reorder group bar plot according to the Specie column

I want to make a group bar plot with ggplot. but i want to reorder the bar according to the specie, for example first bars belong to sp1 , sp2 and then sp3 should be shown in a decsending order in the graph. So far I am able to plot the graph like this but genotype belong to sp1 should come first sp2 second and then genotype belong to sp3. I am using this code

ggplot(data=data, aes(x=reorder(Genotype, -var) , y=var, fill=Treatment)) +
  geom_bar(stat="identity", position=position_dodge(width=0.85)) +
  scale_fill_manual(values = c('#4850CE','#D37A3E'),
                    labels = c("Control Temperature (CT)","Heat tress (HS)")) +
  geom_errorbar(aes(ymin = var, ymax = var+e,colour=Treatment),
                width=0.75, position = position_dodge(0.85))+
  scale_colour_manual(values=c('#4850CE','#D37A3E'))+
  theme_bw() + labs(x=NULL, y=expression("a. weight"^~g))+
  scale_y_continuous(breaks = seq(0, max(data$var+data$e), length.out = 6),
                     labels = number_format(accuracy = 0.01))+
  geom_text(aes(label = Genotype, y = 0),angle=90, hjust=0, size=3)+
  theme(panel.grid.minor = element_blank(),
        axis.text.x = element_blank(),
        axis.ticks.x = element_blank(),
        axis.title.y = element_text(colour = "black", size=8, face="bold"),
        axis.ticks.y = element_line(colour= "black"),
        axis.text.y =element_text(colour="black", size = 8),
        legend.position = c(0.8, 0.92), legend.background = element_blank(),
        legend.key.size = unit(4, 'mm'),
        legend.title = element_blank(),
        legend.text = element_text(size = 8,face="bold"))+
  guides(colour = FALSE)

The basic code you need is:

library(tidyverse)

df %>%
  arrange(Specie, desc(var)) %>%
  mutate(Genotype = factor(Genotype, unique(Genotype))) %>%
  ggplot(aes(Genotype, var, fill = Treatment)) + 
  geom_col(position = 'dodge')

Then add the other codes