Search results for "Parental investment"

It takes two to tango

2003

Abstract In most taxa, females are more likely than males to care for offspring. Why? Ever since Trivers' landmark work, the answer has been traced back to sexual differences in pre-mating reproductive investment (unequal gamete size or anisogamy). However, recent work shows that parental investment theory has inadvertently ignored a profoundly simple fact of life: every offspring has a mother and father. Taking this into account completely changes how we should think about sex differences in parental care.

Manipulation of offspring number and size: benefits of large body size at birth depend upon the rearing environment

2003

Summary 1. Allocation of reproductive effort between the number and size of offspring determines the immediate rearing environment for the growing young. As the number of offspring increases, the amount of parental investment per individual offspring decreases, and the quality of the rearing environment is expected to decrease. This may result in a lower quality of offspring reared in such conditions. 2. We studied the effects of the rearing environment on the quality of juvenile bank voles, Clethrionomys glareolus , with different initial body sizes at birth in a 2 〈 2 factorial experiment. The rearing environment was manipulated by enlarging both the litter size by two extra pups, and mea…

Negative association between parental care and sibling cooperation in earwigs: a new perspective on the early evolution of family life?

2015

International audience; The evolution of family life requires net fitness benefits for offspring, which are commonly assumed to mainly derive from parental care. However, an additional source of benefits for offspring is often overlooked: cooperative interactions among juvenile siblings. In this study, we examined how sibling cooperation and parental care could jointly contribute to the early evolution of family life. Specifically, we tested whether the level of food transferred among siblings (sibling cooperation) in the European earwig F orficula auricularia (1) depends on the level of maternal food provisioning (parental care) and (2) is translated into offspring survival, as well as fem…

Clutch size and egg volume in great tits (Parus major) increase under low intensity electromagnetic fields: a long-term field study.

2012

Exposure to electromagnetic fields (EMFs) can affect a wide range of biological processes, including reproduction, growth and development. Experiments aimed at investigating the biological effects of EMFs, focused on potential harmful effects on humans, have been mostly carried out in vitro or with animal models in laboratory conditions. By contrast, studies performed on wild animals are scarce. The effects of EMFs created by an electric power line on reproductive traits of a wild great tit (Parus major) population were explored by analysing data gathered during nine breeding seasons. EMF exposure significantly increased clutch size (7%) and egg volume (3%), implying a 10% increase in clutc…

Parental effects on offspring longevity--evidence from 17th to 19th century reproductive histories.

2004

Family studies provide support for a modest genetic influence on offspring life span, although the magnitude of these correlations is small.The study aimed to clarify the relative contributions of parental age at birth and overall parental longevity on offspring lifespan, and to identify the biological and cultural mechanisms.Information was derived from two village genealogies (1650-1927) encompassing 9979 births (5315 males, 4664 females). Data selection was guided by the inclusion of information about parental age at birth and lifespan, offspring lifespan and cohort-specific life expectancy.Parental age at reproduction displayed a negative association with offspring survivability, which …

Assortative mating and female clutch investment in black grouse

1999

Variation in female behaviour has only recently received attention in studies of sexual selection. It has been suggested that females may invest differentially in their offspring in relation to the quality of their mate. This may lead to females that mate with high-quality and/or attractive males laying larger clutches. Females may also differ in their ability to choose between males. For example, females in good physical condition may make better choices. If physical condition and clutch size are positively correlated, this hypothesis could also produce a relationship between male attractiveness and female clutch size. We found, in lekking black grouse, Tetrao tetrix, that females mated to…

Could male tergal secretions be considered as a nuptial gift in the Madeira cockroach?

2008

International audience; Many male insects provide somatic nuptial gifts that may strongly influence reproductive fitness, ensuring effective copulation or mediating paternal resource benefits in offspring. Although the courtship feeding behaviour on tergal gland secretions has been described in numerous cockroaches, studies on the function of these so-called nuptial gifts are lacking in this group. In this study, we examined, in the Madeira cockroach, Leucophaea maderae, the functional significance of tergal secretions by manipulating their availability on the back of males. We tested whether male tergal secretions function as a form of mating effort, and/or as a form of paternal investment…

Do Pied Flycatcher Females Defend an Extra Nest Hole Against Conspecific Females?

1999

AbstractIn birds, females are often aggressive against conspecific females during the breeding. There are many explanations for this intrasexual aggression by females: e.g., nest site or food resource defence, prevention of intraspecific brood parasitism or infanticide, and monopolization of paternal care. A pair might also benefit by defending an alternative nest site in addition to the current nest site. Here, I study by experimentation whether pied flycatcher (Ficedula hypoleuca) females defend an extra nest box as an alternative nesting site. Further, I examine whether females behave differently when their mate is present vs not present. I measured the reactions by resident females to a…

Female-female aggression and male polyterritoriality in the pied flycatcher

1994

Sex roles and the evolution of parental care specialization

2019

Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by s…