scholarly journals Parental Care System and Brood Size Drive Sex Difference in Reproductive Allocation: An Experimental Study on Burying Beetles

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenxia Wang ◽  
Long Ma ◽  
Maaike A. Versteegh ◽  
Hua Wu ◽  
Jan Komdeur

Life-history theory predicts that increased resource allocation in current reproduction comes at the cost of survival and future reproductive fitness. In taxa with biparental care, each parent can adjust investment on current reproduction according to changes in their partner’s effort, but these adjustments may be different for males and females as they may have different reproductive strategies. Numerous theoretical and empirical studies have proposed the mechanism underlying such adjustments. In addition, the value of the brood or litter (brood size) has also been suggested to affect the amount of care through manipulation of brood size. While the two conditions have been studied independently, the impact of their interplay on potential sex-dependent future reproductive performance remains largely unknown. In this study, we simultaneously manipulated both care system (removal of either parent vs. no removal) and brood size in a burying beetle (Nicrophorus vespilloides) to understand their joint effect on reproductive allocation and trade-off between current and future reproduction. Our results show that males compensated for mate loss by significantly increasing the level of care regardless of brood size, while females exhibited such compensation only for small brood size. Additionally, with an increase in allocation to current reproduction, males showed decreased parental investment during the subsequent breeding event as a pair. These findings imply a dual influence of parental care system and brood size on allocation in current reproduction. Moreover, the impact of such adjustments on sex-dependent differences in future reproduction (parental care, larvae number, and average larval mass at dispersal) is also demonstrated. Our findings enhance the understanding of sex roles in parental investment and highlight their importance as drivers of reproductive allocation.

Behaviour ◽  
1978 ◽  
Vol 65 (1-2) ◽  
pp. 62-87 ◽  
Author(s):  
Lazarus John ◽  
Inglis I.R.

In this study we describe the pattern of parental investment in the pink-footed goose (Anser brachyrhynchus) during the fledging period in Iceland, concentrating particularly on the analysis of vigilant behaviour as one important element of parental care. We quantify parental investment, and its cost to the parent, by comparing the behaviour of parents with that of 'pairs' of adults without young (most of which are probably failed breeders). Each partner's strategy of investment is not expected to be purely selfish in this long-term pair-bonding species, and the sex differences in parental care are examined in this light. The time budgets of parents and pairs differed, parents walking more, grazing more and preening less. Parents also spent more time in the extreme head up posture and less in the head low and head on back postures than pairs but time devoted to the head up posture was the same for both. Brood size had no effect on the time budget. Time spent extreme head up declined over the study period in parents but not in pairs. Spacing patterns and behaviour varied independently in non-breeding birds but families sat closer to other geese when the vigilance level of the parents was low (i.e. in the head on back or head low postures) than when it was high (the head up or extreme head up postures). All agonistic encounters between parents and non-breeders were both initiated and won by the parents. Tied encounters occurred between birds of equivalent status in terms of brood size or non-breeding group size. The potential sources of parental care are summarized (Table 6) and, after considering the evidence for each, it is concluded that (apart from brooding) two types of parental investment are made by parents: (1) enhancement of offspring feeding efficiency by reducing competition through agonistic behaviour, and perhaps avoidance; and (2) protection from predators by (a) active defence, (b) seeking proximity with other geese when resting, and (c) visual scanning for predators (mainly by the male) using the extreme head up posture. Parents paid for this investment by devoting less time to preening and sleeping. The male's investment in predator vigilance was made at the cost of a reduced feeding time and to compensate for this he pecked at a faster rate than his mate. These sex differences are explicable in terms of earlier differences during incubation. The adoption of unrelated goslings was observed and the implications of the phenomenon are discussed. For individuals in non-breeding groups the time spent extreme head up declined as group size increased. The functional significance of this finding is discussed and it is concluded that in sitting groups extreme head up is probably used to scan for predators.


1985 ◽  
Vol 63 (9) ◽  
pp. 2114-2120 ◽  
Author(s):  
Shirley J. Rushforth Guinn ◽  
Bruce D. J. Batt

Time budgets of pintail brood hen behaviour were collected at Oak Hammock Marsh, Manitoba, from June to August 1979. Hens spent 60.8% of their time at self-maintenance activities (feed, comfort movements) and 34.6% of their time at dominant parental care activities (alert, lead, follow). Hens with large broods allocated more time to self-maintenance than did hens with small broods. Time spent at parental care activities did not vary with brood size. The total time spent at parental care activities was higher for class I than class II broods. However, this pattern was not consistent across activities. Brood age did not influence time spent at self-maintenance. Hens spent more time at self-maintenance (feeding) and less time at parental care in late than in early season. We related this to the hen's need to recover weight lost during incubation, to acquire energy for a complete body plumage molt, and to prepare for fall migration. This paper describes patterns of time allocated to parental care. We conclude that estimates of costs of parental investment during the brood rearing period are also required.


Behaviour ◽  
1978 ◽  
Vol 65 (1-2) ◽  
pp. 62-87 ◽  
Author(s):  
Lazarus John ◽  
Inglis I.R.

In this study we describe the pattern of parental investment in the pink-footed goose (Anser brachyrhynchus) during the fledging period in Iceland, concentrating particularly on the analysis of vigilant behaviour as one important element of parental care. We quantify parental investment, and its cost to the parent, by comparing the behaviour of parents with that of 'pairs' of adults without young (most of which are probably failed breeders). Each partner's strategy of investment is not expected to be purely selfish in this long-term pair-bonding species, and the sex differences in parental care are examined in this light. The time budgets of parents and pairs differed, parents walking more, grazing more and preening less. Parents also spent more time in the extreme head up posture and less in the head low and head on back postures than pairs but time devoted to the head up posture was the same for both. Brood size had no effect on the time budget. Time spent extreme head up declined over the study period in parents but not in pairs. Spacing patterns and behaviour varied independently in non-breeding birds but families sat closer to other geese when the vigilance level of the parents was low (i.e. in the head on back or head low postures) than when it was high (the head up or extreme head up postures). All agonistic encounters between parents and non-breeders were both initiated and won by the parents. Tied encounters occurred between birds of equivalent status in terms of brood size or non-breeding group size. The potential sources of parental care are summarized (Table 6) and, after considering the evidence for each, it is concluded that (apart from brooding) two types of parental investment are made by parents: (1) enhancement of offspring feeding efficiency by reducing competition through agonistic behaviour, and perhaps avoidance; and (2) protection from predators by (a) active defence, (b) seeking proximity with other geese when resting, and (c) visual scanning for predators (mainly by the male) using the extreme head up posture. Parents paid for this investment by devoting less time to preening and sleeping. The male's investment in predator vigilance was made at the cost of a reduced feeding time and to compensate for this he pecked at a faster rate than his mate. These sex differences are explicable in terms of earlier differences during incubation. The adoption of unrelated goslings was observed and the implications of the phenomenon are discussed. For individuals in non-breeding groups the time spent extreme head up declined as group size increased. The functional significance of this finding is discussed and it is concluded that in sitting groups extreme head up is probably used to scan for predators.


2015 ◽  
Author(s):  
Bram Kuijper ◽  
Rufus A Johnstone

Abstract Existing models of parental investment have mainly focused on interactions at the level of the family, and have paid much less attention to the impact of population-level processes. Here we extend classical models of parental care to assess the impact of population structure and limited dispersal. We find that sex-differences in dispersal substantially affect the amount of care provided by each parent, with the more philopatric sex providing the majority of the care to young. This effect is most pronounced in highly viscous populations: in such cases, when classical models would predict stable biparental care, inclusion of a modest sex difference in dispersal leads to uniparental care by the philopatric sex. In addition, mating skew also affects sex-differences in parental investment, with the more numerous sex providing most of the care. However, the effect of mating skew only holds when parents care for their own offspring. When individuals breed communally, we recover the previous finding that the more philopatric sex provides most of the care, even when it is the rare sex. Finally, we show that sex-differences in dispersal can mask the existence of sex-specific costs of care, because the philopatric sex may provide most of the care even in the face of far higher mortality costs relative to the dispersing sex. We conclude that sex-biased dispersal is likely to be an important, yet currently overlooked driver of sex-differences in parental care.


2021 ◽  
Vol 9 ◽  
Author(s):  
Tom Ratz ◽  
Katerina Kremi ◽  
Lyndon Leissle ◽  
Jon Richardson ◽  
Per T. Smiseth

In species where both parents cooperate to care for their joint offspring, one sex often provides more care than the other. The magnitude of such sex differences often varies both between and within species and may depend on environmental conditions, such as access to resources, predation risk and interspecific competition. Here we investigated the impact of one such environmental variable – access to resources for breeding – on the magnitude of sex differences in parental care in the burying beetle Nicrophorus vespilloides. This species breeds on the carcasses of small vertebrates, which are the sole food source for parents and offspring during breeding. We manipulated access to resources by providing pairs with mouse carcasses from a broad mass range (3.65–26.15 g). We then monitored subsequent effects on the duration and amount of care provided by males and females, male and female food consumption and weight change during breeding, and larval traits related to offspring performance. We found that males increased their duration of care as carcass mass increased, while females remained with the brood until it had completed its development irrespective of carcass mass. There were thus more pronounced sex differences in parental care when parents had access to fewer resources for breeding. Overall, our findings show that sex differences between caring parents vary depending on access to resources during breeding. The finding that males extended their duration of care on larger carcasses suggests that access to more resources leads to a shift toward more cooperation between caring parents.


Author(s):  
Nur Widiastuti

The Impact of monetary Policy on Ouput is an ambiguous. The results of previous empirical studies indicate that the impact can be a positive or negative relationship. The purpose of this study is to investigate the impact of monetary policy on Output more detail. The variables to estimatate monetery poicy are used state and board interest rate andrate. This research is conducted by Ordinary Least Square or Instrumental Variabel, method for 5 countries ASEAN. The state data are estimated for the period of 1980 – 2014. Based on the results, it can be concluded that the impact of monetary policy on Output shown are varied.Keyword: Monetary Policy, Output, Panel Data, Fixed Effects Model


2020 ◽  
Author(s):  
Yumiko Murai ◽  
Ryohei Ikejiri ◽  
Yuhei Yamauchi ◽  
Ai Tanaka ◽  
Seiko Nakano

Cultivating children’s creativity and imagination is fundamental to preparing them for an increasingly complex and uncertain future. Engaging in creative learning enables children to think independently and critically, work cooperatively, and take risks while actively engaging in problem solving. While current trends in education, such as maker movements and computer science education, are dramatically expanding children’s opportunities for engagement in creative learning, comparatively few empirical studies explore how creative learning can be integrated into the school curriculum. The educational design research described in this paper focuses on a curriculum unit that enables students to engage with creative learning through computer programming activities while meeting curriculum goals. The data provided in this paper were drawn from three classroom tryouts, the results of which were used to drive an iterative design process. This paper also shares several insights on the impact of creative learning in curriculum teaching.


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