Spider mating season

This study examined the onset of estrus, nutritional conditions during the mating season, and female reproductive parameters in a troop of unprovisioned Japanese macaques (Macaca fuscata fuscata). The mean interbirth interval (IBI) was 25.1 mo, suggesting a 2-yr birth cycle. The mean IBI following the death of an infant before the mating season was only 19.8 mo, whereas the mean IBI was 27.8 mo when the infant survived. Estrus occurred during the time of the greatest food quality, in the autumn (i.e., mating season). A female whose infant did not survive the mating season tended to come into estrus more readily than one with a surviving infant. Only one of the 19 females whose infants survived came into estrus, whereas 43 of the 58 (74.1%) females whose infants did not survive came into estrus. Fruit conditions during the mating season each year were evaluated by the seed crop of the two species (Fagus crenata and Zelkova serrata) that constituted the main food source for the macaques; fruiting levels were classified as "high-fruit" or "low-fruit." Females came into estrus more often during high-fruit mating seasons than during low-fruit mating seasons: 36 (97.3%) of 37 females came into estrus during high-fruit mating seasons, whereas eight (20%) of 40 females came into estrus during low-fruit mating seasons. Although females came into estrus under both high- and low-fruit conditions during the mating season, estrus seldom occurred when females had a surviving infant, and it appears that the absence of a surviving infant is an almost essential variable for the onset of estrus. When females with a surviving infant were excluded from the analysis because they were unlikely to come into estrus, all 35 remaining females (100%) came into estrus during high-fruit mating seasons, whereas only eight (34.8%) of 23 females came into estrus during low-fruit mating seasons. Therefore, the onset of estrus is strongly affected not only by the survival of infants through the mating season, but also by fruiting conditions, especially the availability of high-quality food.

A histological study was undertaken to clarify seasonal changes in the spermatogenic epithelium of Japanese macaques. Testicular tissue samples were excised by biopsies from five adult laboratory-maintained males in mating and non-mating seasons. The samples were fixed with Bouin's solution, embedded in paraffin, and stained with PAS and hematoxylin. Microscopic observations on cross-sections of seminiferous tubules revealed that the seminiferous epithelium in the mating season was thicker than in the non-mating season. PAS-stained granules were found in some of the dark A-type spermatogonia, which significantly increased in the non-mating season. Spermatids of the steps preceding the appearance of the acrosomic cap in stages I to III were observed significantly more often than those in the step coinciding with the formation of the acrosomic cap in stage IV. In stage I, the ratio of mature spermatids or spermatozoa to immature spermatids in the mating season was higher than that in the non-mating season. These findings suggest that spermiogenesis, as well as spermatocytogenesis, is inhibited in the non-mating season.

Rhinopithecus roxellana are generally seasonal breeders, although copulation can occur throughout the year. Previous studies suggest that estradiol modulates female sexual behavior during the mating season. However, the effects of social context on estrogen levels and behavior have not been fully explored. We studied the relationship between sexual behaviors and fecal estrogens in a group of captive R. roxellana during a period of social instability. We collected behavioral data for six months and collected fecal samples at 2-3-day intervals for four months spanning the mating and nonmating seasons, and analyzed fecal estrogen levels via RIA. Females showed clear cyclic solicitation and copulation peaks in the mating season, which corresponded with sharp peaks in fecal estrogens. During the nonmating season, solicitation rates, copulation rates, and fecal estrogens were generally low. However, one nonpregnant female displayed a sharp peak in solicitations, copulations, and estrogens during the nonmating season 10-14 days after a male replacement. Our results provide preliminary evidence that social and behavioral changes affect estrogen levels in R. roxellana.

Sympatric rattlesnakes with contrasting mating systems show differences in seasonal patterns of plasma sex steroids

BackgroundParental care is exclusively provided by females in most mammals, and mothers use several spatiotemporal behavioral tactics to minimize risks to offspring and to enhance fitness of both the mother and offspring. In species with infanticide and varying maternal care duration, dependent offspring remain vulnerable to male infanticide until separation from the mother. However, extending maternal care likely results in parent–offspring conflicts. We investigated the spatiotemporal behavioral tactics of lone female brown bears and mothers accompanied by offspring of varying ages in relation to infanticide risk and offspring separation during the mating season.MethodsWe used data from 144 individuals (92 females and 52 males, 2003–2022) to characterize female spatiotemporal behavioral responses to males during the mating season by contrasting home range and encounter area sizes, proximity to males, and dyadic associations in relation to female reproductive status. We investigated the spatiotemporal behavioral responses of mothers from a socio-spatial perspective by connecting large-scale movement behavior (home range and overlap) and small-scale social behavior (proximity and associations) of adult females and males.ResultsWe found that females with dependent offspring of any age avoided males during the mating season. In comparison, lone females or mothers that lost or separated from their offspring during the mating season used larger areas and moved in closer proximity to males. The home range of mothers that remained with their offspring still largely overlapped with male home ranges, however, they did not associate (< 100 m) with males. Additionally, mothers with yearlings had similar sized home ranges as solitary females, but larger home ranges in comparison to mothers with cubs-of-the-year. This suggests that mothers with yearlings are more conspicuous on the landscape which may result in a higher detectability by males.ConclusionOur results suggest that mothers with offspring of any age perceive adult males as potential source of infanticide and use spatiotemporal avoidance tactics. Generally, family groups had high home range overlap with adult males, but family groups that remained together throughout the mating season did not associate with any adult male. Mothers with yearlings used larger areas in comparison to mothers with cubs, potentially indicating their increasing energetic needs. The use of spatiotemporal behavioral tactics to avoid infanticide by females with dependent offspring irrespective of age likely disrupts movement, mating, and social dynamics and on the long-term potentially increases the risk of infanticide to older offspring.

Diurnal changes in basal cortisol levels and stress reactivity were assessed in male and female squirrel monkeys. Blood samples were collected at four-hour intervals throughout the day and night in the mating and nonmating seasons. Basal cortisol levels in females were similar in both seasons, but males tended to have higher cortisol levels during the mating season, especially at night. For both sexes, cortisol secretion was highest between 0400 and 0800 preceding the onset of the diurnal activity period. Assessment of cortisol responses following brief handling and anesthesia indicated that stress responses were relatively stable across the year, but cortisol increments were slightly higher in the nonmating season. Cortisol levels post-stress were generally related to prior baseline values. Thus, a knowledge of biorhythmic changes in basal hormone levels was important for predicting hormone levels after acute stressors. Males also underwent marked seasonal variation in their basal testosterone levels, which markedly altered the nature of their testosterone responses 30-minutes poststress. © 1995 Wiley-Liss, Inc.

The ability to determine hormonal profiles of primate populations using non-invasive techniques can help to monitor physical fitness, stress, and physiological responses to environmental changes. We investigated fecal glucocorticoids (fGC) and DHEAS concentrations in captive Japanese macaques (Macaca fuscata) in relation to environmental, biological, and social factors. The subjects were female Japanese monkeys from 4 months to 31 years old housed in captivity (27 in social groups and 12 in single cages). Fecal samples were collected from all females, and behavioral data from the social groups during the mating season and the following birth season. Hormonal concentrations were analyzed by enzyme immunoassay. Our results revealed that both fGC and fecal DHEAS concentrations are higher in females housed indoors in single cages than in those living outdoors in social groups. We also found that fGC concentrations were higher in the cycling females during the mating (winter) season than the lactating females in the birth (spring) season. Age was negatively associated to both fGC and fecal DHEAS levels, but the relationship between age and fecal DHEAS was more evident in females housed indoors in single cages than in females housed in outdoor social groups. We did not observe any association of dominance rank with either fecal DHEAS or fGC. This study showed that measurement of fecal DHEAS and fGC can be a good method to assess stress in Japanese macaques. These findings provide insights about the physiology of these two adrenal hormones in female Japanese macaques, which can be applied to wild populations and is fundamental for captive management and conservation biology.

Reproductive cycles and mating capacity in male American lobsters (Homarus americanus)

The influence of lactation on copulatory behaviors and ovarian functions was studied in Japanese monkeys (Macaca fuscata fuscata) during the mating season. Three lactating females were housed in an outdoor group cage with their infants, and three nonlactating females were housed in an adjacent outdoor cage. They were mated by introduction of one of four rotationally chosen males into the females' cage, for two hours three times a week; the occurrence of ejaculatory copulations was recorded. Blood samples were collected on each observation day, and plasma levels of estradiol, progesterone, and luteinizing hormone (LH) were measured by specific radioimmunoassays. In nonlactating females, plasma estradiol increased during the transition into the mating season, and rose to levels over 90 pg/ml for the first time on about 50 days before the first ovulation. Shortly after plasma estradiol exceeded 90 pg/ml in the nonlactating females, the onset of ejaculatory copulations occurred. They received ejaculations continuously up to the early ovarian luteal phase. On the other hand, in lactating females, there were lower levels of plasma estradiol (below 90 pg/ml) during the transition into the mating season, and they received no ejaculation during that period. Two of the three lactating females ovulated only once, and they received ejaculations only during the periovulatory period, coinciding with the rise of their plasma estradiol levels over 90 pg/ml. The remaining lactating female remained anovulatory and received no ejaculation throughout the entire mating season. These results have demonstrated that the low sexual activity of lactating females is clearly correlated with low levels of plasma estradiol due to suppressed ovarian function.

Males of species with promiscuous mating systems are commonly observed to use larger ranges during the mating season relative to non‐mating seasons, which is often attributed to a change in movements related to reproductive activities. However, few studies link seasonal range sizes to variation in daily space use patterns to provide insight into the behavioral mechanisms underlying mating season range expansion. We studied 20 GPS‐tagged male wild turkeys (Meleagris gallopavo), a large upland gamebird, during the mating and summer non‐mating seasons to test the hypothesis that larger mating season ranges resulted from male wild turkeys expanding the scale of daily movement activities to locate and court females. We delineated mating and non‐mating seasons based on intensity of gobbling, a vocalization tied to courtship behavior, recorded by autonomous recording units distributed across the study area. Mating season ranges were significantly larger than non‐mating season ranges. Daily ranges were larger in the mating season, as were distances between roost sites used on consecutive nights. Variance in daily range size was greater in the mating season, but low temporal autocorrelation suggested considerable daily variability in both seasons. We found no evidence that male wild turkeys changed how they distributed daily movements within seasonal ranges, or differences in habitat use, suggesting larger mating season ranges result from male wild turkeys increasing the scale of their daily movements, rather than a systematic shift to a nomadic movement strategy. Likely, the distribution of females is more dynamic and ephemeral compared to other resources, prompting males to traverse larger daily ranges during the mating season to locate and court females. Our work illustrates the utility of using daily movement to understand the behavioral process underlying larger space use patterns.

Dietary composition may have profound effects on the activity budgets, level of food competition, and social behavior of a species. Similarly, in seasonally breeding species, the mating season is a period in which competition for mating partners increases, affecting amicable social interactions among group members. We analyzed the importance of the mating season and of seasonal variations in dietary composition and food competition on reconciliation in wild female Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Yakushima macaques are appropriate subjects because they are seasonal breeders and their dietary composition significantly changes among the seasons. Though large differences occurred between the summer months and the winter and early spring months in activity budgets and the consumption of the main food sources, i.e., fruits, seeds, and leaves, the level of food competition and conciliatory tendency remained unaffected. Conversely, conciliatory tendency is significantly lower during the mating season than in the nonmating season. Moreover, conciliatory tendency is lower when 1 or both female opponents is in estrous than when they are not. Thus the mating season has profound effects on reconciliation, whereas seasonal changes in activity budgets and dietary composition do not. The detrimental effects of the mating season on female social relationships and reconciliation may be due to the importance of female competition for access to male partners in multimale, multifemale societies.

Behavioural aspects of the raccoon mating system: determinants of consortship success

Nurse sharks have not previously been known to migrate. Nurse sharks of the Dry Tortugas (DRTO) mating population have a highly predictable periodic residency cycle, returning to the Dry Tortugas Courtship and Mating Ground (DTCMG) annually (males) or bi- to triennially (females) during the June/July mating season. For 23 years we have followed the movements of 76 recaptured adults of a total of 115 tagged adults. Telemetry detections of 40 females tagged with acoustic transmitters show that most tagged and presumably post-partum females are continuously present in the DRTO in the fall, winter and early spring following the June mating season but these females depart in late March to early May. Detections reveal these females avoid the DTCMG completely during the next mating season, returning from late summer to fall. Telemetry records of nine of 17 adult males that co-habited with these females in the DTCMG depart DRTO waters every July. Both sexes may overwinter in the DRTO. Between 2011 and 2016 three males and five females with transmitters were detected to move up the west coast of Florida outside of the mating season as far north as the waters off Tampa Bay (335 km). Six others were only detected in the lower Florida Keys (292 km). Nine sharks returned to DRTO; one returned six times. Some overwintered and some resumed courtship in June, demonstrating both resident and migratory contingents within their population, partial migration and an ability to navigate with high spatial and temporal precision.

Among animals, the fast-slow continuum is the dominant axis that shapes life-history variation. As resources are limited a trade-off occurs between a short lifespan, young age at maturity, high reproductive rates and high aging rates or the other way round. At an ultimate level, rates of adult mortality with age are assumed to determine whether a species falls in the one or in the other continuum, at which high rates of extrinsic mortality select for fast life-histories. Within terrestrial vertebrates (tetrapods), the current record holder for short lifespan is the Labord’s chameleon, Furcifer labordi. These chameleons, inhabiting the seasonal western and southwestern deciduous dry forests of Madagascar, were found to have a post-hatching lifespan of only several months. At the onset of the active respectively rainy season, in November, a cohort of hatchlings emerges. Their early life is determined by rapid growth, resulting in fast sexual maturity and subsequent reproduction in January-February. After the mating season, senescent declines become apparent, and at the beginning of the dry season, a fast die-off has been observed in both sexes. Hereafter, the population only exists as eggs, probably as an adaption to survive the harsh dry season. High adult mortality combined with relatively high juvenile (here egg) survival might have ultimately selected for this annual life-history. It is unique in tetrapods and makes this chameleon an intriguing model species for investigating the proximate and ultimate factors shaping rapid senescence, especially because perennial, sympatric congeners are available for comparative studies. &#13;\n\tSemelparity, i.e. the strategy to allocate all energy in one reproduction event, is rarely found in tetrapods and has apart from a very few reptile species only been detected in a few small-sized marsupial species. However, in these marsupial species the die-off following the mating season is restricted to males, while several females survive until the next breeding season. Apart from these species, for which the male die-off is obligate, less extreme cases of semelparity have been documented. Here, facultative male die-off is restricted to some populations and/or only observed in some years and has been linked to variable resource availability. Strong prey seasonality that leads to a short breeding season has been suggested to explain male semelparity in marsupials, at which high levels of sperm competition combined with female reproductive synchrony select for obligate semelparity. Interestingly, males that were captured before engaging in reproductive season, can survive for more than two years. However, while captivity may shield males from early death due to extrinsic factors, they still experience loss in body mass and irreversible regression of sexual organs as observed in their wild conspecifics after the mating season, proposing an annual, intrinsic pacesetter. In contrast to these marsupials, the proximate causes leading to the short life in this chameleon species remain entirely unknown. Is it the consequence of extrinsic factors, such as intense intra-sexual competition, high predation rates, and low food availability, or are the physiological changes leading to rapid senescence internally “programmed” and thus impending? In the marsupials mentioned above, both factors seem to play a role. Furthermore, so far, only one population in the southernmost and thus driest distribution range of this species has been studied in detail. Thus, the ultimate aim of my thesis is to reflect on the interplay between the external and internal factors that favour the short life-history of this chameleon species.&#13;\n\tIn the first study, I investigated the variability of lifespan in a population of F. labordi in the Kirindy Forest, which has a much longer rainy season compared to the more southern habitat. I documented that the population wide die-off is prolonged in Kirindy several months forward. Moreover, I showed a bias in sex-specific mortality, in which females have a longevity advantage. To exclude most extrinsic factors of mortality, I kept several individuals in captivity and demonstrated that both sexes could survive until the next season of activity. Therefore, this study revealed considerable plasticity of this life-history that is associated to differences in ecological factors. Within the second study, I compared the life-history of F. labordi with those of the congeneric and sympatric species F. cf. nicosiai and F. oustaleti in the Kirindy forest and tested for potential niche segregation that might have driven evolutionary selection for this short lifespan. In all three species, I found high interspecific differences in time of hatching, growth rates, age at reproduction, adult body size and lifespan. While the cohort of F. labordi was already adult, hatchlings of the F. oustaleti and subsequently F. cf. nicosiai emerged. As hatchlings in these species are similar-sized, these differences indicate dietary niche segregation. However, I found that compared to other similar sized lizards, the lifespans of F. cf. nicosiai and F. oustaleti are considerably short and probably attributed to the ecology of chameleons. In the third study, I examined to which extend parasite infection as a proxy of overall health in F. labordi might be connected to the short lifespan. Therefore, I inspected gastrointestinal, - blood - and ectoparasite burden and compared my findings to those of the sympatric and longer living F. cf. nicosiai and the caged individuals. Within F. labordi, I found an intense increase of prevalence in gastrointestinal parasites over the reproductive period. Males showed a higher prevalence that could be caused by frequent male-male combats resulting in higher baseline stress levels and their earlier disappearance. Contrary to our expectations, gastrointestinal, - blood - and ectoparasite burden was higher in adult F. cf. nicosiai. In captivity, both sexes showed less parasite burden and were longer living than their wild conspecifics. The final study aimed at determining the effect of glucocorticoids (GCs) and telomere shortening as well as their interplay on the acceleration of the aging process in F. labordi. To indirectly measure baseline stress levels, I used the ratio between heterophils to lymphocytes (H/L ratio) in blood smears as an indicator of physiological stress since a rise in GC level is closely correlate with a decrease in lymphocytes and increase of heterophils. I quantified telomere length using real-time quantitative PCR (qPCR) in relative telomere length (TL) in blood cells. I found that H/L ratios were higher in wild F. labordi compared to F. cf. nicosiai. TL was longer in F. cf. nicosiai, but shortened rapidly towards the dry season. The captive specimens showed lower H/L ratios compared to their wild conspecifics. &#13;\n\tIn summary, I evidenced that the short lifespan of F. labordi is not entirely “programmed” but highly variable and linked to ecological factors. Moreover, I found that males were the shorter living sex in the wild, but no significant intersexual differences in lifespan under protected caged conditions were observed. This implies that despite their earlier mortality, males do not obligatory experience faster senescence in components of health. Concerning gastrointestinal parasite infections, I found an increase towards the dry season in both sexes, whereas males showed continuously higher prevalences. Parasite infection was considerably low in the caged individuals, which might have affected their comparatively longer survival. In concordance to these findings, H/L ratios were higher in wild F. labordi compared to their captive conspecifics, probably resulting from the isolation of external stressors. The interspecific comparison with the longer living species F. cf. nicosiai suggests that the relatively slow growing juveniles invest comparatively more energy in self-maintenance. Contrary to our predictions, adult stages seem to suffer from visible senescent declines towards the dry season. Therefore, the disappearance in the wild towards the dry season seems to be a “post-reproductive” phenomenon in both species. In conclusion, the results of this thesis support the fundamental predictions of life-history theory, at which species that experience high extrinsic mortality risk in the wild invest their cellular energy into growth and reproduction at the expense of cellular repair mechanisms. As observed in the semelparous marsupials, both intrinsic and extrinsic mechanisms seem to shape the life-history of F. labordi.

Factors affecting the reproductive performance of goats under intensive conditions in a hot arid environment