scholarly journals Context-dependent strategies of food allocation among offspring in a facultative cooperative breeder

2019 ◽  
Vol 30 (4) ◽  
pp. 975-985 ◽  
Author(s):  
Jianqiang Li ◽  
Yong Wang ◽  
Lei Lv ◽  
Pengcheng Wang ◽  
Ben J Hatchwell ◽  
...  
Keyword(s):  
Natural Selection ◽  
Brood Size ◽  
Competitive Ability ◽  
Food Resources ◽  
Food Allocation ◽  
Context Dependent ◽  
Nestling Begging ◽  
Parental Strategies ◽  
Allocation Decisions

Abstract Natural selection should favor adoption of parental strategies that maximize fitness when allocating investment among offspring. In birds, begging displays often convey information of nestling need and quality, allowing parents to make adaptive food allocation decisions. We investigated how adults utilized cues likely to represent nestling competitive ability (begging position) and need (begging intensity) and a cue independent of nestling control (nestling sex) to distribute food among nestlings in a facultative cooperative breeder, the black-throated tit (Aegithalos concinnus). We found that parents reduced their efforts when helped, suggesting that parents of helped broods would have the potential to satisfy nestling needs more than unhelped parents. This suggestion was supported by the fact that nestling mass increased faster in helped than in unhelped nests. We found no effect of nestling sex on food allocation, but, as predicted, we found that adults responded differently to begging signals in relation to the presence of helpers and brood size. First, helped parents were more responsive to nestling begging intensity than parents without helpers. Second, female parents and helpers had a stronger preference for nestling begging position in large than in small broods. Third, the preference for nestling begging position was greater for unhelped than for helped female parents. These results provide evidence that carers adjust their preference for different offspring begging signals based on availability of food resources.

Larval habitats impose trait-dependent limits on the direction and rate of adult evolution in dragonflies

2021 ◽  
Vol 17 (5) ◽  
pp. 20210023
Author(s):  
Michael P. Moore
Keyword(s):  
Natural Selection ◽  
Comparative Study ◽  
Adult Stage ◽  
Larval Habitat ◽  
Adult Size ◽  
Larval Habitats ◽  
Size Evolution ◽  
Fitness Benefits ◽  
Context Dependent ◽  
Ornament Evolution

Natural selection on juveniles is often invoked as a constraint on adult evolution, but it remains unclear when such restrictions will have their greatest impact. Selection on juveniles could, for example, mainly limit the evolution of adult traits that mostly develop prior to maturity. Alternatively, selection on juveniles might primarily constrain the evolution of adult traits that experience weak or context-dependent selection in the adult stage. Using a comparative study of dragonflies, I tested these hypotheses by examining how a species’ larval habitat was related to the evolution of two adult traits that differ in development and exposure to selection: adult size and male ornamentation. Whereas adult size is fixed at metamorphosis and experiences consistent positive selection in the adult stage, ornaments develop throughout adulthood and provide context-dependent fitness benefits. My results show that species that develop in less stable larval habitats have smaller adult sizes and slower rates of adult size evolution. However, these risky larval habitats do not limit ornament expression or rates of ornament evolution. Selection on juveniles may therefore primarily affect the evolution of adult traits that mostly develop prior to maturity.

The relationship between facial whorl direction and sidedness in ridden horses

2006 ◽  
Vol 35 ◽  
pp. 247-250
Author(s):  
H. Randle ◽  
E. Elworthy
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Competitive Ability ◽  
Close Association ◽  
Human Behaviour ◽  
Physical Ability ◽  
Facial Hair ◽  
Selection For ◽  
The Relationship ◽  
The Brain

The influence of Natural Selection on the evolution of the horse (Equus callabus) is minimal due to its close association with humans. Instead Artificial Selection is commonly imposed through selection for features such as a ‘breed standard’ or competitive ability. It has long been considered to be useful if indicators of characteristics such as physical ability could be identified. Kidd (1902) suggested that the hair coverings of animals were closely related to their lifestyle, whether they were active or passive. In 1973 Smith and Gong concluded that hair whorl (trichloglyph) pattern and human behaviour is linked since hair patterning is determined at the same time as the brain develops in the foetus. More recently Grandin et al. (1995), Randle (1998) and Lanier et al. (2001) linked features of facial hair whorls to behaviour and production in cattle. Hair whorl features have also been related to temperament in equines (Randle et al., 2003).

Begging form and growth pattern of nestlings correlate with parental food-allocation patterns in the Horned Lark (Eremophilaalpestris)

2015 ◽  
Vol 93 (4) ◽  
pp. 273-279 ◽  
Author(s):  
Bo Du ◽  
Chang-Jing Liu ◽  
Shi-Jie Bao
Keyword(s):  
Reproductive Success ◽  
Growth Pattern ◽  
Brood Size ◽  
Life History Theory ◽  
Reproductive Value ◽  
Behavioral Strategies ◽  
Tarsus Length ◽  
Food Allocation ◽  
Allocation Patterns ◽  
Horned Lark

Life-history theory assumes that selection favors parents that can maximize their reproductive success via behavioral strategies. As brood size determines the reproductive value of each nestling, parents may adjust their food-allocation patterns according to brood size. We test this assumption in the Horned Lark (Eremophila alpestris (L., 1758)). Our findings revealed that nestling begging forms varied with brood size, by gaping in one-chick broods and postural activity in two- and three-chick broods. Accordingly, parental food-allocation patterns differed in different-sized broods. In one-chick broods, parents increased feeding rates with the gaping duration of nestling. In two-chick broods, parents did not change food-allocation patterns according to nestlings’ begging. In three-chick broods, however, they fed later-hatched nestlings more even when early-hatched nestlings begged more intensely. Horned Larks exhibited obvious sexual differences in parenting style and ability, which resulted in nestlings from two- and three-chick broods changing their begging intensity according to the sex of the provisioning adult. Furthermore, nestling growth pattern diverged with brood sizes, with body mass growing faster in one-chick broods than in two- and three-chick broods. Growth rate of beak gape and tarsus length did not differ significantly among brood sizes, but beak gape was larger and tarsus length was shorter in one-chick broods than in larger broods at fledging. Our results thus support the idea that parents may use food allocation to regulate sibling rivalry, which in turn cause nestlings to beg food in different forms and grow in different patterns so that their reproductive success can be enhanced.

scholarly journals Group provisioning limits sharing conflict among nestlings in joint-nesting Taiwan yuhinas

2010 ◽  
Vol 6 (3) ◽  
pp. 318-321 ◽  
Author(s):  
Sheng-Feng Shen ◽  
Hsueh-Chen Chen ◽  
Sandra L. Vehrencamp ◽  
Hsiao-Wei Yuan
Keyword(s):  
Cooperative Breeding ◽  
Video Recording ◽  
Food Delivery ◽  
Food Distribution ◽  
Sibling Competition ◽  
Short Intervals ◽  
Food Allocation ◽  
Adult Feeding ◽  
Large Party ◽  
Nestling Begging

Offspring often compete over limited available resources. Such sibling competition may be detrimental to parents both because it entails wasted expenditure and because it allows stronger offspring to obtain a disproportionate share of resources. We studied nestling conflict over food and its resolution in a joint-nesting species of bird, the Taiwan yuhina ( Yuhina brunneiceps ). We show that adult yuhinas coordinate their feeding visits, and that this coordination limits competition among nestlings, leading to a ‘fairer’ division of resources. Transponder identification and video-recording systems were used to observe adult feeding and nestling begging behaviours. We found that: (i) yuhinas feed nestlings more often in large parties than in small parties; (ii) feeding events occurred non-randomly in bouts of very short intervals; and (iii) food distribution among nestlings was more evenly distributed, and fewer nestlings begged, during large-party feeding bouts compared with small-party feeding bouts. To our knowledge, this is the first study in a cooperative breeding species showing that adults can influence food allocation and competition among nestlings by coordinating their feeding visits. Our results confirm the hypothesis that the monopolizability of food affects the intensity of sibling competition, and highlight the importance of understanding the temporal strategies of food delivery.

scholarly journals Selection for a threshold character in Drosophila II. Homeostatic behaviour on relaxation of selection

1966 ◽  
Vol 8 (2) ◽  
pp. 205-218 ◽  
Author(s):  
B. D. H. Latter
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Competitive Ability ◽  
Reproductive Capacity ◽  
Correlated Responses ◽  
Genetic Sampling ◽  
Bristle Number ◽  
Large Populations ◽  
Selection For ◽  
Two Phases

This paper is concerned with three related aspects of the behaviour of populations under artificial selection for increased scutellar bristle number: (i) the pattern of response on the probit scale; (ii) the homeostatic behaviour of the selection lines on relaxation of artificial selection; and (iii) correlated responses in generation interval, reproductive capacity and competitive ability. The study was designed so that linkage would be a comparatively unimportant factor in promoting correlated responses to selection, and the effects of genetic sampling from generation to generation were also reduced to a low level.Progress from the base mean of 4·05 bristles in females to a level of almost 8 bristles has been shown to involve two distinct phases with realized heritabilities of 0·34 and 0·10 respectively, the zone of transition corresponding closely to the position of the 6/7 threshold on the underlying scale. In addition to an apparent average reduction of about 25% in the additive genetic standard deviation in phase II by comparison with phase I, the loss in response due to the opposition of natural selection has been shown to reach a maximum near the zone of separation of the two phases.The pattern of behaviour of the populations under artificial and natural selection has suggested the presence in the base population of genes of large effect on both bristle number and reproductive fitness. There is also evidence of additional genetic variation in bristle number which is effectively neutral with respect to fitness. Continued selection for increased scutellar bristle number in large populations has been shown to reduce mean competitive ability by more than 80%.

scholarly journals Community-level natural selection modes: A quadratic framework to link multiple functional traits with competitive ability

2018 ◽  
Vol 107 (3) ◽  
pp. 1457-1468 ◽  
Author(s):  
Andrés G. Rolhauser ◽  
Marisa Nordenstahl ◽  
Martín R. Aguiar ◽  
Eduardo Pucheta
Keyword(s):  
Natural Selection ◽  
Functional Traits ◽  
Competitive Ability ◽  
Community Level

Does Brood Size Manipulation Affect Later Competitive Behaviour of Offspring?

Behaviour ◽  
1997 ◽  
Vol 134 (3-4) ◽  
pp. 161-172 ◽  
Author(s):  
C.H. De Kogel
Keyword(s):  
Brood Size ◽  
Competitive Ability ◽  
Field Experiments ◽  
Food Competition ◽  
The Other ◽  
Long Term Effects ◽  
Significant Difference ◽  
Competitive Behaviour

AbstractData from several field experiments support the existence of a trade-off between number and quality of offspring. However, long term effects of brood size on fitness related traits of offspring have been a relatively neglected area of research. In a laboratory experiment the effect of manipulated brood size on subsequent competitive ability of adult offspring was investigated. Zebra finches, Taeniopygia guttata, were reared in small or large broods and young were exchanged in such a way that natural siblings from different rearing conditions could be compared. Competitive behaviour was assessed in two different contexts: competition for food (both sexes tested) and competition for mates (only males tested). There was no significant difference between males from small and large broods in number of succesfull attacks (after which the other male moved away) during male-male aggressive interactions provoked by the presentation of a female in an adjacent cage. Nor did brood size affect latency to eat, time spent eating or success at displacing the other bird from the feeder during food competition tests. The results thus suggest consistently that later competitive ability of offspring is not affected by brood size in this species.

scholarly journals Ecological determinants of life-history evolution

1991 ◽  
Vol 332 (1262) ◽  
pp. 25-30 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Natural Selection ◽  
Competitive Ability ◽  
Life History Evolution ◽  
Experimental System ◽  
Food Utilization ◽  
Physiological Basis ◽  
Laboratory Populations ◽  
Very High

Density-dependent natural selection has been studied, empirically with laboratory populations of Drosophila melanogaster . Populations kept at very high and low population density have become differentiated with respect to important fitness-related traits. There is now some understanding of the behavioural and physiological basis of these differences. These studies have identified larval competitive ability and efficiency of food utilization as traits that are negatively correlated with respect to effects on fitness. Theory that illuminates and motivates additional research with this experimental system has been lacking. Current research has focused on models that incorporate many details of Drosophila ecology in laboratory environments.

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