太行山猕猴牙齿与颅长的相关性

对太行山猕猴牙齿有关变量做了测量,统计,并就其与颅骨长间的异速生长和相关程度进行了研究。结果表明,太行山猕猴牙齿具有明显的性别差异,雄性牙齿的变异程度在犬齿和中央门齿表现尤为突出。在线性型或面积方面,雄性牙齿的异速生长均快于雌性和雄＋雌,此与其生活史对策相适应,在雄性,雌性或雄＋雌,下颌齿变量与颅骨长的相关程度比上颌更为密切,与有关资料的比较表明,太行山猕猴与金丝猴之间的差异小于与菲氏叶猴之间的差异。     

滇金丝猴、藏酋猴和猕猴咀嚼装置骨学特征的比较

本文对滇金丝猴、藏酋猴和猕猴毛耳亚种中与咀嚼有关的48项骨学特征作了比较,试图探讨它们在功能与形态及行为方面的相关关系。对所得变量进行了多变量统计分析、齿弓对称性分析及咀嚼能力分析。结果表明：滇金丝猴与猕猴属具有不同的下颌形状。前者齿弓对称性比后者好,且具有更强的咀嚼能力;藏酋猴的咀嚼能力远较毛耳猴接近滇金丝猴;咬啐坚果的能力与咀嚼能力大小相反。在下颌发育中有异速生长现象。据此对食性的推测与已有的野外观察资料相符。     

滇金丝猴下颌的生物力学研究

利用生物力学原理,判别分析和异速生长对我国特有的滇金丝猴下颌研究表明,由于雄性比雌性具有相对更长的下颌,导致了整个下颌结构在两性间的差异。在所分析的8个变量中,4个被选为性别鉴别的重要特征,判别式为:D=-27.65-0.729CONM1+0.596MANDL+1.204MANDSYM-1.778MANCORPW。与猕猴和长鼻猴相比,滇金丝猴具有相对短的下颌骨,较宽的下颌髁和较高的下颌体。这些特征保障了下颌齿,特别是颊齿列更有利于叶类食物的咀嚼,即有利于咀嚼过程中消除下颌的疲劳。     

笼养川金丝猴不同年龄阶段的发育特征

198 9～ 1998年间 ,对 46只不同年龄阶段的笼养川金丝猴 (Rhinopithecusroxellana)的外形、生理、行为等特征进行了比较。根据不同年龄阶段个体的综合特征 ,川金丝猴的发育期可划分为 5个年龄段 :婴幼阶段 ,少年阶段 ,青年阶段 ,亚成年阶段和成年阶段。观察发现 ,从出生到青年阶段 ,雌雄在体形大小和体重方面增长速度很接近。然而 ,从青年阶段开始 ,雄性的增长速度超过雌性。到了成年阶段 ,成年雄性的体重、坐高、尾长、头围、犬齿齿冠及被毛长度明显大于雌性 ,成年雌性的体重仅为成年雄性的 5 4% ,表现出显著的性二型性。雌性 3 6± 0 5 (n =5 )岁出现月经 ,其开始成功繁殖的年龄为 4～ 6岁 ;雄性 6 5 (n =4)岁出现射精行为 ,其开始成功繁殖年龄为 7～ 8岁。此外 ,对川金丝猴所特有的嘴角瘤的观察发现 ,雄性进入性发育年龄阶段后开始长出嘴角瘤 ;嘴角瘤大小随年龄增长而逐渐增大 ,直到性成熟。而雌性川金丝猴多无此结构或只有一个约绿豆大的痕迹。因此 ,嘴角瘤可以作为雄性川金丝猴性成熟的标志 ,是成年雄性川金丝猴的副性征。     

菲氏叶猴和黑叶猴的齿弓

本文对菲氏叶猴(Presbytis phayrei)和黑叶猴(Presbytis francoisi)成年头颅的上下齿弓进行了比较研究。结果说明,在黑叶猴中,由于与颧骨眶低点相连,垂直于M~3根部齿弓的距离非常显著地大于菲氏叶猴,因而其面颅体积显著性地大于菲氏叶猴,而且菲氏叶猴的面颅比黑叶猴更为凸出。在对齿弓的对称性研究时发现,除黑叶猴的上齿弓向右偏离外,别的都向左侧发生偏离。这种偏离似乎与用手优势相联系。在进行多变量分析时发现,两种叶猴所研究的变量下颌的比上颌的发生了更大的变异。进一步证实了运动的器官比固定的器官易产生变异。     

短尾猴下颌骨的性二型

对30个成年短尾猴下颌骨的8个有关变量作了性二型研究。单因子分析说明,8个变量均达到了显著差异水平。判别分析得到的第一判别式为:D=-11.013+1.151下颌骨髁长+0.269下颌骨髁宽。当D=-1.271±0.182时,标本为雌性;当D=0.973±0.290时为雄性。雄性下颌骨髁比雌性更长和更宽,且变化较为稳定,可作为种内性别间的鉴别特征。雄性比雌性具有较大咀嚼阻力臂(下颌长),但其他阻力臂则比雌性相对较短。与一些灵长类相同变量的比较说明,短尾猴下颌骨结构与猕猴较为接近,与长尾叶猴则相差甚远。这可反映它们食性和行为方面的亲疏关系。     

金丝猴长骨的异速生长研究

文章利用14副成年金丝猴骨架(包括滇金丝猴Rhinopithecus bieti;黔金丝猴R.brelichi)对其长骨与体重间的异速生长进行了分析研究。结果表明,在金丝猴的生长发育过程中,前肢的生长速度大于后肢。这种形态特征与金丝猴在运动过程中攀爬垂直支撑物相联系。从肢间指数和生长系数看,金丝猴的前后肢与其它灵长类相比较,相对于体重来说比较短。这是在树上攀缘过程中使重心更接近支撑攀物和使身体稳定的一种适应。对躯干长(STL),肱骨、桡骨、股骨和胫骨经多维变量分析说明了金丝猴的长骨与体重之间的关系,长骨的结构特征与狮尾狒(Theropithecus)、狒狒(Papio)、叶猴(Presbytis)、猕猴(Mcaaca)及长鼻猴(Nasalis)更为接近。在金丝猴的运动特征上,我们据此推测,它们有一部分时间在地上活动,但休息、睡觉、寻食及逃避敌害等时在树上。因此,在运动中,跳跃、臂摆荡和悬吊不是它们的主要运动方式。     

养殖条件下克氏原螯虾亲虾的形态性状研究

为了解人工养殖的克氏原螯虾(Procambarus clarkii)亲虾的生长和形态性状,为人工放养亲本的选择提供参考依据,测定了342尾体重大于20 g的克氏原螯虾的体重(W)、全长(TL)、头胸甲长(CL)、头胸甲宽(CW)、螯足长(ChL)和螯足宽(ChW),比较了雌性和雄性生长和形态参数的差异性,模拟了各参数间的回归方程,并探讨了各参数间的相关性。结果显示,雌性个体体重、螯足长和螯足宽的均值显著低于雄性,而头胸甲长和头胸甲宽的均值则显著高于雄性,全长和丰满度在雌雄之间差异不显著。雌性和雄性个体的优势全长范围均为90～119. 99 mm,优势体重范围分别为20. 0～39. 9 g和30. 0～44. 9 g。克氏原螯虾全长-体重的关系为W_♀=0. 000 01×TL~(3. 381 3)、W_♂=0. 000 01×TL~(3. 230 9),雌性和雄性均为正异速生长;头胸甲长-体重的关系为W_♀=0. 000 1×CL~(3. 215 5)、W_♂=0. 000 2×CL~(3. 179 8);头胸甲长-全长的关系为TL_♀=2. 928 6+2. 027×CL、TL_♂=-5. 036 9+2. 370 1×CL;头胸甲宽-头胸甲长的关系为CL_♀=5. 479 2+1. 942 3×CW、CL_♂=9. 646 8+1. 765 6×CW;螯足宽-螯足长的关系为ChL_♀=-13. 721+6. 679×ChW、ChL_♂=-4. 828+6. 148 7×CW。相关性分析表明,总体上6个参数之间均有显著的正相关关系,其中与体重相关性较高的为全长和头胸甲长与宽。     

淮河上游南湾湖麦穗鱼年龄与生长的研究

2014年的3月、5月、7月和12月在淮河上游南湾湖采集麦穗鱼(Pseudorasbora parva)样本532尾, 对麦穗鱼的年龄组成与生长进行分析。结果表明样本的体长分布范围为35.82—88.28 mm, 平均体长为(61.61±11.8) mm, 体重的分布范围为3.07—59.17 g, 平均体重为(19.23±10.73) g。雄性个体比雌性个体大, 雌雄性比为0.64鲶1。群体的年龄组成为1—3龄, 其中3龄样本数量占优势为57.38%。体长与体重的关系是雌性W=9.602E–5L2.928 (R2=0.883); 雄性W=4.487E–5L3.116 (R2=0.889), 雌雄样本间存在显著性差异(F=5.241, P<0.05)。麦穗鱼的鳞径与体长之间呈线性关系, 并且雌雄样本的鳞径与体长之间的关系差异性显著(F=78.405, P<0.05)。生长参数分别是雌性: L_∞=107.005, K=0.246, t₀= –0.76; 雄性: L_∞=145.254, K=0.181, t₀= –0.66。生长拐点是雌性3.607龄对应的体长和体重分别为70.46 mm和24.72 g, 雄性5.619龄对应的体长和体重分别为98.64 mm和73.53 g。研究结果表明雌性为匀速生长, 雄性为异速生长; 雄性麦穗鱼比雌性麦穗鱼的生长速度快。     

金丝猴肩带和前肢的性二型

本文研究了两种金丝猴(Rhinopitheous bieti和R.brelichi)肩带及上肢的62项线性变量及指数的性二型,其中64.5%达到了显著性差异水平。结果表明,两性在运动行为上存在一些差异。在所分析的变量中,性别间的差异主要由于成熟时间的不同所引起(雄性比雌性具更长的生长时期),其次是生长速率的不同(雄性比雌性具有更明显的正异速生长率)。对一些指数及不同部位的性二型分析表明,在上肢利用和尺、桡骨的前旋及后旋活动方面,两性也具一些不同。     

Evolutionary dental changes.

In the evolution of primates there has been a tendency towards reduction in jaw length and prognathism, mandibular canine size and first molar cusp number, and third molar presence. These oral structures were contrasted, and compared with cranial size, body height and weight, and finger length in 118 males and 102 females of the Burlington Growth Centre. Body weight was significantly related to canine width and to jaw length and prognathism. These relationships were stronger in the males than in the females. The evolutionary reduction in these dental dimensions may result from an evolutionary reduction in genetically determined body size. In the males the number of molar cusps was related to finger length and cranial height. Agenesis of third molars was related to the length of the maxilla in both sexes. In the females, canine width was related to the number of cusps of the first molars, agenesis of third molars, and length of a finger. Simultaneous reductions in dental structures were more frequent in the females.     

Birotundal diameter of the human sphenoid bone from age six years to early adulthood

Longitudinal data for a twenty-year period are presented for a dimension of the human sphenoid bone as seen on postero-anterior roentgenograms of 22 males and 18 females (healthy, American-born Caucasoids). Birotundal diameter measured as the distance between the centers of the right and left foramen rotundum averaged near 32.0 mm for each sex at age 6 years. Individual increase in size to age 26 years ranged between 3.2 mm and 8.3 mm. There is no correlation between size at age 6 years and change between this age and early adulthood. For 54 males and 50 females at age 9 years, intercorrelations were obtained among six variables: birotundal diameter, head breadth, bizygomatic diameter, bigonial diameter, upper and loweer dental arch widths at the permanent first molars. The r's were nonsignificant or low positive (with the exception of upper-lower dental arch, r = 0.76). The results of this study are aligned with three previous studies of human cranial base width.     

Postcanine tooth size in female primates

The results of many allometric studies of postcanine tooth size in mammals have not corresponded to expectations of tooth size based on energy requirements and dental function. The purpose of this study is to investigate the relationship between postcanine occlusal surface area, body size, and the metabolic demands of pregnancy and lactation in female primates. Tooth and body sizes from 38 primate species were taken from the literature to test two hypotheses: 1) females should have relatively larger teeth than males in order to masticate additional food for the energetic costs of reproduction; 2) taxa with the largest neonatal size (a measure of average metabolic costs of pregnancy and lactation) should have females with a greater degree of relative dental enlargement. The results show that relatively large female teeth are not found consistently in primate species. Females have less occlusal surface area than expected on the basis of the male tooth and body size regression in 21% of the species, and there is no correlation between relative female tooth size and relative newborn size across higher primate taxa. The degree of female dental enlargement is most closely related to degree of sexual dimorphism in body weight. The correlation between degree of body weight dimorphism and relatively larger postcanine teeth in females than in males is 0.87 in the 38 species. Species that are monomorphic in weight tend to be monomorphic in tooth size even though females apparently require more food than males.(ABSTRACT TRUNCATED AT 250 WORDS)     

The ontogeny of sexual dimorphism in the cranium of Bornean orang-utans (Pongo pygmaeus pygmaeus): II. Allometry and heterochrony

Based on a homogeneous sample of 212 individuals spanning all postnatal periods, we examine the ontogeny of cranial sexual dimorphism in Bornean orang-utans (Pongo pygmaeus pygmaeus) by means of allometric analysis and in terms of heterochrony. The bivariate growth allometries of 20 cranial dimensions against basicranial length yield two major patterns. Confirming the null hypothesis, strong ontogenetic scaling, where growth regressions of both sexes fall along a single ontogenetic continuum, and where shape differences between adult males and females result from the extension of relative growth in the smaller females to larger size in males, is found in 10 cases. Ontogenetic scaling is particularly strong in proportions of (1) the neurocranium directly associated with brain size, (2) the orbital region, and (3) the dental arcade. In terms of heterochrony such a pattern most likely is the result of a process termed "time hypermorphosis", i.e. an extension of the growth period in time in males. The second major pattern seen in the remaining 10 cases shows a departure from ontogenetic scaling, with males exhibiting a significantly steeper slope than females. Departures from ontogenetic scaling, where size and shape are dissociated with adult males being disproportionately larger than adult females, are found in proportions of cranial regions directly associated with secondary sexual character development: prognathism, canine size, and cheek pad area. In terms of heterochrony such a pattern most likely is the result of a process termed "acceleration", i.e. the rate of shape change is increased in males.     

Interspecific allometry of the mandible,dental arch,and molar area in anthropoid primates: Functional morphology of masticatory components

Allometric equations relating the lengths and widths of the mandible and dental arch, and of molar area, were obtained in a wide range of anthropoid primates grouped into four subsets, pongids, cercopithecids, nonmarmoset platyrrhines, and marmosets. Mandibular width is negatively allometric against length across anthropoids but cercopithecids had relatively wider mandibles than nonmarmosets of the same size class. Mandibular length relative to dental arch length was isometric within and between the four groups but dental arch width scaled negatively against all the other dimensions examined in this study, indicating a functional dissociation between the dental arcade and the bony mandible. Molar area showed various scaling patterns relative to mandibular length (isometry) and width (positive). There were no parameters that scaled positively against body weight across groups, except for molar area in cercopithecids (strongly) and nonmarmoset (moderately). Notable functional specializations include relatively long dental arches in cercopithecoids, related to large, elongate bilophodont molars, and the tendency to increase relative jaw length across the range of anthropoid sizes, reflecting negative allometry of the brain (cranial bicondylar width). We caution that various allometry and functional patterns may be masked by generalizing from broad taxonomic comparison involving a large sweep of adaptative patterns.     

Forceps size and immune function in the earwig Forficula auricularia L.

Females of many species select their mates on the basis of the size or intensity of sexual ornaments, and it has been suggested that these provide reliable signals of a male's ability to resist parasites and pathogens. European earwigs, Forficula auricularia , are sexually dimorphic in forceps shape and length. Male forceps are used as weapons in male contests for access to females, but recent findings suggest that females also choose males on the basis of their forceps length. In the present study, we tested the hypotheses that in the European earwig, F. auricularia , the size of forceps is correlated with immune function and that immune function differs between the sexes. We found that encapsulation rate was not correlated with the length of forceps in either sex, but was negatively correlated with body size. By contrast, lytic activity of the haemolymph increased with overall body size in both sexes but, in females, lytic activity increased with relative forceps length whereas, in males, it decreased with relative forceps length. After accounting for effects of body size, there was no remaining significant correlation in females but the negative correlation in males remained. Furthermore, we found that males had higher encapsulation rate and higher lytic activity than females, suggesting that males have stronger immune defence. The results of the study indicate that the size of forceps in male earwigs does not reliably reflect male immune defence.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 509–516.     

Sexual dimorphism in leg length among orb-weaving spiders: a possible role for sexual cannibalism

The degree and direction of sexual dimorphism across different species is commonly attributed to differences in the selection pressures acting on males and females. The extent of these differences is especially apparent in species that practise sexual cannibalism, where the female attempts to capture and eat a courting male. Here, we investigate the relationship between sexual dimorphism in size and leg length, sexual cannibalism and courtship behaviour in three taxonomic groups of orb-weaving spiders, using morphological data from 249 species in 36 genera. Females are larger than males in all three taxonomic groups, and males have relatively longer legs than females in both the Araneinae and Tetragnathidae. Across genera within each taxonomic group, male body size is positively correlated with both female body size and male leg length, and female body size is positively correlated with female leg length. Sexual size dimorphism is negatively correlated with relative male leg length within the Araneinae, but not within either the Tetragnathidae or the Gasteracanthinae. There was no negative correlation between sexual size dimorphism and relative female leg length in any taxonomic group. We argue that the relationship between sexual size dimorphism and relative male leg length within the Araneinae may be the result of selection imposed by sexual cannibalism by females.     

Sexual size dimorphism and allometric growth of Morelet's crocodiles in captivity

Few studies have conducted morphological analyses of crocodilians, and little information exists on differences between size-classes and sexes in Neotropical crocodilians. In this study, we measured nine morphological traits in 121 captive Morelet's crocodiles Crocodylus moreletii (81 females and 40 males). Our results revealed that individuals < 2 m total length do not exhibit sexual dimorphism in morphometric characteristics. However, for crocodiles over 2 m in length, males were significantly larger than females in terms of dorsal-cranial length, cranial width, snout width and snout-ventral length. In general, morphological traits demonstrated a strongly significant relationship with total length at the smaller size class of 150-200 cm length. However, in the highest size class of 250-300 cm length (large adult males), morphological traits were no longer significantly related with total length. Male crocodiles demonstrated allometric growth of cranial morphology with significantly greater increase in cranial width, snout width, and mid-snout width relative to total length at higher size classes. Morphological dimorphism and allometric growth may be associated with adaptive strategies for reproductive success.     

PROXIMATE MECHANISMS OF SEXUAL SELECTION IN WOOD FROGS

Observations and several types of field experiments on the mating behavior of wood frogs have revealed the proximate mechanisms for a size-related reproductive advantage in both males and females. For females, larger individuals produce larger clutches; for males, larger individuals can better remain clasped to females when contested by rival males and can better depose males clasped to other females. No results obtained support of the existence of mate choice in either males or females. Males were estimated to be 4.74 times as variable as females in the number of zygotes produced per individual per season; however, much of the variation in male RS resulted from a male-biased sex ratio at the breeding site rather than from sexual selection. After taking sex ratio effects into consideration, males were estimated to be only 1.63 times as variable as females. Patterns of variation in RS in males and females are associated with numerous sex-specific differences in life history and morphology. Life history differences include differential growth rates, ages at sexual maturity, and rates of mortality. Interpretation of how the body size dimorphism (females larger than males) in this species relates to sexual selection is consistent with information on how similar variations in body size influence RS for each sex, and how males and females differ in the functional relationship between body size and RS. Average RS increases more with body size in females than in males. Although body size directly influences RS for females, the possibility exists that, for males, other anatomical features correlated with body size more directly affect RS. Preliminary evidence suggests that sexual selection influences male arm length and that the male body size : RS relationship results as an incidental correlation.     

Sexual dimorphism and allometry in two seed beetles (Coleoptera: Bruchidae)

Male Callosobruchus chinensis (Coleoptera: Bruchidae) have elaborated, pectinate antennae, which are absent from conspecific females and both sexes of a congener, Callosobruchus maculatus. To begin to unravel the mechanisms producing this striking dimorphism, we examined which morphological traits best explain body size variation in bruchid beetles and quantified sexual dimorphism of antenna size through allometric analyses. Using principal component analyses, we found that elytron length and pronotum width were significantly correlated with the first principal component, which was interpreted as explaining variation in body size. Regressions of log‐transformed body size measures on log‐transformed antenna length revealed that males of both species had longer antennae than conspecific females for any given body size, although most of this effect was attributable to higher intercepts, rather than increased allometry, in males. Comparisons among heterospecific males revealed that C. maculatus males have noticeably longer antennae than C. chinensis males at large body sizes. Callosobruchus chinensis males, thus, appear to have increased the receptive area of their antennae by adding to the width of, rather than further elongating, their antennae. Finally, we found evidence for positive allometry between log‐transformed antenna length and log‐transformed antenna width in C. chinensis males. We discuss our results in the context of evidence supporting the presence of an additional, and potentially unique, sex pheromone in C. chinensis females.