ANOSIM e PERMANOVA

Embora tenhamos respostas quanto a diversidade beta, não testamos diferenças estatísticas. Fazemos isso com análise de variância permutacional (PERMANOVA) ou análise de similaridade (ANOSIM). Eles testam se os locais amostrados diferem de acordo com uma variável de interesse.

PERMANOVA

A PERMANOVA (Permutation Multivariate Analysis of Variance) é uma análise multivariada não paramétrica que testa a hipótese nula de que a dispersão das observações são equivalentes em todos os grupos formados. Para tal a analise compara a SQ entre os grupos e dentro dos grupos.

Usamos o pacote vegan para calcular distâncias e rodar a PERMANOVA. Dessa forma podemos incluir todas as variáveis de interesse em um modelo, bem como suas interações.

Carregando os dados:

data(dune)
data(dune.env)

Relembrando os dados:

head(dune)
##   Achimill Agrostol Airaprae Alopgeni Anthodor Bellpere Bromhord Chenalbu
## 1        1        0        0        0        0        0        0        0
## 2        3        0        0        2        0        3        4        0
## 3        0        4        0        7        0        2        0        0
## 4        0        8        0        2        0        2        3        0
## 5        2        0        0        0        4        2        2        0
## 6        2        0        0        0        3        0        0        0
##   Cirsarve Comapalu Eleopalu Elymrepe Empenigr Hyporadi Juncarti Juncbufo
## 1        0        0        0        4        0        0        0        0
## 2        0        0        0        4        0        0        0        0
## 3        0        0        0        4        0        0        0        0
## 4        2        0        0        4        0        0        0        0
## 5        0        0        0        4        0        0        0        0
## 6        0        0        0        0        0        0        0        0
##   Lolipere Planlanc Poaprat Poatriv Ranuflam Rumeacet Sagiproc Salirepe
## 1        7        0       4       2        0        0        0        0
## 2        5        0       4       7        0        0        0        0
## 3        6        0       5       6        0        0        0        0
## 4        5        0       4       5        0        0        5        0
## 5        2        5       2       6        0        5        0        0
## 6        6        5       3       4        0        6        0        0
##   Scorautu Trifprat Trifrepe Vicilath Bracruta Callcusp
## 1        0        0        0        0        0        0
## 2        5        0        5        0        0        0
## 3        2        0        2        0        2        0
## 4        2        0        1        0        2        0
## 5        3        2        2        0        2        0
## 6        3        5        5        0        6        0
head(dune.env)
##    A1 Moisture Management      Use Manure
## 1 2.8        1         SF Haypastu      4
## 2 3.5        1         BF Haypastu      2
## 3 4.3        2         SF Haypastu      4
## 4 4.2        2         SF Haypastu      4
## 5 6.3        1         HF Hayfield      2
## 6 4.3        1         HF Haypastu      2

Obtendo as distâncias entre os locais:

distancia_dune = vegdist(dune)

Lembrando que o índice padrão da função vegdist é o Bray-Curtis!

Obtendo um dendrograma:

cluster_dune = hclust(distancia_dune, method = "average")
plot(cluster_dune)

Rodando a PERMANOVA:

adonis2(distancia_dune ~ Management*A1, data = dune.env, permutations = 1000)
## Permutation test for adonis under reduced model
## Terms added sequentially (first to last)
## Permutation: free
## Number of permutations: 1000
## 
## adonis2(formula = distancia_dune ~ Management * A1, data = dune.env, permutations = 1000)
##               Df SumOfSqs      R2      F   Pr(>F)   
## Management     3   1.4686 0.34161 3.2629 0.001998 **
## A1             1   0.4409 0.10256 2.9387 0.015984 * 
## Management:A1  3   0.5892 0.13705 1.3090 0.211788   
## Residual      12   1.8004 0.41878                   
## Total         19   4.2990 1.00000                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

A interação Management x A1 não foi significativa, o que fazer?

adonis2(distancia_dune ~ Management+A1, data = dune.env, permutations = 1000)
## Permutation test for adonis under reduced model
## Terms added sequentially (first to last)
## Permutation: free
## Number of permutations: 1000
## 
## adonis2(formula = distancia_dune ~ Management + A1, data = dune.env, permutations = 1000)
##            Df SumOfSqs      R2      F   Pr(>F)   
## Management  3   1.4686 0.34161 3.0730 0.007992 **
## A1          1   0.4409 0.10256 2.7676 0.022977 * 
## Residual   15   2.3895 0.55583                   
## Total      19   4.2990 1.00000                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

ANOSIM

Se você tiver tamanhos de grupo muito diferentes, considere a análise de semelhanças/similaridades (ANOSIM) em vez de PERMANOVA. Este teste não assume igualdade de variâncias entre os grupos. No entanto, ele só permite modelos simples de 1 variável sem interações e só pode ser usado para variáveis categóricas. Portanto é uma analise confirmatória pois verifica se os grupos obtidos são de fato diferentes via teste estatístico.

Selecionando a variável de interesse do arquivo de dados dune.env:

dune.env
##      A1 Moisture Management      Use Manure
## 1   2.8        1         SF Haypastu      4
## 2   3.5        1         BF Haypastu      2
## 3   4.3        2         SF Haypastu      4
## 4   4.2        2         SF Haypastu      4
## 5   6.3        1         HF Hayfield      2
## 6   4.3        1         HF Haypastu      2
## 7   2.8        1         HF  Pasture      3
## 8   4.2        5         HF  Pasture      3
## 9   3.7        4         HF Hayfield      1
## 10  3.3        2         BF Hayfield      1
## 11  3.5        1         BF  Pasture      1
## 12  5.8        4         SF Haypastu      2
## 13  6.0        5         SF Haypastu      3
## 14  9.3        5         NM  Pasture      0
## 15 11.5        5         NM Haypastu      0
## 16  5.7        5         SF  Pasture      3
## 17  4.0        2         NM Hayfield      0
## 18  4.6        1         NM Hayfield      0
## 19  3.7        5         NM Hayfield      0
## 20  3.5        5         NM Hayfield      0

Analisando a variável “Management”:

dune.env$Management
##  [1] SF BF SF SF HF HF HF HF HF BF BF SF SF NM NM SF NM NM NM NM
## Levels: BF HF NM SF

Assim, utiliza-se a função anosim no R:

anosim_dune = anosim(distancia_dune, grouping = dune.env$Management, permutations = 1000)
summary(anosim_dune)
## 
## Call:
## anosim(x = distancia_dune, grouping = dune.env$Management, permutations = 1000) 
## Dissimilarity: bray 
## 
## ANOSIM statistic R: 0.2579 
##       Significance: 0.010989 
## 
## Permutation: free
## Number of permutations: 1000
## 
## Upper quantiles of permutations (null model):
##   90%   95% 97.5%   99% 
## 0.125 0.166 0.215 0.254 
## 
## Dissimilarity ranks between and within classes:
##         0%   25%    50%     75%  100%   N
## Between  4 58.50 104.00 145.500 188.0 147
## BF       5 15.25  25.50  41.250  57.0   3
## HF       1  7.25  46.25  68.125  89.5  10
## NM       6 64.75 124.50 156.250 181.0  15
## SF       3 32.75  53.50  99.250 184.0  15

Grafico:

plot(anosim_dune)
## Warning in bxp(list(stats = structure(c(4, 58.5, 104, 145.5, 188, 5, 15.25, :
## some notches went outside hinges ('box'): maybe set notch=FALSE

SIMPER

Analise de porcentagem de similaridades. Mostra o quanto cada especie contribuiu para a formação dos grupos formados entre os locais.

sim <- with(dune.env, simper(dune, Management))
summary(sim)
## 
## Contrast: SF_BF 
## 
##           average       sd  ratio    ava    avb  cumsum
## Agrostol 0.061374 0.034193 1.7949 4.6667 0.0000 0.09824
## Alopgeni 0.052667 0.036476 1.4439 4.3333 0.6667 0.18255
## Lolipere 0.048116 0.039445 1.2198 3.0000 6.0000 0.25957
## Trifrepe 0.046297 0.025525 1.8138 1.3333 4.6667 0.33368
## Poatriv  0.046020 0.033801 1.3615 4.6667 3.6667 0.40734
## Scorautu 0.043697 0.024922 1.7534 1.3333 4.3333 0.47729
## Bromhord 0.033677 0.025860 1.3023 0.5000 2.6667 0.53120
## Achimill 0.030152 0.020821 1.4482 0.1667 2.3333 0.57947
## Planlanc 0.028585 0.021549 1.3265 0.0000 2.0000 0.62522
## Elymrepe 0.028074 0.029778 0.9428 2.0000 1.3333 0.67016
## Bracruta 0.025501 0.023902 1.0669 2.0000 2.0000 0.71098
## Poaprat  0.025129 0.023967 1.0485 2.5000 4.0000 0.75121
## Sagiproc 0.024326 0.022149 1.0983 1.8333 0.6667 0.79014
## Bellpere 0.019859 0.017088 1.1622 0.6667 1.6667 0.82193
## Eleopalu 0.018611 0.042958 0.4333 1.3333 0.0000 0.85172
## Anthodor 0.017543 0.025804 0.6798 0.0000 1.3333 0.87981
## Juncbufo 0.016031 0.023708 0.6762 1.1667 0.0000 0.90547
## Vicilath 0.014671 0.013306 1.1026 0.0000 1.0000 0.92895
## Hyporadi 0.010286 0.015198 0.6768 0.0000 0.6667 0.94542
## Ranuflam 0.009306 0.013595 0.6845 0.6667 0.0000 0.96031
## Juncarti 0.006979 0.016109 0.4333 0.5000 0.0000 0.97148
## Callcusp 0.006979 0.016109 0.4333 0.5000 0.0000 0.98266
## Rumeacet 0.004526 0.010444 0.4333 0.3333 0.0000 0.98990
## Cirsarve 0.003983 0.009185 0.4336 0.3333 0.0000 0.99628
## Chenalbu 0.002326 0.005370 0.4333 0.1667 0.0000 1.00000
## Airaprae 0.000000 0.000000    NaN 0.0000 0.0000 1.00000
## Comapalu 0.000000 0.000000    NaN 0.0000 0.0000 1.00000
## Empenigr 0.000000 0.000000    NaN 0.0000 0.0000 1.00000
## Salirepe 0.000000 0.000000    NaN 0.0000 0.0000 1.00000
## Trifprat 0.000000 0.000000    NaN 0.0000 0.0000 1.00000
## 
## Contrast: SF_HF 
## 
##           average       sd  ratio    ava avb  cumsum
## Agrostol 0.047380 0.031273 1.5151 4.6667 1.4 0.08351
## Alopgeni 0.046433 0.032897 1.4115 4.3333 1.6 0.16535
## Lolipere 0.041986 0.027007 1.5546 3.0000 4.0 0.23935
## Planlanc 0.039198 0.033208 1.1804 0.0000 3.0 0.30844
## Rumeacet 0.038992 0.027369 1.4247 0.3333 3.2 0.37716
## Elymrepe 0.031877 0.029550 1.0787 2.0000 2.0 0.43334
## Poatriv  0.028466 0.021522 1.3227 4.6667 4.8 0.48352
## Bracruta 0.025261 0.021044 1.2004 2.0000 2.8 0.52804
## Eleopalu 0.024974 0.038877 0.6424 1.3333 0.8 0.57206
## Poaprat  0.023932 0.019180 1.2478 2.5000 3.4 0.61424
## Anthodor 0.023409 0.021430 1.0923 0.0000 1.8 0.65550
## Sagiproc 0.023144 0.020479 1.1301 1.8333 0.8 0.69629
## Trifprat 0.023080 0.023432 0.9850 0.0000 1.8 0.73697
## Juncarti 0.022850 0.025677 0.8899 0.5000 1.6 0.77724
## Trifrepe 0.022383 0.019487 1.1486 1.3333 2.8 0.81669
## Juncbufo 0.021643 0.022237 0.9733 1.1667 1.2 0.85484
## Scorautu 0.020509 0.016422 1.2489 1.3333 2.8 0.89099
## Achimill 0.015183 0.011393 1.3326 0.1667 1.2 0.91775
## Bromhord 0.013375 0.014504 0.9222 0.5000 0.8 0.94132
## Ranuflam 0.010661 0.013387 0.7964 0.6667 0.4 0.96011
## Bellpere 0.009991 0.012571 0.7948 0.6667 0.4 0.97772
## Callcusp 0.006623 0.015076 0.4393 0.5000 0.0 0.98939
## Cirsarve 0.003809 0.008669 0.4394 0.3333 0.0 0.99611
## Chenalbu 0.002208 0.005025 0.4393 0.1667 0.0 1.00000
## Airaprae 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## Comapalu 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## Empenigr 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## Hyporadi 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## Salirepe 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## Vicilath 0.000000 0.000000    NaN 0.0000 0.0 1.00000
## 
## Contrast: SF_NM 
## 
##           average       sd  ratio    ava    avb cumsum
## Poatriv  0.078284 0.040947 1.9118 4.6667 0.0000 0.1014
## Alopgeni 0.071219 0.046958 1.5167 4.3333 0.0000 0.1936
## Agrostol 0.056508 0.044176 1.2792 4.6667 2.1667 0.2667
## Lolipere 0.054851 0.059914 0.9155 3.0000 0.3333 0.3378
## Eleopalu 0.048027 0.047168 1.0182 1.3333 2.1667 0.3999
## Poaprat  0.040724 0.031790 1.2810 2.5000 0.6667 0.4527
## Bracruta 0.040008 0.034398 1.1631 2.0000 2.8333 0.5045
## Elymrepe 0.035598 0.038515 0.9243 2.0000 0.0000 0.5506
## Scorautu 0.032475 0.034813 0.9328 1.3333 3.1667 0.5926
## Trifrepe 0.030430 0.031634 0.9619 1.3333 1.8333 0.6320
## Sagiproc 0.030304 0.030477 0.9943 1.8333 0.5000 0.6712
## Salirepe 0.029275 0.032014 0.9144 0.0000 1.8333 0.7092
## Anthodor 0.024541 0.036694 0.6688 0.0000 1.3333 0.7409
## Callcusp 0.022763 0.029443 0.7731 0.5000 1.1667 0.7704
## Ranuflam 0.022566 0.022819 0.9889 0.6667 1.3333 0.7996
## Juncarti 0.022543 0.028598 0.7883 0.5000 1.1667 0.8288
## Hyporadi 0.020108 0.031291 0.6426 0.0000 1.1667 0.8548
## Juncbufo 0.019860 0.029034 0.6840 1.1667 0.0000 0.8806
## Planlanc 0.015420 0.022769 0.6772 0.0000 0.8333 0.9005
## Airaprae 0.014883 0.021881 0.6802 0.0000 0.8333 0.9198
## Bellpere 0.012317 0.015921 0.7737 0.6667 0.3333 0.9357
## Comapalu 0.011883 0.017407 0.6826 0.0000 0.6667 0.9511
## Achimill 0.009294 0.014931 0.6224 0.1667 0.3333 0.9632
## Bromhord 0.007172 0.016333 0.4391 0.5000 0.0000 0.9724
## Rumeacet 0.005590 0.012751 0.4384 0.3333 0.0000 0.9797
## Empenigr 0.005225 0.012001 0.4354 0.0000 0.3333 0.9864
## Cirsarve 0.004782 0.010889 0.4391 0.3333 0.0000 0.9926
## Chenalbu 0.002893 0.006602 0.4382 0.1667 0.0000 0.9964
## Vicilath 0.002792 0.006425 0.4345 0.0000 0.1667 1.0000
## Trifprat 0.000000 0.000000    NaN 0.0000 0.0000 1.0000
## 
## Contrast: BF_HF 
## 
##           average      sd  ratio    ava avb  cumsum
## Rumeacet 0.038666 0.02606 1.4838 0.0000 3.2 0.08163
## Poatriv  0.033301 0.02579 1.2911 3.6667 4.8 0.15194
## Planlanc 0.031852 0.01830 1.7401 2.0000 3.0 0.21918
## Bromhord 0.028651 0.01799 1.5926 2.6667 0.8 0.27967
## Lolipere 0.028431 0.02215 1.2834 6.0000 4.0 0.33970
## Elymrepe 0.027822 0.02959 0.9404 1.3333 2.0 0.39843
## Trifrepe 0.025838 0.01656 1.5603 4.6667 2.8 0.45298
## Anthodor 0.023582 0.02042 1.1547 1.3333 1.8 0.50277
## Achimill 0.023426 0.01474 1.5893 2.3333 1.2 0.55223
## Bracruta 0.022733 0.01802 1.2617 2.0000 2.8 0.60022
## Alopgeni 0.021610 0.02308 0.9363 0.6667 1.6 0.64584
## Trifprat 0.021514 0.02207 0.9747 0.0000 1.8 0.69126
## Juncarti 0.020084 0.02555 0.7860 0.0000 1.6 0.73367
## Scorautu 0.019318 0.01356 1.4241 4.3333 2.8 0.77445
## Bellpere 0.018290 0.01486 1.2305 1.6667 0.4 0.81306
## Agrostol 0.017605 0.02284 0.7708 0.0000 1.4 0.85023
## Juncbufo 0.015000 0.02066 0.7260 0.0000 1.2 0.88190
## Vicilath 0.012848 0.01140 1.1274 1.0000 0.0 0.90903
## Sagiproc 0.011685 0.01297 0.9008 0.6667 0.8 0.93369
## Eleopalu 0.010169 0.02111 0.4817 0.0000 0.8 0.95516
## Hyporadi 0.008950 0.01312 0.6824 0.6667 0.0 0.97406
## Poaprat  0.007203 0.01010 0.7133 4.0000 3.4 0.98927
## Ranuflam 0.005084 0.01055 0.4817 0.0000 0.4 1.00000
## Airaprae 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Chenalbu 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Cirsarve 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Comapalu 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Empenigr 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Salirepe 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## Callcusp 0.000000 0.00000    NaN 0.0000 0.0 1.00000
## 
## Contrast: BF_NM 
## 
##           average      sd  ratio    ava    avb cumsum
## Lolipere 0.090681 0.02644 3.4292 6.0000 0.3333 0.1243
## Poatriv  0.054684 0.04465 1.2248 3.6667 0.0000 0.1992
## Poaprat  0.052511 0.01813 2.8966 4.0000 0.6667 0.2712
## Trifrepe 0.051287 0.02756 1.8611 4.6667 1.8333 0.3415
## Bromhord 0.039689 0.02920 1.3590 2.6667 0.0000 0.3959
## Bracruta 0.035723 0.02869 1.2452 2.0000 2.8333 0.4448
## Eleopalu 0.033759 0.03573 0.9449 0.0000 2.1667 0.4911
## Agrostol 0.033446 0.03473 0.9630 0.0000 2.1667 0.5369
## Achimill 0.033190 0.02338 1.4198 2.3333 0.3333 0.5824
## Scorautu 0.031356 0.02026 1.5480 4.3333 3.1667 0.6254
## Anthodor 0.028060 0.03295 0.8517 1.3333 1.3333 0.6638
## Planlanc 0.027319 0.02193 1.2458 2.0000 0.8333 0.7013
## Salirepe 0.026770 0.02927 0.9145 0.0000 1.8333 0.7379
## Bellpere 0.023529 0.01909 1.2322 1.6667 0.3333 0.7702
## Hyporadi 0.021721 0.02450 0.8864 0.6667 1.1667 0.8000
## Ranuflam 0.020314 0.02275 0.8928 0.0000 1.3333 0.8278
## Elymrepe 0.019993 0.02926 0.6833 1.3333 0.0000 0.8552
## Callcusp 0.017833 0.02681 0.6653 0.0000 1.1667 0.8796
## Juncarti 0.017694 0.02600 0.6806 0.0000 1.1667 0.9039
## Vicilath 0.015773 0.01447 1.0902 1.0000 0.1667 0.9255
## Sagiproc 0.015432 0.01857 0.8310 0.6667 0.5000 0.9466
## Airaprae 0.013410 0.01969 0.6809 0.0000 0.8333 0.9650
## Comapalu 0.010739 0.01571 0.6835 0.0000 0.6667 0.9797
## Alopgeni 0.009997 0.01463 0.6833 0.6667 0.0000 0.9934
## Empenigr 0.004787 0.01105 0.4332 0.0000 0.3333 1.0000
## Chenalbu 0.000000 0.00000    NaN 0.0000 0.0000 1.0000
## Cirsarve 0.000000 0.00000    NaN 0.0000 0.0000 1.0000
## Juncbufo 0.000000 0.00000    NaN 0.0000 0.0000 1.0000
## Rumeacet 0.000000 0.00000    NaN 0.0000 0.0000 1.0000
## Trifprat 0.000000 0.00000    NaN 0.0000 0.0000 1.0000
## 
## Contrast: HF_NM 
## 
##           average       sd  ratio ava    avb  cumsum
## Poatriv  0.071553 0.013681 5.2302 4.8 0.0000 0.09913
## Lolipere 0.054533 0.029625 1.8408 4.0 0.3333 0.17468
## Rumeacet 0.046546 0.030806 1.5109 3.2 0.0000 0.23917
## Poaprat  0.041750 0.018852 2.2146 3.4 0.6667 0.29701
## Planlanc 0.041633 0.029560 1.4084 3.0 0.8333 0.35469
## Bracruta 0.035340 0.020104 1.7579 2.8 2.8333 0.40365
## Eleopalu 0.032043 0.032315 0.9916 0.8 2.1667 0.44805
## Agrostol 0.031915 0.028887 1.1048 1.4 2.1667 0.49227
## Trifrepe 0.030372 0.022871 1.3280 2.8 1.8333 0.53434
## Elymrepe 0.029811 0.038676 0.7708 2.0 0.0000 0.57565
## Anthodor 0.028717 0.024799 1.1580 1.8 1.3333 0.61543
## Juncarti 0.027414 0.028537 0.9607 1.6 1.1667 0.65341
## Trifprat 0.025843 0.025972 0.9951 1.8 0.0000 0.68922
## Salirepe 0.025340 0.027291 0.9285 0.0 1.8333 0.72432
## Alopgeni 0.024459 0.032399 0.7549 1.6 0.0000 0.75821
## Scorautu 0.020703 0.014125 1.4658 2.8 3.1667 0.78689
## Ranuflam 0.019285 0.019939 0.9672 0.4 1.3333 0.81361
## Juncbufo 0.018181 0.024648 0.7376 1.2 0.0000 0.83880
## Hyporadi 0.017141 0.026548 0.6457 0.0 1.1667 0.86255
## Callcusp 0.016833 0.024901 0.6760 0.0 1.1667 0.88587
## Achimill 0.016555 0.014900 1.1111 1.2 0.3333 0.90881
## Sagiproc 0.015282 0.016535 0.9243 0.8 0.5000 0.92998
## Airaprae 0.012605 0.018243 0.6910 0.0 0.8333 0.94744
## Bromhord 0.012094 0.015169 0.7973 0.8 0.0000 0.96420
## Comapalu 0.010105 0.014556 0.6942 0.0 0.6667 0.97820
## Bellpere 0.008801 0.013732 0.6409 0.4 0.3333 0.99039
## Empenigr 0.004536 0.010325 0.4393 0.0 0.3333 0.99668
## Vicilath 0.002399 0.005461 0.4393 0.0 0.1667 1.00000
## Chenalbu 0.000000 0.000000    NaN 0.0 0.0000 1.00000
## Cirsarve 0.000000 0.000000    NaN 0.0 0.0000 1.00000
## Permutation: free
## Number of permutations: 0