Adaptation of gastrointestinal nematode parasites to host genotype: single locus simulation models

Table 4 The regression of replicate mean WEC on time for flocks in Scenario 5

Mechanism of the A allele	Frequency of the A allele (x)	Flock average WEC (epg)		Regression coefficient (epg/yr)		∆p
Mechanism of the A allele	Frequency of the A allele (x)	Year 1	Year 20	Estimate	s.e.	∆p
E	0.0	710	710	0.72	0.87
E	0.1	640	670	3.21	0.80	Decrease
E	0.2	540	510	−1.07	0.58
E	0.3	470	500	2.08	0.50	Decrease
E	0.4	380	430	1.16	0.45
E	0.5	340	340	−0.17	0.50
E	0.6	290	300	0.39	0.36
E	0.7	250	260	1.02	0.37
E	0.8	210	230	1.62	0.26	Increase
E	0.9	180	220	1.83	0.18	Increase
E	1.0	140	190	2.54	0.20	Increase
M	0.0	720	800	2.94	0.56	Decrease
M	0.1	640	650	1.22	0.65
M	0.2	580	620	2.39	0.66
M	0.3	500	480	−0.08	0.62
M	0.4	440	440	−0.89	0.54
M	0.5	370	370	−1.40	0.43
M	0.6	340	350	1.81	0.39	Increase
M	0.7	290	310	1.07	0.27	Increase
M	0.8	260	320	3.62	0.24	Increase
M	0.9	220	300	4.35	0.30	Increase
M	1.0	180	290	5.53	0.29	Increase
F	0.0	720	800	2.94	0.56	Decrease
F	0.1	660	660	0.10	0.80
F	0.2	570	540	−1.13	0.58
F	0.3	480	520	4.02	0.63	Decrease
F	0.4	410	430	−0.52	0.53
F	0.5	360	340	0.08	0.53
F	0.6	310	320	−0.69	0.47
F	0.7	250	240	−0.33	0.45
F	0.8	230	210	0.55	0.37
F	0.9	180	170	−0.30	0.29
F	1.0	140	170	0.99	0.16	Increase

Postulated mechanisms to reduce WEC in sheep through the ‘resistance’ A allele: E = reduced worm establishment, M = increased worm mortality and F = reduced female worm fecundity; epg = eggs per gram; s_h = 25%; s_p = 10%; bold characters = coefficients significantly different to zero (P < 0.001) with the directional change in frequency for the alternate B allele in worms (∆p).

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