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Hit or Miss: Fertilization Outcomes of Natural Inseminations by Japanese Quail.

Adkins-Regan E - PLoS ONE (2015)

Bottom Line: Variation in fertilization success underlies sexual selection, yet mating does not guarantee fertilization.Both sexes gained similar numbers of fertilized eggs by mating with a second partner the next day, but males, unlike females in a previous study, did not gain by having two females to mate with at the same time.Even double inseminations often failed to fertilize any eggs, and multiple matings would be needed for an entire clutch to be fertilized with high certainty.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
Variation in fertilization success underlies sexual selection, yet mating does not guarantee fertilization. The relationship between natural inseminations and fertilization success is essential for understanding sexual selection, yet that relationship and its underlying mechanisms are poorly understood in sperm-storing vertebrates such as birds. Here the relationship is analyzed in mating trials using Japanese quail (Coturnix japonica), which show striking variation in the fertilizing success of inseminations. Failures of males' inseminations to fertilize eggs were mainly due to failures prior to sperm-egg contact. Fertilization probabilities on any given day were unrelated to whether the female had laid an egg the previous day, arguing against stimulation of sperm release from sperm storage tubules by the events of the daily egg-laying cycle. Instead, an unfertilized egg laid between two fertilized eggs predicted a longer sperm storage interval. Both sexes gained similar numbers of fertilized eggs by mating with a second partner the next day, but males, unlike females in a previous study, did not gain by having two females to mate with at the same time. Instead, they were both behaviorally and sperm limited, whereas females gain by mating twice in quick succession. Even double inseminations often failed to fertilize any eggs, and multiple matings would be needed for an entire clutch to be fertilized with high certainty. Paradoxically, this low and probabilistic fertilization success co-occurs with other notable characteristics of male quail suggestive of past sexual selection for increased success, including vigorous copulatory behavior, forced copulations, foamy secretion aiding in sperm competition, large testes and unusual sperm morphology.

No MeSH data available.


Related in: MedlinePlus

Experiment 2.The day in the laying sequence when the last fertilized egg was laid for trials/females with or without a fertilization gap on day 2 or later in the sequence. The box plots show the median, lower and upper quartiles and range. N = 37 trials for no fertilization gap, 10 for an unfertilized egg on day 2 and 35 for an unfertilized egg between days 3–10. ** p < 0.005 compared with trials with no fertilization gap.
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pone.0131786.g004: Experiment 2.The day in the laying sequence when the last fertilized egg was laid for trials/females with or without a fertilization gap on day 2 or later in the sequence. The box plots show the median, lower and upper quartiles and range. N = 37 trials for no fertilization gap, 10 for an unfertilized egg on day 2 and 35 for an unfertilized egg between days 3–10. ** p < 0.005 compared with trials with no fertilization gap.

Mentions: A fertilization gap after fertilization had begun occurred in 44 (43%) of the trials. In another 11 trials, the first fertilized egg occurred on day 3 or later instead of day 2, creating another kind of fertilization gap. Three of those contained a fertilization gap later in the sequence as well. One female laid her only fertilized egg on day 6. Taken together, 50% of the trials produced some kind of fertilization gap. Fig 4 shows the last fertilized egg days for trials with and without a fertilization gap. The results are shown separately for cases where the gap occurred at the beginning of the sequence (i. e., a delayed start to fertilization, as in the second row of Fig 2) and those where fertilization began but a gap appeared later in the sequence (as in the third row of Fig 2). There was no statistically significant difference in the last fertilized egg day between trials with a day 2 gap and trials with no gap (Mann-Whitney U = 181, p = 0.93), but the last egg day was significantly later for trials with a gap after day 2 than for trials with no gap (U = 367, p = 0.0016).


Hit or Miss: Fertilization Outcomes of Natural Inseminations by Japanese Quail.

Adkins-Regan E - PLoS ONE (2015)

Experiment 2.The day in the laying sequence when the last fertilized egg was laid for trials/females with or without a fertilization gap on day 2 or later in the sequence. The box plots show the median, lower and upper quartiles and range. N = 37 trials for no fertilization gap, 10 for an unfertilized egg on day 2 and 35 for an unfertilized egg between days 3–10. ** p < 0.005 compared with trials with no fertilization gap.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519265&req=5

pone.0131786.g004: Experiment 2.The day in the laying sequence when the last fertilized egg was laid for trials/females with or without a fertilization gap on day 2 or later in the sequence. The box plots show the median, lower and upper quartiles and range. N = 37 trials for no fertilization gap, 10 for an unfertilized egg on day 2 and 35 for an unfertilized egg between days 3–10. ** p < 0.005 compared with trials with no fertilization gap.
Mentions: A fertilization gap after fertilization had begun occurred in 44 (43%) of the trials. In another 11 trials, the first fertilized egg occurred on day 3 or later instead of day 2, creating another kind of fertilization gap. Three of those contained a fertilization gap later in the sequence as well. One female laid her only fertilized egg on day 6. Taken together, 50% of the trials produced some kind of fertilization gap. Fig 4 shows the last fertilized egg days for trials with and without a fertilization gap. The results are shown separately for cases where the gap occurred at the beginning of the sequence (i. e., a delayed start to fertilization, as in the second row of Fig 2) and those where fertilization began but a gap appeared later in the sequence (as in the third row of Fig 2). There was no statistically significant difference in the last fertilized egg day between trials with a day 2 gap and trials with no gap (Mann-Whitney U = 181, p = 0.93), but the last egg day was significantly later for trials with a gap after day 2 than for trials with no gap (U = 367, p = 0.0016).

Bottom Line: Variation in fertilization success underlies sexual selection, yet mating does not guarantee fertilization.Both sexes gained similar numbers of fertilized eggs by mating with a second partner the next day, but males, unlike females in a previous study, did not gain by having two females to mate with at the same time.Even double inseminations often failed to fertilize any eggs, and multiple matings would be needed for an entire clutch to be fertilized with high certainty.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
Variation in fertilization success underlies sexual selection, yet mating does not guarantee fertilization. The relationship between natural inseminations and fertilization success is essential for understanding sexual selection, yet that relationship and its underlying mechanisms are poorly understood in sperm-storing vertebrates such as birds. Here the relationship is analyzed in mating trials using Japanese quail (Coturnix japonica), which show striking variation in the fertilizing success of inseminations. Failures of males' inseminations to fertilize eggs were mainly due to failures prior to sperm-egg contact. Fertilization probabilities on any given day were unrelated to whether the female had laid an egg the previous day, arguing against stimulation of sperm release from sperm storage tubules by the events of the daily egg-laying cycle. Instead, an unfertilized egg laid between two fertilized eggs predicted a longer sperm storage interval. Both sexes gained similar numbers of fertilized eggs by mating with a second partner the next day, but males, unlike females in a previous study, did not gain by having two females to mate with at the same time. Instead, they were both behaviorally and sperm limited, whereas females gain by mating twice in quick succession. Even double inseminations often failed to fertilize any eggs, and multiple matings would be needed for an entire clutch to be fertilized with high certainty. Paradoxically, this low and probabilistic fertilization success co-occurs with other notable characteristics of male quail suggestive of past sexual selection for increased success, including vigorous copulatory behavior, forced copulations, foamy secretion aiding in sperm competition, large testes and unusual sperm morphology.

No MeSH data available.


Related in: MedlinePlus