首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
    
A new species of Oswaldofilaria is described from Tropidurus torquatus (Tropiduridae: Iguania); its prevalence at the rocky study area at Juiz de Fora, Minas Gerais, Brazil, was approximately 30% and its mean intensity 3.13 ± 2.51. Oswaldofilaria chabaudi n. sp. is distinct from the thirteen Oswaldofilaria species known in Australia, Africa and South-America in having the following characteristics: oesophagus medium-sized, left spicule 1 mm long and high spicular ratio (about 5), tail extremity ornated in both sexes with a bifurcated projection, and tooth-like structures near phasmids in the female. A long left spicule and high spicular ratio are convergent derived characters also found in a parasite of Australian crocodilians, O. kanbaya, and in several species of the closely related genus Befilaria, such as the Central American B. puertoricensis from polychrotids. Oswaldofilaria in South America is represented by eight species. Within these, a primitive group that is parasitic in Iguanidae, Polychrotidae (Iguania) and Crocodylidae and that possesses a long oesophagus is recognised, together with two distinct derived lines: three species with numerous, aligned precloacal papillae, parasitic in Teiidae (Laterata) and Scincidae (Scincomorpha), and O. chabaudi n. sp., in which this character is absent. Tropidurids (Tropiduris and Plica) had previously been reported in the host range of two oswaldofilarine genera, Oswaldofilaria and Piratuba, and their parasites assigned to known species described from other groups of lizards.https://doi.org/10.1051/parasite/2010174307  相似文献   

2.
    
We used null model analyses to investigate the existence of structure in lizard assemblages from open vegetation enclaves in Rondónia, southwestern Amazonia, in relation to species richness, species co‐occurrence, diet, and size overlap. These enclaves presumably have been isolated since the Holocene, providing a history of long‐term isolation. We assumed that the presence of structure in lizard assemblages from the Rondónia enclaves is consistent with the notion that extinctions are a deterministic process, some species being more prone to extinction than others. We grouped enclaves into four categories: latosoil cerrado, sandy cerrado, transitional forest, and rocky field. We collected 14 Cerrado lizard species, consisting of five families in all sampled areas. Analyses of species richness, co‐occurrence, diet overlap, and size overlap patterns suggested lack of organization in the assemblages. The assemblages from the rocky fields of Guajarí–Mirim and the sandy cerrados in Vilhena were significantly structured in diet overlap, whereas the remaining assemblages lacked structure. This probably resulted from phylogenetic inertia and not from ecological interactions. Our results suggest that extinctions proceeded in a stochastic fashion and that historical factors had a dominant role in shaping lizard assemblages in detriment of present‐day ecological factors. In addition, we identified endemic species in the enclaves as well as a tight association between unique ecogeographic features of the landscape and species occurrences. We propose that conservation measures in the region must adequately preserve these features to ensure the survival of the species.  相似文献   

3.
  总被引:1,自引:0,他引:1  
Aim  To determine if the distributions of lizard species from Seasonally Dry Tropical Forest (SDTF) enclaves within the Cerrado biome in central Brazil are associated with the Tropical Seasonal Forests Region, a recently proposed phytogeographic unit of South America, corroborating the existence of a Pleistocenic Arc of SDTFs.
Location  SDTF remnants in the Paranã River valley, municipality of São Domingos, Goiás, Brazil.
Methods  Lizards were extensively sampled using haphazard sampling, funnel traps, and pitfall traps with drift fences during four expeditions. The composition of the SDTF lizard assemblage was compared with those from other South American phytogeographic regions (Caatinga, Cerrado, Chaco, Llanos, and the dry forests of Colombia and Bolivia), based on the literature and our own unpublished data.
Results  The SDTF lizard assemblage contained 20 species, including 11 species with extensive distributions among the regions considered, seven species shared exclusively with Cerrado localities, a single species shared exclusively with other SDTFs, and one endemic species. The presence of Lygodactylus klugei (Smith, Martin & Swain, 1977), presumably endemic to the Pleistocenic Arc formed by the Tropical Seasonal Forests Region, considerably extends the known distribution of this species, suggesting historical connections between Caatinga and Cerrado SDTF enclaves.
Main conclusions  The composition of the lizard assemblage in Cerrado SDTF enclaves seems to corroborate the recent proposal that the SDTF should be recognized as a phytogeographic unit (or dominium). The presence of disjunct populations and endemic species highlights the urgency of considering the uniqueness of the Paranã River valley SDTFs and the importance of its conservation.  相似文献   

4.
    
Larval water mites parasitise a wide range of aquatic insects and may have a negative impact on host fitness. One host taxon susceptible to water mite parasitism is the whirligig beetle (Coleoptera: Gyrinidae). We made 11 collections of the whirligig beetle Dineutus nigrior Roberts from May to October of 2006 to investigate patterns of water mite parasitism on that host species. Mites were identified as of the genus Eylais. Mite intensity ranged from 1 to 11. Median intensity was 1.0 and ranged from 1.0 to 3.0 for individual samples. There did not appear to be temporal patterns in mite intensity. Prevalence was 30.9% but varied substantially over the sampling period ranging from 2.5 to 63.3%. Mites were attached to the metathoracic wings and the body tergites under the elytra. When all samples were considered there was equal use of wings and body tergites but there was temporal variation in the use of attachment sites.  相似文献   

5.
    
Platypsyllus castoris is closely associated with beavers and displays a unique set of structural specializations. We document the morphology of adults with modern techniques, and interpret evolutionary changes linked with the specific life style. The small subfamily Platypsyllinae has evolved an entire suite of features correlated with a more or less close association with mammals, for instance a flattened body, a dorsal cephalic shield, flightlessness, eye reduction, and depigmentation. Within this small group, Platypsyllus displays numerous autapomorphic features, correlated with a close association with the beaver. Essential is a combination of mechanical stabilization and firm anchorage on the host, and efficient forward movement in the fur. Exo- and endoskeletal structures of the head and thorax are reinforced by vertical cuticular columns and by an array of internal ridges. The antennae are shortened and strongly modified, the mandibles distinctly reduced and flattened, unsuitable for cutting, scraping or grinding. The musculature of the mouthparts is simplified, whereas an enhanced set of prepharyngeal and pharyngeal dilators forms an efficient sucking pump. The prothoracic musculature is strongly developed. In contrast, the pterothoracic muscle system is distinctly simplified, even though leg muscles are strongly developed. Using the legs, the flattened beetles move sideways through the dense fur of the beaver, using posteriorly directed groups of setae and ctenidia to prevent being pushed backwards by the densely arranged hairs. In contrast to the anterior body, the cuticle of the abdomen is thin, and the entire tagma flexible, with thin layers of segmental muscles. The hind gut is not connected with the mid gut. The beetles probably consume liquid, possibly with emulgated minute skin debris. As the morphology of the mouthparts excludes damage to the skin of the host, the association should not be addressed as ectoparasitic but as commensalism.  相似文献   

6.
Aim This goal of this paper is to present an up‐to‐date, accurate check‐list and distribution of the monitor lizards on the African continent. No such list of their distribution has been attempted since Robert F. Mertens' (1942) treatise (Abhandlungen Senckenbergischen Naturforschenden Gesellschaft, 462 , 465 , 466 ). Location The localities included herein are all countries on the African continent, and adjacent islands, with a list of Varanus known to Yemen and Saudi Arabian Republics included for clarity. One fossil Varanus rusingensis is included, as it is the first, and only described, fossil African Varanus known. Methods Locality records were reviewed from literature sources, museum voucher specimens, personal comments, field observations and photographic records. Results A summation of 3,268 locality records are included herein from the methods listed, with maps depicting these records. Main conclusions From the locality records listed herein, it is evident that the Nile monitor (V. niloticus) has the widest distribution, and that the Yemen monitor (V. yemenensis) has the most restricted distribution; paradoxically, both features may be indicative of their relic habitation on the African continent.  相似文献   

7.
枸杞木虱啮小蜂寄生行为及生物学特性的研究   总被引:3,自引:0,他引:3  
枸杞木虱啮小蜂Tetrastichussp .是枸杞木虱ParatriozasinicaYang&Li若虫的外寄生蜂 ,自然寄生率可达 86 5 %。在温度为 2 0~ 2 5℃的室内条件下 ,完成 1个世代需 1 4~ 2 0d。成虫寿命与取食有关 ,取食 1 5 %的蜂蜜水 ,雌性成虫寿命为 1 2~ 1 7d,雄性成虫为 4~ 6d。成蜂最喜欢在 3龄和 4龄若虫上产卵。自然种群消长与寄主虫口密度相关。每年 7月到 8月下旬该蜂寄生率高 ,9月份下降 ,1 0月份几乎不见。  相似文献   

8.
9.
    
Ectoparasites are abundant in natural communities, can have pronounced deleterious fitness consequences to their host and are important vectors of transmissible parasitic disease. Yet very few studies have estimated the magnitude of heritable genetic variation underlying resistance against ectoparasitism, which significantly limits our ability to predict the evolution of this ecologically important character. The present paper reports results of artificial selection for increased resistance in Drosophila nigrospiracula against ectoparasitic, haematophagous mites, Macrocheles subbadius. In this system, which occurs naturally in the Sonoran Desert of North America, ectoparasitism significantly damages the expression of host fitness traits, including longevity, fecundity and male mating success. In the present study, resistance, which was modelled as a threshold trait, responded significantly to selection applied on either sex. Realized heritability, calculated as a mean across four replicates, was estimated to be 0.152 +/- 0.014 (SE). The heritability estimate from selection on males did not differ from that on females, but both estimates differed significantly from zero. This documented presence of additive genetic variation for resistance, coupled with knowledge of the fitness consequences of ectoparasitism, indicates that the host population possesses significant evolutionary potential. Selection was applied on the pre-attachment phase, thereby targeting behavioural forms of defence. This study therefore establishes parallels between insects and other animals in their ability to protect themselves and evolve behavioural defences against ectoparasites.  相似文献   

10.
    
We conducted a field study and a laboratory experiment to test whether ectoparasitic mites, Macrocheles subbadius, generate parasite-mediated sexual selection in the Sonoran desert endemic fruit fly, Drosophila nigrospiracula. Male flies gather on the outer surfaces of necrotic saguaro cacti where they engage in male–male competitive interactions and vigorous female-directed courtship. At these sites, operational sex ratios were significantly skewed toward males. The degree to which mites were aggregated among flies varied across the 25 fly populations sampled. The degree of mite aggregation across fly populations was strongly positively related to the mean number of mites per fly (intensity of infestation). Both the intensity and prevalence of infestation (fraction of flies infested) increased with the age of the cactus necrosis. Infested flies of both sexes were significantly less likely to be found in copula than uninfested flies, and mean intensity of infestation was significantly more pronounced in noncopulating than in copulating flies. The effect of attached mites on copulatory success exhibited dose-dependency, and this effect was more stringent in males: males or females with more than two and four mites, respectively, were never found in copula. The magnitude of parasite-mediated sexual selection was estimated for 12 fly populations by calculating selection differentials for each sex separately. The relation between intensity of infestation and magnitude of parasite-mediated sexual selection was stronger in males but significant for both sexes. We also assayed copulatory success of field-caught males in the laboratory, both during infestation and after experimental removal of mites. Males infested with two mites copulated less frequently than uninfested individuals, and in mating trials after mites had been removed, previously infested males copulated as many times as flies with no history of infestation. These findings, and the lack of difference in the number of mite-induced scars on copulating and single individuals in nature, strongly suggest that the reduced copulatory success of infested flies is attributable to an effect of mites per se, rather than to a character correlated with parasitism or previous parasite infestation.  相似文献   

11.
Host attachment sites and frequency distribution of parasitism were investigated for the larval erythraeid mite Leptus indianensis parasitising a sample of 500 harvestmen, Leiobunum formosum in Tennessee, USA. A significant difference was found in the number of mites attached to different body segments of the harvestmen with the greatest number of mites attached to femurs I–IV. Scanning electron microscopy revealed that the mites attached to smooth areas of the host integument between rows of stout setae. The frequency distribution of mites parasitising the harvestman population was highly clumped (Coefficient of Dispersion=3.34) with a relatively small number of hosts being parasitised by most of the mites.  相似文献   

12.
Aspects of the reproduction and growth of Phrynosoma ditmarsi from Sonora, Mexico, were observed in captivity. Lizards were maintained indoors with a seasonally adjusted photoperiod. Mating occurred from August through December, with the majority of copulations observed in August, September, and October. Lizards were over-wintered between temperatures of 13°C and 16°C, with occasional drops to 8° C. The female reproductive cycle is not completely understood. Females may have stored sperm over the winter months, with ovulation and fertilization occurring in the following spring. Alternatively, embryogenesis may have been interrupted during the winter. Parturition occurred in June and July. Males became sexually mature at 13 months of age. Females first copulated at this age, resulting in the production of young at 24 months of age. Courtship and non-receptive behaviors were similar to those of other Phrynosoma.  相似文献   

13.
    
One of the most remarkable hand movements is grasping. This ability has been repetitively associated with the evolution of the human lineage towards the development of technology. Besides mammals, other tetrapods have also evolved significant, and in some cases surprising, forelimb prehensile capabilities. In this study, we present a qualitative analysis of the carpal bones in diverse lizard taxa. Our main goal is to make a survey of the carpal morphology of different squamatans and to interpret its variability in the context of both lizard skilled forelimb movements and the evolutionary history of Squamata.  相似文献   

14.
    
The evolution of viviparity alters the physical relationship between mothers and offspring and the prevalence of viviparity among squamate reptiles presents an opportunity to uncover patterns in the evolution of placental structure. Understanding the breadth of this diversity is limited because studies of placental structure and function have emphasized a limited number of lineages. We studied placental ontogeny using light microscopy for an embryological series of the Mexican gerrhonotine lizard, Mesaspis viridiflava. This species develops an elaborate yolk sac placenta, an omphaloplacenta, which receives vascular support arising in a structure known only from other gerrhonotine lizards. A prominent feature of the omphaloplacenta is a zone of uterine and embryonic epithelial cell hyperplasia located at the upper shoulder of the yolk mass, often extending above the yolk mass. The omphaloplacenta covers more than one-half of the surface area of maternal—embryonic contact. The chorioallantoic placenta has a more restricted distribution because the allantois remains in the embryonic hemisphere of the egg throughout development and lies internal to the vascular support for the omphaloplacenta in areas where they overlap. The structural profile of the chorioallantoic placenta indicates a potential for respiratory exchange and/or hemotrophic nutritive transport, while that of the omphaloplacenta suggests that nutritive transfer is primarily via histotrophy. An eggshell is present in the earliest embryonic stages examined but regresses relatively early in development. Placental specializations of this species are consistent with a pattern of matrotrophic embryonic nutrition and have evolved in a unique lineage specific developmental pattern.  相似文献   

15.
    
Three experimental manipulations were conducted to assess the influence of heat source selection and active thermoregulation on ultraviolet (UV) light exposure in captive spiny-tailed iguanas (Oplurus cuvieri) at the Jersey Wildlife Preservation Trust. Four replicates per manipulation were conducted on six individual lizards. All animals were tested in a separate enclosure to which they were acclimated before observations. Data on choice of thermal sources were collected during the first 2 hr of light, when lizards were actively thermoregulating. Animals were allowed to choose between incandescent light, UV light and a non-light heat source (thermotube) in different combinations. Recorded temperatures close to the incandescent light (37°C) were always significantly higher than at the thermotube (33°C) and at the UV light (29°C). Manipulation 1 offered the animals a choice of an UV light and an incandescent light as thermal sources. Manipulation 2 presented animals with the thermal choices in Manipulation 1, but substrates under each source in Manipulation 1 were switched. In Manipulation 3, animals could choose between an incandescent light and the thermotube. All studied lizards were significantly more attracted to the incandescent light than to the UV light or thermotube. Incandescent light elicited a significantly higher proportion of basking behaviors in all individuals than the other sources. A high proportion of time basking was also spent in front of the thermotube but fewer individuals and less time were spent basking under the UV light. Heat source selection was generally found to be independent of substrate. Management applications of this preference are suggested for juvenile diurnal heliothermic iguanids. Zoo Biol 16:391–401, 1997. © 1997 Wiley-Liss, Inc.  相似文献   

16.
海南岛蜥蜴类多样性   总被引:1,自引:2,他引:1  
经过多年调查,共得海南岛蜥蜴类动物标本238号,隶属5科16属22种。综合文献记录,海南岛实有蜥蜴类动物8科19属28种,约占全国总数的17%,多于福建,与广东省(含香港)相当,略少于台湾和广西。海南蜥蜴类均为东洋界物种,物种多样性较高,但特有种较少。  相似文献   

17.
Geographical variation in the degree of thermoregulatory behaviour of the lizard Tropidurus torquatus was studied in 10 restinga populations along approximately 1500 km of Brazilian coast. An index of thermoregulation was estimated using the difference between body and environmental (air and substrate) temperatures and the percentage of negative values for these differences (proportion of body temperatures lower than environmental temperatures). In most populations, the lizards primarily used active thermoregulation, through behavioural means, and mainly in relation to substrate temperatures. Along the restingas, the degree of active thermoregulation increased as a function of the increase in the local environmental temperatures along the restingas. Behavioural thermoregulation of T. torquatus helps the lizards to maintain their body temperatures within an optimal range in which to perform their normal daily activities.  相似文献   

18.
Ectoparasitism may be recognized as one of the main costs of coloniality, but little is known about how it affects the fitness and social structure of bats, the most gregarious of mammals. We studied these issues using the colonial bat Miniopterus schreibersii and its haematophagous parasitic mite Spinturnix psi as a model. Body condition is an important indicator of individual fitness that is potentially affected by ectoparasitism. Thus, we measured host body condition and mite loads in a total of 969 bats throughout the annual cycle. Mites were rare while hosts hibernated, increased in abundance in spring and peaked during nursing season of bats, when they were particularly abundant on lactating females and young bats. This strong seasonal variation in mite loads is related to the reproductive cycle of mites, which in turn appears to be synchronized with the reproductive cycle of their hosts. Mite loads and the condition of bats were negatively correlated, and information available suggests that this may be due to an effect of parasitism, although other possible causes for this trend cannot be excluded. However, a negative correlation was only observed during the bat's nursing season, when mites were most abundant, and heavily parasitized bats lost about 10% of their weight. Mite parasitism did not seem to be a significant disadvantage of coloniality, except in nurseries, where it might impose some costs. However, as females and young usually aggregate in these colonies, we presume that for them such costs are probably offset by advantages of group living. Adult males, however, are usually absent from nurseries, which may be a strategy to minimize mite parasitism. Overall, the results suggest that ectoparasitism may play a role in determining the social structure of M. schreibersii and of many other temperate bats that have similar life cycles and ectoparasitic loads.  相似文献   

19.
We are presenting a list of the reptile species from Lençóis Maranhenses National Park (LMNP), Maranhão, Brazil, obtained during 235 days of field work. The study area is located in the contact zone between three major Neotropical ecosystems: Amazonia, Caatinga, and Cerrado. The PNLM encompasses the largest dune fields in Brazil, wide shrubby areas (restingas), lakes, mangroves, and many freshwater lagoons. We have recorded 42 species of reptiles in the area: 24 snakes, 12 lizards, two worm lizards, three turtles, and one alligator. About 81 % of the recorded species occurred only in restinga areas. Our data highlights the uniqueness of the PNLM in the context of the biomes that surround it and shows the importance of efforts to improve the conservation of reptiles living in the restinga, which currently comprise only about 20 % of the total area protected by the park, but which are the mesohabitat containing most of the reptile species in the Lençóis Maranhenses complex of habitats.  相似文献   

20.
The fine structure of the different stages of the Fallisia effusa (Haemosporina: Garniidae), infecting the thrombocytes of the semi-aquatic Amazonian lizard Neusticurus bicarinatus (Reptilia: Teiidae) is described. Gametocytes, meronts, and merozoites of Fallisia effusa were found within a parasitophorous vacuole (PV). Multiple infections of micro- and macrogametocytes were observed. A circumferential coil of microtubules was seen in the cytoplasm of the infected host cell and this microtubule array was pronounced in cells harboring gametocytes. A deep invagination of the inner membrane complex of gametocytes may be involved in nutrition. The non-pigmented parasites underwent both merogony and gametogony in thrombocytes of the peripheral blood. No infection of the erythrocytes was observed. These observations confirm that Fallisia effusa displays characteristic features distinguishing it from other members of the Haemosporidian families, and that it has the ability to modulate microtubule assembly.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号