Causes of Natal Dispersal in the Lesser Kestrel: Inbreeding Avoidance or Resource Competition?

10.2307/5917 ◽  
1997 ◽  
Vol 66 (5) ◽  
pp. 640 ◽  
Author(s):  
Juan J. Negro ◽  
Fernando Hiraldo ◽  
J. A. Donazar
Keyword(s):  
Resource Competition ◽  
Inbreeding Avoidance ◽  
Natal Dispersal ◽  
Lesser Kestrel

Sex-biased natal dispersal and inbreeding avoidance in American black bears as revealed by spatial genetic analyses

2008 ◽  
Vol 17 (21) ◽  
pp. 4713-4723 ◽  
Author(s):  
CECILY M. COSTELLO ◽  
SCOTT R. CREEL ◽  
STEVEN T. KALINOWSKI ◽  
NINH V. VU ◽  
HOWARD B. QUIGLEY
Keyword(s):  
Inbreeding Avoidance ◽  
Black Bears ◽  
Natal Dispersal ◽  
Genetic Analyses ◽  
American Black ◽  
American Black Bears

Genetic consequences of natal dispersal in the colonial lesser kestrel

2008 ◽  
Vol 17 (8) ◽  
pp. 2051-2059 ◽  
Author(s):  
JOAQUÍN ORTEGO ◽  
GUSTAU CALABUIG ◽  
JOSÉ MIGUEL APARICIO ◽  
PEDRO J. CORDERO
Keyword(s):  
Natal Dispersal ◽  
Lesser Kestrel

The Proximate Mechanisms of Natal Dispersal in Female Horses

Behaviour ◽  
1996 ◽  
Vol 133 (13-14) ◽  
pp. 1095-1124 ◽  
Author(s):  
Patrick Duncan ◽  
Vincent Boy ◽  
Anne-Marie Monard
Keyword(s):  
Sexual Attraction ◽  
Intrasexual Competition ◽  
Inbreeding Avoidance ◽  
Natal Dispersal ◽  
Reproductive Competition ◽  
Young Females ◽  
Proximate Mechanisms ◽  
Competition Hypothesis ◽  
Low Levels ◽  
Close Relatives

AbstractThe aim of this study was to investigate proximate mechanisms of natal dispersal by female horses, Equus caballus (i.e. proximate causes and the factors influencing the timing), and to test predictions from two functional hypotheses: the intrasexual competition hypothesis, and inbreeding avoidance. The data concerned 40 individuals born between 1974-1985 in a closely monitored herd which developed a natural social structure during this period. All the females dispersed from their natal groups; none became solitary; 80% transferred to existing harems, the others formed new groups with bachelor stallions. Abduction by stallions affected only a quarter of the females whose transfers were observed. The results of this study do not support the hypothesis that a function of natal dispersal is to reduce intrasexual competition. The young females were not expelled by resident females of their natal groups, and did not, as a rule, experience increased aggression from these females before emigration. Their social bonds with members of their natal groups showed no progressive weakening prior to departure, and there was no gradual strengthening of bonds with individuals in the groups to which they transferred. There was no evidence for reproductive competition between the young females and resident mares of their natal groups, since the young females always refused the sexual approaches by males of these groups. Finally, age at dispersal did not decrease with the number of resident females in the groups they left. In contrast, as predicted by the inbreeding avoidance hypothesis, the primary cause of dispersal appeared to be sexual attraction to unfamiliar males. When in oestrus and before dispersing, the young females accepted matings only with males of other groups in spite of frequent sexual approaches by males of their natal groups (normally close relatives). In addition, none dispersed before first oestrus, and most did so during an oestrous period, at or before the conception of their first foal. The mothers of most young females interposed themselves when close kin males of the natal group approached their daughters sexually; this could contribute to the avoidance of close inbreeding. Among the other factors examined, some did not influence dispersal of the young females : they experienced low levels of aggression by adult stallions of their natal groups, particularly at the time of departure; their weight and body condition had no significant effects on leaving age nor did their mother's rank, the number of siblings, or the birth of another. In contrast, as the number of groups and the breeding sex ratio increased, dispersal age declined, occurring at a median age of 23 months (range 12-42 months) in the later years, when the herd had developed a natural social system.

Inbreeding avoidance and male-biased natal dispersal in Antechinus spp. (Marsupialia: Dasyuridae)

1985 ◽  
Vol 33 (3) ◽  
pp. 908-915 ◽  
Author(s):  
Andrew Cockburn ◽  
Michelle P. Scott ◽  
David J. Scotts
Keyword(s):  
Inbreeding Avoidance ◽  
Natal Dispersal

Natal dispersal of juvenile arctic ground squirrels in the boreal forest

1999 ◽  
Vol 77 (7) ◽  
pp. 1048-1059 ◽  
Author(s):  
Andrea E Byrom ◽  
Charles J Krebs
Keyword(s):  
Population Density ◽  
Resource Competition ◽  
Yukon Territory ◽  
Ground Squirrels ◽  
Natal Dispersal ◽  
Risk Of Mortality ◽  
Mortality Cost ◽  
Arctic Ground Squirrels ◽  
Dispersal Distances ◽  
Juvenile Males

Natal dispersal is assumed to be costly because of the risk of mortality, yet rarely are movement patterns and survival of dispersers observed directly. We determined the fates and dispersal distances of 150 radio-collared juvenile arctic ground squirrels from 1993 to 1995 at Kluane, Yukon Territory, Canada (61°N, 138°W). We tested the hypothesis that dispersal has a high mortality cost, and we also attempted to distinguish among three hypotheses to explain natal dispersal: competition for mates, competition for resources, and inbreeding avoidance. Juveniles were radio-collared at emergence from the natal burrow on five 9-ha grids nested within larger (1 km2) experimental manipulations: two controls, a predator exclosure, a food-supplemented grid, and a predator exclosure + food grid. In all years and on all areas, dispersing juveniles were more likely to die than philopatric squirrels, and the risk of mortality increased with distance from the natal burrow for both sexes. Overall, survival of philopatric squirrels was 73%, whereas survival of dispersing squirrels ranged from a maximum of 40% to a minimum of 25%. Juvenile females were strongly philopatric independent of population density, except on the predator exclosure + food grid in 1995, where population density was extremely high and resources other than food were probably limiting. Resource competition may explain patterns of philopatry and dispersal in female arctic ground squirrels. Juvenile males moved farther from their natal site than females and more of them died. Males also had a strong tendency to disperse that was independent of food availability or population density, which suggests that male arctic ground squirrels ultimately may disperse to avoid either inbreeding with female relatives or intrasexual competition for mates.

Causes and consequences of sex-biased dispersal in Columbian ground squirrel, Spermophilus columbianus

Behaviour ◽  
2006 ◽  
Vol 143 (8) ◽  
pp. 1013-1031 ◽  
Author(s):  
Peter Neuhaus
Keyword(s):  
Resource Competition ◽  
Inbreeding Avoidance ◽  
Ground Squirrels ◽  
Minor Role ◽  
Proximate Cause ◽  
Factors Affecting ◽  
Spermophilus Columbianus ◽  
Significant Difference ◽  
A Minor ◽  
Columbian Ground Squirrels

AbstractDispersal is a fundamental process with wide ranging evolutionary consequences. In birds and mammals, members of one sex typically disperse more frequently, sooner and/or further than members of the other sex. The aim of this study was to examine factors affecting dispersal by yearling male and female Columbian ground squirrels (Spermophilus columbianus), and to determine whether inbreeding avoidance, competition or other factors can explain why inter-colony dispersal is more common in males than in females. Males who stayed in their natal colony as adults emerged as yearlings heavier and later from hibernation than males who disappeared in their yearling year, whereas for females, this was not the case. Males who had sisters emerging as yearlings in the same colony were not more likely to leave the colony than males who were alone or with brothers. Further, there was no significant difference in the probability that females would mate with an immigrant compared to a natal male. Finally, three-year-old males who stayed in the colony moved significantly further away from their natal burrow than females of the same age.I conclude that sex differences in inter-colony dispersal, while promoting outbreeding, are not directly due to inbreeding avoidance, but that inbreeding avoidance may play a role in governing intra-colony dispersal distances. Further, resource competition seems to play a minor role. Aggression by adults against yearling males and the acceptance of yearling females by their mothers may be the proximate cause for male bias in inter-colony dispersal in Columbian ground squirrels. To conclusively demonstrate this effect, however, we need to look at aggression in more detail.

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