Honours thesis defense

Basal plant facilitation extends to insect community structure in the Mojave Desert, California

Ally Ruttan

Positive Interactions

Often in regions of high abiotic stress

Molenda et al. 2012

(Flores and Jurado 2003; Lortie and Callaway 2009; Arredondo‐Nunez et al. 2009)

What is a nurse plant?

?

(Callaway and Walker 1997; Holmgren et al. 1997; Miriti 2006)

Why insects?

Pollination

Dispersal(Feldman et al. 2004; Sieber et al. 2011)

Why arid systems?

Desertification

Endemic species(Grainger 1990; Schlesinger et al. 1990)

Hypothesis

Basal plant facilitation positively influences trophic levels other than plants through the facilitation of insect community structure

+

Predictions

1. Nurse = effect on insect communities

2. Nurse = different key indicator families

3. Nurse act as magnets for pollinators in particular

Study Site

Kelso Dunes

600 ft.

*Study Site

N

Study Site – Kelso Dunes

Chaenactis fremontii

Malocothrix glabrataAliciella leptomeria

Eriophyllum wallacei

Experimental Design

Methods

Insect Diversity

Mutillidae

Insect Diversity

Meloidae

Insect Diversity

Megachilidae: Anthidium

Insect Diversity

Megachilidae: Ashmediella

Insect Diversity

Chrysididae

Insect Diversity

Meloidae

Results - RII

All community measures facilitated by shrub except evenness

(Armas et al. 2004)

Results - NMDS

NMDS1

NM

DS

2

Tachinidae

melyridae

Sarcophagidae

Formicidae

Pompilidae

Crabronidae

Halictidae

Glaphyridae

Chrysididae

Rhopalidae

Megachilidae

Andrenidae

Meloidae

Muscidae

Bombyliidae

AsilidaeGeometridae

ApioceridaePteromalidaeSphingidae

Bethylidae

ElateridaeColletidaeMilichiidae

Geocoridae

AcrididaeTephritidae

Tabanidae

Mordellidae

MydidaeMiridaeVespidae

Chloropidae

MelittidaeLauxaniidae

Anthomyiidae

PipunculidaeChalcididaeSphecidaeBradynobaenidae

Apidae

Syrphidae

23

301

67

343

515

24

437

304

531

148

66

391

399

518

360328

21

535

516

440

451

364

269

494

57

78

285

525

259

55

53219

2

58

380

487

473

522

249359

25

294

288

34997

70

119

333

81

332

268

287

436

325

404

63

252

22

37

454

336

82

411

348393

405

169

365175

267

537

61

7585

275

445

181

530255501

344 474540124

490250

262

538274

87

385172

447

54

528

290

233

462

256

524

334

90

357

43

264

62

382

18

381

254

151

207

150

31

214

190

160

276

361126

493251504

427

523

186

331

16112

470

178

4

433

144

10

187

521

223

120

466

242

283

346

313

131

478

277

102253

502

167

429

363

121

496

83

100

52

319

309

32459

111

96

104

372

213

220

335

166

342

458

408

197

139145

165

235

132

147

243

299

286

29

529

179

110

215

18434

402

218263

400118

367

461

211

84

236

448

536

39

76

221

321

5216

351

240

241

406

312245

12

142

152425

476

472191

506

115

41

133

354

368

394

526

412

468

450

539

513

48

114

92

303

234

370

106157

489

91

14

200

33

72

134

480

225

246509

164

219

143

155

130

149117

415

441

390

320185

69

171

416

297322

330

209204

337

40

38

99

135140

503

125163

109

519

30392

284

158

226

455

136

101

398

227

28

409

127

122

261520

189

210 410

444

273

15153

527

420

369

159

183

439

20

248

6

278

291182

384

386

280

9

534

180

341

421

29573339

345

3

452

387

60

310

417

228

431

177378198

174

467

199

279298314

11

162

533

371471

229105

49

237453

374

397401

239

27

432230

1548

36483

517

270

89

481

281

50

98

491

469

512265464

168

308296

266

195

418

231499 505

86356

376

305

395

80

340326

44

59

272

56

107257

47224311 282

355

71

508

238

350 511477

188

353498495

383

426

347

13

443

446460

49277

194

317

465 488

94

46

260

192

129

38920627142

388

323300

423

457377486324

484

403375373

123

53217

93161

419

292

5141

42220817

302

128

414

64

42474327

32940788

232366289449

3793067

222

352

OpenShrub

NMDS1

NM

DS1

MRPP = 0.001

NM

DS2

Community composition significantly different between microsite and pan trap colour

Results - Indicator Species Analysis

(Dufrene and Legendre 1997)

Bee abundance

Not different between microsite

Why?

Many bees associated with L. tridentata

Horizontal foraging patterns

Trap method

(Minckley and Cane 2000)

Implications – Seed Dispersal

Enhance annual community

Displacement from parent plant

(O’Dowd and Hay 1980; Rissing 1981)

Implications – Restoration

L. tridentata keystone species

Restoration of degraded systems, mediate desertification

(Castro et al. 2004; Gomez and Aparicio 2004)

Conclusions

L. tridentata facilitates multiple trophic levels in the desert community

Acknowledgements