N Burley | University of California, Irvine (original) (raw)
Papers by N Burley
Emu, 1989
... secondary sex ratio is a population concept that does not necessarily specify the optimal rat... more ... secondary sex ratio is a population concept that does not necessarily specify the optimal ratio for individual parents (Trivers & Willard 1973; Myers 1978; Burley 1982; Blank & Nolan ... The sex ratio at hatching is close to parity in a majority of species studied (Clutton-Brock 1986). ...
The Auk
Color-banding is a research technique widely uti-lized to facilitate recognition of individuals a... more Color-banding is a research technique widely uti-lized to facilitate recognition of individuals and membership in "groups" such as age classes. Despite the fact that many species of birds routinely attire themselves in colorful plumes, the possibility that color-marking by humans ...
Ethology and Sociobiology, 1983
Patterns of positive assortative mating are commonly inferred to result from homotypic preference... more Patterns of positive assortative mating are commonly inferred to result from homotypic preferences (preferences for self's type). This paper demonstrates that such preferences can result from heterotypic and type preferences as well. Because several kinds of preferences can lead to the same pattern, experimentation to measure preferences is necessary to determine the process responsible. The apparent weight of evidence for homotypic preferences may result from the kinds of preferences experimenters have selected to examine.
Ethology and Sociobiology, 1980
... religion in particular, therefore made high fertility a great virtue and low fertility ... At... more ... religion in particular, therefore made high fertility a great virtue and low fertility ... At the same Human Fertility, Evolutionary Biology and the Demographic Transition time ... Unfortunately, the relationshipbetween socioeconomic development and lower growth rates, while real, is ...
Ornithological Monographs, 1985
... Results 87 Discussion 92 CHAPTER 8. The Influence of Demography on the Evolution of Monogamy ... more ... Results 87 Discussion 92 CHAPTER 8. The Influence of Demography on the Evolution of Monogamy by Bertram G. Murray, Jr 100 Introduction 100 ... Quantifications of male and female variance, both in the lab (eg, Bateman 1948) and field (eg, LeBoeuf 1974; Clutton-Brock et al. ...
Ornithological Monographs, 1998
Many researchers have explored the ramifications of the idea that extra-pair copulation (EPC) is ... more Many researchers have explored the ramifications of the idea that extra-pair copulation (EPC) is a male reproductive tactic to obtain parentage while avoiding parental investment since this concept was advanced by Trivers in 1972. Consortship between males and their ...
The American Naturalist, 1998
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
The American Naturalist, 1979
... In principle there is no conflict between continuous receptivity and female sensation of ovul... more ... In principle there is no conflict between continuous receptivity and female sensation of ovulation ... some security about a female's intention; the most important and revealing knowledge may ... social factors including war and slavery, rejection of parental roles ("laziness"), desertion ...
Science, 1981
Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), i... more Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), indicate that sex ratio of offspring is affected by non-genetic markers (colored plastic leg bands) that vary in attractiveness to birds. Results suggest that natural selection favors individuals that produce offspring of the sex of the more attractive parent within a breeding pair.
Science, 1982
units of the reduced size (14). We conclude that factors correlated with the original size, such ... more units of the reduced size (14). We conclude that factors correlated with the original size, such as territorial qualities and parental age, had ho statistically significant influence on the difference between natural units of two or three members and units of six, seven, and eight members. In this study, both unit size and reproductive success were correlated with vegetation on the territory and with parental age (15). Comparison of these and other variables revealed no significant differences between experimental and control groups of the same original size. In summary, the positive correlation between reproductive success and the number of helpers is not the result of other variables that are correlated with unit size and reproductive success. It is caused mainly by the helpers or by an interaction of the helpers with another variable. We reject the hypothesis that helpers do more harm than good. Because helpers in this species are typically offspring of the breeder in their units (16), we have demonstrated, without the reservations expressed in (7), that helpers significantly improved the reproductive success of their parents, thereby increasing their own indirect fitness (17).
Proceedings of the Royal Society B: Biological Sciences, 2004
The steroid environment encountered by developing vertebrates has important organizational effect... more The steroid environment encountered by developing vertebrates has important organizational effects on physiology and behaviour that persist throughout an organism's lifetime. Optimal allocation of maternal steroids to zygotes may be difficult to achieve because of the sexually antagonistic effects of steroids; thus, for example, a hormone environment beneficial to a developing male may be much less beneficial to a developing female. Research into the important topic of how mothers might adaptively adjust steroid titres experienced by particular young has been constrained by the difficulty of measuring the steroid environment experienced by the embryo at critical times in development. A potential approach to this problem has been suggested by research on variation in digit ratios in humans, where the ratio of the length of the second and fourth digits reflects the steroid environment experienced by the foetus; notably, digit 4 lengthens in response to androgens. In light of the conservative nature of homeobox genes regulating early development in tetrapods, we questioned whether a sex difference in digit ratio exists in a passerine bird, the zebra finch, Taeniopygia guttata castanotis, and whether observed variation in the ratio is consistent with the previously reported pattern that androgen allocation to zebra finch egg yolk declines across laying order. We established an aviary population of outbred, wild-type zebra finches, and allowed them to breed freely. Hatchlings were marked to correspond to their egg order, and their digit ratios were measured after birds reached adulthood. We found that digit ratio increased across egg order, which is consistent with a pattern of decreasing androgen allocation. Moreover, digit ratios differed between the sexes. We also investigated whether variation in digit ratio among adult females predicted variation in their performance in mate-choice tests. Digit ratio accounted for almost 50% of the variance in strength of female preference for an attractive male trait: specifically, females with higher (presumably less 'androgenized') ratios had stronger preferences for attractive males. Digit ratio may prove to be an extremely useful tool for addressing a wide range of questions about vertebrate differentiation and behaviour.
Proceedings of the National Academy of Sciences, 1977
Current theory in sexual selection is extended to predict within-sex variability with regard to s... more Current theory in sexual selection is extended to predict within-sex variability with regard to selectivity towards mates in different mating systems. Generally, the sex that invests more in the care of each offspring should be more selective of mates than the sex investing less. Within each sex, individuals of low mate quality should be less selective than individuals of high quality, but there should be less variation in selectivity among individuals of the sex investing more. When only one sex contributes parental care, however, individuals of that sex should be uniformly selective, while the other sex is expected to mate indiscriminately. Using feral pigeons (Columba livia), these hypotheses are tested for the case in which both sexes contribute substantial parental care, but in which females contribute more than males. As predicted, females were found to be more selective of mates than males were. On certain criteria, males of lower quality were less selective of mates than males of higher quality.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2002
A stage model traces key behavioural tactics and life–history traits that are involved in the tra... more A stage model traces key behavioural tactics and life–history traits that are involved in the transition from promiscuity with no parental care, the mating system that typifies reptiles, to that typical of most birds, social monogamy with biparental care. In stage I, females assumed increasing parental investment in precocial young, female choice of mates increased, female–biased mating dispersal evolved and population sex ratios became male biased. In stage II, consortships between mating partners allowed males to attract rare social mates, provided a mechanism for paternity assessment and increased female ability to assess mate quality. In stage III, relative female scarcity enabled females to demand parental investment contributions from males having some paternity certainty. This innovation was facilitated by the nature of avian parental care; i.e. most care–giving activities can be adopted in small units. Moreover, the initial cost of care giving to males was small compared wit...
Emu, 1989
... secondary sex ratio is a population concept that does not necessarily specify the optimal rat... more ... secondary sex ratio is a population concept that does not necessarily specify the optimal ratio for individual parents (Trivers & Willard 1973; Myers 1978; Burley 1982; Blank & Nolan ... The sex ratio at hatching is close to parity in a majority of species studied (Clutton-Brock 1986). ...
The Auk
Color-banding is a research technique widely uti-lized to facilitate recognition of individuals a... more Color-banding is a research technique widely uti-lized to facilitate recognition of individuals and membership in "groups" such as age classes. Despite the fact that many species of birds routinely attire themselves in colorful plumes, the possibility that color-marking by humans ...
Ethology and Sociobiology, 1983
Patterns of positive assortative mating are commonly inferred to result from homotypic preference... more Patterns of positive assortative mating are commonly inferred to result from homotypic preferences (preferences for self's type). This paper demonstrates that such preferences can result from heterotypic and type preferences as well. Because several kinds of preferences can lead to the same pattern, experimentation to measure preferences is necessary to determine the process responsible. The apparent weight of evidence for homotypic preferences may result from the kinds of preferences experimenters have selected to examine.
Ethology and Sociobiology, 1980
... religion in particular, therefore made high fertility a great virtue and low fertility ... At... more ... religion in particular, therefore made high fertility a great virtue and low fertility ... At the same Human Fertility, Evolutionary Biology and the Demographic Transition time ... Unfortunately, the relationshipbetween socioeconomic development and lower growth rates, while real, is ...
Ornithological Monographs, 1985
... Results 87 Discussion 92 CHAPTER 8. The Influence of Demography on the Evolution of Monogamy ... more ... Results 87 Discussion 92 CHAPTER 8. The Influence of Demography on the Evolution of Monogamy by Bertram G. Murray, Jr 100 Introduction 100 ... Quantifications of male and female variance, both in the lab (eg, Bateman 1948) and field (eg, LeBoeuf 1974; Clutton-Brock et al. ...
Ornithological Monographs, 1998
Many researchers have explored the ramifications of the idea that extra-pair copulation (EPC) is ... more Many researchers have explored the ramifications of the idea that extra-pair copulation (EPC) is a male reproductive tactic to obtain parentage while avoiding parental investment since this concept was advanced by Trivers in 1972. Consortship between males and their ...
The American Naturalist, 1998
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
The American Naturalist, 1979
... In principle there is no conflict between continuous receptivity and female sensation of ovul... more ... In principle there is no conflict between continuous receptivity and female sensation of ovulation ... some security about a female's intention; the most important and revealing knowledge may ... social factors including war and slavery, rejection of parental roles ("laziness"), desertion ...
Science, 1981
Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), i... more Laboratory experiments performed on a monogamous estrildid, the zebra finch (Poephila guttata), indicate that sex ratio of offspring is affected by non-genetic markers (colored plastic leg bands) that vary in attractiveness to birds. Results suggest that natural selection favors individuals that produce offspring of the sex of the more attractive parent within a breeding pair.
Science, 1982
units of the reduced size (14). We conclude that factors correlated with the original size, such ... more units of the reduced size (14). We conclude that factors correlated with the original size, such as territorial qualities and parental age, had ho statistically significant influence on the difference between natural units of two or three members and units of six, seven, and eight members. In this study, both unit size and reproductive success were correlated with vegetation on the territory and with parental age (15). Comparison of these and other variables revealed no significant differences between experimental and control groups of the same original size. In summary, the positive correlation between reproductive success and the number of helpers is not the result of other variables that are correlated with unit size and reproductive success. It is caused mainly by the helpers or by an interaction of the helpers with another variable. We reject the hypothesis that helpers do more harm than good. Because helpers in this species are typically offspring of the breeder in their units (16), we have demonstrated, without the reservations expressed in (7), that helpers significantly improved the reproductive success of their parents, thereby increasing their own indirect fitness (17).
Proceedings of the Royal Society B: Biological Sciences, 2004
The steroid environment encountered by developing vertebrates has important organizational effect... more The steroid environment encountered by developing vertebrates has important organizational effects on physiology and behaviour that persist throughout an organism's lifetime. Optimal allocation of maternal steroids to zygotes may be difficult to achieve because of the sexually antagonistic effects of steroids; thus, for example, a hormone environment beneficial to a developing male may be much less beneficial to a developing female. Research into the important topic of how mothers might adaptively adjust steroid titres experienced by particular young has been constrained by the difficulty of measuring the steroid environment experienced by the embryo at critical times in development. A potential approach to this problem has been suggested by research on variation in digit ratios in humans, where the ratio of the length of the second and fourth digits reflects the steroid environment experienced by the foetus; notably, digit 4 lengthens in response to androgens. In light of the conservative nature of homeobox genes regulating early development in tetrapods, we questioned whether a sex difference in digit ratio exists in a passerine bird, the zebra finch, Taeniopygia guttata castanotis, and whether observed variation in the ratio is consistent with the previously reported pattern that androgen allocation to zebra finch egg yolk declines across laying order. We established an aviary population of outbred, wild-type zebra finches, and allowed them to breed freely. Hatchlings were marked to correspond to their egg order, and their digit ratios were measured after birds reached adulthood. We found that digit ratio increased across egg order, which is consistent with a pattern of decreasing androgen allocation. Moreover, digit ratios differed between the sexes. We also investigated whether variation in digit ratio among adult females predicted variation in their performance in mate-choice tests. Digit ratio accounted for almost 50% of the variance in strength of female preference for an attractive male trait: specifically, females with higher (presumably less 'androgenized') ratios had stronger preferences for attractive males. Digit ratio may prove to be an extremely useful tool for addressing a wide range of questions about vertebrate differentiation and behaviour.
Proceedings of the National Academy of Sciences, 1977
Current theory in sexual selection is extended to predict within-sex variability with regard to s... more Current theory in sexual selection is extended to predict within-sex variability with regard to selectivity towards mates in different mating systems. Generally, the sex that invests more in the care of each offspring should be more selective of mates than the sex investing less. Within each sex, individuals of low mate quality should be less selective than individuals of high quality, but there should be less variation in selectivity among individuals of the sex investing more. When only one sex contributes parental care, however, individuals of that sex should be uniformly selective, while the other sex is expected to mate indiscriminately. Using feral pigeons (Columba livia), these hypotheses are tested for the case in which both sexes contribute substantial parental care, but in which females contribute more than males. As predicted, females were found to be more selective of mates than males were. On certain criteria, males of lower quality were less selective of mates than males of higher quality.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2002
A stage model traces key behavioural tactics and life–history traits that are involved in the tra... more A stage model traces key behavioural tactics and life–history traits that are involved in the transition from promiscuity with no parental care, the mating system that typifies reptiles, to that typical of most birds, social monogamy with biparental care. In stage I, females assumed increasing parental investment in precocial young, female choice of mates increased, female–biased mating dispersal evolved and population sex ratios became male biased. In stage II, consortships between mating partners allowed males to attract rare social mates, provided a mechanism for paternity assessment and increased female ability to assess mate quality. In stage III, relative female scarcity enabled females to demand parental investment contributions from males having some paternity certainty. This innovation was facilitated by the nature of avian parental care; i.e. most care–giving activities can be adopted in small units. Moreover, the initial cost of care giving to males was small compared wit...