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1.
The wild boar (Sus scrofa) is a medium-sized ungulate that produces a large variety of marks. Traditionally, wallowing is an activity that has fundamentally been related to several processes such as thermoregulation, reduction in the number of ectoparasites or disinfection of wounds in the skin of males resulting from fights to reach females. In this study, I analysed another possible function of wallowing in free-ranging wild boar populations when temperatures are low and parasitic numbers are not significant. The results indicate that during the sampling time, from October to February, the number of wild boars with a mud layer on their skin was 47, out of a total of 558 wild boar analysed. Of these 47 wild boars, 44 were males and within this group, 40 individuals were adult males. The wallowed males were bigger and older than non-wallowed males hunted at the same time. In addition, I found that males wallowed mainly during autumn (90.9% of all cases). In the total number of wild boars analysed, I did not notice individuals with wounds resulting from fights other than from the hunting day. On the other hand, the analysis of the females reproductive systems indicated that the rut period took place during the last days of October and the first days of November. From these results, the coincidence of the rut period with the maximum of wallowing in adult males could be indicative of a sexual function of this activity.  相似文献   

2.
Pholidoteuthis is unusual amongst genera of squid in that the mantle is beset with close-packed dermal cushions (scales). Despite frequent reference to species in this genus, considerable systematic confusion surrounds usage of the generic name, erected prematurely given that the same systematic characters apply for the earlier Tetronychoteuthis Pfeffer, 1900, and species attributed to it. The synonymy and ontogenetic morphology of Pholidoteuthis massyae (Pfeffer 1912) new comb., the senior synonym of P. boschmai Adam, 1950, is reported. The relationship between this species and others referred to Tetronychoteuthis, Lepidoteuthis, the Pholidoteuthidae Adam, 1950, Lepidoteuthidae Pfeffer, 1912 and Octopoteuthidae Berry, 1912, is discussed. A conjectural account of the mechanics of mating in P. massyae is provided based on the nature of spermatophore insertion in the female mantle, and modification to the terminal region of the male’s genital apparatus.  相似文献   

3.
The presence of multigerm seedballs in the chenopodiacious genusSpinacia is noted. In the wild, colonising, and weedy dioecious species,S. turkestanica andS. tetrandra, the distribution of a multigerm seedball could effectively overcome the problem posed by isolation of the sexes. The hypothesis is tested assessing the extent of intra-seedball progeny hybridisations and seed production in the two wild species. The success in seed production by intra-seedball progeny crosses suggests that the distribution of such seedball progeny groups permits not only a percentage survival under isolation of these dioecious plants, but also the colonisation of areas outside that of the parent populations.  相似文献   

4.
Plant species that secrete oil as their primary floral reward are rare and sporadically found in the angiosperms. We report here thatMonttea, a genus previously unsuspected of being an oil-plant, produces lipids from trichome elaiophores on the inside of the lower (anterior) lip. The discovery of the production of oils by species of this S. American genus explains the occurrence of unusual dual-function collecting structures in ArgentineCentris (Hymenoptera: Anthophoridae) and explains the presence of oil-collecting bees in regions where oil-secreting flowers were previously thought to be absent. The behavior of these centridine pollinators onMonttea flowers parallels that of oil-collecting bees onDiascia (Scrophulariaceae) in S. Africa.  相似文献   

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We investigated the phylogenetic relationships among most Chinese species of lizards in the genus Phrynocephalus (118 individuals collected from 56 populations of 14 well-defined species and several unidentified specimens) using four mitochondrial gene fragments (12S rRNA, 16S rRNA, cytochrome b, and ND4-tRNA(LEU)). The partition-homogeneity tests indicated that the combined dataset was homogeneous, and maximum-parsimony (MP), neighbor-joining (NJ), maximum-likelihood (ML) and Bayesian (BI) analyses were performed on this combined dataset (49 haplotypes including outgroups for 2058bp in total). The maximum-parsimony analysis resulted in 24 equally parsimonious trees, and their strict consensus tree shows that there are two major clades representing the Chinese Phrynocephalus species: the viviparous group (Clade A) and the oviparous group (Clade B). The trees derived from Bayesian, ML, and NJ analyses were topologically identical to the MP analysis except for the position of P. mystaceus. All analyses left the nodes for the oviparous group, the most basal clade within the oviparous group, and P. mystaceus unresolved. The phylogenies further suggest that the monophyly of the viviparous species may have resulted from vicariance, while recent dispersal may have been important in generating the pattern of variation among the oviparous species.  相似文献   

9.
This study examines early embryogenesis in two species of darters, Etheostoma caeruleum and E. zonale (Teleostei: Percidae), and their hybrids. Results document the course of ontogeny from fertilization until the onset of pigmented eyes. Comparing fertilization and developmental success of conspecific versus heterospecific crosses revealed an asymmetric postmating reproductive barrier. E. caeruleum eggs treated with E. zonale sperm exhibited fertilization and developmental success similar to that of conspecific crosses. In contrast, E. zonale eggs treated with E. caeruleum sperm exhibited reduced fertilization relative to conspecific crosses and abnormal development. Development in this latter cross was compromised at all stages, but appeared to be concentrated around epiboly, or cell migration. As epiboly represents the stage of ontogeny when zygotic genes of both species jointly contribute to embryogenesis, results provide insight into the genetic mechanisms underlying postmating barriers in Etheostoma. Finally, the observed asymmetry in fertilization success is consistent with predictions based on the behavioral ecology of these species. Etheostoma zonale spawn in the open water column, whereas E.␣caeruleum bury their eggs under the substrate. The observed fertilization barrier may have therefore resulted from selection favoring increased fertilization specificity in E. zonale.  相似文献   

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The antennae of Lepidoptera Neopseustidae were examined with the scanning electron microscope. The studied species, Nematocentropus cfr. omeiensis, Neopseustis meyricki, Synempora andesae, Apoplania valdiviana and Apoplania penai possess nine types of antennal flagellum sensilla: multiporous large sensilla basiconica, multiporous thin sensilla basiconica, multiporous small sensilla basiconica, multiporous sensilla trichodea, multiporous sensilla coeloconica; uniporous sensilla chaetica; aporous sensilla chaetica, aporous stylus-shaped sensilla chaetica, aporous sensilla styloconica.The multiporous sensillum type here termed “multiporous large sensillum basiconicum” is unknown from other Lepidoptera and probably constitutes an autapomorphy of the family Neopseustidae. This sensillum type is remarkable by having a single base in female Apoplania and Synempora while in male Apoplania it has a bifid or trifid base, and in male Synempora it is composed of two or three incompletely separated hairs. This may be the first recorded example of a sexually dimorphic lepidopteran sensillum type. The stylus-shaped sensillum chaeticum is a primitive type which occurs only in some lower Lepidoptera.  相似文献   

12.
The caudal fin represents the posteriormost region of the vertebrate axis and is one location where forces are exerted to the surrounding medium. The evolutionary changes of its skeleton have been well analyzed in gnathostomes and revealed transitions from heterocercal to diphycercal and homocercal tails. In contrast, we only know little about the evolutionary transformations of the muscular system of the caudalis and about possible ways of force transmission from anterior myomeres to the caudal fin. The goals of this study are to gain insight into evolutionary transformations of the musculoskeletal system in the four basal actinopterygian groups (Cladistia, Chondrostei, Ginglymodi, and Halecomorphi) and to identify likely pathways of force transmission to the tail. In this context, the connective tissue of the myosepta is considered to be an essential part of the musculoskeletal system. For the first time, this system is analyzed for the whole postanal region. The use of microdissection techniques and polarized light microscopy revealed the collagen fiber architecture and the insertions of all postanal myosepta from cleared and stained specimens. The collagen fiber architecture is similar in all investigated specimens and thus represents the primary actinopterygian condition. All parts of postanal myosepta are dominated by longitudinally arranged myoseptal tendons (lateral and myorhabdoid tendons) that span several vertebral segments. This architecture supports the view that posterior myosepta are well designed to transfer muscular forces that are generated in anterior myomeres. In contrast to the uniform myoseptal architecture, the musculoskeletal system differs between the four basal actinopterygian groups. Among them, chondrosteans have retained the plesiomorphic condition of actinopterygian tails. For the remaining taxa several evolutionary novelties in the musculoskeletal system of the tail are revealed. Most of these have evolved independently in the cladistian and neopterygian stem lineage. In these groups extensions of all epaxial and hypaxial parts of myosepta are present that insert on caudal fin rays. This remarkable contribution of epaxial muscle masses to the caudal fin organization is in contrast to the skeletal organization, that largely derives from hypaxial material only. In contrast to former studies the hypochordal longitudinalis muscle is shown to be a synapomorphy of Halecostomi (Halecomorphi + Teleostei). The morphological framework presented here allows to generate new hypotheses on the function of caudal fins that can be tested experimentally.  相似文献   

13.
Synopsis Etheostoma swaini, the gulf darter, was collected from the Black Creek drainage in southern Mississippi (February 1978 – April 1979). The gulf darter generally inhabits small- to moderate-size creeks and occurs over a sand or sandy mud bottom, often in association with aquatic vegetation or a layer of organic debris. Larval dipterans were the most important food items, both numerically and volumetrically. Chironomids were found in 71–100% of the stomachs in all except the unusual March 16 collection. The length frequency distribution and the scale annuli analysis indicated there were three year-classes present in the population at any one time. Fifty-one percent of the specimens taken were less than 12 months old. During the mid-February to late March spawning season gulf darters were most often collected over clean gravel or gravelsand substrates. Laboratory observations suggest that the female burrows into the gravel where the demersal, adhesive eggs are deposited. Female gulf darters significantly outnumbered males at a ratio of 59:41.  相似文献   

14.
Snubnose darters comprise one of the largest subgenera of the percid genus Etheostoma. Many species are described based on differences in male breeding coloration. Few morphological synapomorphies have been proposed for the subgenus and their relatives, making it difficult to delineate monophyletic clades. The phylogenetic relationships of the 20 snubnose darter species of the subgenus Ulocentra and 11 members of its proposed sister subgenus Etheostoma were investigated with partial mitochondrial DNA sequences including 1033 bp encompassing the entire mitochondrial control region, the tRNA-Phe gene, and part of the 12S rRNA gene. Two hypotheses on the relationship and monophyly of the two subgenera were evaluated. Both maximum-parsimony and neighbor-joining analyses supported monophyly of the subgenus Ulocentra and resolved some species-level relationships. The banded darter, E. zonale, and its sister taxon, E. lynceum, were not closely related to the snubnose darters and appear to be diverged from the other members of the subgenus Etheostoma, fitting their former distinction as the recognized subgenus Nanostoma. The sister group to Ulocentra appears to be a restricted species assemblage within the subgenus Etheostoma containing E. blennioides, E. rupestre, E. blennius, and the E. thalassinum species group. The placement of the harlequin darter, E. histrio, is problematic, and it may represent a basal member of Ulocentra or of the restricted subgenus Etheostoma. Despite recent estimates of divergence times between nominal Ulocentra taxa, each species exhibits its own unique set of mtDNA haplotypes, providing no direct evidence for current genetic exchange between species. The nominal taxa of snubnose darters thus appear to be evolving independently from each other and therefore constitute valid species under the Phylogenetic Species Concept.  相似文献   

15.
The morphology of an unarmored chain-forming harmful dinoflagellate Cochlodinium polykrikoides and its similar species such as Cochlodinium catenatum, Cochlodinium fulvescens, and Cochlodinium convolutum was carefully observed, emphasizing the single cell stage for clarifying taxonomically important morphological features. To differentiate C. polykrikoides from C. convolutum, the shape and the position of the nucleus are useful characters. C. polykrikoides also differs from C. fulvescens in being smaller in size, possessing many rod-shaped chloroplasts and having the sulcus running just below the cingulum on the dorsal surface. Careful observation of the ichnotype of C. catenatum suggests that C. catenatum sensu Kofoid and Swezy collected from off La Jolla, CA, USA, is not identical to C. catenatum sensu Okamura and is probably a different species, in having no chloroplasts and a nucleus positioned at the center of the cell. In addition, C. polykrikoides has many morphological features in common with C. catenatum sensu Okamura except for slightly elongate cells and is probably a junior synonym of this species.  相似文献   

16.
Preimaginal development and adult longevity and reproduction of Dichochrysa prasina Burmeister were studied at six constant temperatures (15, 20, 25, 27, 30 and 33 °C) and a photoperiod of 16:8 (L:D). Eggs of the flour moth Ephestia kuehniella (Zeller) were used as food throughout preimaginal development, whereas the adults of D. prasina fed on a liquid diet of water, yeast hydrolysate, sugar and honey. At the highest tested temperature of 33 °C no larvae completed their development. At the rest of the tested temperatures the egg to adult developmental period ranged from approximately 92 days at 15 °C to 25 days at 30 °C. Percentages of adult emergence ranged from 36% at 15 °C to 84% at 30 °C. Both adult longevity and fecundity were significantly affected by temperature and the intrinsic rate of increase (rm) reached its maximum value at 27 °C. These results could be useful for the establishment of a small scale rearing and mass production of D. prasina.  相似文献   

17.
Cabomba aquatica has been found for the first time in India. Both, submerged and floating leaves are epistomatic. The stomata are anomocytic and perigenous in their development. The metaxylem vessel elements have simple perforation plates and spiral side wall thickening. Vessel elements are found in roots, rhizomes and aerial stems. The venation pattern is of two types like the dimorphic leaves. On the basis of these and other featuresCabomba deserves family rank.  相似文献   

18.
Stratiolaelaps ( = Hypoaspis) miles (Berlese) (Acari: Mesostigmata: Laelapidae) is a polyphagous soil-dwelling predatory mite that is widely marketed for use in greenhouse production systems to manage populations of dark-winged fungus gnats, Bradysia spp. (Diptera: Sciaridae) and for supplemental control of thrips. The suggestion by Walter and Campbell (2003, Biol. Control 26: 253–269) that North American commercial cultures of S. miles may actually be S. scimitus was confirmed. The development and reproduction at 21–23 °C of S. scimitus provided ad libidum with one of three different prey – the fungus gnat Bradysia aff. coprophila (Lintner), potworms (Enchytraeidae), or Sancassania aff. sphaerogaster (Zachvatkin, 1937) (Acari: Astigmata: Acaridae) – were compared. Developmental duration of the egg and non-feeding larval stages were 2.47 and 1.11 days, respectively; mortalities were 8.3 and 5.5%. Stratiolaelaps scimitus failed to develop beyond the protonymphal stage when provided with S. aff. sphaerogaster alone, although some feeding was observed. Development and reproduction of S. scimitus was successful on both fungus gnat larvae and enchytraeids, with no influence of prey on protonymphal duration (4.70 days) and mortality (8.3%), or on deutonymphal duration (4.61 days) and mortality (6.1%). Adult female S. scimitus feeding on potworms, compared to those feeding on fungus gnat larvae, had a significantly shorter pre-oviposition period (2.69 vs. 4.59 days). However, diet did not influence other adult female developmental or reproductive characteristics (oviposition period, 18.6 days; post-oviposition period, 6.2 days; total adult longevity, 27.3 days; total number of eggs, 26.5). S. scimitus reared on potworms tended (p = 0.06) to have a higher intrinsic rate of increase, a higher finite rate of increase and a shorter doubling time (r m = 0.142 day−1, λ = 1.153, Dt = 4.85 days) than those reared on fungus gnat larvae (r m = 0.105 day−1, λ = 1.110, Dt = 6.58 days), but differences in net reproductive rate (R 0) and generation time (G) were not significant.  相似文献   

19.
Seedling morphology was studied in 22 species ofLespedeza, of which six belong to subgenusMacroles-pedeza and 16 to subgenusLespedeza. Two seedling types were recognized: 1) those with opposite leaves at the first node; 2) those having the first and subsequent leaves alternate. The two types are distinguished in the number of leaf primordia in the plumule of the seed: the opposite type has two leaf primordia, but the alternate type has only one primordium. Most species exhibited one of the two types, but rarely both types were observed in several species. In species having two types, one type always far outnumbers the other. The opposite type was common in Asian species, while the alternate type was common in North American ones. Because seedlings are of the opposite type inKummerowia which is the most closely related genus withLespdeza, the alternate type is considered to be apomorphic inLespedeza. The apomorphic seedling morphology is, there-fore, dominantly occurred in North American species ofLespedeza. This fact may be an evidence which suggests a monophyletic origin for North American species from an Asian ancesfor.  相似文献   

20.
A new genus, Cystobasidiopsis, and a new species, Cystobasidiopsis nirenbergiae, are described for a fungus isolated from an arable loess soil in Ahlum near Braunschweig, Niedersachsen, Germany. An integrated analysis of morphological, ecological, ultrastructural and molecular data indicates that the new species belongs to the Chionosphaeraceae within the Agaricostilbales. Relevant characteristics of the new species are discussed and compared with those of related taxa.  相似文献   

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