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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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no |
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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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Call Number |
refbase @ user @ |
Serial |
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 |
Type |
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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English |
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ISSN |
0962-8452 |
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Notes |
PMID:15306293 |
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no |
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Call Number |
refbase @ user @ |
Serial |
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 |
Type |
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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Address |
Arizona State University, School of Life Sciences, Tempe, Arizona 85287, USA. Gro.Amdam@asu.edu |
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ISSN |
1476-4687 |
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Notes |
PMID:16397498 |
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no |
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Call Number |
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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Address |
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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no |
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Call Number |
refbase @ user @ |
Serial |
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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Abstract |
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Address |
IUCN-The World Conservation Union/Species Survival Commission Equid Specialist Group |
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English |
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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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no |
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refbase @ user @ |
Serial |
680 |
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Author |
Klingel, H. |
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Title |
Social organization and reproduction in equids |
Type |
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 |
7-11 |
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Keywords |
Animals; Behavior, Animal; Female; Male; Perissodactyla/*physiology; Reproduction; *Sexual Behavior, Animal; Social Behavior; Territoriality |
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Abstract |
There are two distinct types of social organization and, accordingly, two types of mating systems in equids. In the horse, Plains zebra and Mountain zebra, the adults live in non-territorial and cohesive one-male groups and in stallion groups. The family stallions have exclusive mating rights which are respected by all others. In Grevy's zebra and in the African and Asiatic wild asses, the stallions are permanently territorial and have exclusive mating rights within their territories. Ecological and evolutionary aspects are discussed. |
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0449-3087 |
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PMID:1060868 |
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Equine Behaviour @ team @ |
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2303 |
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Author |
Westlin-van Aarde, L.M.; van Aarde, R. J.; Skinner, J. D. |
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Title |
Reproduction in female Hartmann's zebra |
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Journal Article |
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Year |
1988 |
Publication |
Journal of Reproduction and Fertility |
Abbreviated Journal |
J Reprod Fert |
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Volume |
84 |
Issue |
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Pages |
505-511 |
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Keywords |
zebra; reproduction; ovaries; seasonality; progesterone |
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Abstract |
Ovaries, fetuses and plasma were collected from zebra mares shot in the Etosha National Park in Namibia between 15 and 25 August 1983. Ovarian weight was affected by reproductive status and most of the non-pregnant mares were anoestrous. The number of follicles varied between individuals and only pro-oestrous/oestrous mares had follicles larger than 20 mm in diameter. The largest follicle in pregnant mares was only 9 mm in diameter. Corpora lutea and corpora albicantia were found in non-pregnant as well as pregnant mares: 4 pregnant mares had only corpora albicantia. The presence of secondary corpora lutea could not be confirmed in any of the pregnant mares. Implantation was estimated to occur at around 73 days of gestation, and most mares (84%) had conceived between November and April. Peripheral concentrations of plasma progesterone during pregnancy varied from 0·5 to 2·4 ng/ml. |
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from Professor Hans Klingels Equine Reference List |
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yes |
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Call Number |
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Serial |
1705 |
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