Article

Senescent sperm performance in old male birds.

CNRS, UMR 7103, Laboratoire de Parasitologie Evolutive, Université Pierre et Marie Curie, Paris Cedex, France.
Journal of Evolutionary Biology (impact factor: 3.28). 12/2008; 22(2):334-44. DOI:10.1111/j.1420-9101.2008.01650.x pp.334-44
Source: PubMed

ABSTRACT Senescence is the deterioration of the phenotype with age caused by negative effects of mutations acting late in life or the physiological deterioration of vital processes. Birds have traditionally been assumed to senescence slowly despite their high metabolic rates, high blood sugar levels and high body temperature. Here we investigate the patterns of age-related performance of sperm of a long distance migrant, the barn swallow Hirundo rustica, varying in age from 1 to 6 years, analysed by the computer-assisted sperm analysis equipment. Sperm showed deteriorating performance in terms of linear movement, track velocity, straight line velocity and reduced proportions of rapidly moving, progressive and motile sperm with age. In a second series of experiments, we assessed performance of sperm from the same males in neutral medium and in medium derived from the reproductive tract of females in an attempt to test if sperm of old males performed relatively better in female medium, as expected from extra-pair paternity being negatively related to male age, but not to female age. Older males showed consistently better performance in female medium than in neutral medium in terms of track velocity, straight line velocity and reduced proportions of rapidly moving, progressive and motile sperm, whereas young males showed better performance in neutral medium. These results provide evidence of declining sperm performance for important reproductive variables not only with age, but also with the sperm of old males performing differentially better in female medium than young males.

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Keywords

6 years
 
age-related performance
 
blood sugar levels
 
body temperature
 
computer-assisted sperm analysis equipment
 
female age
 
female medium
 
females
 
Hirundo rustica
 
line velocity
 
male age
 
metabolic rates
 
motile sperm
 
negative effects
 
old males
 
Older males
 
reproductive tract
 
sperm performance
 
track velocity
 
young males