Possible factors influencing vertebrate sex ratios: An introductory overview

Applied Animal Behaviour Science

Volumn 51, Issue 3-4, 1997, Pages 217-241

  Hardy, Ian C W ^a  

^a LEIDEN UNIVERSITY   (Netherlands)

Author keywords

Empirical sex ratios; Sex determination mechanisms; Sex ratio theory

Indexed keywords

VERTEBRATA;

EID: 0030938932     PISSN: 01681591     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0168-1591(96)01106-9     Document Type: Note

References (152)

1. Ankney, C.D., 1982. Sex ratio varies with egg production sequence in lesser snow geese. Auk, 99: 662-666.
2. Antolin, M.F., 1993. Genetics of biased sex ratios in subdivided populations: models, assumptions, and evidence. Oxf. Surv. Evol. Biol., 9: 239-281.
3. Armitage, K.B., 1987. Do yellow-bellied marmots adjust the sex ratios of their offspring? Am. Nat., 129: 501-519.
4. Austad, S.N. and Sunquist, M.E., 1986. Sex-ratio manipulation in the common opossum. Nature. 324: 58-60.
5. Bednarz, J.C. and Hayden, T.J., 1991. Skewed brood sex ratio and sex-biased hatching sequence in Harris's hawks. Am. Nat., 137: 116-132.
6. Bérubé, C.H., Festa-Bianchet, M. and Jorgenson, J.T., 1996. Reproductive costs of sons and daughters in Rocky Mountain bighorn sheep. Behav Ecol., 7: 60-68.
7. Blumberg, M.S., Mennella, J.A., Moltz, H. and McClintock, M.K., 1992. Facultative sex-ratio adjustment in Norway rats: litters bom asynchronously are female biased. Behav. Ecol. Sociobiol., 31: 401-408.
8. Bull, J.J., 1983. Evolution of Sex Determining Mechanisms. Benjamin/Cummings, Menlo Park, CA.
9. Bull, J.J. and Charnov, E.L., 1988. How fundamental are Fisherian sex ratios? Oxf. Surv. Evol. Biol., 5: 98-135.
10. Bull, J.J. and Charnov, E.L., 1989. Enigmatic reptilian sex ratios. Evolution, 43: 1561-1566.
11. Bulmer, M.G., 1986. Sex ratio theory in geographically structured populations. Heredity, 56: 69-73.
12. Burley, N., 1982. Facultative sex-ratio manipulation. Am. Nat., 120: 81-107.
13. Caley, M.J. and Nudds, T.D., 1987. Sex-ratio adjustment in Odocoileus: does local resource competition play a role? Am. Nat., 129: 452-457.
14. Charnov, E.L., 1979. The genetical evolution of patterns of sexuality: Darwinian fitness. Am. Nat., 113: 465-480.
15. Charnov, E.L., 1982. The Theory of Sex Allocation. Princeton University Press, Princeton, NJ.
16. Chamov, E.L., Los-den Hartogh, R.L., Jones, W.T. and van den Assem, J., 1981. Sex ratio evolution in a variable environment. Nature, 289: 27-33.
17. Clark, A.B., 1978. Sex ratio and local resource competition in a prosimian primate. Science, 201: 163-165.
18. Clark, M.M. and Galef, B.G., Jr., 1995. Prenatal influences on reproductive life history strategies. Trends Ecol. Evol., 10: 151-153.
19. Clark, M.M., Bone, S. and Galef, B.G, Jr., 1990. Evidence of sex-biased maternal investment by Mongolian gerbils. Anim. Behav., 39: 735-744.
20. Clark, M.M., Waddington, C.L. and Galef, B.G., Jr., 1991a. Further evidence of sex-biased maternal investment by Mongolian gerbil dams. Anim. Behav., 42: 161-162.
21. Clark, M.M., Galef, B.G., Jr. and vom Saal, F.S., 1991b. Nonrandom sex composition of gerbil, mouse, and hamster litters before and after birth. Dev. Psychobiol., 24: 81-90.
22. Clark, M.M., Karpuik, P. and Galef, B.G., Jr., 1993. Hormonally mediated inheritance of aquired characteristics in Mongolian gerbils. Nature, 364: 712.
23. Clutton-Brock, T.H., 1986. Sex ratio variation in birds. Ibis, 128: 317-329.
24. Clutton-Brock, T.H., 1991. The Evolution of Parental Care. Princeton University Press, Princeton, NJ.
25. Clutton-Brock, T.H. and Iason, G.R., 1986. Sex ratio variation in mammals. Q. Rev. Biol., 61: 339-374.
26. Clutton-Brock, T.H., Albon, S.D. and Guinness, F.E., 1981. Parental investment in male and female offspring in polygynous mammals. Nature, 289: 487-489.
27. Clutton-Brock, T.H., Albon, S.D. and Guinness, F.E., 1982. Competition between females relatives in a matrilocal mammal. Nature, 300: 178-180.
28. Clutton-Brock, T.H., Albon, S.D. and Guinness, F.E., 1985. Parental investment and sex differences in juvenile mortality in birds and mammals. Nature, 313: 131-133.
29. Clutton-Brock, T.H., Albon, S.D. and Guinness, F.E., 1986. Great expectations, dominance, breeding success and offspring sex ratios in red deer. Anim. Behav., 34: 460-471.
30. Cockburn, A., 1990. Sex ratio variation in marsupials. Aust. J. Zool., 37: 467-79.
31. Cockburn, A., 1994. Adaptive sex allocation by brood reduction in antechinuses. Behav. Ecol. Sociobiol., 35: 53-62.
32. Cockburn, A., Scott, M.P. and Dickman, C.R., 1985. Sex ratio and intrasexual kin competition in mammals. Oecologia, 66: 427-429.
33. Cook, J.M., 1993. Sex determination in the Hymenoptera - a review of models and evidence. Heredity, 71: 421-435.
34. Cook, J.M. and Crozier, R.H., 1995. Sex determination and population biology in the Hymenoptera. Trends Ecol. Evol., 10: 281-286.
35. Cooke, F. and Harmsen, R., 1983. Does sex ratio vary with egg sequence in lesser snow geese? Auk, 100: 215-217.
36. Craig, T.P. and Mopper, S., 1993. Sex ratio variation in sawflies. In: M.R. Wagner and K.F. Raffa (Editors), Sawfly Life History Adaptations to Woody Plants. Academic Press, New York, pp. 61-92.
37. Crews, D., 1994. Animal sexuality. Sci. Am., Jan. 1994: 96-103.
38. Darwin, C., 1871. The Descent of Man and Selection in Relation to Sex, Murray, London.
39. Dickman, C.R., 1988. Sex-ratio in response to interspecific competition. Am. Nat., 132: 289-297.
40. Dijkstra, C., Daan, S. and Buker, J.B., 1990. Adaptive seasonal variation in the sex ratio of kestrel broods. Funct. Ecol., 4: 143-147.
41. Emlen, S.T., Emlen, J.M. and Levin, S.A., 1986. Sex-ratio selection in species with helpers-at-the-nest. Am. Nat., 127: 1-8.
42. Festa-Bianchet, M., 1996. Offspring sex ratio studies of mammals: does publication depend upon the quality of the research or the direction of the results? Ecoscience, in press.
43. Fiala, K.L., 1980. On estimating the primary sex ratio from incomplete data. Am. Nat., 115: 442-444.
44. Fisher, R.A., 1930. The Genetical Theory of Natural Selection. Clarendon Press, Oxford.
45. Foster, W.A. and Benton, T.G., 1992. Sex ratio, local mate competition and mating behaviour in the aphid Pemphigus spyrothecae. Behav. Ecol. Sociobiol., 30: 297-307.
46. Frank, S.A., 1987. Individual and population sex allocation patterns. Theor. Popul. Biol., 31: 47-74.
47. Frank, S.A., 1990. Sex allocation theory for birds and mammals. Ann. Rev. Ecol. Syst., 21: 13-55.
48. Frank, S.A. and Swingland, I.R., 1988. Sex ratio under conditional sex expression. J. Theor. Biol., 135: 415-418.
49. Gerber, H.S. and Klostermeyer, E.G., 1970. Sex control by bees: a voluntary act of egg fertilization during oviposition. Science, 167: 82-84.
50. Godfray, H.C.J., 1990. The causes and consequences of constrained sex allocation in haplodiploid animals. J. Evol. Biol., 3: 3-17.
51. Godfray, H.C.J., 1994. Parasitoids: Behavioral and Evolutionary Ecology. Princeton University Press, Princeton, NJ.
52. Godfray, H.C.J. and Hunter, M.S., 1992. Sex ratios of heteronomous hyperparasitoids: adaptive or non-adaptive? Ecol. Entomol., 17: 89-90.
53. Godfray, H.C.J. and Hunter, M.S., 1994. Heteronomous hyperparasitoids, sex ratios and adaptations - a reply. Ecol. Entomol., 19: 93-95.
54. Gosling, L.M., 1986. Selective abortion of entire litters in the coypu: adaptive control of offspring production in relation to quality and sex. Am. Nat., 127: 772-795.
55. Gowaty, P.A., 1991. Facultative manipulation of sex ratios in birds: rare or rarely observed? Curr. Ornithol., 8: 141-171.
56. Gowaty, P.A., 1993. Differential dispersal, local resource competition and sex ratio variation in birds. Am. Nat., 141: 263-280.
57. Gowaty, P.A. and Lennartz, M.R., 1985. Sex ratio of nestling and fledgling red-cockaded woodpeckers (Picoides borealis) favour males. Am. Nat., 126: 347-353.
58. Green, R.F., Gordh, G. and Hawkins, B.A., 1982. Precise sex ratios in highly inbred parasitic wasps. Am. Nat., 120: 653-665.
59. Hamilton, W.D., 1967. Extraordinary sex ratios. Science, 156: 477-488.
60. Hamilton, W.D., 1979. Wingless and fighting males in fig wasps and other insects. In: M.S. Blum and N.A. Blum (Editors), Sexual Selection and Reproductive Competition in Insects. Academic Press, New York, pp. 167-220.
61. Hardy, I.C.W., 1992. Non-binomial sex allocation and brood sex ratio variances in the parasitoid Hymenoptera. Oikos, 65: 143-158.
62. Hardy, I.C.W., 1994. Sex ratio and mating structure in the parasitoid Hymenoptera. Oikos, 69: 3-20.
63. Hardy, I.C.W. and Cook, J.M., 1995. Brood sex ratio variance, developmental mortality and virginity in a gregarious parasitoid wasp. Oecologia, 103: 162-169.
64. Hardy, I.C.W., Ode, P.J. and Strand, M.R., 1993. Factors influencing brood sex ratios in polyembryonic Hymenoptera. Oecologia. 93: 343-348.
65. Harmsen, R. and Cooke, F., 1983. Binomial sex-ratio in the lesser snow goose: a theoretical enigma. Am. Nat., 121: 1-8.
66. Harrey, J.L., Briscoe, D.A. and Williams, K.L., 1995. Putting the heat on sex determination. Genetica, 87: 1-6.
67. Hartl, D.L., 1971. Some aspects of natural selection in arrhenotokous populations. Am. Zool., 11: 309-325.
68. Hiraiwa-Hasegawa, M., 1993. Skewed birth sex ratios in primates: should high-ranking mothers have daughters or sons? Trends Ecol. Evol., 8: 395-400.
69. Hogg, J.T., Hass, C.C. and Janni, D.A., 1992. Sex-biased maternal expenditure in rocky mountain bighorn sheep. Behav. Ecol. Sociobiol., 31: 243-251.
70. Hoogland, J.L., 1981. Sex ratio and local resource competition. Am. Nat., 117: 796-797.
71. Holekamp, K.E. and Smale, L.S., 1995. Rapid change in offspring sex ratio after clan fission in the spotted hyena. Am. Nat., 145: 216-278.
72. Hornig, L.E. and McClintock, M.K., 1994. Unmasking sex-ratio biasing through targeted analysis. Anim. Behav., 47: 1224-1226.
73. Hrdy, S.B., 1987. Sex-biased parental investment among primates and other mammals: a critical evaluation of the Trivers-Willard hypothesis. In: R.J. Gelles and J.B. Lancaster (Editors), Child Abuse and Neglect: Biosocial Dimensions. Aldine de Gruyter, New York.
74. Huck, U.W., Seger, J. and Lisk, R.D., 1990. Litter sex ratios in the golden hamster vary with time of mating and litter size and are not binomially distributed. Behav. Ecol. Sociobiol., 26: 99-109.
75. Hunter, M.S. and Godfray, H.C.J., 1995. Ecological determinants of sex allocation in an autoparasitoid wasp. J. Anim. Ecol., 64: 95-106.
76. James, W.H., 1993. Continuing confusion. Nature, 365: 8.
77. Janzen, F.J. and Paukstis, G.L., 1991. Environmental sex determination in reptiles: ecology, evolution and experimental design. Q. Rev. Biol., 66: 149-179.
78. Johnson, C.N., 1988. Dispersal and the sex ratio at birth in primates. Nature, 332: 726-728.
79. Judson, O.P., 1994. Killing the sex ratio. Nature, 372: 503-504.
80. Kent, J.P., 1992. Birth sex ratios in sheep over six lambing seasons. Behav. Ecol. Sociobiol., 30: 151-155.
81. Kent, J.P., 1995. Birth sex ratios in sheep over nine lambing seasons: years 7-9 and the effects of ageing. Behav. Ecol. Sociobiol., 36: 101-104.
82. King, B.H., 1993. Sex ratio manipulation by parasitoid wasps. In: D.L. Wrensch and M.A. Ebbert (Editors), Evolution and Diversity of Sex Ratio in Insects and Mites. Chapman and Hall, New York, pp. 418-441.
83. King, B.H. and King, R.B., 1994. Sex ratio manipulation in response to host size in the parasitoid wasp Spalangia cameroni: is it adaptive? Behav. Ecol., 5: 448-454.
84. King, B.H. and Lee, H.E., 1994. Test of the adaptiveness of sex ratio manipulation in a parasitoid wasp. Behav. Ecol. Sociobiol., 35: 437-443.
85. Kolman, W., 1960. The mechanism of natural selection for the sex ratio. Am. Nat., 94: 373-377.
86. Komdeur, J., 1996. Facultative sex ratio bias in the offspring of Seychelles warblers. Proc. R. Soc. Lond. B., 263: 661-666.
87. Krackow, S., 1990. Sex-specific embryonic mortality during concurrent pregnancy and lactation in house mice. J. Exp. Zool., 256: 106-112.
88. Krackow, S., 1992. Sex ratio manipulation in wild house mice: the effect of fetal resorption in relation to the mode of reproduction. Biol. Reprod., 47: 541-548.
89. Krackow, S., 1993a. Note on the falconiforms sex ratios given in Olsen and Cockburn 1991: avian raptors exhibit no unique sex-ratio bias. Behav. Ecol. Sociobiol., 32: 429-430.
90. Krackow, S., 1993b. The effect of weaning weight on offspring fitness in wild house mice (Mus musculus domesticus): a preliminary study. Ethology, 95: 76-82.
91. Krackow, S., 1995. Potential mechanisms for sex ratio adjustment in mammals and birds. Biol. Rev., 70: 225-241.
92. Krackow, S. and Gruber, F., 1990. Sex ratio and litter size in relation to parity and mode of conception in three inbred strains of mice. Lab. Anim., 24: 354-352.
93. Krackow, S. and Hoeck, H.N., 1989. Sex ratio manipulation, maternal investment and behaviour during concurrent pregnancy and lactation in house mice. Anim. Behav., 27: 177-186.
94. Kumm, J., Laland, K.N. and Feldman, M.W., 1994. Gene-culture coevolution and sex ratios: the effects of infanticide, sex-selective abortion, sex selection, and sex-biased parental investment on the evolution of sex ratios. J. Theor. Biol., 40: 249-278.
95. Labov, J.B., Huck, U.W., Vaswani, P. and Lisk, R.D., 1986. Sex ratio manipulation and decreased growth of male offspring of undernourished golden hamsters (Mescocricetus auratus). Behav. Ecol. Sociobiol., 18: 241-294.
96. Lambin, X., 1994. Sex ratio variation in relation to female philopatry in Townsend's voles. J. Anim. Ecol., 63: 945-953.
97. Leigh, E.G., Jr., 1970. Sex ratio and differential mortality between the sexes. Am. Nat., 104: 205-210.
98. Lessels, C.M. and Avery, M.I., 1987. Sex ratio in species with helpers at the nest: some modifications of the repayment model. Am. Nat., 129: 610-620.
99. Luck, R.F., Stouthamer, R. and Nunney, L.P., 1993. Sex determination and sex ratio patterns in parasitic Hymenoptera. In: D.L. Wrensch and M.A. Ebbert (Editors), Evolution and Diversity of Sex Ratio in Insects and Mites. Chapman and Hall, New York, pp. 442-476.
100. Malcolm, J.R. and Marten, K., 1982. Natural selection and the communal rearing of pups in African wild dogs (Lycaon pictus). Behav. Ecol. Sociobiol., 10: 1-13.
101. Masters, J.C., Centner, M.R. and Caithness, W., 1982. Sex ratios in galagos revisited. S. Afr. J. Sci., 87: 198-202.
102. Maynard Smith, J., 1980. A new theory of sexual investment. Behav. Ecol. Sociobiol., 7: 247-251.
103. McFarland Symington, M., 1987. Sex ratio and maternal rank in wild spider monkeys: when daughters disperse. Behav. Ecol. Sociobiol., 20: 421-425.
104. McGinley, M.A., 1984. The adaptive value of male-biased sex ratios among stressed animals. Am. Nat., 124: 597-599.
105. McShea, W.J. and Madison, D.M., 1986. Sex ratio shifts within litters of meadow voles (Micolus pennsylvanicus). Behav. Ecol. Sociobiol., 18: 431-436.
106. Meikle, D.B., Drickamer, L.C., Vessey, S.H., Rosenthal, T.L. and Fitzgerald, S., 1993. Maternal dominance rank and secondary sex ratio in domestic swine. Anim. Behav., 46: 79-85.
107. Mendl, M., Zanella, A.J., Broom, D.M. and Whittemore, C.T., 1995. Maternal social status and birth sex ratio in domestic pigs: an analysis of mechanisms. Anim. Behav., 50: 1361-1370.
108. Milligan, B.N. and Brigham, R.M., 1992. Sex ratio variation in the yuma bat (Myotis yumanensis). Can. J. Zool., 71: 937-940.
109. Mittwoch, U., 1996. Sex-determining mechanisms in animals. Trends Ecol. Evol., 11: 63-67.
110. Myers, J.H., 1978. Sex ratio adjustment under food stress: maximization of quality of numbers of offspring. Am. Nat., 112: 381-388.
111. Nagelkerke, C.J., 1993. Evolution of sex allocation strategies of pseudo-arrhenotokous predatory mites (Acari: Phytoseiiae). Ph.D. Thesis, University of Amsterdam.
112. Nagelkerke, C.J., 1996. Discrete clutch sizes, local mate competition, and the evolution of precise sex allocation. Theor. popul. Biol., 49: 314-343.
113. Nagelkerke, C.J. and Hardy, I.C.W., 1994. The influence of developmental mortality on optimal sex allocation under local mate competition. Behav. Ecol., 5: 401-411.
114. Nagelkerke, C.J. and Sabelis, M.W., 1991. Precise sex ratio control in the pseudo-arrhenotokous phytoseiid mite Typhlodromus occidentalis Nesbitt. In: R. Schuster and P.W. Murphy (Editors), The Acari: Reproduction, Development, and Life History Strategies. Chapman and Hall, London, pp. 193-207.
115. Negro, J.J. and Hiraldo, F., 1992. Sex ratios of the lesser kestrel Falco naumanni. Ibis, 134: 190-191.
116. Newton, I. and Marquiss, M., 1979. Sex ratio among nestlings of the European sparrowhawk. Am. Nat., 113: 309-315.
117. Ode, P.J. and Strand, M.R., 1995. Progeny and sex allocation decisions of the polyembryonic wasp Copidosoma floridanum. J. Anim. Ecol., 64: 213-224.
118. Ode, P.J., Antolin, M.F. and Strand, M.R., 1995. Brood-mate avoidance in the parasitic wasp Bracon hebetor Say. Anim. Behav., 49: 1239-11248.
119. Oksanen, L., 1981. All-female litters as a reproductive strategy: defense and generalization of the Trivers-Willard hypothesis. Am. Nat., 117: 109-111.
120. Olsen, P.D. and Cockburn, A., 1991. Female-biassed sex allocation in peregrine falcons and other raptors. Behav. Ecol. Sociobiol., 28: 417-423.
121. Orzack, S.H., 1986. Sex-ratio control in a parasitic wasp, Nasonia vetripennis II. Experimental analysis of an optimal sex ratio model. Evolution, 40: 341-356.
122. Packer, C. and Pusey, A.E., 1987. Intrasexual cooperation and the sex ratio in African lions. Am. Nat., 130: 636-642.
123. Perret, M., 1990. Influence of social factors on sex ratio at birth, maternal investment and young survival in a prosimian primate. Behav. Ecol. Sociobiol., 27: 447-454.
124. Ridley, M., 1993. The Red Queen. Penguin, London.
125. Ridley, M., 1994. Why presidents have more sons. New Sci., 1954: 28-31.
126. Sabelis, M.W. and Nagelkerke, C.J., 1987. Sex allocation strategies of pseudo-arrhenotokous phytoseiid mites. Neth. J. Zool., 37: 117-136.
127. Sabelis, M.W. and Nagelkerke, C.J., 1993. Sex allocation and pseudoarrhenotoky in phytoseiid mites. In: D.L. Wrensch and M.A. Ebbert (Editors), Evolution and Diversity of Sex Ratio in Insects and Mites. Chapman and Hall, New York, pp. 512-541.
128. Seger, J. and Charnov, E.L., 1988. Benevolent sisterhood. Nature, 331: 303.
129. Silk, J.B., 1983. Local resource competition and facultative adjustment of sex ratios in relation to competitive abilities. Am. Nat., 121: 56-66.
130. Silk, J.B., 1984. Local resource competition and the evolution of male-biased sex ratios. J. Theor. Biol., 108: 203-213.
131. Silk, J.B., 1988. Maternal investment in captive bonnet macaques (Macaca radiata). Am. Nat., 132: 1-19.
132. Simpson, M.J.A. and Simpson, A.E., 1982. Birth sex ratios and social rank in rhesus monkeys. Nature, 300: 440-441.
133. Slagsvold, T. and Amundsen, T., 1992. Do great tits adjust hatching spread, egg size and offspring sex ratio to changes in clutch size? J. Anim. Ecol., 61: 249-258.
134. Smiseth, P.T. and Lorentsen, S-H., 1995. Evidence of equal maternal investment in the sexes in the polygynous and sexually dimorphic grey seal (Halichoerus grypus). Ecol. Sociobiol., 36: 145-150.
135. Stenseth, N.C., 1978. Is the female biased sex ratio in woodlemming Myopus schistcolor maintained by cyclic inbreeding? Oikos, 30: 83-89.
136. Taylor, P.D. and Sauer, A., 1980. The selective advantage of sex ratio homeostasis. Am. Nat., 116: 305-310.
137. Trivers, R.L. and Willard, D.E., 1973. Natural selection of parental ability to vary the sex ratio of offspring. Science, 179: 90-92.
138. Tuljapurkar, S., Li, N. and Feldman, M.W., 1995. High sex ratios in China's future. Science, 267: 874-876.
139. Van Schaik, C.P. and Hrdy, S.B., 1991. Intensity of local resource competition shapes the relationship between maternal rank and sex ratios at birth in cercopithencine primates. Am. Nat., 138: 1555-1562.
140. Verner, J., 1965. Selection for the sex ratio. Am. Nat., 99: 419-422.
141. Walter, G.H. and Clarke, A.R., 1992. Unisexual broods and sex ratios in a polyembryonic encyrtid parasitoid (Copidosoma sp.: Hymenoptera). Oecologia, 89: 147-149.
142. Walter, G.H. and Donaldson, J.S., 1994. Heteronomous hyperparasitoids, sex ratios and adaptations. Ecol. Entomol., 19: 89-92.
143. Watson, J.S., 1982a. Parental manipulation of the sex ratio of offspring: a historical note. Am. Nat., 119: 283-284.
144. Watson, J.S., 1982b. On artificially selecting for the sex ratio. Ethol. Sociobiol., 13: 1-2.
145. Werren, J.H., 1984. A model for sex ratio selection in parasitic wasps: local mate competition and host quality effects. Neth. J. Zool., 34: 81-96.
146. Wibbels, T., Martin, R.E., Owens, D.W. and Amoss, M.S., Jr., 1995. Female-biased sex ratio of immature loggerhead sea turtles inhabiting the Atlantic coastal waters of Florida. Can. J. Zool., 69: 2973-2977.
147. Wiebe, K.L. and Borlotti, G.R., 1992. Facultative sex ratio manipulation in American kestrels. Behav. Ecol. Sociobiol., 30: 379-386.
148. Wiley, D.N. and Clapham, P.J., 1993. Does maternal condition affect the sex ratio of offspring in humpback whales? Anim. Behav., 46: 321-324.
149. Williams, G.C., 1979. The question of adaptive sex ratio in outcrossed vertebrates. Proc. R. Soc. London, Ser. B, 205: 567-580.
150. Wrensch, D.L. and Ebbert, M.A., 1993. Evolution and Diversity of Sex Ratio in Insects and Mites. Chapman and Hall, New York.
151. Wright, D.D., Ryser, J.J. and Kiltie, R.A., 1995. First-cohort advantage hypothesis: a new twist on facultative sex ratio adjustment. Am. Nat., 145: 133-145.
152. Zijlstra, M., Daan, S. and Bruinenberg-Rinsma, J., 1992. Seasonal variation in the sex ratio of marsh harrier Circus aeruginosus broods. Funct. Ecol., 6: 553-559.