Table 3

Fixed effects of general and generalized linear models for infection levels in eight Tropheus populations
Infection presence Abundance Infection intensity
Parasite group Effect Num DF Den DF F P F P F P
Acanthocephalans site 7 605/483 9.01 < 0.0001 23.46 < 0.0001 11.92 < 0.0001
day 2 605/483 0.76 0.4673 1.02 0.3622 01.25 0.2886
sex 1 605/483 0.01 0.9100 0.04 0.8484 0.04 0.8351
SL 1 605/483 12.62 0.0004 57.06 < 0.0001 47.92 < 0.0001
year(site) 6 605/483 5.02 < 0.0001 7.57 < 0.0001 5.02 < 0.0001
Nematodes site 7 605/47 2.38 0.0210 2.64 0.0106 1.32 0.2640
day 2 605/47 0.63 0.5336 0.78 0.4591 2.41 0.1005
sex 1 605/47 1.09 0.2974 1.36 0.2434 1.17 0.2843
SL 1 605/47 0.10 0.7557 0.05 0.8185 1.39 0.2436
year(site) 6 605/47 0.89 0.5011 2.19 0.0428 0.74 0.6009
Gyrodactylus site 7 616/24 3.95 0.0003 5.47 < 0.0001 0.83 0.5692
day 2 616/24 0.90 0.4091 0.37 0.6927 4.88 0.0167
sex 1 616/24 0.30 0.5811 0.09 0.7607 1.16 0.2926
SL 1 616/24 0.26 0.6093 0.27 0.6016 1.25 0.2751
. year(site) 6 616/24 0.35 0.9071 0.60 0.7344 0.93 0.4933
Cichlidogyrus site 7 476/418 2.85 0.0064 18.85 < 0.0001 15.14 < 0.0001
day 2 476/418 2.80 0.0617 5.50 0.0043 2.54 0.0803
sex 1 476/418 3.62 0.0578 7.58 0.0061 4.00 0.0462
SL 1 476/418 6.60 0.0105 77.90 < 0.0001 74.38 < 0.0001
year(site) 6 476/418 2.80 0.0108 3.68 0.0014 1.73 0.1131
Ergasilus site 7 476/158 1.73 0.1001 2.40 0.0201 1.86 0.0792
day 2 476/158 0.70 0.4984 0.14 0.8729 1.36 0.2602
sex 1 476/158 0.15 0.6978 0.10 0.7479 0.00 0.9537
SL 1 476/158 0.58 0.4485 3.28 0.0708 5.30 0.0227
year(site) 6 476/158 0.70 0.6489 0.55 0.7696 0.23 0.9667

Fixed effects included sampling site, processing day, sex, standard length (SL), and sampling year (nested in site). Observer effects were included as random (not shown), except for Gyrodactylus sp. for which there was only one observer. The model for infection presence assumes a binomial distribution and models the logit of the probability of infection. For the models for abundance and infection intensity, the dependent variable was square-root transformed. Note that the denominator degrees of freedom (Den DF) are higher for the infection presence and abundance model (before the dash) than for the infection intensity model (after the dash). P-values in bold indicate significance at α = 0.05.

Raeymaekers et al.

Raeymaekers et al. BMC Evolutionary Biology 2013 13:41   doi:10.1186/1471-2148-13-41

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