Local Resource Competition and Facultative Adjustment of Sex Ratios in Relation to Competitive Abilities

1983 ◽  
Vol 121 (1) ◽  
pp. 56-66 ◽  
Author(s):  
Joan B. Silk
Keyword(s):  
Resource Competition ◽  
Sex Ratios ◽  
Local Resource Competition ◽  
Local Resource ◽  
Competitive Abilities

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 Birth-sex ratios and local resource competition in roe deer, Capreolus capreolus

1996 ◽  
Vol 7 (4) ◽  
pp. 461-464 ◽  
Author(s):  
A. J. Mark Hewison ◽  
J. M. Gaillard
Keyword(s):  
Resource Competition ◽  
Roe Deer ◽  
Sex Ratios ◽  
Capreolus Capreolus ◽  
Local Resource Competition ◽  
Local Resource

Local resource competition and the evolution of male-biased sex ratios

1984 ◽  
Vol 108 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Joan B. Silk
Keyword(s):  
Resource Competition ◽  
Sex Ratios ◽  
Local Resource Competition ◽  
Local Resource

Intensity of Local Resource Competition Shapes the Relationship between Maternal Rank and Sex Ratios at Birth in Cercopithecine Primates

1991 ◽  
Vol 138 (6) ◽  
pp. 1555-1562 ◽  
Author(s):  
Carel P. van Schaik ◽  
Sarah Blaffer Hrdy
Keyword(s):  
Resource Competition ◽  
Sex Ratios ◽  
Local Resource Competition ◽  
Local Resource ◽  
The Relationship

scholarly journals Maternal rank and local resource competition do not predict birth sex ratios in wild baboons

2005 ◽  
Vol 272 (1565) ◽  
pp. 859-864 ◽  
Author(s):  
Joan B Silk ◽  
Elisabeth Willoughby ◽  
Gillian R Brown
Keyword(s):  
Resource Competition ◽  
Sex Ratios ◽  
Local Resource Competition ◽  
Local Resource ◽  
Wild Baboons

scholarly journals Problems with primate sex ratios

2000 ◽  
Vol 355 (1403) ◽  
pp. 1627-1635 ◽  
Author(s):  
Craig Packer ◽  
D. Anthony Collins ◽  
Lynn E. Eberly
Keyword(s):  
Sex Ratio ◽  
Environmental Conditions ◽  
National Park ◽  
Resource Competition ◽  
Sex Ratios ◽  
Adaptive Variation ◽  
Gombe National Park ◽  
Local Resource Competition ◽  
Local Resource ◽  
Complex Processes

Birth sex ratios of baboons in Gombe National Park, Tanzania, show an overall male bias of ca . 20%, but there is no obvious explanation for this trend. Individual females did not alter their sex ratios according to persistent levels of local resource competition. Sex ratios showed an unexpected relationship between age and rank: subordinate females had more sons when they were young; dominant females had more sons when they were old. The sex ratio of low–ranking females also varied with the severity of environmental conditions during pregnancy. Our findings suggest that mammalian sex ratios might be the product of more complex processes than is generally recognized or that sex–determining mechanisms impose sufficient constraints to prevent adaptive variation in all contexts.

Sex Ratio and Local Resource Competition in a Prosimian Primate

Science ◽  
1978 ◽  
Vol 201 (4351) ◽  
pp. 163-165 ◽  
Author(s):  
A. B. CLARK
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource
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