© Ricardo Solar/UFMG - compartilhamento e utilização não-comercial livres. Não reproduzir sem autorização

1 Variavel resposta = Dados de pressenca/ausencia (0 ou 1):

rm(list=ls())

dados<-read.table("Formigas.txt",header=T)
summary(dados)
##   Canopy_cover        SolInv         CreTen      
##  Min.   :0.0000   Min.   :0.00   Min.   :0.0000  
##  1st Qu.:0.7999   1st Qu.:0.00   1st Qu.:0.0000  
##  Median :0.8468   Median :0.00   Median :0.0000  
##  Mean   :0.8054   Mean   :0.25   Mean   :0.3793  
##  3rd Qu.:0.8878   3rd Qu.:0.25   3rd Qu.:1.0000  
##  Max.   :0.9520   Max.   :1.00   Max.   :1.0000
plot(dados)

names(dados)
## [1] "Canopy_cover" "SolInv"       "CreTen"

2 Responda qual ? o efeito da cobertura vegetal sobre a presen?a de cada uma das esp?cies:

Solenopsis invicta (SolInv) Crematogaster tenuicola (CreTen)

Dados de presenca/ausencia (Bernoulli, binarios) : funcao de ligacao ainda eh logit = log (p/1-p)

2.1 Para a especie Solenopsis invicta

m.completoSI = glm(SolInv~Canopy_cover, family=binomial, data=dados)
anova(m.completoSI,test="Chisq")
summary(m.completoSI)
## 
## Call:
## glm(formula = SolInv ~ Canopy_cover, family = binomial, data = dados)
## 
## Deviance Residuals: 
##     Min       1Q   Median       3Q      Max  
## -1.8229  -0.6465  -0.5603  -0.2981   2.1202  
## 
## Coefficients:
##              Estimate Std. Error z value Pr(>|z|)    
## (Intercept)     4.636      1.520   3.051 0.002281 ** 
## Canopy_cover   -7.253      1.892  -3.834 0.000126 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## (Dispersion parameter for binomial family taken to be 1)
## 
##     Null deviance: 130.46  on 115  degrees of freedom
## Residual deviance: 109.30  on 114  degrees of freedom
## AIC: 113.3
## 
## Number of Fisher Scoring iterations: 4
with(m.completoSI, deviance/df.residual)
## [1] 0.9587829
##Dispersao OK

library(RT4Bio)
## Loading required package: MASS
## Loading required package: survival
rdiagnostic(m.completoSI)

DHARMa::simulateResiduals(m.completoSI, plot=T)

## Object of Class DHARMa with simulated residuals based on 250 simulations with refit = FALSE . See ?DHARMa::simulateResiduals for help. 
##  
## Scaled residual values: 0.1474335 0.8900209 0.9375736 0.4623027 0.4761113 0.4115664 0.9587229 0.08897467 0.4367838 0.5749464 0.7218649 0.352572 0.3414428 0.1908792 0.7419757 0.9394594 0.5293834 0.07718971 0.3055862 0.1929606 ...

2.2 Para a especie Crematogaster tenuicola

m.completoCT = glm(CreTen~Canopy_cover, family=binomial, data=dados)
anova(m.completoCT,test="Chisq")
with(m.completoCT, deviance/df.residual)
## [1] 1.194863
##Dispersao OK

rdiagnostic(m.completoCT)

DHARMa::simulateResiduals(m.completoCT, plot=T)

## Object of Class DHARMa with simulated residuals based on 250 simulations with refit = FALSE . See ?DHARMa::simulateResiduals for help. 
##  
## Scaled residual values: 0.3997087 0.8388238 0.4180393 0.4868932 0.7773231 0.7790711 0.3279211 0.06762075 0.7504804 0.3531814 0.488426 0.7947877 0.1064237 0.05854699 0.9313812 0.743161 0.8135357 0.6945322 0.2143449 0.1376952 ...

2.3 Representação dos dados de forma grática

Uma forma um pouco diferente de representar os resultados, vamos plotar ambas as especies no mesmo grafico

SI <- coef(m.completoSI)

CT <- coef(m.completoCT)

plot(SolInv~Canopy_cover, data=dados, axes=F, type="n", xlab="", ylab="Ocorrencia da especie")
axis(1, lwd=2)
axis(2,lwd=2, las=1, at=c(0,0.5,1))
box(bty="l", lwd=3)

##Pontos e curve para Solenopsis invicta
points(SolInv~Canopy_cover, data=dados, pch=21, bg=2)
points(SolInv~Canopy_cover, data=dados, pch=21, bg="#CC000050")
curve(plogis(SI[1]+SI[2]*x), add=T, lwd=2, col=2)

##Pontos e curve para Crematogaster tenuicola
##Vou dar uma melhorada aqui, e deslocar de leve os pontos de CreTen pra poder visualizar melhor
CreTen2 <- ifelse(dados$CreTen==1, dados$CreTen-0.03, dados$CreTen+0.03)
points(CreTen2~Canopy_cover, data=dados, pch=21, bg=1)
curve(plogis(CT[1]+CT[2]*x), add=T, lwd=2, col=1)

legend(0,.3, c("Cre ten", "Sol inv"), col=1:2, lty=1, lwd=2, pch=21, pt.bg = 1:2, bty="n")