Ecological Archives E091-052-A1

**Eric W. Seabloom, Elizabeth T. Borer, Charles E. Mitchell, and Alison G. Power. 2010. Viral diversity and prevalence gradients in North American Pacific Coast grasslands. Ecology 91:721–732.**

Appendix A. Tables showing provenance, lifespan, and pathogen interactions of the monitored hosts; site locations, precipitation, soil nitrate, overall viral prevalence, and viruses per host averaged across three host species of four barley and cereal yellow dwarf viruses in 26 Pacific Coast grasslands; among-host comparisons in prevalence and viral species diversity in infected hosts; environmental drivers of prevalence and viral species diversity averaged across three host species; and effects of soil nitrogen on prevalence and viral species diversity averaged across three host species.

TABLE A1. Provenance, lifespan, and pathogen interactions of the monitored hosts. All hosts are from the subfamily Pooideae.


	Avena Fatua	Bromus hordeaceus	Elymus glaucus

Life span	Annual	Annual	Perennial
Provenance	Exotic	Exotic	Native
Vector fecundity (aphids day^-1) ^a	1.08	1.03	0.52
Vector preference (aphids g^-1 of host) ^b	14.41	17.86	2.62
Pathogen-induced reduction in fecundity ^c	0.41	0.39	0.23
Pathogen-induced reduction in among-year survival ^d	NA	NA	0.12
Tribe within the Poaceae	Poeae	Bromeae	Hordeinae

^a Aphid production based on experimental out-plants (Borer et al. 2009). ^b Aphid density in foraging preference trials adjusted for host size (grams of dry tissue) (Borer et al. 2009). ^c Reduction in fecundity in inoculated plants (C. E. Mitchell, unpublished data). ^d Increase in among-year mortality in inoculated plants (Malmstrom et al. 2005, Borer et al. 2007)

TABLE A2. Site locations, precipitation, soil nitrate, overall viral prevalence, and viruses per host average across three host species of four barley and cereal yellow dwarf viruses in 26 Pacific Coast grasslands.
Prevalence and species diversity are averaged across three host grasses: Avena fatua, Bromus hordeaceus, and Elymus glaucus.


State/ Province	County	Reserve	Site	Overall infection proportion	Viral species per host	Latitude	Longitude	2006 precipitation (mm)	Soil nitrate (ppm)

British Columbia	Vancouver Island	NA	Cowichan Annual	0.300	2.167	48.810	-122.369	1285	NA
British Columbia	Vancouver Island	NA	Cowichan Perennial	0.050	3.000	48.810	-122.369	1285	NA
Oregon	Polk	Baskett Slough	Smithfield Rd.	0.200	1.500	44.962	-122.738	1448	10
Oregon	Polk	Baskett Slough	Baskett Butte	0.105	2.500	44.962	-122.738	1448	10
Oregon	Benton	W. L. Finley	Bruce Rd.	0.350	2.286	44.421	-122.676	1094	10
Oregon	Benton	W. L. Finley	Quarry	0.700	2.071	44.421	-122.676	1094	10
Oregon	Benton	W. L. Finley	Pigeon Butte	0.250	2.200	44.421	-122.676	1094	10
Oregon	Benton	Fort Hoskins	Collins	0.475	1.786	44.408	-122.722	1094	10
Oregon	Linn	Horserock Ridge	IAE	0.100	1.500	44.107	-122.926	1504	NA
California	Yuba	Sierra Foothill	Koch Rd6	0.000	NA	39.294	-121.288	1001	2
California	Yuba	Sierra Foothill	Koch K6	0.100	1.000	39.285	-121.289	1001	5
California	Yuba	Sierra Foothill	Camp	0.143	1.500	39.256	-121.280	1001	6
California	Mendocino	Hopland	Riley	0.050	1.500	39.015	-123.060	1029	2
California	Mendocino	Hopland	Foster	0.000	NA	39.003	-123.090	1029	1
California	Mendocino	Hopland	Lake	0.050	1.000	38.995	-123.070	1382	2
California	Yolo	McLaughlin	Reservoir	0.050	1.333	38.857	-122.362	1067	2
California	Yolo	McLaughlin	Middle	0.033	1.000	38.853	-122.366	1067	2
California	Napa	McLaughlin	Mine Pit	0.050	2.000	38.842	-122.356	1067	4
California	Monterey	Hastings	Native	0.150	1.800	36.387	-121.554	627	3
California	Monterey	Hastings	Schoolhouse	0.150	1.611	36.385	-121.548	627	2
California	Monterey	Hastings	Martin Road	0.150	2.000	36.379	-121.549	627	3
California	Santa Barbara	Sedgwick	Figueroa	0.509	1.444	34.718	-120.050	434	6
California	Santa Barbara	Sedgwick	Lisque	0.500	1.178	34.718	-120.050	434	8
California	Santa Barbara	Sedgwick	Middle	0.217	1.254	34.718	-120.050	434	8
California	Orange	Irvine Ranch	Irvine Annual	0.451	1.429	33.751	-117.683	224	10
California	Orange	Irvine Ranch	Irvine Perennial	0.250	1.286	33.751	-117.683	224	10

TABLE A3. Among host comparisons in prevalence and viral species diversity in infected hosts. The final model includes only significant terms based on backwards selection^a.


Response	Source	Estimate	Std. Error	t value	P

Prevalence (df = 49)	Intercept	-12.669	2.811	-4.506	0.000
	Avena vs. Bromus hosts	0.924	0.306	3.020	0.004
	Perennial vs. annual hosts	0.245	0.159	1.544	0.130
	Latitude (degrees)	0.411	0.093	4.408	0.000
	Precipitation in 2006 (mm)	-0.005	0.001	-5.021	0.000
	Avena × Peren. Grass Cover	-0.051	0.032	-1.591	0.119
	Bromus × Peren. Grass Cover	0.044	0.019	2.270	0.028
	Elymus × Peren. Grass Cover	-0.029	0.015	-1.943	0.059
α diversity (strains per host; df = 40)	Intercept	-0.977	0.433	-2.257	0.030
	Latitude (degrees)	0.037	0.011	3.396	0.002

^aTotal aboveground biomass, host richness, cover of non-hosts, and cover of perennial grasses were included in the full model, but were not significant in any final models. Nonsignificant contrasts were left in the final model if one of the contrasts was significant.

TABLE A4. Environmental drivers of prevalence and viral species diversity (α, β, and γ) averaged across three host species. The final model includes only significant terms based on backwards selection^a.


Response	Source	Estimate	Std. Error	t value	P

Prevalence (df = 25)	Intercept	-10.375	2.532	-4.097	0.000
	Latitude (degrees)	0.337	0.085	3.989	0.001
	Precipitation in 2006 (mm)	-0.005	0.001	-4.562	0.000
α diversity (viruses per host; df = 23)	Intercept	-2.049	0.499	-4.108	0.001
	Latitude (degrees)	0.076	0.016	4.732	0.000
	Precipitation in 2006 (mm)	-0.001	0.000	-2.511	0.020
β diversity (a/g; df = 23)	Intercept	2.454	0.497	4.942	0.000
	Latitude (degrees)	-0.046	0.013	-3.661	0.001
γ diversity (viruses per site; df = 23)	Intercept	1.099	0.060	18.250	0.000

^aTotal aboveground biomass, host richness, cover of non-hosts, and cover of perennial grasses were included in the full model, but were not significant in any final models. Nonsignificant contrasts were left in the final model if one of the contrasts was significant.

TABLE A5. Effects of soil nitrogen (nitrate) on prevalence and viral species diversity (α, β, and γ) averaged across three host species.
Nitrate data were missing at three sites, and so were not included in the full regression models in Tables A3 and A4.


Response	Source	Estimate	Std. Error	t value	P

Prevalence (df = 22)	Intercept	-2.761	0.438	-6.306	0.000
	Soil nitrate (ppm)	0.233	0.059	3.932	0.001
α diversity (viruses per host; df = 20)	Intercept	0.270	0.127	2.131	0.046
	Soil nitrate (ppm)	0.031	0.017	1.830	0.083
β diversity (α/γ; df = 20)	Intercept	0.669	0.157	4.263	0.000
	Soil nitrate (ppm)	0.001	0.022	0.030	0.976
γ diversity (viruses per site; df = 20)	Intercept	0.983	0.148	6.650	0.000
	Soil nitrate (ppm)	0.02044	0.02007	1.019	0.321

LITERATURE CITED

Borer, E. T., V. Adams, G. A. Engler, A. Adams, C. Schumann, and E. W. Seabloom. 2009. Responses by aphid-vectors of a generalist viral pathogen to host life history, provenance, and nutrition. Ecological Applications 19:1187–1196.

Borer, E. T., P. R. Hosseini, E. W. Seabloom, and A. P. Dobson. 2007. Pathogen-induced reversal of native dominance in a grassland community. Proceedings of the National Academy of Sciences of the United States of America 104:5473–5478.

Malmstrom, C. M., C. C. Hughes, L. A. Newton, and C. J. Stoner. 2005. Virus infection in remnant native bunchgrasses from invaded California grasslands. New Phytologist 168:217–230.

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