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Author |
Khalil, A.M.; Murakami, N.; Kaseda, Y. |
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Title |
Relationship between plasma testosterone concentrations and age, breeding season and harem size in Misaki feral horses |
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Journal Article |
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Year |
1998 |
Publication |
The Journal of veterinary medical science / the Japanese Society of Veterinary Science |
Abbreviated Journal |
J Vet Med Sci |
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Volume |
60 |
Issue |
5 |
Pages |
643-645 |
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Keywords |
Age Factors; Animals; Animals, Wild; *Horses; Japan; Male; Reproduction; Seasons; Sexual Behavior, Animal; Sexual Maturation; *Social Behavior; Testosterone/*blood |
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Abstract |
Jugular vein blood samples were collected from 23 young and sexual mature feral stallions to examine the relationship between plasma testosterone concentration and age, breeding season or harem size. Testosterone concentration increased with the age of the stallions until they formed their own harems, at about 4 to 6 years old. Seasonal variations in testosterone concentrations were observed, and found to be significantly higher (P<0.001) throughout the breeding season than non-breeding season, from 3 years of age. Testosterone levels were correlated with harem size for individual stallions. It can be inferred from these results that there is a relationship between plasma testosterone concentration and age, breeding season and harem size. |
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Laboratory of Animal Behavioral Science, Faculty of Agriculture, Miyazaki University, Japan |
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0916-7250 |
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PMID:9637303 |
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Call Number  |
refbase @ user @ |
Serial |
137 |
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Author |
Kirkpatrick, J.F.; Turner, A. |
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Title |
Absence of effects from immunocontraception on seasonal birth patterns and foal survival among barrier island wild horses |
Type |
Journal Article |
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Year |
2003 |
Publication |
Journal of applied animal welfare science : JAAWS |
Abbreviated Journal |
J Appl Anim Welf Sci |
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Volume |
6 |
Issue |
4 |
Pages |
301-308 |
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Keywords |
Animals; Animals, Newborn; Animals, Wild/*physiology; Birth Rate; Case-Control Studies; Contraception, Immunologic/methods/*veterinary; Egg Proteins/administration & dosage; Female; Horses/*physiology; Maryland/epidemiology; Membrane Glycoproteins/administration & dosage; Population Control; Pregnancy; *Receptors, Cell Surface; *Reproduction; Seasons; Vaccines, Contraceptive/administration & dosage |
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Abstract |
Despite a large body of safety data, concern exists that porcine zonae pellucidae (PZP) immunocontraception--used to manage wild horse populations--may cause out-of-season births with resulting foal mortality. Our study at Assateague, Maryland indicated the effects of immunocontraception on season of birth and foal survival between 1990 and 2002 on wild horses from Assateague Island. Among 91 mares never treated, 69 (75.8%) of foals were born in April, May, and June (in season). Among 77 treated mares, 50 (64.9%) were born in season. Of 29 mares foaling within 1 year after treatment (contraceptive failures), 20 (68.9%) were born in season. Of 48 mares treated for greater than 2 years then withdrawn from treatment, 30 (62.5%) of 48 foals were born in season. There were no significant differences (p <.05) between either treatment group or untreated mares. Survival did not differ significantly among foals born in or out of season or among foals born to treated or untreated mares. Data indicate a lack of effect of PZP contraception on season of birth or foal survival on barrier island habitats. |
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Science and Conservation Center Zoo Montana, Billings, Montana 59106, USA. jkirkpatrick@montana.net |
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1088-8705 |
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PMID:14965784 |
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140 |
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Author |
Cameron, E.Z. |
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Title |
Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism |
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Journal Article |
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Year |
2004 |
Publication |
Proceedings. Biological sciences / The Royal Society |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
271 |
Issue |
1549 |
Pages |
1723-1728 |
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Keywords |
Age Factors; Animals; Body Constitution; *Evolution; Female; Glucose/metabolism/physiology; Litter Size; Male; Mammals/*physiology; *Models, Biological; Reproduction/physiology; Seasons; Sex Factors; *Sex Ratio; Time Factors |
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Abstract |
Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios. |
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Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za |
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0962-8452 |
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PMID:15306293 |
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Call Number |
refbase @ user @ |
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413 |
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Author |
Amdam, G.V.; Csondes, A.; Fondrk, M.K.; Page, R.E.J. |
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Title |
Complex social behaviour derived from maternal reproductive traits |
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Journal Article |
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Year |
2006 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
439 |
Issue |
7072 |
Pages |
76-78 |
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Keywords |
Aging/physiology; Animals; Bees/*physiology; *Evolution; Feeding Behavior/*physiology; Female; Infertility, Female; Maternal Behavior/*physiology; Ovary/physiology; Pollen/metabolism; Reproduction/*physiology; *Social Behavior |
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Abstract |
A fundamental goal of sociobiology is to explain how complex social behaviour evolves, especially in social insects, the exemplars of social living. Although still the subject of much controversy, recent theoretical explanations have focused on the evolutionary origins of worker behaviour (assistance from daughters that remain in the nest and help their mother to reproduce) through expression of maternal care behaviour towards siblings. A key prediction of this evolutionary model is that traits involved in maternal care have been co-opted through heterochronous expression of maternal genes to result in sib-care, the hallmark of highly evolved social life in insects. A coupling of maternal behaviour to reproductive status evolved in solitary insects, and was a ready substrate for the evolution of worker-containing societies. Here we show that division of foraging labour among worker honey bees (Apis mellifera) is linked to the reproductive status of facultatively sterile females. We thereby identify the evolutionary origin of a widely expressed social-insect behavioural syndrome, and provide a direct demonstration of how variation in maternal reproductive traits gives rise to complex social behaviour in non-reproductive helpers. |
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Arizona State University, School of Life Sciences, Tempe, Arizona 85287, USA. Gro.Amdam@asu.edu |
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1476-4687 |
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Notes |
PMID:16397498 |
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refbase @ user @ |
Serial |
531 |
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Author |
Dunbar, R. |
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Title |
Evolution of the social brain |
Type |
Journal Article |
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Year |
2003 |
Publication |
Science |
Abbreviated Journal |
Science |
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Volume |
302 |
Issue |
5648 |
Pages |
1160-1161 |
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Keywords |
Animals; Animals, Wild; *Cognition; Endorphins/physiology; *Evolution; Female; Grooming; Hierarchy, Social; Language; Neocortex/anatomy & histology/physiology; Papio/physiology/*psychology; *Reproduction; *Social Behavior; Social Dominance; Social Support; Vocalization, Animal |
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School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK. rimd@liv.ac.uk |
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1095-9203 |
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Notes |
PMID:14615522 |
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refbase @ user @ |
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548 |
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Author |
Moehlman, P.D. |
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Title |
Endangered wild equids |
Type |
Journal Article |
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Year |
2005 |
Publication |
Scientific American |
Abbreviated Journal |
Sci Am |
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Volume |
292 |
Issue |
3 |
Pages |
74-81 |
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Keywords |
Africa; Americas; Animals; *Animals, Wild/physiology; Asia; *Conservation of Energy Resources; Environment; *Equidae/physiology; Food Chain; Humans; Male; Reproduction |
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Address |
IUCN-The World Conservation Union/Species Survival Commission Equid Specialist Group |
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0036-8733 |
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PMID:15859216 |
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refbase @ user @ |
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551 |
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Author |
Keiper, R.; Houpt, K. |
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Title |
Reproduction in feral horses: an eight-year study |
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Journal Article |
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Year |
1984 |
Publication |
American journal of veterinary research |
Abbreviated Journal |
Am J Vet Res |
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Volume |
45 |
Issue |
5 |
Pages |
991-995 |
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Keywords |
Abortion, Veterinary/epidemiology; Anestrus; Animal Population Groups/*physiology; Animals; Animals, Wild/*physiology; Birth Rate; Female; Fertility; Horse Diseases/epidemiology; Horses/*physiology; Lactation; Male; Maryland; Pregnancy; *Reproduction; Seasons; Sex Ratio; Virginia |
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Abstract |
The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area. |
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0002-9645 |
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PMID:6732036 |
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refbase @ user @ |
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665 |
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Author |
Collery, L. |
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Title |
Observations of equine animals under farm and feral conditions |
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Journal Article |
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Year |
1974 |
Publication |
Equine veterinary journal |
Abbreviated Journal |
Equine Vet J |
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Volume |
6 |
Issue |
4 |
Pages |
170-173 |
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Keywords |
Aggression; Animals; Animals, Newborn; Breeding; Circadian Rhythm; Feeding Behavior; Female; Horses/*physiology; Housing, Animal; Humans; Male; Pregnancy; Puberty; Reproduction; Sexual Behavior, Animal; Social Dominance |
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0425-1644 |
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PMID:4473340 |
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refbase @ user @ |
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680 |
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Author |
Feist, J.D.; McCullough, D.R. |
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Title |
Reproduction in feral horses |
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Journal Article |
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Year |
1975 |
Publication |
Journal of Reproduction and Fertility. Supplement |
Abbreviated Journal |
J Reprod Fertil Suppl |
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Volume |
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Issue |
23 |
Pages |
13-18 |
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Keywords |
Age Factors; Animals; Female; Horses/*physiology; Leadership; Male; Maternal Behavior; Population; Reproduction; *Sexual Behavior, Animal; Social Dominance; Sucking Behavior |
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Abstract |
A behavioural study of feral horses was conducted on the Pryor Mountain Wild Horse Range in the western United States. All 270 horses on the Range were identified individually. The sex ratio was nearly balanced. Foal to adult female ratio was 43-2:100. Morality was concentrated among foals and old horses. Horses were organized as forty-four harem groups each with a dominant stallion, one to two immature stallions, one to three immature mares, one to three adult mares and their yearling and foal offspring, and 23 bachelor groups of one to eight stallions. Harem groups were quite stable year-round because of dominance and leadership by the stallions and group fidelity by mares and their offsring. Most changes occurred during the breeding season and involved immature females. Defeat of dominant stallions was infrequent. Immature males were tolerated because of their submissive behaviour. Bachelor stallion groups were inherently unstable. Mares came into heat after foaling in May/June, and were mated by harem stallions only. |
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0449-3087 |
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PMID:1060766 |
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refbase @ user @ |
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1964 |
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Author |
Chenoweth, P.J.; Chase, C.C.; Larsen, R.E.; Thatcher, M.-J.D.; Bivens, J.F.; Wilcox, C.J. |
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Title |
The assessment of sexual performance in young Bos taurus and Bos indicus beef bulls |
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Journal Article |
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Year |
1996 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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Volume |
48 |
Issue |
3-4 |
Pages |
225-235 |
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Keywords |
Bos indicus; Sex behavior; Cattle reproduction; Mating behavior; Tests |
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Abstract |
Yearling beef bulls, representing different Bos indicus and Bos taurus breeds, were given two sexual performance assessments (libido score, number of services, time to first mount and time of sexual inactivity) at four test periods (January, April, July and October) in 1991 (Trial 1) and 1992 (Trial 2) at the Subtropical Agricultural Research Station, Brooksville, Florida. Breed and test period, as well as their interactions, influenced most results. Sexual performance assessments generally improved with age in Bos taurus breeds, but not in Bos indicus. The temperate Bos taurus breeds (Angus and Hereford) were most sexually active, the tropically adapted Bos taurus breeds (Senepol and Romosinuano) intermediate and the two Bos indicus breeds (Brahman and Nellore x Brahman) were least active. Service rates were generally low. Seasonal patterns in sexual performance were not apparent, with breed and year differences occurring. Although breeds showed consistent test results, the failure of Bos indicus bulls to service in any test, indicates either sexual immaturity, or inadequate procedures for assessment of sexual performance in this breed group. |
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refbase @ user @ |
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2865 |
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