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Multiple Offspring (multiple + offspring)

Distribution by Scientific Domains
Life Sciences75%

Selected Abstracts

Mating system, philopatry and patterns of kinship in the cooperatively breeding subdesert mesite Monias benschi

MOLECULAR ECOLOGY, Issue 11 2005
N. SEDDON
Abstract In the first molecular study of a member of the threatened avian family, Mesitornithidae, we used nine polymorphic microsatellite loci to elucidate parentage, patterns of within-group kinship and occurrence of extra-group paternity in the subdesert mesite Monias benschi, of southwest Madagascar. We found this cooperatively breeding species to have a very fluid mating system. There was evidence of genetic monogamy and polygynandry: of the nine groups with multiple offspring, six contained one breeding pair with unrelated helpers and three contained multiple male and female breeders with related helpers. Although patterns of within-group kinship varied, there was a strong positive relationship between group size and relatedness, suggesting that groups form by natal philopatry. There was also a strong positive correlation between within-sex and between-sex relatedness, indicating that unlike most cooperatively breeding birds, philopatry involved both sexes. In contrast to predictions of kin selection and reproductive skew models, all monogamous groups contained unrelated individuals, while two of the three polygynandrous groups were families. Moreover, although between-group variation in seasonal reproductive success was related to within-group female relatedness, relatedness among males and between the sexes had no bearing on a group's reproductive output. While kin selection may underlie helping behaviour in females, factors such as direct long-term fitness benefits of group living probably determine helping in males. Of the 14 offspring produced by fully sampled groups, at least two were sired by males from neighbouring groups: one by a breeding male and one by a nonbreeding male, suggesting that males may augment their reproductive success through extra-group paternity. [source]

Variations in male parenting behavior and physiology in the common marmoset

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2009
Toni E. Ziegler
Infant survival and wellbeing is dependent upon good parenting skills. In some species of primates, fathers are necessary to ensure both positive developmental and social outcomes for their offspring. Common marmosets and the related cotton-top tamarin monkeys provide extensive paternal care of multiple offspring and are essential for infant survival. However, we have found significant variation in a father's motivation to respond to infant stimuli. Additionally, marmoset males who are experienced fathers are significantly more motivated to respond to infants and infant stimuli than adult males who have yet to be fathers. Expectant fathers appear to be preparing for their energetic role in infant care by responding with increases in multiple reproductive hormones and showing weight gain during their mate's pregnancy. Male marmosets have been shown to be hormonally responsive to scent signals. Males show increased testosterone shortly after smelling periovulatory scents and lower levels of testosterone following presentation of their own infant's scent. These two inverse testosterone responses combined indicate that paternal males have a flexible system of responding to socially relevant odor cues. Thus males can be ready to mate when their mate is fertile while continuing to be responsive to their infants when these two events occur simultaneously. A male's hormonal and physical responsiveness to parenting may be due to pair bonding between the male and his mate. Examining the variability between males in their behavioral, physical, and hormonal responses to their mate's pregnancy, and infant stimuli provides the means for determining the mechanisms of good parenting in fathers. Am. J. Hum. Biol., 2009. © 2009 Wiley-Liss, Inc. [source]

Superparasitism in gregarious hymenopteran parasitoids: ecological, behavioural and physiological perspectives

PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2007
SILVIA DORN
Abstract Superparasitism in gregarious wasps occurs with the deposition of a clutch of eggs by a female into a host already parasitized by itself or a conspecific female. This review synthesizes and interprets the available results in the literature reported from field studies, and from behavioural and physiological investigations. To study superparasitism at the ecosystem level, methodological issues have to be solved to determine threshold values beyond which multiple offspring can be indisputably classified as originating from superparasitism. This life strategy is then discussed from the parasitoid's perspective, considering time and egg limitation, host discrimination, clutch size, offspring body size and sex ratio, as well as development time and survival rate of offspring, with special emphasis on physiological facilitation and constraints. Then, superparasitism in gregarious species is evaluated from the host's angle, addressing host survivorship and development, host food consumption and growth. Although superparasitism may be beneficial for either the first or the superparasitizing female, depending on the system, it is detrimental for both of them under conditions of extreme superparasitism. Recent methodological and experimental advances encourage further studies on the adaptive host choice under field and laboratory conditions, as well as on mechanisms underlying success of the first or the superparasitizing female and their progeny. [source]

Hybrid crossover operators with multiple descendents for real-coded genetic algorithms: Combining neighborhood-based crossover operators

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2009
Ana M. Sánchez
Most real-coded genetic algorithm research has focused on developing effective crossover operators, and as a result, many different types of crossover operators have been proposed. Some forms of crossover operators are more suitable to tackle certain problems than others, even at the different stages of the genetic process in the same problem. For this reason, techniques that combine multiple crossovers, called hybrid crossover operators, have been suggested as alternative schemes to the common practice of applying only one crossover model to all the elements in the population. On the other hand, there are operators with multiple offsprings, more than two descendants from two parents, which present a better behavior than the operators with only two descendants, and achieve a good balance between exploration and exploitation. © 2009 Wiley Periodicals, Inc. [source]