Effect of face lift on earlobe ptosis and pseudoptosis

The authors have previously described a classification system for earlobe ptosis and established criteria for earlobe pseudoptosis. Earlobe heights were characterized on the basis of anatomic landmarks, including the intertragal notch, the otobasion inferius (the most caudal anterior attachment of the earlobe to the cheek skin), and the subaurale (the most caudal extension of the earlobe free margin). The classification system was derived from earlobe height preferences as determined by a survey of North American Caucasians and identified the ideal free caudal segment (otobasion inferius to subaurale distance) measuring 1 to 5 mm (grade I ptosis). Also, earlobe pseudoptosis was defined by an attached cephalic segment (intertragal notch to otobasion inferius distance) measuring greater than 15 mm. In this study, the authors evaluated the effects of standard face lift surgery on earlobe ptosis and pseudoptosis by comparing the preoperative and postoperative earlobe height measurements from life-size photographs of 44 patients who underwent rhytidectomy performed by the senior author. The postoperative attached cephalic segment (intertragal notch to otobasion inferius distance, 12.22 +/- 0.364 mm) increased over its preoperative attached cephalic segment (intertragal notch to otobasion inferius distance, 11.10 +/- 0.406 mm) (p = 0.041). The postoperative free caudal segment (otobasion inferius to subaurale distance, 6.32 +/- 0.438 mm) demonstrated only a trend toward decreased heights when compared with the preoperative free caudal segment (otobasion inferius to subaurale distance, 7.15 +/- 0.489 mm) (p = 0.210). The incidence of pseudoptosis, defined by an attached segment (intertragal notch to otobasion inferius distance) greater than 15 mm, increased from 12.3 percent of preoperative patient earlobes to 17.3 percent of postoperative patient earlobes. An ideal free caudal segment (otobasion inferius to subaurale distance), defined by a range of 1 to 5 mm, was observed in only 37.0 percent of postoperative earlobes versus 22.2 percent of preoperative earlobes. Significant increases in the attached cephalic segments (intertragal notch to otobasion inferius distance) following rhytidectomies correlated with increased incidence of earlobe pseudoptosis, as observed in 17.3 percent of postoperative patient earlobes. Because the free caudal segment was negligibly affected by rhytidectomy, a majority of earlobes (63.0 percent) demonstrated persistent nonoptimal free caudal segment heights (otobasion inferius to subaurale distance > 5 mm). Earlobe height changes can result from either age-related lobule ptosis (increase in free caudal segment) as previously described or in patients undergoing rhytidectomy (increase in attached cephalic segment). Therefore, ideal lobule distances along with the effects of aging and rhytidectomy surgery on the lobule should be discussed with patients who are seeking a more youthful facial appearance, so that the aging ear may be addressed concurrently with the aging face.     

Incidence of earlobe ptosis and pseudoptosis in patients seeking facial rejuvenation surgery and effects of aging

The authors have previously described a classification system for earlobe ptosis and have established a criterion for earlobe pseudoptosis. Earlobe heights were characterized based on anatomic landmarks, including the intertragal notch, the otobasion inferius (the most caudal anterior attachment of the earlobe to the cheek skin), and the subaurale (the most caudal extension of the earlobe free margin). The classification system was derived from earlobe height preferences as determined by a survey of North American Caucasians, and it identified the ideal free caudal lobule height range to measure 1 to 5 mm from otobasion inferius to subaurale (grade I ptosis). Also, earlobe pseudoptosis was defined by the attached cephalic lobule height measuring an intertragal notch to otobasion inferius distance greater than 15 mm. In this study, the preoperative earlobe height measurements of 44 patients seeking facial rejuvenation were evaluated. The average attached cephalic segment (intertragal notch to otobasion inferius distance) of patient earlobes measured 11.10 +/- 0.46 mm, and the average free caudal segment (otobasion inferius to subaurale distance) of patient earlobes measured 7.15 +/- 0.49 mm. Assessment of patient groups based on single-decade age differences demonstrated an increase in the free caudal segment (otobasion inferius to subaurale distance) with increasing age (p = 0.003). Assessment of patient groups based on single-decade age differences demonstrated no increase in the attached cephalic segment (intertragal notch to otobasion inferius distances) with increasing age (p = 0.281). When evaluating for the ideal otobasion inferius to subaurale distance, only 22.2 percent of earlobes demonstrated an ideal free caudal earlobe height (grade I ptosis). Moreover, pseudoptosis was detected in 12.3 percent of earlobes. Finally, a majority of earlobes demonstrated intrapatient variability, with only 16.2 percent of patients demonstrating identical attached cephalic segment (intertragal notch to otobasion inferius distances) and 37.8 percent demonstrating identical free caudal segment (otobasion inferius to subaurale distances) when compared with their contralateral ear. Plastic surgeons should be aware that a significant number of patients (77.8 percent of earlobes) may not possess an ideal free caudal segment and that 12.3 percent of earlobes may present with pseudoptosis. Therefore, earlobe height assessment should be an essential aspect of evaluation in patients desiring facial rejuvenation surgery. Evaluation of both ears should be performed independently due to intrapatient earlobe height variations. Finally, patients should be counseled with regard to the ideal earlobe parameters and aging patterns (stable attached cephalic segment versus increasing free caudal segment). With the natural progression of both facial rhytides and caudal segment earlobe ptosis (increasing free lobule segment) with increasing age, independent and accurate assessment of earlobe height is indicated so that the aging ear may be addressed concurrently with the aging face.     

Social rank and antipredator behaviour of Willow Tits Parus montanus in winter flocks

Field experiments on three free-ranging Willow Tit winter flocks, each consisting of one adult pair and two male and two female juveniles (first-year birds), were performed to examine whether preferences for feeding site and antipredator behaviour are related to social rank. The dominance structure was the same in all flocks; adult male > juvenile male 1 > juvenile male 2 > adult female > juvenile female 1 > juvenile female 2.
The proportion of time spent scanning for predators was positively correlated with distance from cover, and adults scanned relatively more than juveniles at the same controlled distance from cover, especially in the afternoon. Given a choice between feeders placed 1 m, 3 m, 5 m, 10 m and 20 m from the forest edge, the tits preferred feeders close to cover. Low-ranking individuals used feeders farther from cover indicating that higher ranked tits prevented them from using the feeders close to cover by means of social dominance. When only the 10m and 20 m feeders were baited, only low-ranked juveniles visited the feeders, subordinate females slightly more than males. The subordinate juveniles increased their use of exposed feeders at low ambient temperature, suggesting that they are prepared to take greater risks during cold periods.
The sequence of return to a feeder, after a life-like stuffed predator model mounted 1 m from a feeder opening was removed, was positively correlated with dominance status, revealing that subordinates take the greatest predation risks.     

Balanced angular profile analysis

To evaluate current preferences and ethnic differences of female soft-tissue profiles, 71 profile photographs of famous female models were collected from Internet Web pages and divided into four groups (Korean, 22; Japanese, 15; Chinese, 16; and Western, 18). Eleven soft-tissue landmarks were recorded on each photograph and 16 angular measurements were made by using V-ceph (CyberMed, Inc., Seoul, Korea). Data from each group are presented to show the means, ranges, p and F values, standard deviations, and standard errors of each measurement. In addition, individual measurements for each group were compared with those of the other groups by one-way analysis of variance using a p value corrected for multivariable testing. Between-group mean value differences were calculated using a Tukey's studentized range test (HSD), at a significance level of p = 0.05. Most of the variables were similar in the groups. Significant between-group differences (p < 0.05) were found for angle of alar curvature point, profile convexity, interlabial contour, and nasolabial contour. In addition, we divided all data into two groups (Western and Asian). The t test (with significance level set to p = 0.05) was performed to compare the two. Significant between-group differences (p < 0.05) were found for angle of alar curvature, angle of labiale inferius, profile convexity, and lower lip projection angle, but no significant racial differences were found in terms of several profile angles. These findings suggest that point of ala curvature point, subnasale, and the labiale inferius of Asian models may differ from those of Western models. These peculiar angular patterns of Asian models led the authors to create a new characteristic angular concept, termed the "ethnic pyramid," which is composed of soft-tissue profile points of alar curvature point, subnasale, pronasale, and labiale inferius. This ethnic pyramid describes the characteristic patterns of the ethnic differences. The results of this study suggest that the soft-tissue profiles of famous female models have some common features but also show differences among ethnic groups and races. This simple method of profile analysis may provide aesthetic surgeons with a simple formula and reference data for creation and application of an attractive face. On the basis of their balanced angular profile analysis data, the authors suggest that appropriate and harmonious aesthetic operations reflecting these differences should be considered.     

Effects of male apparent length on female preference for absolute body size in <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Female green swordtails (Xiphophorus helleri) prefer males of longer body and sword lengths, which may reflect perceptual constraints. Larger males project a larger image onto the female’s retina at a given viewing distance, which may elicit greater stimulation of the visual system and a stronger behavioral response. This study investigates the effects of male apparent size, as affected by proximity and sword length, on female preference for absolute body size in X. helleri. Females were presented pairs of dummy males in ten treatments organized into six categories: (1) the Actual Length Control where identically sized males were held at different viewing distances from the female; (2) the Sword Compensation Treatment in which viewing distance and apparent length (body + sword) were held constant, pairing sworded with swordless dummies of equal total length; (3) the Body Length Preference Treatment where male distance from the female was held constant, while varying body size; (4) the Apparent (Sword) Length Preference Treatments where male distance from the female was held constant, while varying sword length; (5) the Apparent Length Controls where body length, sword length, and viewing distances varied while holding apparent length constant; and (6) the Experimental Treatment in which the smaller-sworded male of the pair appeared larger. In each of the Actual Length Control, Body, and Sword Length Treatments, females preferred the closer, larger-bodied, and longer-sworded males, respectively. However, females exhibited preferences in neither any of the Apparent Size Control treatments nor any of the Sword Compensation Treatment. Additionally, females in the Experimental Treatment preferred the apparently longer-sworded dummy to the male whose sword was actually longer. These results suggest that female preference for male body and sword length is based on the male’s apparent rather than actual size.     

Surgical design and algorithm for correction of earlobe ptosis and pseudoptosis deformity

A previously described classification system for earlobe ptosis and criterion for earlobe pseudoptosis deformity was based on height measurements of the two earlobe components: the free caudal segment and the attached cephalic segment. The "ideal" ear lobule free caudal segment was found to be between 1 and 5 mm (grade I ptosis), and the "ideal" attached cephalic segment was 15 mm or less. Earlobe pseudoptosis was defined by an attached cephalic segment measuring greater than 15 mm. Previous studies revealed an association between the elongated free caudal segment and increasing patient age and between the elongated attached cephalic segment and rhytidectomy. Sixteen fresh cadaver earlobes were used to design surgical patterns that would differentially reduce the free caudal segment, the attached cephalic segment, or both. A horizontal, medially based triangular excision pattern was designed. Triangular excisions limited to the attached cephalic segment resulted in 98 +/- 5 percent reduction of excision height from the attached cephalic segment but also resulted in an unexpected 32 +/- 2 percent augmentation of the excision height in the free caudal segment. Triangular excisions limited to the free caudal segment resulted in 88 +/- 4 percent reduction of the excision height from the free caudal segment and negligible reduction of 4 +/- 4 percent of excision height in the cephalic attached segment. An algorithm for correction of earlobe ptosis and pseudoptosis was subsequently derived and implemented in a clinical case. The authors propose that surgical treatment of patients with pseudoptosis be dependent on the ptosis grade. If the ptosis is grade I (1 to 5 mm), then excision of only the attached cephalic segment is recommended. If the ptosis is grade II or higher (more than 5 mm), then a combined attached cephalic and free caudal segment excision is recommended. In cases of isolated ptosis grade II or higher without pseudoptosis, then excision location of only the free caudal segment is recommended. The above simple algorithm and surgical designs will enable plastic surgeons to differentially correct earlobe ptosis and pseudoptosis.     

Long-term changes in dominance ranks among ring-tailed lemurs at Berenty Reserve, Madagascar

A study was conducted between 1989 and 2001 to monitor changes in the dominance ranks among adult ring-tailed lemurs (Lemur catta) at Berenty Reserve, Madagascar. Adult females were observed to be dominant over adult males. Their rank fluctuated greatly. However, in some troops, female rank orders were fairly stable over a period of several years. In general, male ranks were more unstable than female ranks. Most young females aged 3 years occupied the lowest ranks among adult females. However, several were also observed to have attained relatively higher ranks, placing them right beneath their high-ranking mothers; this suggested the existence of dependent ranks. Mothers were dominant over their daughters. Similarly, older sisters were usually dominant over younger sisters. The mean duration of alpha status for females was 1.95 years, although considerable variation was observed in the duration of the alpha status (1–5 or more years). Most young males aged 3 years initially occupied the lowest ranks in their natal troops, and then they migrated to non-natal troops around the age of 4 years. They ascended in rank between the ages of 4 and 6 years, although there was considerable variation in the acquirement of high rank. The mean duration of alpha status for males was 2.2 years. Larger males were observed to occupy higher ranks. Occasionally, both males and females showed intense aggression (i.e., targeting aggression) towards others.     

Relation between the dominance rank of female rhesus monkeys and their access to males

Systematic observations were made on 12 measures of the sexual, aggressive, and social interactions of 24 male–female pairs of rhesus monkeys in six social groups, each consisting of one male and four ovariectomized females tested in a large room. Each female in a group was treated in turn first with estradiol alone and then with estradiol and progesterone in combination. When hormone-treated, the female was also observed during pair tests with the male in the same large observation room (four males, eight females, 240 group tests, 240 pair tests). The dominance ranks of females during group tests were determined post hoc by means of the dominance index [Zumpe & Michael, American Journal of Primatology 10:291–300, 1986]. In all six groups, the most dominant female virtually monopolized the male, and the subordinate females' interactions with the male, assessed during pair tests, were almost completely suppressed during group tests. This “dominant female effect” was a robust phenomenon that depended solely on female dominance rank. It was independent of the identity and hormonal status of females and of the social preferences of males as expressed in pair tests. These findings demonstrate the existence of female mate competition in an Old World primate.     

Morphometry of the adult human earlobe: a study of 547 subjects and clinical application

The purpose of this study was to define the factors that influence earlobe length and to establish a standard for adult earlobe length by sex and age. The study sample consisted of 547 adult subjects older than 20 years of age. A randomized, prospective design was used. Patients with malignancies, previous surgery or trauma to the earlobe, or congenital earlobe anomalies were excluded. The following variables were studied: sex; age; ethnic origin; skin complexion; height, weight, and body mass index; and piercing. Pearson's correlation, analysis of variance, t test, and multiple regression analysis were used for the statistical analysis. There were 383 women (70 percent) and 164 men (30 percent) aged 20 to 80 years. The average length of the left earlobe was 1.97 cm (SD, 0.42 cm), and that of the right earlobe, 2.01 cm (SD, 0.42 cm) (p < 0.0001). A post hoc test revealed a statistically significant difference among the three age groups (20 to 40 years, 40 to 60 years, and >60 years) in both men and women. Pendulous earlobes were significantly longer and less symmetrical than nonpendulous ones by t test. In men, nonpierced left earlobes were longer than pierced lobes; in women, there was no significant difference between pierced and nonpierced ears. Pearson's correlation tests for weight, height, and body mass index showed that only weight had a significant effect on earlobe length, and only in women. Analysis of variance for ethnic origin and skin color revealed a longer left earlobe in Ashkenazi and Sephardic Jews compared with Ethiopian, Asian, and American Jews and Arabs and a short earlobe in blacks compared with dark and fair-skinned people. On multiple regression analysis, sex and age were the only factors that contributed to earlobe length. A table of average earlobe length by age was formulated on the basis of the authors' findings. These data, together with the knowledge that earlobe length changes little in women over 40, that earlobes are not symmetrical, and that right and left nonpendulous earlobes are symmetrical in individual patients and shorter than pendulous earlobes, can assist the plastic surgeon in deciding on the proper time for loboplasty. The preferable technique is creating a nonpendulous earlobe to minimize the chances of further elongation with time.     

Dominance and its Behavioral Measures in a Captive Group of Bonobos (Pan paniscus)

We investigated the existence of a social dominance hierarchy in the captive group of six adult bonobos at the Planckendael Zoo. We quantified the pattern of dyadic exchange of a number of behaviors to examine to what extent each behavior fits a linear rank order model. Following de Waal (1989), we distinguish three types of dominance: agonistic dominance, competitive ability and formal dominance. Fleeing upon aggression is a good measure of agonistic dominance. The agonistic dominance hierarchy in the study group shows significant and strong linearity. The rank order was: 1. female (22 yr), 2. female (15 yr)., 3. male (23 yr.), 4. female (15 yr.), 5. male (9 yr.), 6. male (10 yr.). As in the wild, the females occupy high ranks. There is prominent but nonexclusive female agonistic dominance. Teeth-baring does not fulfil the criteria of a formal submission signal. Peering is a request for tolerance of proximity. Since its direction within dyads is consistent with that of fleeing interactions, it is a useful additional measure to determine agonistic ranks in bonobos. In competitive situations, the females acquire more food than other group members do. The rank obtained from access to food resources differs from the agonistic rank due to female intrasexual social tolerance, expressed in food sharing. We typify the dominance styles in the group as female intrasexual tolerance and male challenging of rank differences. The agonistic rank order correlates significantly with age and has a strong predictive value for other social behaviors.     

Social dominance relationships and spacing behavior of swine

Dominance ranks were determined within each of eight pens of domestic swine, Susscrofa. Data on spacing and orientation of subjects were obtained from 16 mm time-lapse films and 35 mm overhead photographs with the aid of a digitizer assisted FORTRAN program, DISANGL 2. Dominance orders among subjects were relatively linear and stable. No pattern in pen location preferences (fixed space) was found but there were relationships between dominance rank and portable spacing patterns of the subjects. Distance to a nearest neighbor was the most important variable affecting the orientation of the swine, and the most dominant animal had a lesser tendency to face away from nearest neighbors at any particular distance and a greater tendency to space further from nearest neighbors than was the case for subordinates. The results of this study support the notion that social dominance provides a means by which a possible limited resource, such as personal space, may be differentially allocated to group members.     

MALE DOMINANCE, FEMALE MATE CHOICE, AND INTERSEXUAL CONFLICT IN THE ROSE BITTERLING (RHODEUS OCELLATUS)

An intersexual conflict arises when males and females differ in their reproductive interests. Although experimental studies have shown that females often mate with dominant males, it may not always be in the interest of a female to do so. Here we investigated the impact of male dominance on female mate choice and offspring growth and survival in the rose bitterling ( Rhodeus ocellatus ), a freshwater fish with a resource-based mating system. Three experimental mating trials were conducted using males of known dominance rank, but with different levels of constraint on male behavior. Thus, females were able to choose among; (1) males that were isolated from each other; (2) males that could see and smell each other, but could not directly interact; (3) males that could interact fully. Using a combination of behavioral observation and parentage analyses it was shown that female preferences did not correspond with male dominance and that male aggression and dominance constrained female mate choice, resulting in a potential intersexual conflict. The survival of offspring to independence was significantly correlated with female mate preferences, but not with male dominance. A lack of strong congruence in female preference for males suggested a role for parental haplotype compatibility in mate choice.     

Alternative male mating behaviors in landlocked Dolly Varden (Salvelinus malma) in south-central Alaska

Mating in Dolly Vardens (Salvelinus malma) was studied in relation to individuals' dominance ranks in a landlocked population in south-central Alaska. Two types of tactics were adopted by males: pairing directly with a spawning female and streaking to a spawning pair. Average success in sperm release was 97% in pairing but only 47% in streaking, and depended on the distance to the female. The pairing tactic was mostly monopolized by males of primary and secondary dominance rank. These dominant males were the largest (≥210 mm in fork length) and the oldest (≥6 years) individuals. Their mating success per season was much higher than that of the smaller and younger males.     

Dominance status of adult male Japanese macaques: Relationship to female dominance status,male mating behaviour,seasonal changes,and developmental changes

Aggressive dominance orders of all adults in a confined troop of Japanese macaques (Macaca fuscata) were determined each mating and birth season during a 4-year interval. Males outranked more females in the mating than in the birth season, and some males shifted back and forth from ranks lower than female ranks in the birth season to ranks higher than female ranks in the mating season. Mating behaviour (number of female partners in mount and ejaculation series and ejaculation frequency) did not differ among males with ranks higher than, as high as, or lower than those of most females, nor did individual males mate more in years, when they were high-ranking than in years when they were not. There was a correlation, however, between ejaculation frequency and the number of females defeated by males. A pattern of increasing male rank with age was found.     

Female Choice for Male Morphological Traits in House Sparrows,Passer domesticus

Female mate choice for male morphological traits was examined in captive house sparrows in New Mexico, USA. A study of house sparrows in Denmark indicated that male bib size is important in female choice (Moller 1988, 1989). To examine this issue further, and to compare the selective pressures on male morphological traits between the two populations, bibs of males were manipulated to one of four standard sizes and females were allowed to choose from four males, one of each bib size. The amount of time the female spent with each male was recorded for 40 trials. Males were then ranked in each trial, with a rank of 4 given to the male the female spent the most time with. The ranks a male obtained were then averaged to provide an indication of a male's attractiveness to females. Data from 23 different males indicated that bib size was not correlated with a male's average rank, even when the effects of other traits were controlled statistically. In addition, the size of the original (unaltered) bib was not correlated with male average rank. Bill depth was the only trait significantly correlated with a male's average rank. Differences in the populations studied or the methodologies used may have led to differences between the results obtained in this study and that of Moller (1988).     

The relative importance of orange spot coloration and total length of males in female guppy mate preference

Female mate choice by multiple male traits is an important current topic in animal behavior. However, the relative importance among the multiple cues in female choice is not explored in most cases. Female guppies Poecilia reticulata use both the color saturation of orange spots and the total length of males as mate choice criteria. In the present study, we used digitally modified video playbacks to examine the relative importance of these two male traits to female mate preferences. We initially examined the effective difference in the color saturation of orange spots as well as that in total length between two stimulus male images. Females only showed a strong preference for a bright male image (compared to the dull image) when the difference in color saturation was large (91% versus 25%). Conversely, females only exhibited a preference for larger size when they were presented a choice between two relatively small male images (total length 26.0 mm versus 23.0 mm). When two male images in which both the two traits were modified were presented to females, they prioritized male images possessing higher color saturation of orange spots, indicating the color saturation of male orange spots to be a more important factor than the total length in their mate choice. The color saturation of orange spots may convey more reliable information about the males to the females than their total lengths. These findings imply that females may rank multiple male criteria depending on relative benefits or costs derived from their mate choice based on each criterion.     

Prospective anthropometric analysis of sagittal orbital-globe relationship following fronto-orbital advancement in childhood

Fronto-orbital advancement is a common procedure for correction of supraorbital retrusion in patients with coronal craniosynostosis. The aim of this study was two-fold: to quantitate change in the sagittal orbital-globe relationship following fronto-orbital advancement in childhood and to determine the ratio of skeletal-to-soft tissue movement. Soft-tissue points on the orbital rim, orbitale superius (os), orbitale laterale (ol), orbitale inferius (oi), and nasion (n), referenced to apex corneae (ac), were measured preoperatively and postoperatively by a custom-made anthropometer. Intraoperative bony advancement was measured with a caliper. Patients were selected with uniform advancement at the fronto-nasal suture and laterally at the mortise and tenon. Fifteen patients with syndromic craniosynostosis were included in the study (six male, nine female): Apert (n = 2), Crouzon (n = 5), Pfeiffer (n = 4), Saethre-Chotzen (n = 3), and Boston type (n = 1). Average age at operation was 8.7 years (range, 4.5 to 10.5 years). Age, sex, method of fixation, postoperative interval, diagnosis, and skeletal movement were analyzed for possible effect on the magnitude of soft-tissue advancement. Average intraoperative skeletal advancement was 12.1 mm, and average postoperative soft-tissue movement was 10.3 mm (p < 0.001), measured at the midpoint of the supraorbital rims (os). The soft tissue: skeletal movement ratio was 0.9:1. Os was the only point at which soft-tissue advancement could be predicted (Spearman's rank correlation coefficient = 0.67); soft-tissue changes at ol, oi, and n were unpredictable. Skeletal movement was the only determinant of soft-tissue advancement of all variables tested, i.e., diagnosis, age, sex, previous fronto-orbital advancement, and wire versus plate fixation. We make recommendations for calculating the magnitude of fronto-orbital advancement, based on preoperative anthropometry and a soft-to-hard tissue advancement factor.     

A twenty-year study of long-term and temporary dominance relations among stumptailed macaques (Macaca arctoides)

Consistent individual differences in long-term dominance are a basic underlying assumption of hypotheses linking dominance and reproductive success. Long-term and temporary dominance of a colony group of stumptailed macaques was studied for 20 years. There were two variously constituted groups for the first 4 years and a single group for the last 16. Stumptails displayed the matrilineal dominance organization found for several other cercopithecine species. A method was devised to standardize ranks so they could be compared over the years across groups of varying size and composition. No animal maintained the same dominance rank over the entire period of the research or over the last 16 years, but there was considerable consistency over long periods. Although occupants of the male and female alpha positions changed several times, one female was dominant for 18 of the 20 years. She was dominant in 1968, at the start of the study, and at its end in 1988 at which time her 18-year-old son was the dominant male. Variation in dominance ranks was greatest among members of mid-ranking matrilines and least for the lowest ranking. The same female or her son were the lowest ranking animals of their groups in all samples taken over the entire 20 years.     

Dominance hierarchy and social relationships in a group of Captive black-and-white snub-nosed monkeys (Rhinopithecus bieti)

Different types of dominance hierarchies reflect different social relationships in primates. In this study, we clarified the hierarchy and social relationships in a one-male unit of captive Rhinopithecus bieti observed between August 1998 and March 1999. Mean frequency of agonistic behaviour among adult females was 0.13 interactions per hour. Adult females exhibited a linear hierarchy with a reversal of 10.9%, indicating an unstable relationship; therefore, R. bieti appears to be a relaxed/tolerant species. The lack of a relationship between the agonistic ratio of the adult male towards adult females and their ranks indicated that males did not show increased aggression towards low-ranking females. Differentiated female affiliative relationships were loosely formed in terms of the male, and to some extent influenced by female estrus, implying that relationships between the male and females is influenced by estrus and not rank alone. A positive correlation between the agonistic ratio of adult females and their ranks showed that the degree to which one female negatively impacted others decreased with reduction in rank. Similarly, a positive correlation between the agonistic ratio of females and differences in rank suggests that a female had fewer negative effects on closely ranked individuals than distantly ranked ones. These data indicate that rank may influence relationships between females. A steeper slope of regression between the agonistic ratio and inter-female rank differences indicated that the extent of the power difference in high-ranking females exerting negative effects on low-ranking ones was larger during the mating season than the birth season, suggesting that rank may influence the mating success of females.     

Female Size Influences Mate Preferences of Male Guppies

Guppies (Poecilia reticulata) have a promiscuous mating system in which female choice for brightly coloured males plays an important role. Consequently, much research on guppies has examined how mate choice by females has lead to the evolution of male colour patterns. Much less attention has been devoted to mate choice by males in this species. In this study, we show that male guppies are choosy when selecting a female to associate with, significantly preferring the larger female when presented with two females that differed by ≥2 mm in standard length (SL). The strength of their preference for each female increased with absolute female size. The relative sizes of the females, however, also influenced male mating preferences: males showed stronger preferences for the larger female as the difference in SL between the two females increased. Such a preference for larger females is not unexpected as fecundity generally increases with body size in female fish. Thus, males choosing to mate with the larger female should have higher reproductive success. An apparent, but non‐significant anomaly, whereby males appear to prefer the smaller of the two females when the difference between female SL was <4 mm, deserves further investigation.