is simple and direct, being based on the mathematically well defined eigenvector analysis of a symmetric positive definite (pooled within‐group covariance) matrix and it can be thought of as a step in the computation of canonical variate analysis (CVA). It can be used with CVA (which is the most popular method of biometrically assessing population affinities) to assess the contribution of within‐group components to among‐group discrimination. It is also one of a range of appropriate techniques that can be used to define (and delete if required) within‐group growth effects and is particularly suitable when CVA is being used to assess the population affinities. When used in this way it has the advantage of being more influenced by the groups with the greatest gro

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02412.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

We welcome Dr Thorpe's interesting discussion (Thorpe, 1988), and we would like to take this opportunity to clarify some points.Both MGPCA (multiple group principal component analysis) and CPCA (common principal component analysis) serve essentially the same purpose, namely estimation of principal components simultaneously in several groups, based on the assumption of equality of principal component directions across groups, while eigenvalues may differ between groups. However, CPCA has the distinct advantage that this assumption can actually be tested, using the (CPC) statistic. In analyses involving more than two variables, it is usually difficult to decide, without a formal test, whether or not the assumption of common directions of principal components is reasonable.There is also a conceptual difficulty with MGPCA. In statistical terms, both methods assume that:(a) a certain set of parameters (namely those determining the eigenvectors) are common to all groups(b) there are sets of parameters (namelypeigenvalues per group) which are specific to each group.CPCA sets up a model that reflects this structure and estimates the parameters accordingly. MGPCA, on the other hand, ignores part (b), at least temporarily, by pooling the variance‐covariance matrices and extracting eigenvectors from the single pooled matrix. This may lead to reasonable results, but there is no guarantee that it will indeed do so. The reader may find a more familiar analog in the fitting of regression lines when data are in groups. If it is assumed that all regression lines are parallel, one should set up an appropriate model based on a single slope parameter common to all groups, and groupwise intercepts. One should then estimate the parameters of this model, and not simply apply a technique which is appropriate in the one‐group case o

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02413.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Growth in the spotted hyaena (Crocuta crocuta) was investigated using material obtained from the Southern African subregion. A mathematical approximation for post‐natal growth of this species was best achieved by a Gompertz equation. An analysis of actual growth in this species revealed that the self‐accelerating and self‐retarding phases last for up to three years and 10 years, respectively. The exponentially declining growth rate of linear post‐natal growth indices suggest that the Huggett&Widdas foetal age estimation procedure may have limited value in this species. Furthermore, some observed limitations of the von Bertalanffy equation for describing post‐natal growth in this species are pointed out. The life‐history strategy of this reported precocial carnivore is examined in terms of its development and reproductive char

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02414.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The structure and the mineralization of the scales of the living dipnoan (lungfish)Protoptems annectenshave been investigated by transmission electron microscopy (TEM). The thin and imbricated scales are composed of two layers: the squamulae and the basal plate. At the outer surface, the squamulae form isolated plates superficially ornamented with spines and concretions and made up of acellular bone. After demineralization, the squamulae show a heterogeneous organic matrix composed of thin randomly oriented collagen fibrils forming a loose network within which the concretions appear as electronlucent circular areas. Abundant and aggregated concretions are located within the spines. The crystallites are oriented by the collagen fibrils except in the concretions. Anchoring bundles composed of parallel collagen fibrils arise from the squamulae and connect the scales to the overlying dermis.The basal plate, the most developed part of the scale, is made up of isopedine. Its main component consists of thick, closely packed collagen fibrils organized in a ‘double twisted plywood‐like structure’. Fibroblasts are present in the basal plate. Mineralization occurs only in few plies located beneath the squamulae. Mandl's corpuscles are found in front of the mineralization front. The mineral deposit is oriented by the collagen fibrils.The scales ofProtoptems annectensdiffer from the typical elasmoid scales of the teleosts by the peculiar structure of the squamulae, nevertheless they show enough structural characteristics to support the hypothesis that they can be considered as scales of the elasmoid grade, which have retained some plesiomorphic characteri

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02415.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Information on dive and pause times and the numbers of dives in a sequence were obtained for six guillemots and single razorbill and puffin. There were marked differences in diving performance between the species with the order of ranking, in descending order of dive and pause duration, being guillemot, razorbill and puffin. For guillemots, 80% of dives were of 20–119 sec duration and 80% of pauses were 0–59 sec; the maximum dive lasted 202 sec. Puffin dives and pauses were much shorter, with 81% of dives lasting 0–39 sec and 95% of pauses being less than 20 sec, the longest dive was 115 sec. Comparisons of diving sequences made by the same individual indicated some flexibility in all aspects of the sequence but there were broad interspecific differences in the organization of the sequence. The puffin generally made a large number of relatively short dives separated by very short pauses which resulted in a high diving rate (1–5 dives/min) and the bird spending 78% of its time underwater. In contrast, guillemots had much shorter sequences with a few long dives and pauses and lower rates of diving (0–5‐0‐6 dives/min) and proportions of time underwater (61–65%). Guillemots and puffins may forage at different depths and have different fora

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02416.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

At South Georgia, the diet of Wilson's storm petrel was studied using the regurgitates of adults arriving to feed chicks. Feeding frequency and meal size were estimated by weighing chicks twice daily, or in some cases every 3 h during daytime. Crustaceans contributed 98% of the total number of individual items and 68% of the total weight consumed; fish, 1% of the number of items and 28% of the weight. The most abundant crustacean was the amphipodThemisto gaudichaudii,which accounted for 90% of the total number but only 44% of the total weight of crustaceans eaten. Most (79%) of theThemistowere juveniles. Euphausiids were much less numerous in the diet (5% by number) but were the main group by weight (55%); most (52%) were Antarctic krill, with juveniles and sub‐adults (25–50 mm long) predominating. Mysids, copepods and barnacle larvae were also present. Fish were all myctophids (lanternfish),Protomyctophum normaniandP. bolinibeing identified; specimens were 50–85 mm long and weighed 1–4 g. Meal sizes averaged 6‐5‐7‐5 g (14–22% adult body mass); about 75% of chicks were fed each day (mainly at night), about 10% probably receiving meals from both parents. A review of storm petrel diets emphasizes the importance of fish toOceanodromaspecies and of crustaceans toOceanites, GarrodiaandPelagodroma.Euphausiids and amphipods (chieflyThemistoandHyperia)are the main crustacean prey and range from 5–50 mm and 0‐005‐0‐7 g. Myctophids are the main fish prey and range from 20–100 mm and 1–5 g. Meal size ranges from 15–25% adult body mass and chicks are fed on 50–85% of days. This low delivery rate is mainly responsible for the disproportionately slow growth and long fledgin

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02417.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Available information on the history, population dynamics, body weight and kidney fat indices in free‐living Chinese water deer at Whipsnade Zoo were briefly reviewed.Fifty eight culled animals were examined quantitatively for changing rumen papilla morphology through different seasons using surface enlargement factors (SEF). The results show a much reduced SEF of below four in winter and rarely above eight in spring, summer and autumn. This is atypical for the entire group of concentrate selectors and even for intermediate feeding types. The inference from the data is that the seasonal rumen development was poorer than expected perhaps indicating that this population was undernourishe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02418.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A cave population ofMiniopterus minorhad a seasonally monoestrous reproductive cycle that corrsponded closely to the rainfall‐induced seasonality of coastal Kenya (4 S). Males had pronounced cycles of body weight resulting from the deposition of fat during periods of relative food abundance in both rainy seasons, and its depletion during competitive mating and the dry seasons, when numbers of insects were lowest. The annual period of sexual regeneration clearly followed the increase in body weight which occurred during the ‘long rains’ (April‐June). Testicular recrudescence was accompanied by hypertrophy of the accessory glands and all reproductive organs involuted after mating in July, remaining inactive until the following April. An annual moult corresponded with the improvement in body condition that occurred at the beginning of the ‘long rains’. The growth of new pelage was completed in May, by which time ambient temperatures had dropped and adult males entered a diurnal torpor that lasted over much of the colder ‘long dry season’ (July‐October). The secretion of a pungent substance in the urine of adult males coincided with peak testicular activity during the annually competitive occupancy of a matin

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1988.tb02419.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY