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1.
Patterns of interspecific differentiation in saki monkeys (Pithecia) are quantitatively described and possible evolutionary processes producing them are examined. The comparison of species correlation matrices to expected patterns of morphological integration reveal significant and similar patterns of development-based cranial integration among species. Aspects of the facial region are more heavily influenced by general size variation than features of the neural region. The comparison of pooled within- and between-groups V/CV matrices suggests that genetic drift might be a sufficient explanation for saki cranial evolution. Differential natural selection gradients are also reconstructed because selection may also have caused population differentiation through evolutionary time. These gradients illustrate the inherent multivariate nature of selection, being a consequence of the interaction between existing morphological integration (correlation) among traits and the action of natural selection. Yet, our attempt to interpret selection gradients in terms of their functional significance did not result in any clear association between selection and function. Perhaps this is also an indication that morphological evolution in sakis was mostly neutral.  相似文献   

2.
This study assesses ontogenetic correlates of diet in anthropoid primates. Associations between body weight growth, adult size, and diet are evaluated for a sample of 42 primate species, of which 8 are classifiable as “folivores.” The hypothesis that folivores show a pattern of growth that differs from “nonfolivores” is tested. Ontogenetic variation is summarized through use of parametric and nonparametric regression analysis. Several analytical techniques, including broad interspecific and detailed comparisons among species of similar adult size, are applied. This investigation indicates a clear association between body weight ontogeny and diet: folivorous species grow more rapidly over a shorter duration than comprably sized nonfolivorus species. A positive correlation between adult size and diet is not unambiguously established in this sample. A threshold (at around 1 kg) below which insectivory is very common may adequately characterize the association between adult size and diet in anthropoid primates. Above this threshold, adult size does not appear to covary predictably with diet. Evolutionary correlates of the ontogenetic pattern seen in folivores may include a variety of factors. The distinctive pattern of development in folivores may relate to the profile of ecological and social risks that these species face. Morphophysiological advantages to rapid growth may relate to a need for accelerated alimentary (dental and gut) development. The implications of ontogenetic variation in folivores are discussed. © 1994 Wiley-Liss, Inc.  相似文献   

3.
Ernst Mayr (1904–2005) was the twentieth century's most influential writer to wrestle with the species problem. 1 - 4 The following draws heavily on his work, albeit without presumptuously claiming to mirror his thinking or present any original ideas. As a personal meditation, I am thinking mostly of platyrrhines. Following Mayr, I adhere to what is commonly called the Biological Species Concept (BSC) as a way of thinking about a species in the real‐world biosphere as a taxon. I also hold to the idea that the Linnaean category called species has the same function as other categories: a linguistic tool for organizing and retrieving information about biodiversity while embodying evolutionary hypotheses. In other words, alpha taxonomy, the area of systematics that involves identifying, naming, and classifying species, is not purely an exercise in either biology or inventory because it involves communication as well. The burdensome work of the species category stems partly from tension created by the several purposes associated with the concept: the objective observation and examination of a fundamental biological phenomenon, the collection and interpretation of data in a selective context of relevance, and the intention to deploy scientific decisions as a form of communication within a dynamic but highly structured language system.  相似文献   

4.
We analysed with landmark-based images morphological differences between four species of Talpa which resemble each other morphologically and are all highly adapted to underground life. Subtle shape differences of the skull and mandibular bones were found between all species. However, there is also broad overlap between all species. Talpa caucasica had the largest skull and mandibles, and Talpa levantis the smallest.  相似文献   

5.
The taxonomic relationships among the four genera of the Atelidae family, Alouatta (Howler), Ateles (Spider), Lagothrix (Woolly) and Brachyteles (Muriqui), have been the subject of great debate. In general, almost all authors agree with the assignment of Howler monkeys as the basal genus, either in its own tribe Alouattini or in the subfamily Alouattinae, but they disagree on the associations among the other members of the family. Muriquis have been grouped with Spider monkeys based on the fact that they share various behavioral and morphological characteristics. Cladistic analyses using morphological, biochemical, karyotype and behavioral characteristics depicted a phylogenetic tree that places Howler as the basal genus and the remaining genera in an unresolved politomy. More recent studies using molecular data have suggested that Muriqui and Woolly monkeys are sister groups. However, a recent study based on nuclear and mtDNA argued that politomy is what best represents the relationships among Spider, Woolly and Muriqui. To contribute to this debate we have added new data from two nuclear genes, Transferrin and von Willebrand Factor, and using an alignment of 17,997 bp we demonstrate that a total analysis strongly supports the Muriqui-Woolly clade. A gene-to-gene approach showed that four of the eight nuclear genes provide support for the Muriqui-Woolly clade, two strongly and two moderately, while none of the eight genes provide support for any alternative arrangement. The mitochondrial genes were not able to resolve the politomy. A possible reason for the difficulty in resolving atelid relationships may be the short period of time separating each cladogenetic event in the evolutionary process that shaped this family.  相似文献   

6.
A palynological survey, including LM, SEM and TEM is presented for eight genera, nine species and 76 samples of the Monotropoideae which is composed of 10 genera and 13 species. On the basis of the aperture number and shape, the following six pollen types are recognized: 1) 3-colp(oroid) ate—Allotropa, 2) 2-colpor(oid)ate—Monotropsis andHemitomes, 3) 4-colpor(oid)ate—Pterospora, Sarcodes andPleuricospora, 4) 2- and 3-colpor(oid)ate—Monotropa hypopitys, 5) 3-colporate and-porate —Monotropa uniflora, 6) 3- to 4- porate—Monotropastrum humile. Relationships among taxa within the Monotropoideae are illustrated on the palynological characters including the aperture type, exine sculpture and structure. Both pollen grains with two and four apertures have evolved independently from pollen grains with three apertures, according to the infraspecific variation of aperture numbers and the usual occurrence of three-aperturate pollen grains in the Ericaceae. 3-colp(oroid)ate pollen ofAllotropa is the most primitive and occupies an isolated position in the subfamily, on the other hand 3- to 4-porate pollen ofMonotropastrum humile is most advanced in the subfamily, probably even in the Ericaceae. A reduced sexine inMonotropastrum humile appears to be a specialized pollen character. Infraspecific geographical difference in palynological characters is revealed in two species ofMonotropa for the first time.M. hypopitys is basically characterized by pollen grains with two apertures in the New World vs. three apertures in the Old World.M. uniflora is basically characterized by 3-porate pollen in the New World vs. 3-colporate in the Old World. In both species pollen grains with more primitive characters usually occur in the Old World.  相似文献   

7.
Abstract  Closterocerus cruy (Girault) is newly recorded, both from New Zealand and as a parasitoid of lepidopteran leafminers. The species is redescribed from the Girault type and from New Zealand material. Diagnostic character states are provided for the separation of C. cruy from the closely related Australian agromyzid parasitoid C. mirabilis Edwards and LaSalle.  相似文献   

8.
Many leaf characters are considered in the taxonomy of Crataegus in Europe, and several have been used in studies of the extent of hybridization in populations of northwest Europe. In such analyses it is assumed that the environmental component of phenotypic variation in such characters is insignificant. We tested this assumption by analysing the variation in the size and shape of leaves borne on clone cuttings of Crataegus monogyna maintained under identical conditions apart from the availability of soil nutrients. The resulting variation among leaves from this single genotype was as great as that observed previously across populations. Furthermore, although most of this variation could not be explained, a part could be attributed to differences in nutrient availability; of nine leaf characters investigated, eight showed significant variation due to this source, and in seven, the variation covaried significantly with nutrient level. The systematic implications of this are briefly explored.  相似文献   

9.
    
The main difference between the sponge genera Leucilla and Paraleucilla (Porifera, Calcarea, Amphoriscidae) is the presence of a disorganized zone (DZ) in the inner region of the skeleton of the latter genus. However, it has been repeatedly observed that specimens from different species of Paraleucilla lack this feature. It is assumed that the size of the sponge may have an effect on the presence or the absence of the DZ, but no investigation of this morphological variation has previously tested this hypothesis. Here, we examined this assumption and described the frequency with which the DZ is absent from individuals of Paraleucilla magna. We also investigated possible drivers of the observed variation using generalized linear models to evaluate whether the month of the year, rainfall, reproductive activity, volume, and body wall thickness could influence the presence or the absence of the DZ. The DZ was absent from 46.5% of the analyzed individuals, indicating that it may be misleading to use this trait to identify the genera Leucilla and Paraleucilla. The presence of the DZ in P. magna is influenced negatively by volume and positively by body wall thickness of the individuals. Our results confirm the previous assumptions for the family Amphoriscidae and highlight problems with the current classification of Calcarea. A discussion of the validity of some morphological characters and the importance of analyzing their variation is provided.  相似文献   

10.
    
Despite Juniperus spp. being an important component of Mediterranean arid and semi‐arid ecosystems, there is a lack of complex studies on their biogeographical patterns. Using 16 morphological cone and seed traits and three nuclear microsatellite markers, we investigated the morphological and genetic variability of seven Mediterranean and Macaronesian Juniperus taxa (J. oxycedrus ssp. oxycedrus, J. oxycedrus ssp. badia, J. brevifolia, J. cedrus, J. deltoides, J. macrocarpa and J. navicularis) to identify biogeographical trends and interspecific genetic relationships. The highest gene diversity was measured in J. oxycedrus ssp. oxycedrus (HE = 0.716) and the lowest in J. brevifolia (HE = 0.441). The west Mediterranean was characterized by a higher level of genetic diversity than the east Mediterranean. A lack of significant genetic differences between European and African populations of J. oxycedrus suggests that the Strait of Gibraltar was not a significant barrier to gene flow, but has promoted some morphological differentiation. The genetic and morphological results strongly support the recognition of J. macrocarpa, J. navicularis and J. deltoides at the species rank, whereas J. oxycedrus ssp. badia should be included in J. oxycedrus. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 637–653.  相似文献   

11.
Aim We examined the relationship between species richness and morphological complexity of terrestrial mammal communities along an elevational gradient. Location The gradient is in the Sonoran Desert in Southern California and extends from a sand dune habitat near sea level to coniferous forest ending at >2600 m. Methods Morphological diversity, characterized by both size and shape of coexisting mammal species, was estimated within and between sites from projections of variables on principal components axes. Similarities among species were calculated as Euclidean distances. To tease apart size and shape, we constructed two principal component analyses: one based on log-transformed original measurements, the other on log-transformed proportional shape variables. To test whether species number accounted for the morphological diversity at each site we designed two null models. The models generated were random communities generated from the forty-two-species pool. Indices of morphological diversity for real communities were compared with the results of 500 simulations of each null model. Results Species richness varied along the gradient, peaking in the mid-elevation agave-ocotillo habitat. Morphological diversity of shapes and sizes correlated strongly with species richness. Locomotor, tooth, and skull traits were all important in distinguishing among species. Main conclusions Two important patterns emerged: (1) diversity of both sizes and of shapes of species within communities correlated positively with species number, and both sets of variables behaved similarly across this gradient; (2) the most species rich sites were not composed of specialists on these best places, but rather, a community of species derived from overlapping faunal groups.  相似文献   

12.
    
Leaf anatomy is compared for all species of Raoulia. The species are tabulated according to their lamina structure. Noteworthy anatomical features are lamina type and grade of differentiation, stomatal position, epidermal and cuticle thickness, shape of mesophyll cells, presence or absence of central clear cells, sclerenchyma caps, abaxial collenchyma and protruding midrib. It is shown that leaf anatomy data provide characters which are taxonomically useful in Raoulia. The main subgenera are supported except that the leaf anatomy of R. haastii is anomalous and that of R. youngii is typical of R. subg. Raoulia rather than R. subg. Psychrophyton. The leaf anatomy of R. petriensis is unique in the genus.  相似文献   

13.
    
The Lower Cretaceous (upper Berriasian to lowermost Aptian) nonmarine Wealden succession of southern England has been a prolific source of vertebrate fossils for over 180 years. The sequence is most famous for terrestrial reptiles, particularly dinosaurs; however, significant aquatic tetrapod discoveries including rare nonmarine plesiosaurs have also been reported. The record of Wealden plesiosaurs currently incorporates a single valid taxon, Leptocleidus superstes Andrews, 1922a, based on a partial skeleton and skull from the Barremian Upper Weald Clay Formation of Berwick, Sussex. Traditional classifications place this plesiomorphic pliosauroid with basal Jurassic rhomaleosaurids; however, the genus Leptocleidus has since become a ‘waste basket’ for various Cretaceous rhomaleosaurid‐like plesiosaurs from around the globe. In an attempt to clarify this situation, the type specimen of L. superstes was reexamined and redescribed. Previously unrecorded anatomical features were identified including an elongate, gracile paraoccipital process on the exoccipital‐opisthotic, and tooth ornament comprising widely spaced, coarse striations that are restricted to the lingual surface of the crown (mesiodistal ‘carinae’ are absent). Other indeterminate pliosauroid remains (recovered along with coeval elasmosaurids) from the upper Berriasian–Valanginian Hastings Beds Group also exhibit potentially diagnostic traits: an atlas centrum with no anterolateral exposure and with ventral margin formed by the intercentrum; a single‐headed rib articulation on the atlas centrum extending onto the axis centrum; and epipodials that are longer than broad. The placement of L. superstes is controversial in recent phylogenies. To test the competing hypotheses, L. superstes together with all closely related species were rescored into the most comprehensive published phylogenetic data sets of Plesiosauria and Pliosauroidea. Separate maximum parsimony and Bayesian analyses of each matrix unanimously supported a relationship between L. superstes and pliosauroids but could not confirm placement within either Rhomaleosauridae sensu stricto, or a discrete ‘leptocleidoid’ clade. Examination of character states advocating affinities amongst Leptocleidus spp. suggests homoplasy rather than clear homology between what are potentially palaeobiogeographically disparate genus‐level taxa. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161 , 663–691.  相似文献   

14.
    
We evaluate the correlation between intraspecific variation in egg size and population size in breeding British birds. Using information on abundance, range occupancy, migration status and phylogenetic relationships among species, we show that a wider geographical distribution rather than larger population size per se best predicts egg size variability. A similar result applies to wing length variability. Results from a phylogenetic path analysis suggest that geographical variation is the most parsimonious causal explanation for high intraspecific variation in common species.  相似文献   

15.
    
Allopatric populations that show genetic differentiation but lack phenotypic diagnosability are difficult to classify. In 1946, Arnett described a new species of burying beetle (Silphidae: Nicrophorus) from Luzon Island, Philippines, Nicrophorus benguetensis. In 2002, Sikes et al., finding the species to be inconsistently diagnosable, synonymized N. benguetensis under Nicrophorus nepalensis Hope 1831. We rigorously and quantitatively test the validity of N. benguetensis using several different species delimitation criteria. We employed discrete and quantitative character‐based methods to test similarity criteria using linear morphometrics in a discriminant analysis framework, and percentage sequence divergences based on sequences from four mitochondrial DNA (mtDNA) genes (COI, COII, ND4 and ND5) and two nuclear genes [28S (D2 region) and CAD]. We also employed tree‐based methods to test phylogenetic criteria using mtDNA sequences and morphology with parsimony, Bayesian inference and maximum likelihood. The analysis of discrete phenotypic characters did not reliably diagnose N. benguetensis. The results of the discriminant analysis provided moderate support for the validity of N. benguetensis (71.4% of the specimens were properly classified). There is adequate genetic distance between N. benguetensis and its nearest neighbour for DNA barcoding to identify an unknown sequence, although this may be an artefact of the small sample size. Phylogenetic analyses of the morphological data, with and without the morphometric data, yielded unresolved trees. Molecular phylogenetic results found N. benguetensis to be monophyletic, but neither clearly rejected nor supported its validity. Two of our approaches using molecular data diagnosed N. benguetensis, but those that used phenotypic data did not exceed a 75% success rate. We conclude, therefore, that N. benguetensis, despite being a weakly distinct allopatric population, and deserving of additional study, should remain synonymized until further analysis suggests otherwise. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 311–333.  相似文献   

16.
BACKGROUND AND AIMS: The genetic and morphological variation in the sago palm (Metroxylon sagu, Arecaceae) in Papua New Guinea (PNG) was investigated. METHODS: Amplified fragment length polymorphism (AFLP) was used to investigate the genetic structure of 76 accessions of M. sagu, collected in seven wild and semi-wild stands in PNG. KEY RESULTS: An analysis of ten quantitative morphological variables revealed that most of these were mutually correlated. Principal component analyses of the same morphological variables showed that neither armature (presence or absence of spines) nor geographical separation was reflected clearly in the quantitative morphological variation. Similarity matrices of genetic, quantitative morphological, geographical and armature data were tested for pair-wise correlations, using Mantel's test. The results only showed a significant correlation between genetic and geographical distances. Visual inspection of principal component analyses plots and a neighbour-joining dendrogram based on genetic distances supported this trend, whereas armature showed no relation with genetic distances. CONCLUSIONS: Geographical distribution defines some weak patterns in the genetic variation, whereas the genetic variation does not reflect any patterns in the morphological variation, including armature. The present study supports the accepted taxonomy of M. sagu, recognizing only one species of M. sagu in PNG.  相似文献   

17.
中国东部亚热带青冈果实形态变异的研究   总被引:32,自引:0,他引:32       下载免费PDF全文
青冈为我国亚热带地我广泛分布,并具有较强耐寒和耐瘠薄能力的少数几个常绿树种之一,以果实长度,宽度和体积作为果实大小的指标,宽/长作为果实形状的指标,对采自东部亚热带的10个青冈和群果实形态进行了比较分析,结果如下:(1)青冈果实的大小和形状在种群间,种群内均存在着显著差异,变异幅度最大的是果实的体积(种群间的变异幅度CV1为57.1%,种群间平均单粒果实体积的最大差异为3.5倍)其次为宽度(21.  相似文献   

18.
    
In order to be elaborated by sexual selection, sexual ornaments must vary perceptibly and genetically among individuals in natural populations. Rather little is known about ornament variation in monogamous species, in which sexual selection should act more weakly than in polygynous species. We report phenotypic variation in feather ornament size (elongated tails and pectoral tufts) and body size in the scarlet-tufted malachite sunbird Nectarinia johnstoni , a monogamous, sexually dimorphic nectarivore of East African alpine zones. Fully-expressed male ornaments are highly significantly more variable (CVs = 12–29%) than are skeletal and wing measures primarily affected by natural selection (CVs = 2 4%). Female sunbirds have pectoral tufts which are significantly (22–25%) smaller than those of adult males, but more variable (CVs= 21–22%, CVs= 12–15%), and more variable than body size. Among males with fully-grown ornaments, those with longer tails tend to have longer wings and wider tufts. The high variation in fully-grown ornaments in malachite sunbirds is consistent with the view that the ornaments are condition-dependent sexual signals. Finally, we review studies of feather ornament variation to date, and show that ornaments are much more variable in monogamous than non-monogamous species, apparently due to the relatively weak pressure of sexual selection.  相似文献   

19.
    
On the small oceanic island of Chichijima, two endemic species of land snails, Mandarina mandarina and M. chichijimana, have discrete distributions separated by a hybrid zone. This study investigates the potential of hybridization as a source of morphological novelty in these snails. Mandarina mandarina possesses a shell with a higher whorl expansion rate and a smaller protoconch than M. chichijimana, relative to shell size. The number of whorls and shell size of M. mandarina do not differ from those of M. chichijimana, because the effect of higher expansion rate on number of whorls and size of the former is compensated for by its smaller protoconch. The whorl expansion rate and protoconch diameter of the individuals from the hybrid populations are intermediate or typical of either of the two species, and their average values show clinal changes along the hybrid zone. However, the hybrid populations include exceptionally high shells with many whorls and flat shells with few whorls, which are never found in the pure populations of either species. In addition, gradual increases in variance in shell height and number of whorls were found from the edges to the center of the hybrid zone. A combination of low expansion rate (typical of M. chichijimana) and a small protoconch (typical of M. mandarina) produces a shell with an extremely large number of whorls because of the geometry of shell coiling. However, the combination of high expansion rate and a large protoconch produces a shell with an extremely small number of whorls. Because of the correlation between the number of whorls and shell height, shells with an exceptional number of whorls possess an extraordinarily high or flat spire. Hybrids can inherit a mosaic of characters that, as they play out during growth, lead to novel adult morphologies. These findings emphasize the importance of hybridization as a source of morphological variation and evolutionary novelty in land snails.  相似文献   

20.
    
The classifications of primates, in general, and platyrrhine primates, in particular, have been greatly revised subsequent to the rationale for taxonomic decisions shifting from one rooted in the biological species concept to one rooted solely in phylogenetic affiliations. Given the phylogenetic justification provided for revised taxonomies, the scientific validity of taxonomic distinctions can be rightly judged by the robusticity of the phylogenetic results supporting them. In this study, we empirically investigated taxonomic-sampling effects on a cladogram previously inferred from craniodental data for the woolly monkeys (Lagothrix). We conducted the study primarily through much greater sampling of species-level taxa (OTUs) after improving some character codings and under a variety of outgroup choices. The results indicate that alternative selections of species subsets from within genera produce various tree topologies. These results stand even after adjusting the character set and considering the potential role of interobserver disagreement. We conclude that specific taxon combinations, in this case, generic or species pairings, of the primary study group has a biasing effect in parsimony analysis, and that the cladistic rationale for resurrecting the Oreonax generic distinction for the yellow-tailed woolly monkey (Lagothrix flavicauda) is based on an artifact of idiosyncratic sampling within the study group below the genus level. Some recommendations to minimize the problem, which is prevalent in all cladistic analyses, are proposed.  相似文献   

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