如何在ggplot2的facet_wrap中将第二列strip label移至右侧？

我希望将分面图（facet graph）第二列的strip label移至右侧，如图中标注所示。以下是我当前使用的代码及示例数据集：

当前代码 #

library(reshape2)
library(tidyverse)
library(ggh4x)
library(scales)
library(ggplot2)
#step 1: 处理数据
df <- melt(df, id=c("Specie","Treatment"))
head(df)
#绘图部分
left  <- scale_y_continuous(labels = number_format(accuracy = 0.01))
right <- scale_y_continuous(labels = number_format(accuracy = 0.01),position = "right")

ggplot(df1, aes(x = Specie, y = mean, fill = Treatment, colour=Treatment)) +
  geom_col(position = position_dodge(), width = 0.8)+
  facet_wrap(~ variable, scales = "free_y", ncol = 2, 
             labeller = label_parsed, strip.position = "left")+
  geom_errorbar(aes(ymin = mean, ymax = mean + sd), width = 0.2,
                position = position_dodge(0.9)) +theme_bw()+
  geom_text(aes(y = mean+sd,label = label),position = position_dodge(0.9),
            size = 3.5, vjust=-0.2, family="serif", colour="black")+
  geom_text(aes(y = Q1/2,label = letter),size = 3.5, family="serif", colour="#000000")+
  scale_fill_manual(values=c('#DEB887','#CD853F'))+
  scale_color_manual(values=c('#DEB887','#CD853F'))+
  facetted_pos_scales(y = list(left, right, left, right, left, right))+
  #coord_flip()+
  theme(axis.text.x = element_text(face = "italic"),
        strip.placement = "outside",
        strip.background = element_blank())

示例数据集 #

内容的提问来源于stack exchange，提问作者Ikram Bashir