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Table 5 Model selection table for different models testing the relationship between male competitive ability and fertilization success (sperm traits)

From: Competitive males have higher quality sperm in a monogamous social bee

Selection episode N. obs Response Starting model Fixed effect removed Degrees of freedom χ2 P-value
Colony - Aggregation 47 Sperm viability sampling site*days in incubator interaction 1 0.05 0.82
sampling site + days in incubator sampling site 1 0.29 0.59
sampling site + days in incubator days in incubator 1 0.004 0.95
sampling site sampling site 1 1.82 0.18
days in incubator days in incubator 1 1.54 0.21
1070 Sperm length sampling site sampling site 1 0.01 0.91
107 Sperm length variation sampling site sampling site 1 0.12 0.73
Persistence time in the aggregation 60 Sperm viability days at aggregation days at aggregation 2 7.28 0.03
90 Sperm number days at aggregation days at aggregation 2 3.77 0.15
609 Sperm length days at aggregation days at aggregation 2 12.70 <0.01
61 Sperm length variation days at aggregation days at aggregation 2 16.07 <0.001
  1. The p-values and degrees of freedom refer to Likelihood Ratio Tests (using a χ2 test statistic), in which the full model was compared to a reduced model without each of the predictor variables. Parameters estimates of best models are presented in Table 5