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A C Spinks - One of the best experts on this subject based on the ideXlab platform.
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regulation of reproduction in female common mole rats cryptomys hottentotus hottentotus the effects of breeding season and Reproductive Status
Journal of Zoology, 1999Co-Authors: A C Spinks, Nigel C. Bennett, Jennifer U M JarvisAbstract:The effects of breeding season and Reproductive Status on female reproduction were investigated in the common mole-rat, Cryptomys hottentotus hottentotus, a co-operatively breeding rodent that exhibits seasonal breeding and a Reproductive division of labour. Body mass, Reproductive tract morphometrics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild-caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology revealed that females retained Reproductive function during the winter non-breeding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in Reproductive females during the breeding period. The continuance of Reproductive function during the non-breeding period in female common mole-rats parallels the situation in males, and is believed to be important in dispersal in C. h. hottentotus. The non-breeding period coincides with the period of maximal dispersal opportunities in the winter rainfall areas inhabited by the common mole-rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair-bond formation and thereby facilitate independent reproduction. Reproductive and non-Reproductive females exhibited a similar degree of Reproductive function, and as for season, the only clear-cut Status-related differences were associated with the occurrence of pregnancy in Reproductive females. This absence of a physiologically well-defined suppression of reproduction in female common mole-rats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate outbreeder.
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intercolonial encounters and xenophobia in the common mole rat cryptomys hottentotus hottentotus bathyergidae the effects of aridity sex and Reproductive Status
Behavioral Ecology, 1998Co-Authors: A C Spinks, M J Oriain, Daniel PolakowAbstract:The ecological constraints prevalent in arid environments have promoted the evolution of social groups with a high Reproductive skew in mole rat species occurring there. Outbred social bathyergids face conflict between maintaining colony integrity to enhance personal foraging success and hence survival, and dispersal to maTimizr individual lifetime Reproductive success (LRS). This conflict will be a crucial determinant of the response of colony members to the presence of foreign conspecifics. We investigated how ecological constraints, sex, and Reproductive Status influence die outcome of meetings between foreign common mole rats (Cryptomys hottentotus hottentotus) in a series of dyadic encounters. Individuals from two localities, at the extremes of an aridity gradient, were used to assess the effects of aridity. The efFects of sex and Reproductive Status were investigated by trials between individuals of differing sex and Status. The arid population revealed substantially higher levels of rejection than the mesic population. Sex and Status played a significant role in moderating individual response. For both populations, encounters between different-sexed individuals produced lower levels of rejection than those between same-sexed individuals. For the mesic site, rejection was greatest for encounters between Reproductive animals. Conversely, for the arid site, the levels of rejection were comparatively high and comparable for all combinations of Reproductive Status. Ecological constraints, sex, and Reproductive Status are significant factors in interactions between foreign common mole rats, ultimately influencing individual survival, colony integrity and the differential LRS of all colony members. Our results provide insight into die evolution and maintenance of family groups within the bathyergids.
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influence of breeding season and Reproductive Status on male Reproductive characteristics in the common mole rat cryptomys hottentotus hottentotus
Reproduction, 1997Co-Authors: A C Spinks, G Van Der Horst, Nigel C. BennettAbstract:The effects of breeding season and Reproductive Status on male reproduction were investigated in the common mole-rat (Cryptomys hottentotus hottentotus), a co-operatively breeding rodent that exhibits seasonal reproduction and a Reproductive division of labour. Testicular anatomical and histological morphometrics, and selected sperm parameters were studied in 50 males from 17 wild caught colonies. Males exhibited no apparent manifestation of season on testicular activity: spermatogenesis and sperm quality (motility and percentage normal morphology) were similar in the Reproductively active and inactive periods. This maintenance of Reproductive activity during the non-Reproductive period is essential in C. h. hottentotus males, as this period coincides with the period of maximal dispersal opportunities. Such Reproductive activation in dispersing males may aid intersexual recognition, and assist pair-bond formation or successful assimilation into foreign colonies, thereby facilitating later outbreeding. Consequently, outbreeding opportunities may be important determinants of Reproductive activity in male common mole-rats, moderating seasonal effects. Reproductive and non-Reproductive males revealed no differences in any of the testicular or sperm parameters studied. The absence of a physiologically well-defined suppression of reproduction in male common mole-rats is more typical of social suppression in male mammals.
Nigel C. Bennett - One of the best experts on this subject based on the ideXlab platform.
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Reproductive Status-dependent dynorphin and neurokinin B gene expression in female Damaraland mole-rats.
Journal of Chemical Neuroanatomy, 2019Co-Authors: Cornelia Voigt, Nigel C. BennettAbstract:Abstract Damaraland mole rats (Fukomys damarensis) are cooperatively breeding, subterranean mammals, which exhibit high Reproductive skew. Reproduction is monopolized by the dominant female of the group, while subordinates are physiologically suppressed. The blockade of reproduction results from an inhibition of ovulation, which is caused by inadequate secretion of luteinizing hormone (LH) from the pituitary, which in turn might be brought about by a disruption of the normal GnRH secretion from the hypothalamus. The neuropeptides dynorphin and neurokinin B are expressed together with kisspeptin in a subpopulation of neurons in the arcuate nucleus (ARC). This neuron population is termed KNDy neurons and is considered to constitute the GnRH pulse generator. To assess whether dynorphin (encoded by the Pdyn gene) and neurokinin B (NKB, encoded by the Tac3 gene) are involved in the mechanism of Reproductive suppression we investigated the distribution and gene expression of Pdyn and Tac3 by means of in situ hybridisation in wild-caught female Damaraland mole-rats with different Reproductive Status. In both Reproductive phenotypes, substantial Pdyn expression was found in several brain regions of the telencephalon including the cerebral cortex, the striatum, the hippocampus, the amygdala and the olfactory tubercle. Within the hypothalamus Pdyn expression occurred in the paraventricular nucleus, the dorsomedial nucleus, the supraoptic nucleus, the ventromedial nucleus and the ARC. Prominent Tac3 expression was found in the habenula, the bed nucleus of the stria terminalis, the cerebral cortex, the striatum, the hippocampus, the amygdala, the dorsomedial nucleus, the ARC and the lateral mammillary nucleus. Quantification of the gene expression levels in the ARC revealed decreased Pdyn and increased Tac3 expression in breeding compared to nonbreeding females. This suggests that both neuropeptides play a role in the regulation of reproduction in Damaraland mole-rats. Their exact role in mediating the inhibition of GnRH release in nonbreeding females remains to be determined.
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regulation of reproduction in female common mole rats cryptomys hottentotus hottentotus the effects of breeding season and Reproductive Status
Journal of Zoology, 1999Co-Authors: A C Spinks, Nigel C. Bennett, Jennifer U M JarvisAbstract:The effects of breeding season and Reproductive Status on female reproduction were investigated in the common mole-rat, Cryptomys hottentotus hottentotus, a co-operatively breeding rodent that exhibits seasonal breeding and a Reproductive division of labour. Body mass, Reproductive tract morphometrics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild-caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology revealed that females retained Reproductive function during the winter non-breeding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in Reproductive females during the breeding period. The continuance of Reproductive function during the non-breeding period in female common mole-rats parallels the situation in males, and is believed to be important in dispersal in C. h. hottentotus. The non-breeding period coincides with the period of maximal dispersal opportunities in the winter rainfall areas inhabited by the common mole-rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair-bond formation and thereby facilitate independent reproduction. Reproductive and non-Reproductive females exhibited a similar degree of Reproductive function, and as for season, the only clear-cut Status-related differences were associated with the occurrence of pregnancy in Reproductive females. This absence of a physiologically well-defined suppression of reproduction in female common mole-rats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate outbreeder.
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influence of breeding season and Reproductive Status on male Reproductive characteristics in the common mole rat cryptomys hottentotus hottentotus
Reproduction, 1997Co-Authors: A C Spinks, G Van Der Horst, Nigel C. BennettAbstract:The effects of breeding season and Reproductive Status on male reproduction were investigated in the common mole-rat (Cryptomys hottentotus hottentotus), a co-operatively breeding rodent that exhibits seasonal reproduction and a Reproductive division of labour. Testicular anatomical and histological morphometrics, and selected sperm parameters were studied in 50 males from 17 wild caught colonies. Males exhibited no apparent manifestation of season on testicular activity: spermatogenesis and sperm quality (motility and percentage normal morphology) were similar in the Reproductively active and inactive periods. This maintenance of Reproductive activity during the non-Reproductive period is essential in C. h. hottentotus males, as this period coincides with the period of maximal dispersal opportunities. Such Reproductive activation in dispersing males may aid intersexual recognition, and assist pair-bond formation or successful assimilation into foreign colonies, thereby facilitating later outbreeding. Consequently, outbreeding opportunities may be important determinants of Reproductive activity in male common mole-rats, moderating seasonal effects. Reproductive and non-Reproductive males revealed no differences in any of the testicular or sperm parameters studied. The absence of a physiologically well-defined suppression of reproduction in male common mole-rats is more typical of social suppression in male mammals.
Wendy Saltzman - One of the best experts on this subject based on the ideXlab platform.
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differences in placentophagia in relation to Reproductive Status in the california mouse peromyscus californicus
Developmental Psychobiology, 2014Co-Authors: Juan Pablo Perearodriguez, Wendy SaltzmanAbstract:Parturient females ingest placenta in most mammalian species, whereas fathers may do so in species in which both parents provide care for their offspring. To determine if the propensity to eat placenta varies with Reproductive Status in the biparental California mouse, we presented placenta to virgin (housed with a same-sex pairmate), expectant (pregnant with their first litter), and multiparous adult males and females. Liver was presented identically, 3-7 days later, as a control. Multiparous females were more likely to eat placenta than expectant and virgin females (p-values <0.016), whereas both multiparous and expectant males had higher incidences of placentophagia than virgins (p-values <0.016). Liver consumption did not differ among groups within either sex. These results suggest that propensity to eat placenta increases with maternal/birthing experience in females, and with paternal experience and/or cohabitation with a pregnant female in males.
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effect of Reproductive Status on hypothalamic pituitary adrenal hpa activity and reactivity in male california mice peromyscus californicus
Physiology & Behavior, 2013Co-Authors: Breanna N Harris, Wendy SaltzmanAbstract:article i nfo Previous studies indicate that Reproductive condition can alter stress response and glucocorticoid release. Al- though the functional significance of hypothalamic-pituitary-adrenal (HPA) axis modulation by breeding condition is not fully understood, one possible explanation is the behavior hypothesis, which states that an animal's need to express parental behavior may be driving modulation of the HPA axis. This possibility is con- sistent with findings of blunted activity and reactivity of the HPA axis in lactating female mammals; however, effects of Reproductive Status on HPA function have not been well characterized in male mammals that ex- press parental behavior. Therefore, we tested this hypothesis in the monogamous and biparental California mouse. Several aspects of HPA activity were compared in males from three Reproductive conditions: virgin males (housed with another male), non-breeding males (housed with a tubally ligated female), and first-time fathers (housed with a female and their first litter of pups). In light of the behavior hypothesis we predicted that new fathers would differ from virgin and non-breeding males in several aspects of HPA function and corticosterone (CORT) output: decreased amplitude of the diurnal rhythm in CORT, a blunted CORT increase following predator-odor stress, increased sensitivity to glucocorticoid negative feedback, and/or a blunted CORT response to pharmacological stimulation. In addition, we predicted that first-time fa- thers would be more resistant to CORT-induced suppression of testosterone secretion, as testosterone is im- portant for paternal behavior in this species. We found that virgin males, non-breeding males and first-time fathers did not display any CORT differences in diurnal rhythm, response to a predator-odor stressor, or re- sponse to pharmacological suppression or stimulation. Additionally, there were no differences in circulating testosterone concentrations. Adrenal mass was, however, significantly lower in new fathers than in virgin or non-breeding males. These results suggest that the behavior hypothesis does not explain HPA function across Reproductive conditions in male California mice.
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effects of Reproductive Status on behavioral and endocrine responses to acute stress in a biparental rodent the california mouse peromyscus californicus
Hormones and Behavior, 2011Co-Authors: Miyetani Chauke, Trynke R. De Jong, Jessica L Malisch, Cymphonee Robinson, Wendy SaltzmanAbstract:Abstract In several mammalian species, lactating females show blunted neural, hormonal, and behavioral responses to stressors. It is not known whether new fathers also show stress hyporesponsiveness in species in which males provide infant care. To test this possibility, we determined the effects of male and female Reproductive Status on stress responsiveness in the biparental, monogamous California mouse (Peromyscus californicus). Breeding (N = 8 females, 8 males), nonbreeding (N = 10 females, 10 males) and virgin mice (N = 12 females, 9 males) were exposed to a 5-min predator-urine stressor at two time points, corresponding to the early postpartum (5–7 days postpartum) and mid/late postpartum (19–21 days postpartum) phases, and blood samples were collected immediately afterwards. Baseline blood samples were obtained 2 days prior to each stress test. Baseline plasma corticosterone (CORT) concentrations did not differ among male or female groups. CORT responses to the stressor did not differ among female Reproductive groups, and all three groups showed distinct behavioral responses to predator urine. Virgin males tended to increase their CORT response from the first to the second stress test, while breeding and nonbreeding males did not. Moreover, virgin and nonbreeding males showed significant behavioral changes in response to predator urine, whereas breeding males did not. These results suggest that adrenocortical responses to a repeated stressor in male California mice may be modulated by cohabitation with a female, whereas behavioral responses to stress may be blunted by parental Status.
Jennifer U M Jarvis - One of the best experts on this subject based on the ideXlab platform.
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regulation of reproduction in female common mole rats cryptomys hottentotus hottentotus the effects of breeding season and Reproductive Status
Journal of Zoology, 1999Co-Authors: A C Spinks, Nigel C. Bennett, Jennifer U M JarvisAbstract:The effects of breeding season and Reproductive Status on female reproduction were investigated in the common mole-rat, Cryptomys hottentotus hottentotus, a co-operatively breeding rodent that exhibits seasonal breeding and a Reproductive division of labour. Body mass, Reproductive tract morphometrics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild-caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology revealed that females retained Reproductive function during the winter non-breeding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in Reproductive females during the breeding period. The continuance of Reproductive function during the non-breeding period in female common mole-rats parallels the situation in males, and is believed to be important in dispersal in C. h. hottentotus. The non-breeding period coincides with the period of maximal dispersal opportunities in the winter rainfall areas inhabited by the common mole-rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair-bond formation and thereby facilitate independent reproduction. Reproductive and non-Reproductive females exhibited a similar degree of Reproductive function, and as for season, the only clear-cut Status-related differences were associated with the occurrence of pregnancy in Reproductive females. This absence of a physiologically well-defined suppression of reproduction in female common mole-rats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate outbreeder.
G Van Der Horst - One of the best experts on this subject based on the ideXlab platform.
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influence of breeding season and Reproductive Status on male Reproductive characteristics in the common mole rat cryptomys hottentotus hottentotus
Reproduction, 1997Co-Authors: A C Spinks, G Van Der Horst, Nigel C. BennettAbstract:The effects of breeding season and Reproductive Status on male reproduction were investigated in the common mole-rat (Cryptomys hottentotus hottentotus), a co-operatively breeding rodent that exhibits seasonal reproduction and a Reproductive division of labour. Testicular anatomical and histological morphometrics, and selected sperm parameters were studied in 50 males from 17 wild caught colonies. Males exhibited no apparent manifestation of season on testicular activity: spermatogenesis and sperm quality (motility and percentage normal morphology) were similar in the Reproductively active and inactive periods. This maintenance of Reproductive activity during the non-Reproductive period is essential in C. h. hottentotus males, as this period coincides with the period of maximal dispersal opportunities. Such Reproductive activation in dispersing males may aid intersexual recognition, and assist pair-bond formation or successful assimilation into foreign colonies, thereby facilitating later outbreeding. Consequently, outbreeding opportunities may be important determinants of Reproductive activity in male common mole-rats, moderating seasonal effects. Reproductive and non-Reproductive males revealed no differences in any of the testicular or sperm parameters studied. The absence of a physiologically well-defined suppression of reproduction in male common mole-rats is more typical of social suppression in male mammals.