Local resource enhancement and sex ratios in a primitively social bee

Nature ◽  
1988 ◽  
Vol 331 (6154) ◽  
pp. 346-348 ◽  
Author(s):  
Michael P. Schwarz
Keyword(s):  
Sex Ratios ◽  
Local Resource ◽  
Resource Enhancement ◽  
Local Resource Enhancement ◽  
Social Bee

scholarly journals Sex ratios, virginity, and local resource enhancement in a quasisocial parasitoid

2016 ◽  
Vol 159 (2) ◽  
pp. 243-251 ◽  
Author(s):  
Apostolos Kapranas ◽  
Ian C.W. Hardy ◽  
Xiuyun Tang ◽  
Andy Gardner ◽  
Baoping Li
Keyword(s):  
Sex Ratios ◽  
Local Resource ◽  
Resource Enhancement ◽  
Local Resource Enhancement

Local Resource Enhancement and Sex‐biased Breastfeeding in a Caribbean Community

2005 ◽  
Vol 46 (3) ◽  
pp. 471-480 ◽  
Author(s):  
Robert J. Quinlan ◽  
Marsha B. Quinlan ◽  
Mark V. Flinn
Keyword(s):  
Local Resource ◽  
Caribbean Community ◽  
Resource Enhancement ◽  
Local Resource Enhancement

Predicting cross-cultural patterns in sex-biased parental investment and attachment

2009 ◽  
Vol 32 (1) ◽  
pp. 40-41 ◽  
Author(s):  
Robert J. Quinlan
Keyword(s):  
Parental Investment ◽  
Attachment Styles ◽  
Resource Competition ◽  
Well Being ◽  
Cultural Patterns ◽  
Local Resource Competition ◽  
Local Resource ◽  
Parental Responsiveness ◽  
Resource Enhancement ◽  
Local Resource Enhancement

AbstractIf parenting behavior influences attachment, then parental investment (PI) theory can predict sex differences and distributions of attachment styles across cultures. Trivers-Willard, local resource competition, and local resource enhancement models make distinct predictions for sex-biased parental responsiveness relevant to attachment. Parental investment and attachment probably vary across cultures in relation to “local fitness currencies” for status, wealth, and well-being.

Competitive Motherhood from a Comparative Perspective

2016 ◽  
Author(s):  
Katherine A. Valentine ◽  
Norman P. Li ◽  
Jose C. Yong
Keyword(s):  
Reproductive Success ◽  
Sex Ratio ◽  
Nonhuman Primates ◽  
Resource Competition ◽  
Sex Ratios ◽  
Comparative Perspective ◽  
Future Directions ◽  
Competition Hypothesis ◽  
Resource Enhancement

Mothers play an important role in helping their children achieve maximal reproductive success. We explore how mothers across species manipulate birth sex ratios favoring the sex that will be best suited to their environments and how maternal competition affects offspring reproductive success in nonhuman mammals as well as humans. The Trivers-Willard hypothesis, resource competition hypothesis, resource enhancement hypothesis, and maternal dominance hypothesis are considered with respect to maternal birth sex ratio manipulation. Next, the primate literature is reviewed as inspiration for hypotheses on maternal competition for positive offspring outcomes. Nonhuman primates as well as humans are argued to compete for status, breeding opportunities, and allomothers (i.e., caregivers apart from the mother), and these factors have an impact on their reproductive success. Status is passed on from mother to offspring, amplifying the effects of competition for status. Future directions are delineated to fill in gaps in the existing literature.

scholarly journals Peregrine Falcon Eggs: Egg Size, Hatchling Sex, and Clutch Sex Ratios

The Condor ◽  
2003 ◽  
Vol 105 (2) ◽  
pp. 327-335 ◽  
Author(s):  
William Burnham ◽  
Calvin Sandfort ◽  
James R. Belthoff
Keyword(s):  
New Mexico ◽  
Egg Size ◽  
Resource Competition ◽  
Sex Ratios ◽  
Peregrine Falcon ◽  
Falco Peregrinus ◽  
Local Resource Competition ◽  
Local Resource ◽  
Peregrine Falcons ◽  
Falco Peregrinus Anatum

AbstractEggs (n = 367) collected from wild Peregrine Falcon (Falco peregrinus anatum) nests between 1976 and 1990 in Colorado and New Mexico were artificially incubated and hatched. We retrospectively examined these data for variation in egg length, breadth, and initial mass of hatchlings to resolve questions about relationships among egg size, chick size, and sex; and egg size related to first and second clutches and years. Egg length and breadth were significantly related to chick mass at hatching. Neither egg size nor hatchling mass were related to sex. Egg breadth slightly increased and then decreased over the years eggs were collected, which possibly reflects a re-established and then aging wild falcon population or other environmental variation. We also evaluated clutch sex ratios relative to theory based on sexual size dimorphism and local resource competition. Sex ratios did not significantly differ from 1:1 within first or second clutches separately or when combined. Thus, Peregrine Falcons in this population apparently did not skew clutch sex ratios in accordance with local resource competition or Fisherian theory.Huevos de Halcones Peregrinos: Tamaño, Sexo de los Pichones y Proporción de Sexos en la NidadaResumen. Huevos (n = 367) colectados de nidos silvestres de halcones peregrinos (Falco peregrinus anatum) entre 1976 y 1990 en Colorado y New Mexico fueron incubados artificialmente hasta eclosionar. Examinamos esos datos retrospectivamente en cuanto a la variación en la longitud y ancho del huevo y el peso inicial de los pichones para contestar preguntas sobre las relaciones entre tamaño del huevo, tamaño del pichón y sexo, y entre el tamaño del huevo con relación a primeras y segundas nidadas y años. La longitud y el ancho del huevo estuvieron significativamente relacionados con la masa del pichón al eclosionar. El tamaño del huevo y el peso del pichón no estuvieron relacionados con el sexo. El ancho de los huevos aumentó ligeramente y luego disminuyó a través de los años en que los huevos se colectaron, lo que posiblemente refleja una población silvestre de halcones re-establecida y posteriormente senescente, u otro tipo de variación ambiental. También evaluamos la proporción de sexos en las nidadas con relación a la teoría basada en el dimorfismo sexual de tamaño y la competencia local por recursos. Las proporciones de sexos no difirieron significativamente de 1:1 entre primeras o segundas nidadas separadamente o de forma combinada. Por tanto, los halcones peregrinos en esta población aparentemente no sesgaron la proporción de sexos en sus nidadas de acuerdo a la competencia local por recursos o a la teoría Fisheriana.

scholarly journals A Test of Sex-Ratio Biasing in the White-Throated Magpie-Jay, A Cooperative Breeder with Female Helpers

The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 299-308
Author(s):  
Elena C. Berg
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Bird Species ◽  
Population Level ◽  
Offspring Sex Ratio ◽  
Local Resource ◽  
Offspring Sex ◽  
Local Resource Enhancement ◽  
Genetic Parents ◽  
Dna Microsatellite Analysis

Abstract Recent studies suggest that many bird species are able to vary the sex ratio of their young. Among cooperative breeders, in which adult helpers aid the genetic parents in the rearing of young, two models have been invoked to explain this variation. According to the local resource competition hypothesis, parents should bias offspring sex ratios toward the dispersing sex in order to minimize competition for local resources. In contrast, the local resource enhancement (or “production of helpers”) hypothesis states that parents should overproduce the nondispersing sex if the presence of relatives enhances reproductive success. I examined these models in a Costa Rican population of White-throated Magpie-Jays (Calocitta formosa), a cooperatively breeding corvid with female helpers. Using DNA microsatellite analysis, I sexed 135 offspring from 38 broods and 14 groups over 3 years. I tested for variation in offspring sex ratio at the population level and as a function of social group, helper number, breeding female, and season. Unlike studies of the Seychelles Warbler (Acrocephalus sechellensis), one of the few other avian species with primarily female helpers, I found no evidence for systematic sex-ratio bias supporting either hypothesis. This suggests that female-biased helping is not a sufficient condition for the evolution of offspring sex-ratio biasing. Estudio del Sesgo en el Cociente de Sexos en Calocitta formosa, una Reproductora Cooperativa con Ayudantes Hembras Resumen. Estudios recientes sugieren que muchas especies de aves pueden hacer variar el cociente de sexos de sus crías. Se han utilizado dos modelos teóricos para explicar esta variación en las aves que se reproducen en forma cooperativa, en las cuales los adultos ayudan a los padres genéticos con el cuidado de sus crías. Según la hipótesis de competencia por recursos locales, los padres deben sesgar el cociente de sexos de su prole en favor del sexo que se dispersa con el fin de minimizar la competencia por los recursos locales. Por el contrario, según la hipótesis de incremento de recursos locales (o “producción de ayudantes”), los padres deben sobreproducir el sexo que no se dispersa si la presencia de parientes favorece el éxito reproductivo. Yo estudié estos modelos en una población costarricense de urracas (Calocitta formosa), un córvido de reproducción cooperativa con ayudantes hembras. Utilicé análisis de ADN microsatelital para averiguar el sexo de 135 crías provenientes de 38 nidadas y 14 grupos a lo largo de un período de tres años. Documenté las variaciones en el cociente de sexos de las crías a nivel poblacional y como función del grupo social, la cantidad de ayudantes, la hembra reproductiva y la estación del año. A diferencia de lo encontrado para el caso de Acrocephalus sechellensis, una de las pocas especies de aves con ayudantes principalmente hembras, no encontré indicios de sesgo sistemático en el cociente de sexos que avalara ninguna de las dos hipótesis. Esto sugiere que la ayuda por parte de las hembras no constituye una condición que determine la evolución de un sesgo en el cociente de sexos de las crías.

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