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1.
The «increasing population density effect» (IPDE) proposed by Macchiarelli and Bondioli (1986) represents one of the most recent attempts to account for dental reduction in modern human populations. Under the IPDE, the marked reduction in tooth size observed in post-Pleistocene human groups is seen as merely a side-effect of a more general reduction in body size, which resulted from an increase in population density. The model is dependent upon a strong correlation between tooth size and body size, which after numerous attempts has yet to be convincingly demonstrated in humans. This paper argues that the IPDE neglects the negative consequences on individual fitness of teeth which are too large to fit into diminishing jaws or are more susceptible to pathology, and that the worldwide reduction of tooth size is the result of selection for smaller teeth due to shifts to a softer and/or more cariogenic diet. Although increased population density may have intensified this selective effect by decreasing general fitness by lowering resistance to oral infections, it was not the primary cause of dental reduction. All proposed mechanisms of dental reduction, however, are in need of additional testing, and possible directions are offered for future studies of the phenomenon. 相似文献
2.
Jürgen Haffer 《Journal of Ornithology》1968,109(1):67-69
Summary The uppermost-Pliocene Tilatá formation which outcrops on the Bogotá plateau at 2600 meters elevation today, still contains seeds and pollen of a rich, purely tropical Iowland flora (Hubach 1958,van der Hammen & Gonzalez 1964). On the other hand, the overlying Pleistocene and post-Pleistocene Sabana formation yielded exclusively pollen of an upland flora under cool climate (van der Hammen & Gonzalez 1964). This indicates that the main uplift of the Colombian Andes probably took place during the time interval latest Pliocene — earliest Pleistocene. At that time the lowlands around the Cordilleras emerged and were forest covered. It seems likely that many if not most endemic Colombian bird species inhabiting the uplands and lowlands today were differentiated during the Pleistocene rather than in Tertiary time. 相似文献
3.
The somatic nuclear division ofChaetomium globosum was studied utilizing acetocarmin and aceto-orcein techniques. Nuclear division in hyphae of this species was found to be mitotic, but diversity in morphology and division configuration was noted. Identifiable chromosomes, the metaphase plate, and the chromosome bridge were commonly seen.A combination of extremely small nuclei, difficulties in staining, multinucleate conditions, and protoplasmic streaming in hyphae presented difficulties for these studies. Contradictory views are held on the structure of the nucleus, presence of the centriolar body, and other karyological features as described byFinley (1970)Rabinow &Bakerspigel (1965). Nuclear division structural details in a few other fungal species such as the centriolar body, spindle apparatus, and nuclear membrane disassociation have been examined by electron microscopy (Motta, 1969;Ichida &Fuller, 1968;Namboodiri &Lowry, 1967).The present study and the previous report onC. globosum (Hsu, Yu &Volz, 1972) presents comparative data for a NASA Appollo 16 MEED Mycology investigation now in progress. 相似文献
4.
In a recent articleBocquet-Appel & Masset (1985) renew their criticism of paleodemography and criticizeVan Gerven & Armelagos' (1983) defense of paleodemographic methods. In the present analysis we respond toBocquet-Appel andMasset's criticisms ofVan Gerven andArmelagos and then address the question of whether paleodemographic methods are capable of producing plausible results based on what
is known about contemporary human populations. This is done by expanding the life tables previously analysed byVan Gerven and co-workers for the Medieval Christian site of Kulubnarti in Nubia'sBatn el Hajar. The expanded results are then compared to data obtained from contemporary human populations as well as interpreted in light
of Nubian culture history. 相似文献
5.
The paleobiology of the Cretaceous neoselachian shark,Squalicorax, has largely been based on isolated teeth. We examined partial and nearly complete skeletons of three species ofSqualicorax, S. falcatus (Aoassiz),S. kaupi (Agassiz), andS. pristodontus (Agassiz), that were collected from the U.S.A. These specimens suggest that the total body length (TL) ofS. falcatus typically measured 1.8–2.0 m, and probably did not exceed 3 m. Moderatesized individuals ofS. kaupi andS. pristodontus perhaps measured about 3 m TL. AlthoughS. pristodontus was the largest form among the three species examined, this taxon possessed a set of large jaws (with large but fewer teeth)
relative to its body size compared toS. falcatus orS. kaupi. This suggests that tooth size is not an accurate indicator of the TL if one compares oneSqualicorax species to another. Neurocranial features suggest that the vision ofSqualicorax was not as acute as that of a contemporaneous macrophagous lamniform shark,Cretoxyrhina mantelli (Agassiz) , but olfaction ofSqualicorax may have been better thanC. mantelli. The morphology of placoid scales suggests thatSqualicorax was capable of fast swimming. New skeletal data support the view that the feeding dynamics ofSqualicorax was similar to the modern tiger shark (Galeocerdo
Müller & Henle). The present data do not allow for exact ordinal placement, but, contrary to some previous interpretations,Squalicorax can be excluded from the Hexanchiformes and Orectolobiformes. The taxon should more appropriately be placed within the Lamniformes
or Carcharhiniformes.
相似文献
6.
V. P. Agnihotri 《Mycopathologia》1964,24(4):305-314
Summary The effect of pH, temperature, and carbon and nitrogen interaction on the growth and sporulation ofAspergillus nidulans (Eidam)Wint.,A. rugulosus
Thom &Raper,A. variecolor (Berk. &Br.)Thom &Raper andA. quadrilineatus was studied. All the moulds could grow on a wide range of pH (2.0 to 12.0) but the growth was poor on too acid and too alkaline media. Best growth ofA. rugulosus, A. quadrilineatus, andA. violaceus was seen at pH 6.5 and that ofA. nidulans andA. variecolor at pH 7.0. In general maximum production of perithecia was recorded between pH 6.0 and 8.0.All the above species ofAspergillus under study could grow between a temperature range of 10° C–48° C, but the growth was poor at 10° C and 48° C. The present moulds showed good growth at 20° C, 25°C, and 30° C. At 40° CA. nidulans andA. rugulosus showed moderate growth while the rest of the Aspergilli attained good growth. Temperatures between 20° C–30° C favoured excellent perithecial production.In general, little improvement in growth was noted on media containing good carbon and nitrogen sources. Malic acid was found to be useless when supplied singly. But, poor growth was recorded when supplied in combination with amino acids, amide, and peptone. This was due to the fact that these N sources also supplied carbon for their metabolism. 相似文献
7.
Imitation of facial gestures by an infant chimpanzee 总被引:2,自引:0,他引:2
Masako Myowa 《Primates; journal of primatology》1996,37(2):207-213
A nursery-reared infant chimpanzee (Pan troglodytes) was tested for the ability to imitate human facial gestures, following the procedure ofMeltzoff andMoore (1977). The subject was observed between 5 to 15 weeks of ages. The results showed that the subject could imitate tongue
protrusion in the age of 5–10 weeks and mouth opening between the ages of 5–11 weeks. However, from 12 to 15 weeks, the infant
did not imitate the facial gestures. The present study clearly demonstrated that the infant chimpanzee could imitate human
facial gestures in a particular period. 相似文献
8.
Immunogens were found associated with particular fractions prepared from spherules ofCoccidioides immitis (Kong, Levine &Smith, 1963) and from yeast cells ofHistoplasma capsulatum (Salvin &Ribi, 1955). However,Blastomyces dermatitidis, another dimorphic systemic fungal pathogen was shown to elicit a minimal immunogenic response in experimental animals (Kong &Levine, 1967). It was therefore deemed pertinent to study factors which might enhance the resistance of mice to infection withB. dermatitidis. 相似文献
9.
Scott JE 《American journal of physical anthropology》2011,146(1):20-27
At a given body mass, folivorous colobines have smaller postcanine teeth than frugivorous cercopithecines. This distinction is a notable exception to the general tendency for folivorous primates to have relatively larger postcanine tooth rows than closely related frugivores. The reason for this anomalous pattern is unclear, but one potential explanation is that the difference in facial size between these two subfamilies confounds the comparison-i.e., it may be that the large postcanine teeth of cercopithecines are a consequence of their large faces. The goal of this study was to test this hypothesis. Phylogenetic comparative methods were used to examine the relationships among postcanine area, facial size, and body mass in 29 anthropoid primates, including eight colobines and eight cercopithecines. Results indicate that there is a strong and highly significant partial correlation between postcanine area and facial size when body mass is held constant, which supports the hypothesis that facial size has an important influence on postcanine size. Moreover, colobines have larger postcanine teeth relative to facial size than cercopithecines. Surprisingly, when facial size is held constant, the partial correlation between postcanine area and body mass is weak and nonsignificant. These results suggest that facial size may be more appropriate than body mass for size-adjusting postcanine measurements in some contexts. A phylogenetic comparative test of the association between diet and relative postcanine size (scaled using facial size) confirms that folivorous anthropoids are characterized by relatively large postcanine teeth in comparison to closely related nonfolivores. 相似文献
10.
Paul A. Volz 《Mycopathologia》1972,48(2-3):175-185
The purpose of this study is to determine the ability of select Agaricales species to utilize various sources of carbon, nitrogen, vitamins, and growth hormones. Fungi selected for the studies include:Cantharellus clavatus
Fries,C. cibarius
Fries,Lepista nuda (Bull. ex. Fries)Cooke,Pleurotus ostreatus (Jacq. ex. Fries)Kummer, andVolvariella volvacea (Bull. ex. Fries)Singer. Three strains ofC. cibarius and one mutant ofV. volvacea (V135), V134, were employed to determine if nutritional requirement differences occurred. One species,V. volvacea, is grown commercially as a cottage industry in the Orient (Alicbusan &Ela, 1961) while the other species currently have no commercial value. All species studied possess pleasing flavors and have potential use in the mushroom production industry.A literature compilation of the nutritional regulation of basidiocarp formation and vegetative growth of Agaricales was made with specific mention to the named species (Volz &Beneke, 1969). Recent nutritional studies with one or more of the specific species include those byYusef &Allam (1967), andEger (1970). 相似文献
11.
Summary Six myxomycetous fungi,Cribraria intricata
Schrad.,Elaeomyxa miyazakiensis (Emoto)Hagelst.,Stemonitis flavogenita
Jahn,Didymium vaccinum (Dur. &Mont.)Buchet,Didymium minus (Lister)Morgan andPhysarella oblonga (Berk. &Curt.)Morgan have been figured and described form Cuttack, Orissa, of whichElaeomyxa miyazakiensis (Emoto)
Hagelst.,Stemonitis flavogenita
Jahn,Didymium vaccinum (Dur. &Mont.)Buchet,Didymium minus (Lister)Morgan are new records for India. 相似文献
12.
Summary This paper deals with some interesting new fungi which are described as a contribution for the development of the Mycogeography.Arbuscula
Batista &Peres n. gen. is studied as a member of the family Stilbaceae havingA. eugeniae
Batista &Peres n. sp. on leaves ofEugenia jambolana
Lam. from Lucknow, India, as the type species. Another new genus isEllisia
Batista &Peres, typified byE. ingae
Batista &Peres n. sp. on leaves ofInga fagifolia (L.)Willd. from Manaus. Amazonas, Brazil. Two new binomia are:Eriomycopsis paraensis
Batista &Peres n. sp. on leaves ofBertholletia excelsa H.B.K. from Belem, State of Pará, Brazil,Sporidesmium americanense
Batista &Peres n. sp. on leaves ofQuercus wislizenii A.D.C., from U.S.A. andSporidesmium cookei (Hughes)W. B. Ellis, on leaves of Lauraceae, from Manaus.
Dedicado à Mrmória do Prof.Raffaele Ciferri 相似文献
Zusammenfassung Diese Arbeit bringt einige interessante neue Pilze, welche als Beitrag zur Entwicklung der Mycogeographie beschrieben werden.Arbuscula Batista &Peres n. gen. wurde studiert als ein Mitglied der Familie Stilbaceae, dessen TypusA. eugeniae Batista &Peres n. sp. sich auf Blättern vonEugenia jambolana Lam. aus Lucknow, Indien, befand. Eine andere neue Gattung istEllisia Batista &Peres, typiziert durchE. ingae Batista &Peres n. sp. auf Blättern vonInga fagifolia (L.)Willd. aus Manaus, Amazonas, Brasilien. Zwei neue Binome sind:Eriomycopsis paraensis Batista &Peres n. sp. auf Blättern vonBertholletia excelsa H.B.K. aus Belém, Staat Pará, Brasilien,Sporidesmium americanense Batista &Peres n. sp. auf Blättern vonQuercus wislizenii A.D.C. aus U.S.A. undSporidesmium cookei (Hughes)W. B. Ellis, auf Blättern von Lauraceae, aus Manaus, Amazonas.
Dedicado à Mrmória do Prof.Raffaele Ciferri 相似文献
13.
Summary This paper deals with four new fungi from the State of Rio Grande do Sul, Brazil.Phaeseptoria stenocalycis
Batista, Upadhyay &Da Costa Netto, collected on leaves ofStenocalyx dasyblastus
Bert. from Grammado,Phoma jasmino-macrospora
Batista, Upadhyay &Da Costa Netto, collected on leaves ofJasminum flexicaule
Vahl. from Pôrto Alegre,Melanconium argutidentis
Batista, Upadhyay &Da Costa Netto, collected on leaves ofSebastiana argutidens
Pex &K. Hoff from Grammado andCercospora caleifoleii
Batista, Upadhyay &Da Costa Netto, collected on leaves ofCalea pinnatifida
Banks from Pôrto Alegre are described here.Symptoms on the hosts and morphological characters of the fruitings and spores are described and illustrated.Publicação no 456 of IMUFP. 相似文献
14.
B. V. Timms 《Hydrobiologia》1968,31(3-4):481-491
Summary In a study of four species of centropagid copepods, particularly Boeckella minuta Sars, occurring in south-east Queensland, Australia, body length was found to correlate with the rate of water renewal in the reservoir. Ravera & Tonolli's explanation for interpopulational differences in lengths of copepods has thus been confirmed. There was also a positive correlation between body length and egg number in ovigerous females.Sex ratio (females/males) increased with the rate of water renewal, this providing for relatively more females to be present when population numbers were smaller.
Zusammenfassung In einer Untersuchung von vier Spezies zentropagischer Kopepoden, besonders Boeckella minuta Sars, die sich bei Südostqueens-land, Australien, finden, wurde entdeckt, daß die Körperlänge mit dem Wassererneuerungsgrad in dem Reservoir in Beziehung steht. Ravera & Tonolli's Erklärung für die Verschiedenheiten in Körperlängen von Kopepoden zwischen der Bevölkerung ist, auf diese Weise, bestätigt worden. Es gab auch eine positive Wechselbeziehung zwischen der Körperlänge und der Anzahl Eier in eiertragenden Weibchen.Das Geschlechtsverhältnis (Weibchen/Männchen) wurde grösser mit dem Wassererneuerungsgrad, wodurch etwas mehr Weibchen anwesend Bind, wenn die Bevölkerungszahl kleiner war.相似文献
15.
M. Laraichi 《BioControl》1978,23(2):121-128
Résumé L'étude du superparasitisme chez les parasites oophages desAelia a été réalisée avec 3 espèces d'Ooencyrtus: O. fecundus
Ferr. & Voeg.,O. nigerrimus
Ferr. & Voeg., etO. telenomicida
Vass. Ces 3 espèces apparaissent comme ayant un pouvoir de discrimination leur permettant d'éviter le superparasitisme lorsqu'elles
ont suffisamment d'h?tes à leur disposition. Dans le cas contraire ou lorsque le nombre de femelles dans un même tube de ponte
s'accro?t, la tendance au superparasitisme augmente. Le superparasitisme se traduit par une baisse de la fécondité, une diminution
de la taille et une modification du taux sexuel de la descendance.
Summary The study of superparasitism in the oophagous parasites of theAelia spp has been realized with 3Ooencyrtus species:O. fecundus Ferr. & Voeg.,O. nigerrimus Ferr. & Voeg. andO. telenomicida Vass. These 3 species appeared to have a discriminating ability which enable them to avoid superparasitism when the host population at their disposal is sufficient. In the opposite case or, when the number of females increases in the same tube, superparasitism tends to increase. Superparasitism results in a decrease in fecundity as well as in size and the sex-ratio of the offspring.相似文献
16.
Madhava Das Mehrotra 《Mycopathologia》1964,24(3):259-264
Summary The utilization of mixtures of monosaccharides byBlakeslea trispora
Thaxter,Choanephora circinans (Naganish &Kawakami)Hesseltine &Benjamin,Gilbertella persicaria var.indica
Mehrotra &Mehrotra andHelicostylum piriforme
Bainier was studied. The effect of sorbose on the utilization of other sugars present in the mixtures was also studied. It was found that all the mixtures of sugars in combination with asparagine or ammonium chloride were valueless for all the organisms exceptHelicostylum piriforme. Growth ofHelicostylum piriforme on the mixtures with asparagine as the nitrogen source was better than on the mixtures with ammonium chloride as the source of nitrogen. Asparagine being a favourable source counteractecd sorbose inhibition, while ammonium chloride failed to do so. On the other hand, both of the nitrogen sources failed to counteract sorbose inhibition in the rest of the organisms. None of the organisms could finish sorbose and rhamnose from any of the mixtures within the specified period. 相似文献
17.
Walter W. Ferguson 《Primates; journal of primatology》1989,30(4):561-569
Leonard andHegmon (1987) compare a series of dental metrics of ‘Australopithecus afarensis
Johanson, White, andCoppens, 1978’ with criteria for modern apes, to test the hypothesis that ‘A. afarensis’ represents a single species. They also compare the morphology of the lower third premolar. The dental breadth of ‘A. afarensis’ shows a wide range of variation, particularly in the lower third premolar morphology which displays greater variation than
in modern apes—yet the study concludes that the single species hypothesis cannot be rejected.
The study is flawed by applying criteria for pongids inappropriate for a hominid. When ‘A. afarensis’ is compared with criteria for hominids, the range of variation in dental size, breadth, and third premolar morphology is
greater than that in any hominid species. The single species hypothesis is, therefore, once again rejected. Moreover, the
name ‘A. afarensis’ is preoccupied byPraeanthropus africanus (Weinert) and must be dropped. 相似文献
18.
Enigmagraptus n. gen. comprises a group of the smallest known graptolites, with problematical evolutionary ancestors. The species described,
all of Přídolí age are:E. yassensis (Rickards &Wright, 1999),E. cf.yassensis, E. mitchelli (Rickards &Wright, 1999) andE. pennyae n. sp.
相似文献
19.
Hartmut H. Hilger Mechtild Balzer Wolfgang Frey Dieter Podlech 《Plant Systematics and Evolution》1985,148(3-4):291-312
Microparacaryum (M. Pop. exH. Riedl)Hilger & Podlech is described as a new genus of theBoraginaceae-Cynoglosseae. It comprises the annual species hitherto included inParacaryum (DC.)Boiss. andMattiastrum (Boiss.)Brand. Distribution maps are given for all 3 genera.Microparacaryum consists of two species,M. salsum (Boiss.)Hilger & Podlech (M. s.) andM. intermedium (Fresen.)Hilger & Podlech (M. i.). ParticularlyM. i. is a very variable species, and most of the species formerly recognized belong here. Scattered all over the range of the genus, plants occur with nutlets exhibiting flat or incurved marginal wings, often in mixed populations. This fruit polymorphism is taxonomically treated by recognizing formae. In addition, the following new infraspecific taxa and combinations are described:M. i. var.intermedium formaparacaryoides
Hilger & Podlech,M. i. var.stellatum (H. Riedl)Hilger & Podlech,M. i. var.stellatum formamattiastroides
Hilger & Podlech,M. s. formamattiastroides
Hilger & Podlech. 相似文献
20.
In an effort to obtain orange mutants ofBlastocladiella emersonii
Cantino &Hyatt, wild type zoospores were treated with mitomycin. From the variants produced, we obtained a stable, albino mutant (Ma-1) that differs significantly from another, previously described (Shaw &Cantino, 1969) UV-induced, albino variant. This report concerns the origin of Ma-1, its distinguishing features, and its apparent similarity to the few LC (late colorless) plants that normally appear in wild type populations. A preliminary note regarding mitomycin-induced variants ofB. emersonii has been published (Matsumae &Cantino, 1970). 相似文献