丽纹攀蜥头体大小的两性异形和繁殖期的生长

测定了丽纹攀蜥的体长、头长、头宽、头高、尾长和体重等形态指标,以及通过44天的生长后体长、头长、头宽和头高的增长。表明成年两性个体体长无显著的两性异形,局部形态特征皆与体长呈正相关。协方差分析表明,雄性的头长、头宽、头高和尾长显著大于雌性个体,繁殖期雌性个体的体重显著大于雄性个体。丽纹攀蜥繁殖期雄性体长的增长显著大于雌性体长的增长,雌雄两性头长、头宽和头高的增长无显著的差异。     

海南变色树蜥个体发育中形态和食性的变化

研究变色树蜥（Calotes versicolor)头,尾大小和食性在个体发育过程中的变化,以及头,尾大小两性异性的个体发生,成体体长（SVL）无显著的两性差异,两性异形主要表现为雄性个体有较大的头部（头长和头宽）和尾部。头,尾大小的两性异形在初生幼体就已存在,并随个体发育的进行变得更加显著。不同年龄组两性个体头长以及雌体头宽随SVL呈同速增长;雄性头宽随SVL呈异速增长,表现为雄性头宽的增长速率在个体发育过程中逐渐增大。头,尾部的相对大小在个体发育过程中有显著的变化,初生幼体头部相对较大,尾部相对较小,这种形态特征是胚胎优先保证生态学意义更为显著的部分（如头部）生长的结果,有利于初生幼体的早期生存和生长,不同性别和年龄组的变色树蜥摄入食物的种类及各种食物在摄入食物中所的比例有一定程度的差别,因而食物生态位宽度和重叠度有一定程度的差别,然而没有直接的证据表明头部大小的两性异形能导致两性食物生态位的明显分离。     

山地麻蜥个体发育过程中头部两性异形和食性的变化

研究了山地麻蜥(Eremias brenchleyi)个体发育过程中头部两性异形和食性的变化．成体个体大小(SVL)无显著的两性差异,但雄体具有较大的头部(头长和头宽)．头部两性异形在孵出幼体就已存在,成体头部两性异形比幼体(包括孵出幼体)更为显著,雄性较大的头部与其头部随SVL的增长速率大于雌性有关．两性头部总体上随SVL呈异速增长,表现为个体发育过程中头长和头宽与SVL的线性回归方程斜率有显著的变化．孵出幼体有相对较大的头部,这种形态特征是胚胎优先保证生态学意义更为显著的头部生长的结果,有利于孵出幼体的早期生存和生长．相对头部大小在个体发育过程中有显著的变化．不同性别和大小的山地麻蜥摄入食物的种类及各种食物在摄入食物中所占的比例有一定程度的差别,食物生态位宽度和重叠度因此有一定的差别．然而,没有直接的证据表明头部两性异形能导致两性食物生态位的明显分离,并有利于减缓两性个体对食物资源的竞争。     

甘肃密点麻蜥三个地理种群的两性异形研究

通过测量和比较采自甘肃省兰州市、张掖市和民勤县3个地区的密点麻蜥Eremias multiocellata成体样本的8个形态学量度指标,分析密点麻蜥雌雄间的两性差异和异速生长。结果表明,密点麻蜥兰州种群和张掖种群体长的两性差异无统计学意义,民勤种群雄性体长显著大于雌性。3个种群的头部大小、附肢长、尾部及最大腹宽在两性间均存在差异,具有两性异形现象。雄性个体头部较大、附肢和尾部较长;而最大腹宽在不同种群中有所不同,兰州种群和张掖种群雄性的最大腹宽显著小于雌性,民勤种群雄性则显著大于雌性。在个体发育过程中,前肢长、后肢长、头长、头宽、头高、尾长及最大腹宽均出现了不同程度的异速生长。     

密点麻蜥的两性异形和雌性繁殖

蜥蜴繁殖成功率与其形态特征有密切的关系。作者在内蒙古乌拉特后旗采集密点麻蜥(Eremias multio-cellata) ,定量研究该种形态特征的两性异形和雌体繁殖特征,检验与成体形态特征相关的两性繁殖成功率差异是否能促进两性异形的进化。密点麻蜥成体个体大小无显著的两性差异,但头部大小两性差异显著;雄性个体的头长和头宽均大于体长相同的雌性成体。繁殖雌体于五、六月份排卵;在实验室条件下,雌体在六月下旬至七月下旬之间产仔。该种雌体年产单窝仔,每窝2 -4仔。窝仔重与雌体体长呈正相关,但雌体体长仅能解释很少一部分(约19 %)窝仔重的变异。窝仔数和幼仔重均与雌体体长无关。幼仔重与相对生育力(相对于雌体体长的窝仔数)呈显著的负相关,表明该种蜥蜴存在后代数量-大小之间的权衡。密点麻蜥雄体和雌体向较大体型方向进化的选择压力均相对较弱,与成体头部大小相关的两性繁殖成功率的差异是导致该种蜥蜴头部大小两性异形进化的主要原因[动物学报52 (2) : 250 -255 , 2006]。     

北草蜥个体发育过程中头部两性异形及食性的变化

报道了北草蜥（Ｔａｋｙｄｒｏｍｕｓ ｓｅｐｔｅｎｔｒｉｏｎａｌｉｓ）的头部大小两性异形和食性在个体发育过程中的变化,讨论该种两性异形的进化选择压力。北草晰成体体长无显著的两性差异,两性异形主要表现为雄性个体有较大的头部（头长和头宽）。头部大小的两性异形在孵出幼体就已经存在。头部随ＳＶＬ的增长速率在个体发育的不同联合体是不同的,并随个体发育的进行变得更为显著。协方差分析显示,成年雌体特定ＳＶＬ的头部     

浙江九龙山发现北仑姬蛙新种群的两性异形

2017年和2018年的4月在浙江九龙山国家级自然保护区发现一种姬蛙,经形态学比较、16S rRNA序列比对及系统发育分析,鉴定为北仑姬蛙(Microhyla beilunensis),是该种的地理新分布。通过测量31只成体(25雌和6雄)的体长、头长、头宽、吻长、鼻间距、眼间距、眼径、前臂及手长、后肢全长和足长10个形态指标,研究该种的两性异形。结果显示,该种具有雌性大于雄性的个体大小两性异形;体长之外的9个局部形态特征均与体长成正相关,去除体长效应后,北仑姬蛙雄蛙前臂及手长显著大于雌蛙,其余形态特征在两性间均无差异;主成分分析(特征值≥1)显示,头长、头宽、吻长、鼻间距、眼间距、眼径、前臂及手长、后肢全长和足长等9个特定体长的形态变量辨析出两个主成分,共解释了原始数据52.5%的变异,头宽和前臂及手长在第一向量上具有较高的正负载系数,且两性形态在第一向量上差异显著,这表明头宽和前臂及手长可用于区分雌雄个体。     

海陆蛙的两性异形和雌性繁殖特征

用采自海南东寨港红树林保护区的58只(35 ♀♀,23 ♂♂)成体海陆蛙(Fejervarya cancrivora),通过测量头体长、体重、头长、头宽、吻长等11个形态特征指标和雌体卵巢质量(窝卵重),研究该种形态特征的两性异形和雌性繁殖特征,并检验雌性成体大小(头体长和体重)与其繁殖的相关性.雌雄两性个体的最小头体长分别为44.9 mm和45.2 mm.除吻长和眼间距外,其余局部形态特征与头体长皆呈正相关性.头体长在雌雄两性之间差异显著,雌性显著大于雄性;而体重、头长、头宽等局部形态均无两性差异.海陆蛙雌体的窝卵重与头体长和体重之间皆成正相关关系,表明雌性可能是通过增大体型从而增加繁殖输出,而向较大体型发展.     

四眼斑水龟个体大小和体形的两性异形

研究龟鳖的两性异形对理解形态适应具有重要意义。通过测量41只(21♀,20♂)成体四眼斑水龟(Sacalia quadriocellata)的20个形态特征指标,研究四眼斑水龟个体大小和体形的两性异形。结果表明:除头长、头宽、尾长和尾长肛前段长外,四眼斑水龟其他的形态特征均与背甲长呈正相关。雌性的背甲长、腹甲长、腹甲中线长、腹甲曲线长显著大于雄性;雄性的头长、头宽、后肢长、尾长和尾长肛前段长显著大于雌性;雌雄两性的体重、体周长、前肢长、腹甲宽、肛盾切口长、肛盾切口宽以及除背甲长外的所有背甲形态特征指标均无显著差异。研究结果表明,四眼斑水龟存在个体大小和体形两性异形。     

Bite-force performance and head shape in a sexually dimorphic crevice-dwelling lizard, the common chuckwalla [Sauromalus ater (= obesus)]

The Common Chuckwalla [ Sauromalus ater (=  obesus )] is a large, sexually dimorphic lizard with a flattened head that takes refuge from predators in rock crevices. Males use their relatively large heads to bite competing males during territorial fights and to restrain females during copulation. Flattened heads with an antipredator function (i.e. seeking refuge in crevices) and enlarged heads with intrasexual competition and reproductive functions suggest possible antagonism between selective pressures on head morphology in males. To examine this hypothesis, we performed a morphometric analysis and measured the bite-force performance of 49 adult chuckwallas. Males had disproportionately wider heads than females, but did not have deeper heads. Males bit with nearly four times the force of females, consistent with the notion of sexual selection for high bite force in males. Although constrained by crevice-wedging behaviour, head depth was a good predictor of bite force in both sexes. In males, however, osteological head width also was a good predictor of bite force. These results are consistent with the hypothesis that head shape in males is under antagonistic selective pressures, which may partly explain the pattern of head shape dimorphism. The disproportionately wide head of males may reflect anatomical modifications to enhance bite force in response to sexual selection in spite of presumed constraints on head shape for crevice-wedging behaviour  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 215–222.     

Aegean wall lizards switch foraging modes,diet, and morphology in a human‐built environment

Foraging mode is a functional trait with cascading impacts on ecological communities. The foraging syndrome hypothesis posits a suite of concurrent traits that vary with foraging mode; however, comparative studies testing this hypothesis are typically interspecific. While foraging modes are often considered typological for a species when predicting foraging‐related traits or mode‐specific cascading impacts, intraspecific mode switching has been documented in some lizards. Mode‐switching lizards provide an opportunity to test foraging syndromes and explore how intraspecific variability in foraging mode might affect local ecological communities.Because lizard natural history is intimately tied to habitat use and structure, I tested for mode switching between populations of the Aegean wall lizard, Podarcis erhardii, inhabiting undisturbed habitat and human‐built rock walls on the Greek island of Naxos. I observed foraging behavior among 10 populations and tested lizard morphological and performance predictions at each site. Furthermore, I investigated the diet of lizards at each site relative to the available invertebrate community.I found that lizards living on rock walls were significantly more sedentary—sit and wait—than lizards at nonwall sites. I also found that head width increased in females and the ratio of hindlimbs to forelimbs in both sexes increased as predicted. Diet also changed, with nonwall lizards consuming a higher proportion of sedentary prey. Lizard bite force also varied significantly between sites; however, the pattern observed was opposite to that predicted, suggesting that bite force in these lizards may more closely relate to intraspecific competition than to diet.This study demonstrates microgeographic variability in lizard foraging mode as a result of human land use. In addition, these results demonstrate that foraging mode syndromes can shift intraspecifically with potential cascading effects on local ecological communities.     

Sex‐specific evolution of bite performance in Liolaemus lizards (Iguania: Liolaemidae): the battle of the sexes

Although differential selective pressures on males and females of the same species may result in sex‐specific evolutionary trajectories, comparative studies of adaptive radiations have largely neglected within‐species variation. In this study, we explore the potential effects of natural selection, sexual selection, or a combination of both, on bite performance in males and females of 19 species of Liolaemus lizards. More specifically, we study the evolution of bite performance, and compare evolutionary relationships between the variation in head morphology, bite performance, ecological variation and sexual dimorphism between males and females. Our results suggest that in male Liolaemus, the variation in bite force is at least partly explained by the variation in the degree of sexual dimorphism in head width (i.e. our estimate of the intensity of sexual selection), and neither bite force nor the morphological variables were correlated with diet (i.e. our proxy for natural selection). On the contrary, in females, the variation in bite force and head size can, to a certain extent, be explained by variation in diet. These results suggest that whereas in males, sexual selection seems to be operating on bite performance, in the case of females, natural selection seems to be the most likely and most important selective pressure driving the variation in head size. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 461–475.     

Evolution of bite force in Darwin's finches: a key role for head width

Studies of Darwin's finches of the Galapagos Islands have provided pivotal insights into the interplay of ecological variation, natural selection, and morphological evolution. Here we document, across nine Darwin's finch species, correlations between morphological variation and bite force capacity. We find that bite force correlates strongly with beak depth and width but only weakly or not at all with beak length, a result that is consistent with prior demonstrations of natural selection on finch beak morphology. We also find that bite force is predicted even more strongly by head width, which exceeds all beak dimensions in predictive strength. To explain this result we suggest that head width determines the maximum size, and thus maximum force generation capacity of finch jaw adductor muscles. We suggest that head width is functionally relevant and may be a previously unrecognized locus of natural selection in these birds, because of its close relationship to bite force capacity.     

Sexual dimorphism in conspicuousness and ornamentation in the enigmatic leaf‐nosed lizard Ceratophora tennentii from Sri Lanka

Measures of physiological performance capacity, such as bite force, form the functional basis of sexual selection. Information about fighting ability may be conveyed through a structural feature such as a rostrum (i.e. horn) or a colour signal and thereby help reduce costly conflict. We quantified sexual dimorphism in key traits likely to be the targets of sexual selection in Tennent's leaf‐nosed lizard (Ceratophora tennentii) from Sri Lanka, and examined their relationship to bite force and body condition. We found body length and bite force to be similar for males and females. However, head length was significantly greater in males and they had significantly more conspicuous throats and labials (chromatic contrast and luminance) than females. Males also had a proportionally larger rostrum, which we predicted could be an important source of information about male quality for both sexes. Rostrum length was correlated with throat chromatic contrast in males but not females. Nonetheless, the rostrum and aspects of coloration did not correlate with bite force or body condition as we predicted. We have no information on contest escalation in this species but if they rarely bite, as suggested by a lack of difference in bite force between males and females, then bite force and any associated signals would not be a target of selection. Finally, males and females had similar spectral reflectance of the mouth and tongue and both had a peak in the ultra‐violet, and were conspicuous to birds. Lizards only gaped their mouths during capture and not when threatened by a potential predator (hand waving). We hypothesize that conspicuous mouth colour may act as a deimatic signal, startling a potential predator, although this will need careful experimental testing in the future.     

Sex,androgens, and whole‐organism performance in an Australian lizard

Understanding underlying physiological differences between the sexes in circulating androgens and how hormonal variation affects morphology–performance relationships may help clarify the evolution of sexual dimorphism in diverse taxa. Using a widely distributed Australian lizard (Eulamprus quoyii) with weak sexual dimorphism and no dichromatism, we tested whether circulating androgens differed between the sexes and whether they covaried with morphological and performance traits (bite force, sprint speed, endurance). Males had larger head dimensions, stronger bite force, faster sprint speed, and longer endurance compared to females. We found that the sexes did not differ in androgen concentrations and that androgens were weakly associated with both morphological and performance traits. Interestingly, high circulating androgens showed a nonlinear relationship with bite force in males and not females, with this relationship possibly being related to alternative male reproductive tactics. Our results suggest that androgens are not strongly correlated with most performance and morphological traits, although they may play an important organizational role during the development of morphological traits, which could explain the differences in morphology and thus performance between the sexes. Differences in performance between the sexes suggest differential selection on these functional traits between males and females. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 834–849.     

Functional basis for sexual differences in bite force in the lizard Anolis carolinensis

In many species of lizards, males attain greater body size and have larger heads than female lizards of the same size. Often, the dimorphism in head size is paralleled by a dimorphism in bite force. However, the underlying functional morphological basis for the dimorphism in bite force remains unclear. Here, we test whether males are larger, and have larger heads and bite forces than females for a given body size in a large sample of Anolis carolinensis . Next, we test if overall head shape differs between the sexes, or if instead specific aspects of skull shape can explain differences in bite force. Our results show that A. carolinensis is indeed dimorphic in body and head size and that males bite harder than females. Geometric morphometric analyses show distinct differences in skull shape between males and females, principally reflecting an enlargement of the jaw adductor muscle chamber. Jaw adductor muscle mass data confirm this result and show that males have larger jaw adductors (but not jaw openers) for a given body and head size. Thus, the observed dimorphism in bite force in A. carolinensis is not merely the result of an increase in head size, but involves distinct morphological changes in skull structure and the associated jaw adductor musculature.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 111–119.     

Ecological consequences of ontogenetic changes in head shape and bite performance in the Jamaican lizard Anolis lineatopus

It has been documented extensively that body size affects the physiology and musculoskeletal function of organisms. However, less well understood is how body size affects the ecology of organisms through its effects on physiology and performance. We explored the effects of body size on morphology and performance in different ontogenetic classes and sexes of a common Anolis lizard ( A. lineatopus ). Next, we tested whether these morphological and performance differences may affect functional aspects of the diet such as prey size and prey hardness. Our data showed that males, females and juveniles differ significantly in head size, head shape and bite force. Multiple regression models indicated that head shape and bite force are significantly correlated to prey size and hardness. Yet juveniles had relatively large heads and bit disproportionately hard for their size, allowing them to eat prey as large as those of females. However, for a given prey size, males and females ate more robust prey than did juveniles. Additionally, males ate relatively harder prey than did juveniles. These data suggest that: (1) body size affects the dietary ecology of animals through its effect on head size and bite force; (2) changes in head morphology independent of changes in overall size also have important effects on performance and diet.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 443–454.     

乐山棒花鱼形态特征的两性异形和雌性个体生育力

测定了乐山棒花鱼(Abbottina kiatingensis)繁殖期形态特征包括体长、头长、头宽、头高、吻长、眼后头长、眼径、眼间距、体高、尾柄长、尾柄高、尾鳍长、背鳍基前距、背鳍基长、腹鳍基前距、腹臀间距、体重和去内脏体重的两性异形和雌性个体生育力。繁殖期雄性个体的数量显著多于雌性个体,雌雄两性个体的体长差异不显著。特定体长的雌性个体的头长、头宽、头高、吻长、眼后头长、尾柄高、背鳍基前距、背鳍基长和去内脏体重显著小于雄性个体,其余指标不存在明显的差异。回归分析表明,乐山棒花鱼的怀卵数量与体长和体重回归关系显著,雌性通过个体大小(体长和体重)的增加来提高个体生育力。     

Insularity affects head morphology,bite force and diet in a Mediterranean lizard

Island environments differ with regard to numerous features from the mainland and may induce large‐scale changes in most aspects of the biology of an organism. In this study, we explore the effect of insularity on the morphology and performance of the feeding apparatus, a system crucial for the survival of organisms. To this end, we examined the head morphology and feeding ecology of island and mainland populations of the Balkan green lizard, Lacerta trilineata. We predicted that head morphology, performance and diet composition would differ between sexes and habitats as a result of varying sexual and natural selection pressures. We employed geometric morphometrics to test for differences in head morphology, measured bite forces and analysed the diet of 154 adult lizards. Morphological analyses revealed significant differences between sexes and also between mainland and island populations. Relative to females, males had larger heads, a stronger bite and consumed harder prey than females. Moreover, island lizards differed in head shape, but not in head size, and, in the case of males, demonstrated a higher bite force. Islanders had a wider food niche breadth and included more plant material in their diet. Our findings suggest that insularity influences feeding ecology and, through selection on bite force, head morphology. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 469–484.