Maternal Allocation Research Articles

Carotenoid concentration in barn swallow eggs is influenced by laying order, maternal infection and paternal ornamentation.

Carotenoids are critical to embryonic development, immunity and protection from oxidative stress. Transmission of carotenoids to the eggs may affect development and maturation of immunity in offspring, but carotenoids may be available to females in limiting amounts. Females may thus transfer carotenoids to the eggs differentially in relation to the reproductive value of the offspring as affected by sexual ornamentation of their father. In this study of maternal allocation of carotenoids to the eggs in the barn swallow (Hirundo rustica), females whose immune system had been experimentally challenged with an antigen had smaller lutein concentrations in their eggs than controls. We manipulated the size of a secondary sexual character (tail length) of males, and analysed the effect of manipulation on allocation of lutein to eggs by their vaccinated mates. Contrary to our prediction based on parental allocation theory, mates of tail-shortened males had a larger lutein concentration in their eggs compared with those of control and tail-elongated males. According to previous studies, offspring of short-tailed males have larger exposure and/or susceptibility to parasites. A larger lutein concentration in the eggs of females mated to males with experimentally reduced ornaments may thus reflect adaptive maternal strategies to enhance offspring viability.

Mass change in Antarctic fur seal (Arctocephalus gazella) pups in relation to maternal characteristics at the Kerguèlen Islands

Maternal allocation to growth of the pup was measured in Antarctic fur seals (Arctocephalus gazella) at the Kerguèlen Islands during the 1997 austral summer. Absolute mass gain of pups following a maternal foraging trip was independent of the sex of the pup but was positively related to foraging-trip duration and maternal length. However, daily mass gain (i.e., absolute mass gain of the pup divided by foraging-trip duration) decreased with increasing foraging-trip duration but increased with maternal length. While the pup were fasting, their daily mass loss was related to their sex and initial body mass: both heavier pups and female pups lost more mass per day than lighter pups and male pups. The mass-specific rate of mass loss was significantly higher in female than in male pups. Over the study period, the mean growth rate was zero, with no difference between female and male pups. The growth rate in mass of the pup was positively related to maternal length but not to maternal condition, and negatively related to the foraging-trip duration of the mother and the initial mass of the pup. This indicates that during the study period, heavier pups grew more slowly because of their higher rate of daily mass loss during periods of fasting. Interestingly, for a given maternal length, the mean mass of the pup during the study period was higher for male than for female pups, even though the rate of daily mass gain was the same. Such differences are likely to result from sex differences in the mass-specific rate of mass loss. As female pups lose a greater proportion of their mass per day, a zero growth rate (i.e., mass gain only compensating for mass loss) is reached at a lower mass in female pups than in male pups. Our results indicate that maternal allocation does not differ according to the sex of the pup, but suggest that the two sexes follow different growth strategies.

Mass change in Antarctic fur seal (<i>Arctocephalus gazella</i>) pups in relation to maternal characteristics at the Kerguèlen Islands

Maternal allocation to growth of the pup was measured in Antarctic fur seals (Arctocephalus gazella )a t the Kerguelen Islands during the 1997 austral summer. Absolute mass gain of pups following a maternal foraging trip was independent of the sex of the pup but was positively related to foraging-trip duration and maternal length. However, daily mass gain (i.e., absolute mass gain of the pup divided by foraging-trip duration) decreased with increasing forag - ing-trip duration but increased with maternal length. While the pup were fasting, their daily mass loss was related to their sex and initial body mass: both heavier pups and female pups lost more mass per day than lighter pups and male pups. The mass-specific rate of mass loss was significantly higher in female than in male pups. Over the study period, the mean growth rate was zero, with no difference between female and male pups. The growth rate in mass of the pup was positively related to maternal length but not to maternal condition, and negatively related to the foraging-trip dura - tion of the mother and the initial mass of the pup. This indicates that during the study period, heavier pups grew more slowly because of their higher rate of daily mass loss during periods of fasting. Interestingly, for a given maternal length, the mean mass of the pup during the study period was higher for male than for female pups, even though the rate of daily mass gain was the same. Such differences are likely to result from sex differences in the mass-specific rate of mass loss. As female pups lose a greater proportion of their mass per day, a zero growth rate (i.e., mass gain only compensating for mass loss) is reached at a lower mass in female pups than in male pups. Our results indicate that maternal allocation does not differ according to the sex of the pup, but suggest that the two sexes follow different growth strategies. 483

Limits to milk flow and energy allocation during lactation of the hispid cotton rat (Sigmodon hispidus).

Energy allocation for maternal maintenance and milk production was examined in lactating hispid cotton rats (Sigmodon hispidus) supporting three to seven offspring at 10 degrees or 24 degrees C. Lactating mothers obtained most of their energy from dietary intake (ca. 90%), and the remainder was withdrawn from maternal stores. There was no indication that a central limit to maternal energy assimilation constrained lactational performance. Maternal energy assimilation increased with a larger litter size (a higher production cost) and a decline in ambient temperature (a higher thermoregulatory cost) during lactation, without reaching an apparent limit. Further, there was no evidence of competitive energy allocation, which might occur if maternal energy assimilation were limited. Hence, increases in maternal thermoregulatory expenditure during lactation did not decrease the energy allocation for milk production. Lactating mothers had a capacity to increase milk production. Nonetheless, the milk flow did not fully satisfy the energy requirements of dependent offspring in larger litters or at the lower ambient temperature (growth rates of offspring declined in both cases). Local physiological constraints and behavioral effects appear to limit maternal allocation during lactation. Constraints to allocation may be favored by selection because they reduce maternal risk or reproductive cost.

Colour bands, dominance, and body mass regulation in male zebra finches (Taeniopygia guttata)

The arbitrary assignment of different coloured leg bands to zebra finches (Taeniopygia guttata) has profound effects on mate preference, reproductive success, mortality rates, parental investment a...

Body size, litter size, timing of reproduction, and juvenile survival in the Unita ground squirrel, Spermophilus armatus.

The timing of reproduction affected litter size, offspring mass, and offspring survival in the Uinta ground squirrel, Spermophilus armatus, in Grand Teton National Park, Wyoming. Survival of juvenile females to yearling age varied negatively with date of weaning and positively with individual offspring mass. At the same time, juveniles weaned early in the season were lighter, and juveniles weaned later in the season were heavier. The coefficient of variation for juvenile body mass, originally measured at weaning, significantly decreased by the time juveniles entered hibernation, indicating that individuals weaned early and light "caught up" in body mass to individuals weaned later and heavier. From the perspective of the mother's investment in the litter, litter size (corrected for mother's mass) decreased with later wcaning dates, while the relationship of weaning date to litter mass (corrected for mother's mass) was significant in only one year. Maternal allocation of resources in litters changed over the season so that mothers produced many, small offspring early in the season, and fewer, large offspring late in the season.

Population Dynamics of a Reintroduced Asiatic Wild Ass (Equus Hemionus) Herd

Reintroduction is the release of animals into an area where they were extirpated or have significantly declined. Little is known about the factors that determine the success of failure of ungulate reintroduction. We studied the dynamics of a reintroduced Asiatic wild ass (Equus hemionus) population for 10 yr (1983‐1993) following the first successful release into the wild. A total of 14 adult females and 14 adult males were released into a nature reserve in the Negev Desert of southern Israel. Over this 10‐yr span the female population has grown to only 16 adults. Reproductive success of reintroduced females was low in the first 5 yr following release (0.0‐0.8 foals·female‐1·yr‐1), but increased to 0.5‐1.0 foals·female‐1·yr‐1 in the last 5 yr. Reproductive success of wild‐born females ≥3 yr old was higher than that of reintroduced females of similar ages, and ranged from 0.5‐1.0 foals·female·‐1yr‐1. Our study and data from the E. hemionus studbook suggest that young nonprimiparous females produced primarily males, while primiparous and old females produced primarily females. We attribute the low reproductive success following reintroduction to the stress caused by capture, transport, and release procedures; we consider the age‐dependent progeny sex ratio within the framework of Trivers and Willard's (1973) maternal allocation hypothesis. We conclude that the slow growth of the female population was due to: (a) low reproductive success of females in the early years following reintroduction, and (b) a male‐skewed progeny sex ratio among prime‐aged reintroduced females. A simple stochastic Leslie matrix model suggests that high survival and improved reproductive success of reintroduced females at later stages of the study, and the reproductive success of wild‐born females, make the population relatively unsusceptible to extinction from random demographic processes. In‐depth knowledge of the dynamics of reintroduced populations is vital for the correct assessment of their viability. We offer suggestions for increasing the efficacy of future wild ass reintroductions.

Peahens lay more eggs for peacocks with larger trains

Reproduction is costly and individual decisions about when and how much to invest in reproduction will relate to potential benefits in terms of offspring survivorship or mating success. For those organisms that can reproduce more than once, individuals should invest relatively more in reproduction when the potential benefits are high. If females gain directly or indirectly from choosing attractive, highly ornamented males, then it could be predicted that females mated to these males should invest more in reproduction. Here we report the first test of this prediction for a lekking species, peafowl (Pavo cristatus), in which males do not provide resources for offspring, and females prefer to mate with those males that possess the most elaborate trains. We find that peahens randomly mated to males that vary in the degree of ornament produce more eggs for those peacocks with more elaborate trains. We could find no evidence to support the possibility that this difference arises as a result of difference between males in their ability to fertilize eggs.

Egg size and taxon: their influence on survival and development of chrysopid hatchlings after food and water deprivation

Genus- and species-level differences characterize the pattern of life-history variation in two distinct phylogenetic lineages of chrysopids, Chrysopa and Chrysoperla. Species in the genus Chrysopa exhibit significant variation in egg size, and this variation is positively correlated with the ability of hatchlings to withstand periods of food and water deprivation prior to their initial feeding. The variation is also significantly correlated with larval size, as measured by the tibial length of first-instar larvae. Although the six Chrysopa species differ in several other life-history traits (i.e, the incubation period and rate of first-instar larval development), the variation is unrelated to egg size. It appears that maternal allocation of resources to eggs largely serves to enhance embryonic growth and the survival of hatchlings during searching. That is, within the Chrysopa lineage egg size varies; larger eggs yield larger, more robust hatchlings. These hatchlings may or may not develop faster than congeners from small eggs. In comparison with Chrysopa, the genus Chrysoperla has less variability in egg size and developmental rate. Furthermore, although Chrysoperla eggs are relatively small, the ability of hatchlings to endure periods of food or water deprivation is at least as great as it is in the Chrysopa species with large eggs. We conclude that maternal investment in larval fitness has different ontogenetic pathways, ecological roles, and phylogenetic histories in the two genera.

Lactation in the tammar wallaby (Macropus eugenii). II. Intake of milk components and maternal allocation of energy

The intake of milk components (total solids, carbohydrate, protein, lipid, energy) by suckling tammar wallabies (Macropus eugenii), from peak lactation to independence, was measured using a double‐isotope dilution technique and chemical analysis of milk samples. The time of peak intake of milk solids (day 256 of lactation or 1126 g of offspring weight) was similar to that for whole milk. Peak intake of carbohydrate occurred earlier than this (235 days) and peak intakes of protein and lipid occurred later (262 days and 266 days, respectively). Intake of gross energy peaked at 262 days and represented a maternal yield of about 207 KJ.Kg‐0.75.d‐1. This is much lower than peak lactational energy yields in most other mammals, but the duration of lactation is longer in tammars than in other mammals. Total output of energy in milk by tammar mothers was 63 MJ, and this would require an intake of about 98 MJ of metabolizable energy in food. This requirement, which is equivalent to 21 MJ/kg of maternal weight, is similar to those calculated for sheep and cattle, suggesting that there are not large differences between marsupial and placental herbivores in terms of weight‐related allocation of energy to reproduction. We suggest that a strategy of minimizing the peak energetic demand of lactation may be an important adaptation for a small, primarily grazing mammal due to size‐related physiological constraints on elevating herbage intake and the increasing risk from predators when grazing time is increased.

Biased Sex Ratios in Stressed Animals

Previous articleNext article No AccessNotes and CommentsBiased Sex Ratios in Stressed AnimalsL. M. GoslingL. M. Gosling Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 127, Number 6Jun., 1986 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284532 Views: 8Total views on this site Citations: 13Citations are reported from Crossref Copyright 1986 The University of ChicagoPDF download Crossref reports the following articles citing this article:R. Terry Bowyer, Dale R. McCullough, Janet L. Rachlow, Simone Ciuti, Jericho C. Whiting Evolution of ungulate mating systems: Integrating social and environmental factors, Ecology and Evolution 10, no.1111 (Apr 2020): 5160–5178.https://doi.org/10.1002/ece3.6246Eulalia Moreno, María B. Ibáñez, Andrés Barbosa Mother traits and offspring sex in two threatened gazelle species in captivity, Journal for Nature Conservation 19, no.33 (Jul 2011): 148–153.https://doi.org/10.1016/j.jnc.2010.10.004R. Cocchi, F. Riga Control of a coypu Myocastor coypus population in northern Italy and management implications, Italian Journal of Zoology 75, no.11 (Mar 2008): 37–42.https://doi.org/10.1080/11250000701690350Aline Kühl, Atle Mysterud, Gennadiy I Erdnenov, Anna A Lushchekina, Iuri A Grachev, Amankul B Bekenov, E.J Milner-Gulland The ‘big spenders’ of the steppe: sex-specific maternal allocation and twinning in the saiga antelope, Proceedings of the Royal Society B: Biological Sciences 274, no.16151615 (Mar 2007): 1293–1299.https://doi.org/10.1098/rspb.2007.0038Hannah L. Dugdale, David W. Macdonald, Chris Newman OFFSPRING SEX RATIO VARIATION IN THE EUROPEAN BADGER, MELES MELES, Ecology 84, no.11 (Jan 2003): 40–45.https://doi.org/10.1890/0012-9658(2003)084[0040:OSRVIT]2.0.CO;2Angela R. Glatston Sex ratio research in zoos and its implications for captive management, Applied Animal Behaviour Science 51, no.3-43-4 (Feb 1997): 209–216.https://doi.org/10.1016/S0168-1591(96)01105-7Mariko Hiraiwa-Hasegawa Skewed birth sex ratios in primates: Should high-ranking mothers have daughters or sons?, Trends in Ecology & Evolution 8, no.1111 (Nov 1993): 395–400.https://doi.org/10.1016/0169-5347(93)90040-VSven Krackow The Effect of Weaning Weight on Offspring Fitness in Wild House Mice (Mus musculus domesticus): A Preliminary Study, Ethology 95, no.11 (Apr 2010): 76–82.https://doi.org/10.1111/j.1439-0310.1993.tb00458.xD.P. Ryan, M.P. Boland Frequency of twin births among Holstein-Friesian cows in a warm dry climate, Theriogenology 36, no.11 (Jul 1991): 1–10.https://doi.org/10.1016/0093-691X(91)90428-GWilliam J. Zielinski, John G. Vandenbergh, Monica M. Montano Effects of social stress and intrauterine position on sexual phenotype in wild-type house mice (Mus musculus), Physiology & Behavior 49, no.11 (Jan 1991): 117–123.https://doi.org/10.1016/0031-9384(91)90241-FMartine Perret Influence of social factors on sex ratio at birth, maternal investment and young survival in a prosimian primate, Behavioral Ecology and Sociobiology 27, no.66 (Dec 1990): 447–454.https://doi.org/10.1007/BF00164072Sven Krackow, Hendrik N. Hoeck Sex ratio manipulation, maternal investment and behaviour during concurrent pregnancy and lactation in house mice, Animal Behaviour 37 (Feb 1989): 177–186.https://doi.org/10.1016/0003-3472(89)90108-5E. Jean Brennan Demographics of captive De Brazza's guenons, Zoo Biology 8, no.11 (Jan 1989): 37–47.https://doi.org/10.1002/zoo.1430080106

The Adaptive Value of Male-Biased Sex Ratios Among Stressed Animals

The Adaptive Value of Male-Biased Sex Ratios Among Stressed Animals

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle