Seasonal changes in testosterone levels in wild Mexican cottontails Sylvilagus cunicularius

We studied serum testosterone levels in the endemic Mexican cottontail, Sylvilagus cunicularius, which has been reported to show seasonal breeding. Animals were trapped in the wild and in a field enclosure in the National Park La Malinche in central Mexico over a period of five years. Serum testosterone (T) levels were quantified by ELISA from blood samples. T levels of adult males were lowest around 4 months after the onset of the annual reproductive season and were already high prior to the onset of breeding. As expected, the T levels of adult females were consistently lower than in males, and there were no differences in T level with respect to female reproductive state. There were no detectable sex-specific differences in juveniles and subadults, but there was a marked increase in T levels between juvenile and adult males. Overall, our study clearly reflects and confirms the seasonal breeding strategy of this species, showing high similarities to the much better studied European rabbit.     

Reproduction of the large fruit-eating bat Artibeus lituratus (Chiroptera: Phyllostomidae) in a Brazilian Atlantic forest area

In this study we investigated the male testicular activity and the reproductive condition of females in relation to their external reproductive characteristics (pregnant, lactating, post-lactating) in the phyllostomid bat Artibeus lituratus (Olfers, 1818). Five hundred and twenty six individuals were examined (197 males and 329 females) in the period December 2001 to May 2003. Throughout the study most males displayed large scrotal testes. Thirty-three males were randomly selected for histological examination at various times throughout the year and were found to have spermatogenic testes. The reproductive characteristics of the females indicated that they were reproductively active mainly during the wet season. Pregnancy occurs at the end of the dry season and parturition in the wet season. Most individuals captured after this season, mainly the females, were sexually immature. Our results suggest a seasonal monoestrous reproductive pattern for the species; however, adult males being fertile throughout the year could suggest polyoestry. Seasonal polyoestry is a possibility. There was, however, no evidence that females had more than one pregnancy per year.     

Alternative male reproductive tactics in a natural population of prairie voles <Emphasis Type="Italic">Microtus ochrogaster</Emphasis>

Alternative reproductive tactics have been described in male mammals, but little information exists regarding fitness benefits and whether males change tactics. Adult male prairie voles Microtus ochrogaster (Wagner, 1842) display alternative tactics described as resident and wanderer. Enclosure studies provide conflicting data concerning the relative success of each tactic and whether males display one tactic throughout adulthood. To characterize further residents and wanderers in this species, we examined data collected during 5 years of monitoring a natural population in Illinois, USA. We found that during the breeding period, wandering males survived longer, moved longer distances, and were more likely than residents to have scrotal testes. During the nonbreeding period, wandering and resident males differed only in whether or not they established residency. Data on sources and fates of resident and wandering males revealed that a substantial proportion of males switched tactics. Our estimate of the reproductive contribution of wandering males to the population, which is based on the premise that wandering males typically mate with single females, suggests that wanderers contribute 34–38% of young recruited during March through October and 4–12% in November, when single females are less common. Parentage studies in natural populations are necessary to test our estimates.     

Demographic features, distribution, and habitat selection of the gray mouse opossum (Tlacuatzin canescens) in Colima, Mexico

In western Mexico, gray mouse opossums Tlacuatzin canescens typically are not only in tropical deciduous and semideciduous woodlands but also in croplands and orchards. We conducted mark-recapture studies in January 2003–2007 and 2010 in coastal, northern, and central Colima, Mexico. Each year, five grids, established in areas of thick vegetation within a mosaic of habitats, had 100 stations (10?×?10), each with two Sherman traps, one on the ground and another elevated 1–2 m. On 24 of 30 grids, 82 individuals were captured 126 times (85.7 % in elevated traps). Sex ratio did not deviate from 1:1; there was no sexual dimorphism in mass (average for males, 28.21 g; average for females, 25.64 g); 46.3 % of animals were adults, 27.3 % of adult females were reproductively active, and 77.5 % of males had scrotal testes. Distance from centroid of trap locations averaged 15.24 m, with mean minimum distance moved between captures being 33.19 m. Densities usually were low (0.67–8.03/ha), with the species widespread in habitats studied. We assessed 14 environmental characteristics for each station using ANOVA, logistic regression, and nonparametric multiplicative regression (NPMR) to characterize habitat selection. T. canescens was more likely found where percent grass was about 30 % and litter over 50 %, with height of canopy less than 10 m and about 40 % closed. NPMR, being able to recognize hump-shaped response curves where intermediate variable values are preferred, identified two variables (percent grass and percent canopy closed) not detected by other techniques as important in characterizing habitat selection of T. canescens.     

Comparison of the life cycle of potato cyst nematode (<Emphasis Type="Italic">Globodera rostochiensis</Emphasis>) pathotype Ro1 on selected potato cultivars

The life cycle of Globodera rostochiensis pathotype Ro1 was studied under experimental conditions on selected potato cultivars (Korela, Albina, Vivaldi, Veronika, Vera, Monalisa, Victoria, Maranca, Désirée) in Slovakia during two growing seasons. Two peaks of second stage juveniles (J2) were found in the soil; the first peak three and four weeks after planting in the first and second year, respectively. The last J2 were found on 23 September. The number of J2 found in the second peak was much higher. First J2 associated with roots were observed 18 days, on middle early and seritonous cultivars 34 days after planting, but fourth stage juveniles (J4) were observed 40 days after planting in both cultivar groups. First adult males were found in soil 43 and 46 days after planting, respectively, and the last males two weeks later. White females filled with eggs were observed on roots 61 days after planting. The cycle from hatching of J2 in the soil to the hatching of J2 from brown cysts required 68 days in the first year and 60 days in the second year.     

Life-history characteristics of a wild population of vervets (Cercopithecus aethiops sabaeus) in Barbados,West Indies

Life history data are presented for a population of vervets, Cercopithecusaethiops sabaeus, in Barbados, West Indies. The data were obtained from two habituated troops and from vervets captured during a large-scale trapping program. Individuals of known age from one troop were weighed periodically, and separate growth curves generated for males and females. The mean weight of captured adult females was 3.3 kg; that of adult males, 5.3 kg. The average age at sexual maturity is estimated at 34 months for females and 60 months for males. Vervets give birth throughout the year, but most infants are born between April and July. The average interbirth interval following a surviving infant is 11.8 months. The mortality of juveniles is heaviest between birth and 2 years of age and decreases thereafter. Males emigrate from their natal troops at sexual maturity and one incident of a juvenile female emigrating is reported.     

Demography of a West African kob (Kobus kob kob) population

The kob (Kobus kob kob) population studied in the Comoé National Park, Ivory Coast, suffered unsustainable losses to poaching before and during the investigation. This in turn did not only lead to low densities but also changed the population composition, resulting in a strong female bias in all age classes except juveniles. The relative rarity of adult males probably had negative effects on the population recruitment. Although mating occurred throughout the year and birth intervals were short, at least in some females, annual birth‐rate was low compared to earlier studies in the same area. Effective conservation measures are urgently needed to ensure the future existence of the studied population.     

An experimental analysis of social interaction in the common marmoset (Callithrix jacchus jacchus)

Adult and juvenile common marmosets were introduced to unfamiliar conspecifics individually and in whole groups. In introductions using animals of the same sex, adults were mutually hostile unless they were related or socially familiar; juveniles behaved submissively to adults and little aggression was observed between juveniles. In introductions using animals of the opposite sex, males of all ages solicited females but females did not reciprocate. When whole groups were introduced, in two experiments most of the elder group members behaved aggressively and younger animals did not interact frequently; but in a third experiment, in which the adult males were related, little aggression was observed and younger animals behaved amicably. It is argued that the behavioral reactions shown by individual marmosets are related to territorial hostility and that the behavior of juveniles to adults may aid assimilation of younger animals into new groups.     

Seasonality in Reproduction of <Emphasis Type="Italic">Lepilemur edwardsi</Emphasis>

Sportive lemurs are threatened species in the IUCN Red Data Book. However, quantitative information on their reproduction, urgently required for conservation, has been lacking. We collected first data on reproductive activity of Milne-Edwards’ sportive lemurs in a population inhabiting the dry deciduous forest of the Ankarafantsika National Park in northwestern Madagascar during 1998, 2001, and 2003. The species showed a seasonal reproduction. The main mating season extended from May to June, as indicated by the presence of males with high testes volumes and estrus females. In the mating and early postmating season and in the postparturition season, sexes did not differ in body mass. Females had a significantly higher body mass than males in August and November, indicating pregnancy, which together with the presence of small infants in October and November implies that gravidity in females lasted for about 4–5 mo. All litters consisted of singletons. Individuals with body mass at the lower limit of the population either did not develop measurable testes volumes (males) or were not in estrus (females). They were probably juveniles from the previous birth season that achieved sexual maturity not before their second year after birth. The first data on reproduction suggest a low reproduction rate for Lepilemur edwardsi and a request for a higher conservation status than previously attributed and the need for further management strategies.     

Quantitative observations of grooming behavior in free-rangingMacaca mulatta

Quantitative methods of observation and analysis were used in a 12-month study of grooming behavior of free-rangingMacaca mulatta on La Cueva Island at La Parguera, Puerto Rico. Observations lasting 30–120 minutes were made from eight positions on the island at a standard time of day when monkeys were either feeding or resting. Two dependent variables were obtained: (1) the number of monkeys present in the observation area were noted by age and sex class at five-minute intervals throughout each observation, and (2) the frequency of grooming encounters was tabulated by the age and sex class(es) of groomer and recipient. These data were computed as grooms/hour/possible interacting combination of monkeys. Grooming frequencies were higher in non-feeding situations than when monkeys were feeding. The largest social group had the lowest mean grooming rates, while the smallest group had the highest grooming frequencies. More grooming occurred during the November-to-February mating season than at other periods of the year. Adult females were involved in over 60% of all grooming behavior, juveniles participated in 25% of the grooming, while adult males groomed females, primarily during the mating season, and rarely groomed other males or juveniles. Genealogical relationships, levels of group aggression and the feeding or resting context all influenced the frequency of grooming. This study provides support for the hypothesis that the basic social unit for rhesus macaques consists of a core of adult females with their juvenile and infant progeny.     

Movements,reproductive seasonality,and fisheries interactions in the whitetip reef shark (<Emphasis Type="Italic">Triaenodon obesus</Emphasis>) from community-contributed photographs

Despite being a common apex-level predator on coral reefs throughout the tropical Indo-Pacific, surprisingly little is known about whitetip reef shark (Triaenodon obesus) movements and biology. This study used photo-identification from community-contributed photographs to reveal patterns in movements, reproductive biology, and fisheries interactions in this species that have not been previously revealed through more traditional methods. At least 178 individual sharks were identified, and 26 movements were observed. These included movement distances of up to 26.4 km, movement rates of up to 3.27 km/day (9.8 km in 3 days), and movements that required the transit of a 140 m deep channel. Other animals showed high philopatry, being re-sighted at the same locality on multiple occasions (up to 13 sightings for one individual) over periods of up to 7 years. Females showed higher philopatry than males and were more likely than males to be found at shallow (<10 m depth) localities throughout the year. The proportion of male sightings at shallow localities was significantly higher in April and May than other months of the year, possibly due to males coming into the shallows to mate with females. A peak in sightings of late-term females followed by an abrupt decline suggests that pupping season is May into early June, and two females were observed pregnant in consecutive years despite evidence that the gestation period is approximately 1 year for this species. Nine percent of animals carried fishing tackle or exhibited jaw injuries associated with fishery interactions, with multiple individuals found dead after being hooked by fishers.     

Social organization of white‐headed langurs (Trachypithecus leucocephalus) in the Nongguan Karst Hills,Guangxi, China

The number of males per group is the most variable aspect of primate social organization and is often related to the monopolizability of females, which is mainly determined by the number of females per group and their reproductive synchrony. Colobines show both inter‐specific and intra‐specific variations in the number of males per group. Compared with other colobine species, little is known about the social organization of white‐headed langur (Trachypithecus leucocephalus), despite its endangered status and unusual limestone habitat. As a part of a long‐term study of the white‐headed langurs in the Nongguan Karst Hills, Guangxi, China, we quantitatively investigated their social organization by analyzing census data from 1998 to 2003. The population censuses revealed that the predominant social organization of bisexual groups was the one‐male group, similar to a previous report on this species and many other Asian colobines. In such groups, one adult male associated with 5.1 adult females, 0.1 sub‐adult males, 2.6 juveniles and 2.9 infants on average, with a mean group size of 11.7 individuals. In addition, three multi‐male groups were recorded, consisting of 2–3 adult males, 1–5 adult females, 0–2 sub‐adult males, 0–7 juveniles and 0–2 infants. They did not contain more adult females than the one‐male groups and were unstable in group membership. The langurs outside bisexual groups were organized into small nonreproductive groups or lived as solitaries. The nonreproductive groups averaged 1.3 adult males, 1.3 sub‐adult males and 2.6 juveniles. Juvenile females were present in such groups on 52.4% of all occasions. As predicted by the monopolization model, the prevalence of the one‐male pattern in this species may mainly be attributed to the small number of females in the group. The possible reasons for the occurrence of multi‐male groups and the presence of juvenile females in nonreproductive groups are also discussed. Am. J. Primatol. 71:206–213, 2009. © 2008 Wiley‐Liss, Inc.     

Paternal Care in <Emphasis Type="Italic">Propithecus verreauxi coquereli</Emphasis>

Alloparental behavior is documented for several anthropoid primates, but few researchers have investigated the extent or variability of such behavior in prosimians. We report results from a study of male-infant interactions in 2 groups of Coquerel’s sifaka (Propithecus verreauxi coquereli) at the Duke University Primate Center (DUPC). Both groups contained 1 adult pair, 2 juveniles, and a newborn. The adult males exhibited paternal behavior toward their offspring in the form of grooming and holding the infant, though males differed in the amount of time they spent engaged in these activities. Group differences in the proximity maintained between the infants’ parents suggest that the relationship between adult males and females may help account for the variation. The presence of juveniles appeared to diminish paternal behavior in the group exhibiting a higher overall rate of male-infant interaction.     

Mating senescence and male reproductive organ size in the Mexican fruit fly

Ageing can reduce the probability that individuals reproduce. The present study investigates whether ageing influences the mating frequency of mass‐reared fertile and sterile Mexican fruit flies Anastrepha ludens (Loew). The ability of males of different ages to inhibit female remating is also determined, and the growth of male reproductive organs is measured as they age. Young males (6 days old) have a lower mating frequency than older males, and also have a lower capacity to inhibit female remating than older males. However, 7‐day‐old males are as likely to inhibit female remating as older males. Young males also have smaller reproductive organs than middle‐aged (21‐day‐old) or senescent males (57‐day‐old). These results have implications for the sterile insect technique because sterilized males of A. ludens are released in the field 6 days after emergence. The highest mating frequency, the lowest mating latency and the largest size of testes are observed at 21 days of age. Older males (57 days old) have more sperm in their seminal vesicles than young males (6 and 9 days old). Accessory glands take longer to grow to their complete size compared with testes, and mating frequency is more closely associated with accessory gland size than testes size. Furthermore, there are more sperm in the seminal vesicles during the afternoon period of peak sexual activity than during the morning when sexual activity is absent. These results indicate that, even at the onset of reproductive senescence, mass‐reared males of A. ludens are still capable of mating, as well as inhibiting remating in females.     

Causes of Intraspecific Aggression in Alouatta palliata mexicana: Evidence from Injuries,Demography, and Habitat

Although howlers have been traditionally considered to be pacific, showing one of the lowest rates of aggression among primates, new evidence is emerging to question this image. We present data on injuries in Mexican mantled howlers (Alouatta palliata mexicana) in relation to different sociecological parameters. We censused howler populations in 19 forest fragments over a 17-mo period in the Los Tuxtlas Region, southern Veracruz, Mexico. We conducted detailed observations of scars, torn lips, broken fingers, mutilated tails and other visible injuries. We also collected data on the demography, biogeography and vegetation of each fragment in order to relate injury data to them. We censused 333 howlers, of which we exhaustively observed 254 for injuries. Four resident adult females (n = 108) and 29 adult resident males (n = 76) had injuries, while none of the solitary males (n=16), solitary females (n=1), juveniles (n=23) and infants (n=30) had them. We discuss possible interpretative scenarios for the distribution of injuries. Although some results suggest that food resource concentration may determine intergroup agonistic encounters, we propose that physical injury is primarily associated with male-male agonistic encounters during takeovers, and consequently it could indicate migration among troops.     

Reproductive cycle of the blacknose shark Carcharhinus acronotus in the Gulf of Mexico

The reproductive periodicity of blacknose sharks Carcharhinus acronotus in the northern Gulf of Mexico was determined by examining reproductive tissues from specimens collected monthly from 2002 to 2005. Monthly changes in shell gland mass, right ovary mass and ovarian follicle diameter were assessed for 74 mature females. Temporal changes in testes mass, testes width and proportion of mature spermatocysts were examined for 64 mature males. Trends in female reproductive tissues suggested an annual peak in reproductive activity during June and July, while trends in male variables suggested an annual reproductive peak during May and June. Although male and female reproductive activity peaked in different months, a strong synchronicity existed between the proportion of mature spermatocysts and the diameter of the largest ovarian follicle. Based on these results, the mating season of blacknose sharks lasts from mid-May to July in the Gulf of Mexico. Maximum embryo sizes were observed in May, which suggested that partition occurs during late May or early June. Results indicate that blacknose sharks have a clearly defined annual cycle in the Gulf of Mexico. This conclusion is further supported by the complete absence of gravid females without vitellogenic ovarian follicles among all mature females examined.     

Patterns of infant handling and relatedness in Barbary macaques (<Emphasis Type="Italic">Macaca sylvanus</Emphasis>) on Gibraltar

Among papionin primates, the Barbary macaque (Macaca sylvanus) shows the most extensive interactions between infants and group members other than the mother. Two different types of interactions occur: (1) long-lasting dyadic interactions between a handler and an infant, and (2) brief triadic interactions between two handlers involving an infant. Previous investigations showed that infant handling by males is best explained as use of infants to manage relationships with other males. In contrast, no adaptive explanation for infant handling by females emerged. Here, we compared the infant-handling pattern between subadult/adult males and subadult/adult females in a free-ranging group of 46 Barbary macaques on Gibraltar to test whether the relationship management hypothesis also applies to female handlers. We further investigated the infant-handling pattern of juveniles and used microsatellite markers to estimate relatedness between infant handlers and the infant’s mother. We found that males, females and juveniles all participated extensively in triadic interactions using infants of above-average related females. In contrast, only males and juveniles were highly involved in dyadic interactions with infants of related females, while females rarely handled infants other than their own. The pattern of infant handling was entirely compatible with the predictions of the relationship management hypothesis for males and mostly so for females. Moreover, our genetic analysis revealed that males and females differ in their partner choice: while females preferred to interact with related females, males had no significant preference to interact with related males. We further discuss the observed above-average relatedness values between infant handlers and the infant’s mother in the light of kin-selection theory.     

Sperm availability in naturally occurring bisexual-unisexual breeding complexes involvingPoecilia mexicana and the gynogenetic teleost,Poecilia formosa

Synopsis Testicular maturation indices (TMI) were determined for wild-caught males ofPoecilia mexicana by quantitative analysis of the frequency of ongoing stages of spermatogenesis and spermatid differentiation in sections of testes stained with the Feulgen reaction for DNA. In nature, males maintain essentially constant levels of sperm production throughout the year and show no significant variations in mean TMI values associated with season, microhabitat, standard body length, or rank in male dominance hierarchies. Winter males or males isolated from females in the laboratory show accumulation of mature spermatophores. These findings suggest that fluctuations in the microstructure of wild populations ofPoecilia from northeastern Mexico may be due primarily to differences in the temporal scheduling of female reproductive cycles and not to limitations imposed by sperm availability or male reproductive competence. The data are discussed in terms of competitive interactions within unisexual-bisexual breeding complexes involving the Amazon mollyP. formosa, its related triploid hybrids, and the bisexual species,P. mexicana.     

The seasonal changes in somatic energy content of Gulf of Alaska yellowfin sole, Pleuronectes asper

Seasonal measurement of body energy content was made for Pleuronectes asper (Pallas, 1814) from the Gulf of Alaska. Whole body energy content of complete fish (～ 3472 J g^?1 wet wt) was minimal in May for females as their overwintering phase ended, then increased to ～ 4456 J g^?1 prior to spawning. The ovarian index [(g.w./t.w.) × 100] and energy content of ovaries (J g^?1) was highest in June and May respectively, and then declined markedly by August as spawning occurred. Throughout the year male whole body energy content of complete fish ranged from 3351 to 4590 J g^?1 with the lowest values in May and highest values occurring during June to September, the feeding season. The testes index [(g.w./t.w.) × 100] and total energy content of testes (J g^?1) were high in March and lowest during June and July. On a weight-specific basis, males and females had similar whole body energy values throughout the year. Juveniles followed the same seasonal trends in energy storage as adults and had similar whole body energy values. Whole body energy content was linearly related to wet and dry weight condition factor with r² values of 0.70 and 0.87, respectively. Dry body weight as percent of wet body weight was the best predictor of body energy (r²=0.91). Yellowfin sole had an annual energy cycle with energy accumulation and growth from May to September. Thereafter they utilized stored energy for metabolic and reproductive needs. Spawning began in late May or early June and fish were spent by August. Whole body energy content increased by 28, 33 and 35% between May and June, for females, juveniles, and males, respectively, the most dramatic change during the year long survey. This suggests that intense feeding in May must be an important aspect of their energy storage cycle.     

Development of the False Root-knot Nematode,Nacobbus aberrans, on Sugarbeet

The duration of the embryogenic development of Nacobbus aberrans (= N. batatiformis) took 9-10 days at 25 C and 51 days at 15 C. The J₁ molted in the egg; hence the Je emerged from the egg. The effect of distilled water attd root leachates of kochia and sugarbeet was investigated at 5, 10, 15, 20, and 25 C. Root leachates did not significantly affect the percent of cumulative hatch of eggs, but temperature did significantly affect emergence of juveniles (p = 0.05). Less than 1, 5, and 20% of eggs hatched at 5, 10, and 15 C, respectively. The percent of cumulative hatch at 20 C was four times greater than at 15 C, while the highest percentage of juveniles emerged at 25 C. The duration of postembryogenic development from J₂ inoculation until the appearance of mature females with egg masses took 38 days, and the life cycle from egg to egg was completed in 48 days at 25 C. All immature stages, young females and males were migratory endoparasites. Young females were able to leave the root swellings, where they developed from juvenile stages, and re-enter the root, where they formed a true gall and became sedentary. Thirty days after inoculation with J₂ nematodes, specimens were detected in root tissues at 10, 15, 20, 25, and 30 C, hut not at 5 C. Five days after inoculation at 23 C ( ± 2 C), juveniles had penetrated the roots and caused slight swellings of the tip and axis of sugarbeet feeder roots. Large cavities extended from the cortical parenchyma to the periphery of the stelar area, and 50 % of the central cylinder was destroyed 25 days after inoculation at 23 C. No syncytia formation were detected in the sugarbeet root swellings infected with juveniles. Syncytia were associated only with adult females; hyperplasia, abnormal proliferation of lateral roots, and asymmetry of root structure were additional anatomical changes induced by adult females. Only very smooth annules but no cuticular ornamentations were noted by SEM on the perineal area of adult females.