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1.
A natural population ofDrosophila melanogaster in southern France was sampled in three different years and 10 isofemale lines were investigated from each sample. Two size-related
traits, wing and thorax length, were measured and the wing/thorax ratio was also calculated. Phenotypic plasticity was analysed
after development at seven different constant temperatures, ranging from 12‡C to 31‡C. The three year samples exhibited similar
reaction norms, suggesting a stable genetic architecture in the natural population. The whole sample (30 lines) was used to
determine precisely the shape of each reaction norm, using a derivative analysis. The practical conclusion was that polynomial
adjustments could be used in all cases, but with different degrees: linear for the wing/thorax ratio, quadratic for thorax
length, and cubic for wing length. Both wing and thorax length exhibited concave reaction norms, with a maximum within the
viable thermal range. The temperatures of the maxima were, however, quite different, around 15‡C for the wing and 19.5‡C for
the thorax. Assuming that thorax length is a better estimate of body size, it is not possible to state that increasing the
temperature results in monotonically decreasing size (the temperature-size rule), although this is often seen to be the case
for genetic variations in latitudinal clines. The variability of the traits was investigated at two levels—within and between
lines—and expressed as a coefficient of variation. The within-line (environmental) variability revealed a regular, quadratic
convex reaction norm for the three traits, with a minimum around 21‡C. This temperature of minimum variability may be considered
as a physiological optimum, while extreme temperatures are stressful. The between-line (genetic) variability could also be
adjusted to quadratic polynomials, but the curvature parameters were not significant. Our results show that the mean values
of the traits and their variance are both plastic, but react in different ways along a temperature gradient. Extreme low or
high temperatures decrease the size but increase the variability. These effects may be considered as a functional response
to environmental stress. 相似文献
2.
Experiments carried out on underyearlings of four fish species—roach Rutilus rutilus, carp Cyprinus carpio, bream Abramis brama, and perch Perca fluviatilis—at illumination of 200–300 lx showed that the specimens with negative type of rheoreaction move downstream mainly (47–93%)
in the active form, with their heads downstream, and rarer (3–37%) in the active-passive form, with their tails downstream.
Increase of motivation for downstream movement caused by starvation leads to a higher part of fish with an active form of
movement and to greater speed of movement of underyearlings. Active downstream movement is a manifestation of rheoreaction. 相似文献
3.
Yuzuru Hamada Tsuyoshi Watanabe Osamu Takenaka Bambang Suryobroto Yoshi Kawamoto 《Primates; journal of primatology》1988,29(1):65-80
The body color of Sulawesi macaques was measured quantitatively and compared among the different monkeys. As a result, divergence
models for extant Sulawesi macaques, withtonkeana as the starting point and fading as the sole direction of color change, were inferred as follows: (1) fading slightly on
the upper half of the body—nigra, fading more on the proximal part of the body—nigrescens; (2) fading over the whole body—maura; (3) fading greatly on the legs—hecki; and (4) fading on the distal part of the body—ochreata, fading more over the whole body, including the proximal part of the body—brunnescens. The color changed progressively in the order of (1) through (4). The divergence model, excluding the position ofhecki (3), supports the speciation model ofFooden (1969). If the proto-Sulawesi macaques had a body color pattern similar to the livingnemestrina, darkening would have been necessary for the evolution of the Sulawesi macaques after their immigration, and it may have
been acquired as an adaptation to the ground (forest floor) living nature of the Sulawesi macaques, together with influences
deriving from the insularity and/or from the absence of predators. 相似文献
4.
The concept of cooperative communities that enforce norm conformity through reward, as well as shaming, ridicule, and ostracism,
has been central to anthropology since the work of Durkheim. Prevailing approaches from evolutionary theory explain the willingness
to exert sanctions to enforce norms as self-interested behavior, while recent experimental studies suggest that altruistic
rewarding and punishing—“strong reciprocity”—play an important role in promoting cooperation. This paper will use data from
308 conversations among the Ju/’hoansi (!Kung) Bushmen (a) to examine the dynamics of norm enforcement, (b) to evaluate the costs of punishment in a forager society and understand how they are reduced, and (c) to determine whether hypotheses that center on individual self-interest provide sufficient explanations for bearing the
costs of norm enforcement, or whether there is evidence for strong reciprocity.
Polly Wiessner is a professor of anthropology at the University of Utah. She has carried out fieldwork with the Ju/’hoansi
of the Kalahari for the past 30 years on social networks, style in artifacts, economy, population, nutrition, and social change.
She has also worked among the Enga of Papua New Guinea since 1985 on the oral history of exchange, ritual, and warfare. 相似文献
5.
E. D. Pavlov E. V. Mikodina M. A. Sedova N. G. Emel’yanova G. N. Markevich 《Journal of Ichthyology》2010,50(4):321-329
Morphology of gonads and structure of sex cells in females and males of the resident sockeye salmon Oncorhynchus nerka—kokanee—from Tolmachevskoe Reservoir are investigated. Anomalies in structure of sex cells and structure of oocytes are found.
Partial or mass resorpbion of cells in the ovaries of males and testes of males is found, leading to sterility of gonads.
The relationship between anomalies found in structure of the sex system of kokanee, changes in biological parameters of fish
and the increase of the population abundance is discussed. 相似文献
6.
I. A. Niaze 《Journal of biosciences》1996,21(3):273-297
Studies on the effects of exogenous vitamin A palminate on limb development and regeneration in anuran tadpoles carried out
since late 1960s at the author’s laboratory are reviewed and discussed. Most significant was the initial discovery that vitamin
A causes regeneration of complete or nearly complete limbs instead of only the missing distal part, thus altering the P-D
pattern of regeneration—a phenomenon now called proximalization. Often more than one such regenerates develop per stump. Vitamin
A produces proximalizing effect on regeneration cells during their dedifferentiation and blastema formation but inhibits regeneration
if given once redifferentiation begins. Shank-level blastemas from treated tadpoles grafted into orbits of previously treated/untreated
host tadpoles formed complete limbs. Proximalizing effect is proportionate to vitamin A concentration, duration of treatment,
amputational level and stage of tadpoles. Vitamin A produces this effect also if given only prior to amputation. Its influence
persists after cessation of treatment, declining with time. Proximalizing effect is correlated with natural ability in limbs
to regenerate. Vitamin A improves regenerative ability and can induce it to some extent in non-regenerating limbs. Vitamin
A excess retards limb development and produces stage dependent teratogenic defects. Further development of only that limb
region is prevented in which differentiation is beginning when vitamin A is given. Short treatment of tadpoles beginning with
limbs at spatula/paddle stage inhibited foot development in the unoperated limbs hut promoted regeneration of complete limbs
from the contra-lateral amputated limbs. These dual effects were due to cells of the former differentiating and of the latter
dedifferentiating when exposed to vitamin A palmitate. 相似文献
7.
Partial caudal duplication in a newborn associated with meningomyelocele and complex heart anomaly 总被引:1,自引:0,他引:1
Bannykh SI Bannykh GI Mannino FL Jones KL Hansen L Benirschke K Masliah E 《Teratology》2001,63(2):94-99
BACKGROUND: Caudal duplication is a spectrum of rare congenital anomalies with a possible heterogeneous pathogenesis including incomplete separation of monovular twins. METHODS: We report an autopsy case of a full-term infant with incomplete caudal duplication syndrome associated with multiple anomalies. RESULTS: These anomalies included a duplicated penis; double urinary bladder with an attenuated tunica muscularis; duplication of lower bowel with two ilia, appendices and colons; colonic hypogangliosis and left imperforated anus associated with rectourethral fistula. Other anomalies consisted of sacral meningomyelocele, sacral duplication with hypoplastic left sacrum and pelvic bones, muscle atrophy and hypoplasia of the left lower extremity, abnormal lobation of liver with stomach entrapment, omphalocele, and right atrial isomerism syndrome. The complex pattern of anomalies suggests the possibility that partial caudal duplication might be part of the spectrum of conjoined twinning. 相似文献
8.
Philip H. Crowley 《Bulletin of mathematical biology》1977,39(2):157-166
Ifconstancy is a measure of an ecosystem's (in) variability through time andstability is a measure of the system's ability to damp and recover from environmental perturbations, then constancy depends not only
on stability but also on the frequency and amplitude of perturbations—theenvironmental “noise level”. The stability of an ecosystem reflects its texture, extent, and viscosity (fine-scale structure); the noise level experienced
by the system (“effective” noise level) reflects the level at any point (“ambient” noise level), the spectrum of stochastic
scale (regional distribution of stochasticity), and the system's spatial extent (size, or number of patches included). The
coefficient of variation of a limiting stochastic variate is a measure of the effective noise level. Ifp is the total number of patches in the system (its extent) andn is the number of contiguous patches with noise signals correlated through time (its stochastic scale), then the coefficient
of variation is directly proportional to
whenevern<p. Thus ecosystems of small stochastic scalen or large sizep damp out environmental noise by “spreading the risk” in space, thereby reducing their variability in time. 相似文献
9.
F. N. Shkil V. B. Borisov Belay Abdissa S. V. Smirnov 《Russian Journal of Developmental Biology》2010,41(6):369-380
The role of thyroid hormone in the ontogeny of the Large African barb Barbus intermedius sensu Banister, 1973 (Teleostei; Cyprinidae)—the presumed ancestral species for the species flock of the large African Barbs of
Lake Tana (Ethiopia)—has been studied. It has been shown that the thyroid hormone influences the timing and rate of many morphogenetic
processes and a change in its level causes heterochronies, affecting the definitive morphology of fish. Thus, it can be assumed
that even a slight change in activity of the thyroid axis during ontogeny can be the cause of wide morphological variability
in B. intermedius and may underlie explosive diversification of the species flock of Large African Barbs of Lake Tana. 相似文献
10.
Adam D. Gordon 《International journal of primatology》2006,27(1):27-61
I used a new quantitative genetics model to predict relationships between sex-specific body size and sex-specific relative variability when populations experience differences in relative intensity of sex-specific selection pressures—stronger selection on males or females—and direction of selection: increase or decrease in size. I combined Lande's (Evolution 34: 292–305) model for the response of sex-specific means to selection with a newly derived generalization of Bulmer's (Am. Nat. 105: 201–211) model for the response of relative variability to selection. I used this combined response model to predict correlations of sex-specific size and relative variability under various starting conditions, which one can compare to correlations between closely related primate populations. One can then compare predicted patterns of sex-specific selection pressures to social and ecological variables pertaining to those populations to identify likely forces producing microevolutionary change in sexual size dimorphism (SSD). I provide examples of this approach for populations representing three taxa: Papio anubis, Saguinus mystax, and Cercopithecus aethiops pygerythrus. Model results suggest that microevolutionary changes in SSD can result from greater selection acting on males or females, and that natural selection or natural and sexual selection combined, rather than sexual selection alone, may sometimes explain sex-specific selection differentials. 相似文献
11.
E. P. Voronina 《Journal of Ichthyology》2009,49(10):940-961
Structure of nonmodified scales and lateral-line scales (Sll) is compared in 179 species of 105 genera of 13 families of the order Pleuronectiformes. Morphological diversity of Sll depends on the level of development and of interaction of two component parts—the scale plate and the tubular part. Of the
considered characters, the most individually variable character is whether the tubular part is complete or incomplete. The
interspecies differences may manifest themselves in structure of the scale plate, the level of unification of opening of the
tubular part and of the cutaneous canaliculus, or in completeness or incompleteness of the tubular part. As a rule, Sll in species of the same genus is similar in structure. In some cases, special traits of this structure may be diagnostic characters
of genera and contribute to the solution of controversial issues of generic position of species. The families of Pleuronectiformes
are characterized by a different ratio of taxa with certain involved characters of nonmodified scales and Sll. However, their distribution in this order does not give a simple idea on their relationships and on the direction of evolutionary
transformations. This follows from the fact that the structure of Sll depends on a wide complex of factors—morphogenesis of nonmodified scales, level of ossification of trunk canal, time of anlage,
and mutual influence of these structures at early stages of ontogenesis. 相似文献
12.
Ch. Berge 《Human Evolution》1991,6(5-6):365-376
Two multivariate methods — the logarithmic principal component analysis (LPCA), and the logarithmic factorial analysis (LFA)
— have been used tocompare the hip bone proportions of hominoids biometrically. The results have shown that size effects among
apes and hominids interact to a centain extent with locomotor specializations, which are related to the attainment of more
or less terrestrial behaviors.
The pelvic morphology of great apes (Pongo, Pan, Gorilla) has retained numerous morphological traits — such as a gracile and elongated hip bone —, which were inherited from common
adaptations to arboreal locomotion. In spite of these common traits, the African pongids (Pan, Gorilla) present two very different pelvic morphologies corresponding to two adaptative modes of terrestrial quadrupedalism.
The hip bone of humans is proportionnally short and robust, most particularly at the level of its axial part. These characteristics,
as well as the whole pelvic proportions, clearly indicate that gravitational forces exert a strong pressure on the pelvic
walls during bipedalism. Among hominids, the transition from an australopithecine-like pelvic pattern to a human-like one
corresponds to an increase of loading constraints on the hip jiont. This seems to indicate an evident change in locomotor
behavior. Progression apparently became exclusively terrestrial with the genusHomo. 相似文献
13.
Spatial and temporal variability in a butterfly population 总被引:2,自引:0,他引:2
C. D. Thomas 《Oecologia》1991,87(4):577-580
Summary The dynamics of a butterfly (Plebejus argus) population were analysed at two levels, (i) the population as a whole and (ii) sections within the population. Some sections
of the population fluctuated out of synchrony with others, such that the variability [SD Log(Density+1)] shown by the population
as a whole was less than the variability shown by each part of the population — overall temporal variability was dampened
by spatial asynchrony. Since observed population variability depends on the spatial scale that is sampled, comparisons of
population variability among taxa should be carried out only with caution. Implications for island biogeography and conservation
biology are discussed. 相似文献
14.
Due to the variant functions that estrogens play in the regulation of reproduction, development of the mammary gland, growth
and differentiation of cells, estrogen receptors and their genes are considered as a candidates for the markers of production
and functional traits in farm animals, including cattle. In the earliest study, a 2853-bp bovine ER gene 5′-region was PCR
amplified and sequenced. Moreover, for the first time, a polymorphism was described within 5′ region of the bovine ERα gene—A/G
transition lying upstream at position 2591 from acceptor splice site +85, possibly within its promoter—which could be recognized
with RFLP-BglI. In other study we are found second polymorphism—A/G transition at position 1213 from acceptor splice site +85, located
in promoter for exon B. We have examined the specific mRNA expression of ERα in various genotypes using real-time RT-PCR.
We used four animals from each genotype group—AG, GG for BglI and AA, AG for SnaBI—to analyse liver ERα expression at the level of Real-time PCR. Liver samples were taken from the 16 young Friesian bulls
of the different ERα genotypes, slaughtered at the local abattoir. As shown by Real-Time PCR, on the livers of animals with
different genotype ERα mRNA for BglI polymorphism we didn’t found variability, but for SnaBI we have found variability between AG and AA genotypes. 相似文献
15.
Many areas of blanket mire in Britain display apparently degraded vegetation, having a limited range of ericaceous and Sphagnum species. Data are presented here from Wales from the upland locality of Drygarn Fawr (Elenydd SSSI), which is dominated overwhelmingly
by Molinia caerulea. Palaeoecological techniques were used to chronicle vegetation history and to determine the nature and timing of vegetation
changes, as an aid to devising conservation management and restoration strategies. Although for the past 2000 years the pollen
and plant macrofossil data indicate some evidence for cyclic vegetation change, they demonstrate that here the major vegetation
change post-dated the start of the industrial revolution. The palaeoecological data show a greater proportion of Sphagnum than currently. Local extinction of some species (e.g., Myrica gale) apparently took place in Medieval times, but most of the degradation and floral impoverishment apparently occurred during
the 20th Century. The implications for conservation management are far-reaching. The overwhelming dominance of Molinia is clearly unprecedented. While it was locally present for hundreds of years, some factor(s)—possibly a change in grazer
and grazing regime—encouraged its recent ascendancy in the 20th Century. Consequently, any management attempts to reduce the
pre-eminence of Molinia would not be countering an ingrained, long-established dominance. It is suggested that investigation of degraded blanket
mires elsewhere by historical and multi-proxy palaeoecological techniques—through multiple, dated cores to track species extinctions
and directional vegetation changes—would help ascertain previous mire floras and so indicate a range of restoration targets
for mire vegetation. 相似文献
16.
The structure of the junction between inverted repeat (IR) and small single copy (SSC) regions of the chloroplast genome in
the representatives of non-core Caryophyllales is investigated in this work. It was found that for two families—Polygonaceae
and Plumbaginaceae—the extension of inverted region is characteristic. This extension is due to the duplication of the part
of the ycf1 gene that is partly located in the small single copy region in plants with typical structure of IR/SSC junctions. Comparison
of the position of IR/SSC junctions in different species of Polygonaceae has shown that their exact position is not correlated
with the affinity of these species inferred from molecular and morphological data. Possible mechanisms leading to the change
in position of IR/SSC junctions observed in this work are discussed. 相似文献
17.
Volk A Karbasiyan M Semmler A Todt U Urbach H Klockgether T Linnebank M 《Birth defects research. Part A, Clinical and molecular teratology》2007,79(3):249-251
BACKGROUND: The symptom triad of autosomal dominant Currarino syndrome (CS; MIM #176450) consists of anorectal malformation, a sacral bone defect, and presacral masses. Mutations in the homeoboxHLXB9 gene have already been described in a subset of sacrococcygeal anomalies characterized by partial sacral agenesis. CASE: We report a 28-year-old male patient with Currarino syndrome due to a heterozygous novel frame-shift mutation c.336dupG (p.P113fsX224) in the homeoboxHLXB9 gene. CONCLUSIONS: Molecular diagnostics may be helpful in cases of Hirschsprung's disease accompanied by other symptoms suggestive for Currarino syndrome, since it can lead to major complications such as perianal sepsis, meningitis, and malignant transformation. 相似文献
18.
Sasha Daskalova Alex McCormac Nigel Scott Harry Van Onckelen Malcolm Elliott 《Plant Growth Regulation》2007,51(3):217-229
A transgenic approach to manipulation of endosperm development has been investigated. Nicotiana tabacum cv. Xanthi, an endosperm-containing dicotyledon, has been used as a model plant and the 2.6 kb wheat high molecular weight
(HMW) glutenin subunit 12 promoter has been used fused either to the gus reporter gene (HMWgus construct)—to study promoter characteristics—or to the Agrobacterium ipt gene—to study the effect of cytokinin (CK) over-expression on assimilate accumulation in the seed. In transgenic tobacco
the promoter:gus fusion showed that HMW is an endosperm-specific promoter with maximum expression 20 days after anthesis (DAA), corresponding
to the mid to late stages of seed development. Transgenic plants containing the HMWipt construct showed no morphological abnormalities but they had an average increase in seed weight and total ethanol-insoluble
carbohydrates and protein content of 8.1%, 7.0% and 8.3%, respectively. SDS PAGE analysis demonstrated that the effect on
protein accumulation was non-specific. The highest values of the parameters analysed correlated with moderate increases in
the levels of biologically active CKs. These results suggest that ectopic expression of small amounts of CKs can be used to
increase storage assimilate accumulation without a detrimental effect on development. 相似文献
19.
A. Jamsheer C. Henggeler J. Wierzba B. Loeys A. De Paepe Ch. Stheneur N. Badziąg K. Matuszewska G. Matyas A. Latos-Bieleńska 《Journal of applied genetics》2009,50(4):405-410
We report on a 2-year-old Polish girl with typical manifestations of Loeys-Dietz syndrome (LDS), a rare genetic condition
belonging to the group of Marfan-related disorders. The characteristic LDS symptoms observed in the girl included craniofacial
dysmorphism (craniosynostosis, cleft palate, hypertelorism), arachnodactyly, camptodactyly, scoliosis, joint laxity, talipes
equinovarus, translucent and hyperelastic skin, and umbilical hernia. Mild dilatation of the ascending aorta and tortuous
course of the left internal carotid artery were recognized during her second year of life. Molecular genetic testing revealed
a heterozygous missense mutation (c.1582C>T, p.R528C) in the transforming growth factor beta receptor II gene (TGFBR2). This mutation has been previously associated with LDS in 5 unrelated cases, and was never reported in patients with other
Marfan-related disorders. Comparison of the phenotypes of our patient and these 5 individuals with c.1582C>T showed that only
the hallmark triad of the syndrome — consisting of hypertelorism, aortic root dilatation/aneurysm, and cleft palate or bifid
uvula — was present in all 6 cases. Interestingly, none of the 5 individuals who underwent psychological evaluation showed
developmental delay. The pattern of all other LDS features showed interindividual variability. Our data support the recently
reported observation that symptoms of LDS can develop at a very young age, making early diagnosis and management essential
for these patients. This is the first report on a Polish infant with typical LDS symptoms caused by aTGFBR2 mutation. 相似文献
20.
Dragana Drakulović Branka Pestorić Mirko Cvijan Slađana Krivokapić Nenad Vuksanović 《Central European Journal of Biology》2012,7(3):470-486
The goal of this paper was to explain variability of phytoplankton in a shallow coastal area in relation to physico-chemical
parameters. Temporal variability and composition of phytoplankton were investigated in the Kotor Bay, a small bay located
in the south-eastern part of the Adriatic Sea. Samplings were performed weekly from February 2008 to January 2009 at one station
in the inner part of the Kotor Bay, at five depths (0 m, 2 m, 5 m, 10 m, 15 m). Phosphates, nitrites and nitrates ranged from
values under the level of detection to the maximum values of 1.54, 1.53 and 23.91 μmol l−1, respectively. The phytoplankton biomass — represented by chlorophyll a concentration — ranged from 0.12 to 6.78 mg m−3, reaching a maximum in summer. Diatoms were present throughout the whole sampling period, reaching the highest abundance
in March (3.42×105 cells l−1at surface). The peak of dinoflagellates in July (2.2×106 cells l−1 at surface) was due to a single species, Prorocentrum micans. The toxic dinoflagellate Dinophysis fortii occurred at a concentration of 2140 cells l−1 in May. The present results of phytoplankton assemblages and distribution provide valuable information for this part of the
south-eastern Adriatic Sea where data is currently absent. 相似文献