Ecological Archives E088-076-A4

Ingrid M. Parker and Gregory S. Gilbert. 2007. When there is no escape: the effects of natural enemies on native, invasive, and noninvasive plants. Ecology 88:1210–1224.

Appendix D. Results of hypothesis testing: tables of F statistics, P values, and aditional analyses described in the text.

Included here are the following sections: (1) Table D1. Comparisons of levels of endophyte infection for native vs. nonnative species, and invasive vs. noninvasive introduced species, (2) Table D2. Comparisons of the prevalence of disease symptoms for native vs. nonnative species, and invasive vs. noninvasive introduced species, (3) Table D3. Comparisons of the prevalence of damage by herbivores for native vs. nonnative species, and invasive vs. noninvasive introduced species, (4) Table D4. Means and Standard Deviations for severity of leaf damage from disease and herbivory over multiple censuses in Years 1 and 2, (5) Table D5. Statistics for disease and herbivory severity, (6) Table D6. Results of logistic regression models for each species, predicting mortality after 2 weeks from prevalence of herbivory, prevalence of disease, and number of leaves, and (7) Why we did not use severity instead of prevalence for logistic regressions.

TABLE D1. Comparisons of levels of endophyte infection for native vs. nonnative species, and invasive vs. noninvasive introduced species. Nonparametric tests and tests done on transformed data produced results similar to those presented here (usually with less significant P values). There was one exception: analysis of arcsine-square root transformed data in Year 1 suggested that invasive, introduced clovers experienced significantly higher infection than noninvasive, introduced clovers (t = 2.7, P = 0.043). Years were not combined into a single analysis because species are not independent among years. Repeated-measures analysis was not used because the identity of species used varied slightly from year to year. No adjustments were made for multiple comparisons because differences were already nonsignificant.

 

Native vs. introduced

Invasive vs. noninvasive

 

t

df

P

t

df

P

Year 1

0.84

14

0.42

2.22

5

0.08

Year 2

1.89

15

0.08

1.53

6

0.18

Year 3

1.11

13

0.29

1.25

5

0.27

Year 4

0.80

15

0.43

1.40

6

0.21


TABLE D2. Comparisons of disease prevalence for native vs. nonnative species, and invasive vs. noninvasive introduced species. In Years 3 and 4, prevalence (proportion of population showing symptomatic damage) was assessed only at harvest, but in Years 1 and 2, we used an integrated measure of cumulative incidence (area under the disease progress curve, AUDPC). We performed t tests assuming unequal variances; because of this and because different groups of species were used in different years, degrees of freedom differ among tests.

 

Native vs. introduced

Invasive vs. noninvasive

 

t

df

P

t

df

P

Year 1

1.16

8

0.28

6.85

4

0.002

Year 2

0.29

9

0.78

22.42

5

0.00001

Year 3

0.16

9

0.88

9.21

5

0.0002

Year 4

0.66

14

0.52

2.06

5

0.094


TABLE D3. Comparisons of the prevalence of damage by herbivores for native vs. nonnative species, and invasive vs. noninvasive introduced species. In Years 3 and 4, prevalence (proportion of population showing herbivore damage) was assessed only at harvest, but in Years 1 and 2, we used an integrated measure of cumulative incidence (area under the damage progress curve, AUDPC). We performed t tests assuming unequal variances; because of this and because different groups of species were used in different years, degrees of freedom differ among tests.

 

Native vs. introduced

Invasive vs. noninvasive

 

t

df

P

t

df

P

Year 1

3.14

7

0.016

1.15

4

0.31

Year 2

6.27

10

0.00009

2.16

5

0.083

Year 3

0.75

13

0.47

2.83

5

0.037

Year 4

1.57

11

0.14

0.19

1

0.88



TABLE D4. Means and standard deviations for severity of leaf damage from disease and herbivory in Years 1 and 2. Means were calculated by taking the mean of three leaves per plant, and then the means of all plants within each species. Reported are the grand means and standard deviations of those species means. Sample sizes per species and number of species per category are given in Table A2 (Appendix A).

Disease Year 1

     

Census

Native

Introduced

NonInvasive

Invasive

8-Mar

3.09±2.4

5.68±2.16

5.01±2.2

7.34±0.91

21-Mar

2.41±2.16

4.76±4.44

4.81±5.44

4.63±0.12

3-Apr

1.43±1.22

4.63±2.53

4.82±2.95

4.16±1.73

17-Apr

3.83±2.09

5.32±6.12

4.67±7.13

6.94±3.74

16-May

2.24±1.76

3.88±3.24

2.07±1.07

8.4±1.16

         

Herbivory Year 1

     

Census

Native

Introduced

NonInvasive

Invasive

8-Mar

13.8±4.34

8.39±6.27

10.58±6.18

2.94±0.16

21-Mar

13.55±4.15

7.44±5.74

8.97±6.26

3.63±0.1

3-Apr

11.86±2.83

6.54±4.29

7.61±4.75

3.85±0.54

17-Apr

11.81±3.64

3.86±2.74

4.3±3.22

2.76±0.22

16-May

12.68±4.91

3.63±2.68

4.15±3.06

2.31±0.97

Disease Year 2

     

Census

Native

Introduced

NonInvasive

Invasive

21-Mar

0.36±0.69

1.05±1.32

0.6±0.58

2.41±2.38

24-Apr

0.68±0.67

1.28±1.68

0.66±1.01

3.13±2.36

21-May

2.42±2.38

1.77±1.8

1.72±1.93

1.92±2.01

         

Herbivory Year 2

     

Census

Native

Introduced

NonInvasive

Invasive

21-Mar

3.28±2.52

2.84±3.6

3.44±4.03

1.02±0.86

24-Apr

4.57±2.92

2.48±2.23

2.24±2.32

3.19±2.6

21-May

2.79±1.87

2.19±3.38

2.62±3.86

0.91±0.86



TABLE D5. Statistics for disease and herbivory severity. Repeated-measures ANOVA was calculated for Years 1 and 2, using the asin√(proportion leaf area) affected by any disease or any herbivore, using only those leaves that were alive at the time of the census. There were five severity censuses in Year 1 and three censuses in Year 2, with seven blocks each year. The analysis was a repeated-measures analysis across the censuses, treating the mean disease per plant (from the mean of all leaves) as the experimental unit, and then nesting species within origin or invasiveness, and including a block term [Block Type Species(Type)]. For Years 3 and 4, two-factor factorial ANOVA was calculated using asin√(proportion leaf area). Separate analyses were done for Native vs. Introduced (“Type” = Origin) and Invasive vs. Noninvasive within the introduced species (“Type” = Invasiveness).

Year1

 

Native vs. introduced

Invasive vs. noninvasive

Test

Damage

Exact F

df

P

Exact F

df

P

Type

Disease

16.8736

1,157

0.0001

28.3536

1,66

0.0001

Species(Type)

Disease

5.4307

14,157

0.0001

3.8028

5,66

0.0044

Time

Disease

0.8747

4,154

0.4806

1.0249

4,63

0.4014

Block

Disease

1.4297

6,157

0.2065

0.4653

6,66

0.8315

Time × Type

Disease

1.0305

4,154

0.3934

2.4217

4,63

0.0574

Type

Herbivory

66.0271

1,157

0.0001

1.6596

1,66

0.2022

Species(Type)

Herbivory

3.9106

14,157

0.0001

6.5925

5,66

0.0001

Time

Herbivory

1.0570

4,154

0.3799

1.6131

4,63

0.182

Block

Herbivory

1.8109

6,157

0.1002

2.1959

6,66

0.0543

Time × Type

Herbivory

1.9098

4,154

0.1115

1.8340

4,63

0.1334

Year2

 

Native vs. introduced

Invasive vs. noninvasive

Test

Damage

Exact F

df

P

Exact F

df

P

Type

Disease

1.3611

1,49

0.249

5.3180

1,15

0.0358

Species(Type)

Disease

2.4633

16,49

0.008

1.9423

6,15

0.1391

Time

Disease

4.4290

2,48

0.0172

0.4842

2,14

0.6262

Block

Disease

0.9401

6,49

0.4752

0.4882

6,15

0.8072

Time × Type

Disease

1.6413

2,48

0.2044

3.0991

2,14

0.0769

Type

Herbivory

13.3410

1,49

0.0006

1.4344

1,15

0.2496

Species(Type)

Herbivory

1.2469

16,49

0.2689

0.9851

6,15

0.4691

Time

Herbivory

1.4272

2,48

0.25

0.6258

2,14

0.5492

Block

Herbivory

1.3115

6,49

0.2699

1.5328

6,15

0.2342

Time × Type

Hebivory

2.3849

2,48

0.1029

3.6962

2,14

0.0514


Table D5 continued.

               

Year3

 

Native vs. introduced

Invasive vs. noninvasive

Test

Damage

Exact F

df

P

Exact F

df

P

Type

Disease

1.2070

1,14

0.2751

20.8161

1,6

0.0001

Species(Type)

Disease

0.7565

14,84

0.7118

2.0284

6,43

0.0825

Type

Herbivory

1.2985

1,14

0.2577

3.0549

1,6

0.0876

Species(Type)

Herbivory

2.6006

14,84

0.0036

3.4711

6,43

0.0069

               

Year4

 

Native vs. introduced

Invasive vs. noninvasive

Test

Damage

Exact F

df

P

Exact F

df

P

Type

Disease

0.0111

1,15

0.9165

6.6009

1,6

0.0144

Species(Type)

Disease

1.6793

15,79

0.0724

1.3346

6,37

0.2667

Type

Herbivory

1.6451

1,15

0.2034

1.3039

1,6

0.2608

Species(Type)

Herbivory

1.0782

15,79

0.3897

0.9265

6,37

0.4874



TABLE D6. Results of logistic regression models for each species, predicting mortality after two weeks from prevalence of herbivory, prevalence of disease, and number of leaves. These model coefficients were then used to test for differences in the effects of disease or herbivory on mortality for plants of different origin (Table 3). Models fits were unstable for the following: Year 1: M. arabica, T. subterraneum; Year 2: T. glomeratum, T. willdenovii, T. wormskjoldii. Bold indicates species that are invasive in the Bodega Marine Reserve.

   

chisquare (P value)

Model coefficients

 

Origin

Species

Whole Model

Herbivory

Disease

Leaves

Intercept

Herbivory

Disease

Leaves

N

Year 1

                   

Intro

M. polymorpha

2.6 (0.455)

0.1 (0.794)

1.2 (0.277)

0.2 (0.627)

-3.729

0.105

-0.490

-0.031

341

Intro

T. campestre

12.9 (0.005)

0.7 (0.41)

0.1 (0.8)

5.0 (0.026)

-1.775

-0.338

-0.137

-0.455

370

Intro

T. dubium

16.5 (0.0009)

3.8 (0.05)

1.7 (0.19)

6.5 (0.01)

-1.232

0.572

0.472

-0.320

362

Intro

T. glomeratum

27.9 (0.0001)

2.2 (0.137)

0.6 (0.439)

17.6 (0.0001)

-0.423

-0.371

0.242

-0.920

299

Intro

T. repens

15.5 (0.001)

0.2 (0.681)

3.3 (0.0694)

10.2 (0.001)

-0.619

0.103

0.509

-0.851

342

Native

T. barbigerum

19.4 (0.0002)

0.6 (0.43)

2.6 (0.11)

9.4 (0.002)

0.257

-0.367

0.841

-1.124

352

Native

T. bifidum

10.7 (0.0136)

0.1 (0.75)

0.3 (0.6)

5.0 (0.026)

-1.863

-0.095

0.181

-0.212

350

Native

T. fucatum

1.1 (0.787)

0.4 (0.55)

0.2 (0.69)

0.2 (0.69)

-3.624

-0.255

-0.221

-0.024

365

Native

T. gracilentum

12.8 (0.0051)

0.7 (0.41)

0.0 (0.95)

5.2 (0.02)

-1.462

-0.236

-0.018

-0.315

290

Native

T. macraei

36.1 (0.0001)

0.2 (0.66)

0.4 (0.52)

19.2 (0.0001)

-0.150

-0.105

0.207

-0.619

256

Native

T. microdon

9.6 (0.0226)

0.0 (0.84)

1.0 (0.31)

5.2 (0.02)

-1.633

0.052

0.293

-0.178

313

Native

T. microcephalum

30.9 (0.0001)

0.0 (0.889)

0.3 (0.556)

10.9 (0.001)

-0.599

-0.047

0.261

-0.661

360

Native

T. willdenovii

10.1 (0.018)

1.8 (0.17)

0.3 (0.61)

4.3 (0.038)

-2.442

0.526

-0.175

-0.108

310

Native

T. wormskjoldii

7.4 (0.062)

0.1 (0.81)

0.0 (0.96)

4.4 (0.037)

-2.241

0.099

-0.022

-0.461

360


Table D6 continued.

Year 2

                   

Intro

M. arabica

7.9 (0.047)

4.8 (0.028)

1 (0.314)

1.7 (0.19)

-2.100

0.577

-0.307

-0.079

232

Intro

M. lupulina

10.2 (0.017)

5.2 (0.023)

2.8 (0.0942)

4.4 (0.035)

-0.861

0.646

0.616

-0.459

238

Intro

M. polymorpha

5.9 (0.12)

0.4 (0.521)

0.3 (0.5929)

2.6 (0.1063)

-1.997

-0.220

0.175

-0.147

248

Intro

T. campestre

0.7 (0.866)

0.0 (0.95)

0.7 (0.41)

0.0 (0.895)

-1.830

-0.016

0.295

0.008

160

Intro

T. dubium

1.4 (0.702)

0.6 (0.45)

0.1 (0.73)

0.6 (0.42)

-1.939

0.193

-0.183

-0.052

215

Intro

T. repens

7.6 (0.055)

0.0 (0.835)

0.7 (0.39)

6.3 (0.012)

-0.405

0.051

0.357

-0.667

217

Intro

T. subterraneum

4.6 (0.2004)

1.0 (0.31)

1.4 (0.23)

2.1 (0.145)

-1.525

-0.257

0.413

-0.169

236

Native

T. barbigerum

0.7 (0.885)

0.5 (0.47)

0.1 (0.78)

0.1 (0.8)

-2.433

0.195

-0.151

-0.008

191

Native

T. bifidum

2.4 (0.494)

1.3 (0.256)

1.1 (0.286)

1.1 (0.302)

-1.611

0.283

0.374

-0.048

207

Native

T. fucatum

7.5 (0.058)

3.1 (0.077)

1.7 (0.19)

2.3 (0.13)

-2.227

0.937

0.584

-0.097

217

Native

T. gracilentum

9.6 (0.023)

0.3 (0.611)

3.3 (0.071)

5.3 (0.021)

-1.010

0.130

0.613

-0.126

205

Native

T. macraei

2.4 (0.498)

0.4 (0.55)

0.2 (0.64)

2.1 (0.15)

-1.695

0.151

0.195

-0.055

225

Native

T. microdon

4.6 (0.2)

0.0 (0.89)

1.6 (0.199)

2.9 (0.088)

-1.552

0.039

0.473

-0.066

224

Native

T. microcephalum

1.3 (0.73)

0.0 (0.97)

0.2 (0.64)

1.0 (0.312)

-1.765

-0.009

0.166

-0.064

176

Native

T. variegatum

2.1 (0.5559)

0.3 (0.589)

0.0 (0.943)

1.5 (0.2163)

-2.109

0.158

0.029

-0.043

211


Why we did not use severity instead of prevalence for logistic regressions: Data from the severity censuses in Year 1 and Year 2 could not be used for logistic regressions of mortality on percent leaf damage because there were not enough individuals and mortality events (especially for analyses split by species) in the severity census subset. In Year 1, 32 out of 222 severity census plants died over seven census dates, and in Year 2, only three plants out of the 126 severity census plants died over three census dates.




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