scholarly journals Mothers front-load their investment to the egg stage when helped in a wild cooperative bird

2021 ◽  
Author(s):  
Pablo Capilla-Lasheras ◽  
Alastair J Wilson ◽  
Andrew J Young
Keyword(s):  
Maternal Investment ◽  
Reaction Norm ◽  
Beneficial Effects ◽  
Fitness Consequences ◽  
Cooperatively Breeding ◽  
Post Natal Care ◽  
Per Se ◽  
Nestling Feeding ◽  
Maternal Responses ◽  
Maternal Strategy

In many cooperative societies, including our own, helpers assist with the post-natal care of breeders' young, and may thereby benefit the post-natal development of offspring. Here we present evidence of a novel mechanism by which such post-natal helping could also have hitherto unexplored beneficial effects on pre-natal development: by lightening post-natal maternal workloads, helpers may allow mothers to increase their pre-natal investment per offspring. We present the findings of a decade-long study of cooperatively breeding white-browed sparrow weaver, Plocepasser mahali, societies. Within each social group, reproduction is monopolized by a dominant breeding pair, and non-breeding helpers assist with nestling feeding. Using a within-mother reaction norm approach to formally identify maternal plasticity, we demonstrate that when mothers have more female helpers they decrease their own post-natal investment per offspring (feed their nestlings at lower rates) but increase their pre-natal investment per offspring (lay larger eggs, which yield heavier hatchlings). That these plastic maternal responses are predicted by female helper number, and not male helper number, implicates the availability of post-natal helping per se as the likely driver (rather than correlated effects of group size), because female helpers feed nestlings at substantially higher rates than males. We term this novel maternal strategy 'maternal front-loading' and hypothesize that the expected availability of post-natal help allows helped mothers to focus maternal investment on the pre-natal phase, to which helpers cannot contribute directly. Such cryptic maternally mediated helper effects on pre-natal development may markedly complicate attempts to identify and quantify the fitness consequences of helping.

Maternal investment mediates offspring life history variation with context-dependent fitness consequences

Ecology ◽  
2015 ◽  
Vol 96 (9) ◽  
pp. 2499-2509 ◽  
Author(s):  
Michael P. Moore ◽  
Tobias Landberg ◽  
Howard H. Whiteman
Keyword(s):  
Life History ◽  
Maternal Investment ◽  
Life History Variation ◽  
Fitness Consequences ◽  
Context Dependent

scholarly journals THE VALUE OF PENICILLIN IN THE TREATMENT OF AGRANULOCYTOSIS CAUSED BY THIOURACIL

Blood ◽  
1946 ◽  
Vol 1 (1) ◽  
pp. 53-66 ◽  
Author(s):  
MARY CATHERINE TYSON ◽  
PETER VOGEL ◽  
NATHAN ROSENTHAL
Keyword(s):  
Bone Marrow ◽  
Antibacterial Agents ◽  
Bone Marrow Cells ◽  
The Body ◽  
Bacterial Invasion ◽  
Beneficial Effects ◽  
Penicillin Therapy ◽  
History Of ◽  
Per Se ◽  
Hemopoietic System

Abstract Thiouracil has been found to be an effective drug in the treatment of hyperthyroidism. Agranulocytosis following its use occurred in nine cases, four of which terminated fatally. In five others a complete and rapid recovery took place following penicillin therapy. The latter drug is believed to be ideal for all cases of agranulocytosis, and especially those in which chemotherapy has been used and may have been responsible for the condition. Thus far we have not seen any report of any untoward effect on the hemopoietic system from the use of penicillin. The use of antibacterial agents for the treatment of agranulocytosis was suggested by Dameshek and Wolfson21 in 1942. It was believed by these authors that patients with agranulocytosis died not of the leukopenia per se but of the sepsis which developed secondarily to the lack of granulocytes. Two very severe cases of aminopyrine agranulocytosis treated with sulfathiazole made complete recoveries. For the treatment of sulfonamide agranulocytosis, it was suggested that a preparation differing from that which had already been used be given. With the discovery of penicillin, and its complete lack of possible deleterious effect on the bone marrow, its use was suggested by Dameshek17 (1944). A report on the beneficial effects of this medication in a case of sulfonamide agranulocytosis was later reported by Dameshek and Knowlton18 and similar cases by Sprague and Ferguson19 and by Meredith and Fink.20 Since sulfonamides may cause further toxic effect on the bone marrow, we feel that their use should be avoided in the treatment of agranulocytosis, especially where a history of previous use is obtained. We do not agree with others21, 22 who continue the use of sulfonamides in the treatment of leukopenia or agranulocytosis where these very drugs may have been responsible for the condition. It would seem better judgment to use penicillin, which by combating the bacterial invasion of the body and the consequent toxemia enables the patient to survive until the bone marrow cells regenerate.

scholarly journals Inbreeding Depression and its Effects on Natal Dispersal in Red-Cockaded Woodpeckers

The Condor ◽  
2000 ◽  
Vol 102 (3) ◽  
pp. 482-491 ◽  
Author(s):  
Susan J. Daniels ◽  
Jeffrey R. Walters
Keyword(s):  
Spatial Clustering ◽  
Large Population ◽  
Dispersal Distance ◽  
Significant Loss ◽  
Natal Dispersal ◽  
Picoides Borealis ◽  
Fitness Consequences ◽  
Cooperatively Breeding ◽  
Dispersal Behavior ◽  
Close Inbreeding

Abstract Natal dispersal is a key life-history component that may be influenced by the fitness consequences of inbreeding. We studied natal dispersal and inbreeding within a large population of cooperatively breeding, endangered Red-cockaded Woodpeckers (Picoides borealis). We assessed the costs of close inbreeding, the spatial distribution of related males and its relationship to dispersal distance of females, and the change in dispersal behavior of females in the presence of closely related males. Close inbreeding resulted in a significant loss of fitness, through two separate effects: closely related pairs (kinship coefficient ≥ 0.125) exhibited lowered hatching rates and lowered survival and recruitment of fledglings relative to unrelated pairs. Despite a highly predictable spatial clustering of closely related males near the female's natal territory, natal dispersal distance of females was not sufficient to avoid these males as mates. Females changed dispersal behavior in the presence of closely related males on the natal territory: female fledglings were significantly more likely to disperse from natal territories if there were closely related males breeding there in the following year. Females did not change dispersal behavior in the presence of related males that were not on the natal territory. We suggest that dispersal behavior is a trade-off between benefits of short-distance dispersal, e.g., an advantage in competing for scarce breeding vacancies, and the substantial cost of close inbreeding.

Role of Tonsillectomy and Adenoidectomy in the Management of Children with Middle Ear Effusion

1980 ◽  
Vol 89 (5_suppl) ◽  
pp. 43-46 ◽  
Author(s):  
James B. Snow
Keyword(s):  
Otitis Media ◽  
Middle Ear ◽  
Clinical Effectiveness ◽  
First Year ◽  
Middle Ear Effusion ◽  
Beneficial Effects ◽  
Per Se ◽  
Second Year ◽  
Ear Effusion

Evidence for the clinical effectiveness of adenoidectomy or tonsillectomy and adenoidectomy in the management of children with persistent middle ear effusions is incomplete and what evidence there is in the literature is not convincing. In the first year after tonsillectomy and adenoidectomy there is less otitis media. The beneficial effects of tonsillectomy and adenoidectomy on the incidence of otitis media declines in the second year after the operation. The prevailing opinion is that adenoidectomy is not indicated in the vast majority of children in whom a middle ear effusion has persisted for six weeks or more in spite of antibiotic therapy. Factors favoring an adenoidectomy would be persistent nasal obstruction, persistent purulent rhinorrhea and persistent adenoiditis. The role of tonsillectomy is even less clear, but the decision regarding tonsillectomy is made by most clinicians on the basis of the amount of intercurrent or chronic tonsillitis rather than on the basis of the middle ear effusion per se.

scholarly journals Intergroup aggression in meerkats

2019 ◽  
Vol 286 (1917) ◽  
pp. 20191993 ◽  
Author(s):  
Mark Dyble ◽  
Thomas M. Houslay ◽  
Marta B. Manser ◽  
Tim Clutton-Brock
Keyword(s):  
Genetic Relatedness ◽  
Group Living ◽  
Lethal Violence ◽  
Suricata Suricatta ◽  
Group Cooperation ◽  
Fitness Consequences ◽  
Cooperatively Breeding ◽  
Adult Sex Ratio ◽  
Violent Conflicts ◽  
Large Groups

Violent conflicts between groups have been observed among many species of group living mammals and can have important fitness consequences, with individuals being injured or killed and with losing groups surrendering territory. Here, we explore between-group conflict among meerkats ( Suricata suricatta ), a highly social and cooperatively breeding mongoose. We show that interactions between meerkat groups are frequently aggressive and sometimes escalate to fighting and lethal violence and that these interactions have consequences for group territories, with losing groups moving to sleeping burrows closer to the centre of their territories following an intergroup interaction and with winning groups moving further away. We find that larger groups and groups with pups are significantly more likely to win contests, but that the location of the contest, adult sex ratio, and mean within-group genetic relatedness do not predict contest outcome. Our results suggest that intergroup competition may be a major selective force among meerkats, reinforcing the success of large groups and increasing the vulnerability of small groups to extinction. The presence of both within-group cooperation and between-group hostility in meerkats make them a valuable point of comparison in attempts to understand the ecological and evolutionary roots of human warfare.

scholarly journals Intersexual conflict over seed size is stronger in more outcrossed populations of a mixed-mating plant

2018 ◽  
Vol 115 (45) ◽  
pp. 11561-11566 ◽  
Author(s):  
Astrid Raunsgard ◽  
Øystein H. Opedal ◽  
Runa K. Ekrem ◽  
Jonathan Wright ◽  
Geir H. Bolstad ◽  
...  
Keyword(s):  
Mating Systems ◽  
Strong Support ◽  
Maternal Investment ◽  
Arms Race ◽  
Mixed Mating ◽  
Fitness Consequences ◽  
Intersexual Conflict ◽  
Maternal Provisioning ◽  
Hybrid Seeds ◽  
Parent Of Origin

In polyandrous species, fathers benefit from attracting greater maternal investment toward their offspring at the expense of the offspring of other males, while mothers should usually allocate resources equally among offspring. This conflict can lead to an evolutionary arms race between the sexes, manifested through antagonistic genes whose expression in offspring depends upon the parent of origin. The arms race may involve an increase in the strength of maternally versus paternally derived alleles engaged in a “tug of war” over maternal provisioning or repeated “recognition-avoidance” coevolution where growth-enhancing paternally derived alleles evolve to escape recognition by maternal genes targeted to suppress their effect. Here, we develop predictions to distinguish between these two mechanisms when considering crosses among populations that have reached different equilibria in this intersexual arms race. We test these predictions using crosses within and among populations ofDalechampia scandens(Euphorbiaceae) that presumably have experienced different intensities of intersexual conflict, as inferred from their historical differences in mating system. In crosses where the paternal population was more outcrossed than the maternal population, hybrid seeds were larger than those normally produced in the maternal population, whereas when the maternal population was more outcrossed, hybrid seeds were smaller than normal. These results confirm the importance of mating systems in determining the intensity of intersexual conflict over maternal investment and provide strong support for a tug-of-war mechanism operating in this conflict. They also yield clear predictions for the fitness consequences of gene flow among populations with different mating histories.

scholarly journals Dehydroepiandrosterone treatment attenuates oestrogen-induced pituitary hyperplasia

2002 ◽  
Vol 174 (3) ◽  
pp. 447-454 ◽  
Author(s):  
C Suarez ◽  
I Garcia Tornadu ◽  
W Khalil ◽  
D Becu-Villalobos
Keyword(s):  
Serum Prolactin ◽  
Therapeutic Drug ◽  
Sprague Dawley ◽  
Beneficial Effects ◽  
Physiological Importance ◽  
Pituitary Hyperplasia ◽  
Igf I ◽  
Pituitary Enlargement ◽  
Per Se ◽  
Dhea Treatment

The physiological importance of and therapeutic interest in dehydroepiandrosterone (DHEA) has been predominantly in relation to its action as an inhibitor of the promotion and progression of several kinds of tumours, including those of breast, prostate, lung, colon, liver and skin tissues. The aim of the present study was to determine the role of DHEA in diethylstilboestrol (DES)-induced pituitary hyperplasia. Female Sprague-Dawley rats were divided into four treatment groups: DES (implanted s.c. with a 20 mg DES pellet), DHEA (two 50 mg DHEA pellets), DHEA/DES (both DHEA and DES pellets), and controls (not implanted). Every week, all rats were weighed and cycled, and jugular blood samples were obtained. After 7 weeks, rats were killed. Hypophyses were removed and weighed, and serum prolactin, GH, IGF-I and leptin levels were assayed by RIA. DHEA cotreatment reduced pituitary enlargement by 39% in DES-treated rats. It also reduced the hyperprolactinaemia (280.4+/-43.6 ng/ml for DHEA/DES vs 823.5+/- 127.1 ng/ml for DES) and partially reversed the loss of body weight induced by DES. DHEA treatment did not modify the effects of DES on serum GH, IGF-I and leptin levels. But DHEA per se also increased pituitary weight and induced hyperprolactinaemia, although to a lesser degree than DES. We conclude that DHEA administration has beneficial effects on oestrogen-induced pituitary hyperplasia and hyperprolactinaemia, but the fact that DHEA per se also induces diverse hormonal effects and a slight pituitary enlargement limits its use as a possible therapeutic drug.

scholarly journals Prolactin and the regulation of parental care and helping behavior in cooperatively breeding white-browed sparrow weaver societies

2021 ◽  
Author(s):  
Lindsay A Walker ◽  
Linda Tschirren ◽  
Jennifer E York ◽  
Peter J Sharp ◽  
Simone L Meddle ◽  
...  
Keyword(s):  
Parental Care ◽  
Cooperative Breeding ◽  
Natural Variation ◽  
Underlying Mechanism ◽  
Helping Behavior ◽  
Fine Scale ◽  
Physiological Mechanisms ◽  
Nestling Provisioning ◽  
Cooperatively Breeding ◽  
Nestling Feeding

In many cooperatively breeding societies non-breeding individuals help to rear the offspring of breeders. The physiological mechanisms that regulate such cooperative helping behavior are poorly understood, but may have been co-opted, during the evolution of cooperative breeding, from pre-existing mechanisms that regulated parental care. Key among these may be a role for prolactin. Here we investigate whether natural variation in circulating prolactin levels predicts both parental and helper contributions to nestling provisioning in cooperatively breeding white-browed sparrow weavers, Plocepasser mahali. In sparrow weaver groups, a single dominant pair monopolize reproduction and non-breeding subordinates help with nestling feeding. We show that: (i) among parents, dominant females feed nestlings at higher rates, make longer provisioning visits and have higher prolactin levels than dominant males; and (ii) among subordinates, engaged in cooperative helping behavior, those within their natal groups feed nestlings at higher rates and have higher prolactin levels than immigrants. Moreover, continuous variation in prolactin levels positively predicts nestling-provisioning rates and mean provisioning visit durations when all bird classes are combined. These relationships are principally driven by differences among bird classes in both circulating prolactin levels and provisioning traits; the more limited within-class variation in prolactin and provisioning traits were not evidently correlated, highlighting a likely role for additional mechanisms in the fine-scale regulation of care. Our findings broadly support the hypothesis that parental care and cooperative helping behavior are regulated by a common underlying mechanism and highlight the need for experimentation to now establish the causality of any role for prolactin.

scholarly journals The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4028 ◽  
Author(s):  
Tanmay Dixit ◽  
Sinead English ◽  
Dieter Lukas
Keyword(s):  
Life History ◽  
Social Environment ◽  
Group Size ◽  
Egg Size ◽  
Reproductive Investment ◽  
Maternal Investment ◽  
Differential Allocation ◽  
The Social ◽  
Cooperatively Breeding ◽  
The Relationship

BackgroundLife history theory predicts that mothers should adjust reproductive investment depending on benefits of current reproduction and costs of reduced future reproductive success. These costs and benefits may in turn depend on the breeding female’s social environment. Cooperative breeders provide an ideal system to test whether changes in maternal investment are associated with the social conditions mothers experience. As alloparental helpers assist in offspring care, larger groups might reduce reproductive costs for mothers or alternatively indicate attractive conditions for reproduction. Thus, mothers may show reduced (load-lightening) or increased (differential allocation) reproductive investment in relation to group size. A growing number of studies have investigated how cooperatively breeding mothers adjust pre-natal investment depending on group size. Our aim was to survey these studies to assess, first, whether mothers consistently reduce or increase pre-natal investment when in larger groups and, second, whether these changes relate to variation in post-natal investment.MethodsWe extracted data on the relationship between helper number and maternal pre-natal investment (egg size) from 12 studies on 10 species of cooperatively breeding vertebrates. We performed meta-analyses to calculate the overall estimated relationship between egg size and helper number, and to quantify variation among species. We also tested whether these relationships are stronger in species in which the addition of helpers is associated with significant changes in maternal and helper post-natal investment.ResultsAcross studies, there is a significant negative relationship between helper number and egg size, suggesting that in most instances mothers show reduced reproductive investment in larger groups, in particular in species in which mothers also show a significant reduction in post-natal investment. However, even in this limited sample, substantial variation exists in the relationship between helper number and egg size, and the overall effect appears to be driven by a few well-studied species.DiscussionOur results, albeit based on a small sample of studies and species, indicate that cooperatively breeding females tend to produce smaller eggs in larger groups. These findings on prenatal investment accord with previous studies showing similar load-lightening reductions in postnatal parental effort (leading to concealed helper effects), but do not provide empirical support for differential allocation. However, the considerable variation in effect size across studies suggests that maternal investment is mitigated by additional factors. Our findings indicate that variation in the social environment may influence life-history strategies and suggest that future studies investigating within-individual changes in maternal investment in cooperative breeders offer a fruitful avenue to study the role of adaptive plasticity.

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