Endocrine Control of Seminal-Glomus Growth and Function in Starlings of Different Ages

Hilton, Frederick K.

doi:10.1086/physzool.41.3.30155468

Cited by 13 publications

(6 citation statements)

References 4 publications

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“…In a different interpretation of the fertility insurance hypothesis, Sheldon (1994) suggested that male phenotype varies with functional fertility and that females pursue EPCs with males with more exaggerated ornaments as an insurance against their mate being unable to fertilize the entire brood. There is some evidence of a correlation between functional fertility and male age in birds (Hilton 1968; Hill 1994) and reduced functional fertility in subadult males could possibly explain the results of our study. However, in Bullock’s orioles some subadults did not lose any paternity in their own broods and the number of offspring fledged from these broods was no lower than from broods with mixed paternity.…”

Section: Discussionsupporting

confidence: 53%

Extra‐pair paternity in relation to male age in Bullock’s orioles

1999

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Single-locus minisatellite DNA profiling was used to assign paternity in a population of Bullock's orioles, Icterus galbula bullockii, and to determine the contribution of age to a male's success in obtaining extra-pair paternity. There was a very low rate of intraspecific brood parasitism (2/202 = 1.0% of chicks). Older adult males lost less within-pair paternity and gained more extra-pair fertilizations than did yearling subadult males. This resulted in adult males benefiting from an annual reproductive success more than double that of subadult males. Behavioural observations, used to determine the role of female choice in extra-pair copulations (EPCs), indicated that females actively participate in EPCs and that they prefer to obtain them from older males. While it was possible that females obtained EPCs as an insurance against the possible infertility of their social mate, the results of this study fit best with the hypothesis that females were attempting to obtain better-quality genes for their offspring by obtaining EPCs with older, better-quality males.

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Section: Discussionsupporting

confidence: 53%

Extra‐pair paternity in relation to male age in Bullock’s orioles

1999

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“…It is possible that females seek or prefer older males as extra-pair copulation partners since age may be an indicator of quality (see references in Introduction), but it is also possible that older males are relatively more successful than younger males independent of their attractiveness to females, if they transfer more sperm, as a consequence of their larger testes and larger volumes of stored sperm in their seminal glomera (e.g. Hilton 1968). …”

Section: Mechanisms Of Sperm Competitionmentioning

confidence: 99%

Post-copulatory sexual selection and the Zebra Finch

Birkhead

2010

Emu - Austral Ornithology

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“…Bailey 1953;Hilton 1968;Middleton 1972;Wolfson 1952Wolfson , 1954a, the functional significance of interspecific variation in the relative size of the cloacal protuberance has not previously been considered. We consider the following hypotheses :…”

Section: Introductionmentioning

confidence: 99%

Male sperm reserves and copulation frequency in birds

Birkhead

Briskie

Møller

1993

Behav Ecol Sociobiol

105

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Male passerine birds store sperm in a cloacal protuberance during the breeding season. We consider three hypotheses to explain interspecific variation in relative cloacal protuberance size. The copulation efficiency hypothesis states that a relatively large cloacal protuberance facilitates sperm transfer and predicts more rapid copulation in species with larger protuberances. There is insufficient data to test this idea rigorously, but we found no evidence for such an effect. The spermatozoa size hypothesis is a non-functional hypothesis which states that cloacal protuberance size is merely a consequence of sperm size, and predicts that species with larger spermatozoa have relatively larger cloacal protuberances. Sperm length was positively correlated with protuberance size, providing support for this hypothesis, although it seems unlikely that variation in sperm size alone is sufficient to account for variation in protuberance size because the numbers of sperm stored in the cloacal protuberance were also positively correlated with its size. The sperm competition hypothesis states that the cloacal protuberance is a sperm store and predicts that when sperm competition is intense, as measured by male copulation frequency and or mating system, males will have relatively large protuberances and testes mass. The sperm competition hypothesis was supported: in a comparative study in which we controlled for phylogenetic effects, relative cloacal protuberance size was significantly and positively correlated with copulation frequency. Across all mating systems protuberance size was also positively correlated with the mass of seminal glomera tissue, the number of sperm stored in the seminal glomera, and with relative testes size. These results suggest that where sperm competition is intense, a large cloacal protuberance is required to maintain a large sperm reserve for a high copulation rate.

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Endocrine Control of Seminal-Glomus Growth and Function in Starlings of Different Ages

Cited by 13 publications

References 4 publications

Extra‐pair paternity in relation to male age in Bullock’s orioles

Extra‐pair paternity in relation to male age in Bullock’s orioles

Post-copulatory sexual selection and the Zebra Finch

Male sperm reserves and copulation frequency in birds

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