# Composition Diversity and Expression Specificity of the _Tps_ Gene Family among 24 _Ficus_ Species
## 3 Discussion
### Numbers of TPS Genes in 24 Ostiole Bract Transcriptomes  
The _TPS_ gene family is a mid-size family of angiosperms [21]. The number of _TPS_s in angiosperms varies widely, ranging from two _TPS_ in _Zostera marina_[22] to 152 in _Vitis vinifera_[21; 22; 24]. In particular, _TPS_ genes typically follow a lineage-specific evolutionary pattern, resulting in diverse terpenoid products [32; 33]. In addition, given that the _TPS_s are expressed in a spatiotemporal differential and organ-specific manner, the number of _TPS_ genes identified from the transcriptomes is probably smaller than the number localized in plant genomes. In this study, within _Ficus_, using tissues at the same development stage, we also found that the number of _TPS_ genes was quite different among the 24 species. For example, there were only two _TPS_ in _F. fistulosa_, but 19 in _F. altissima_ (Table 1). In addition, for species within the same subgenus, even within the same section of _Ficus_, we did not find any similarities in the distribution pattern of the _TPS_ genes. To further estimate the occurrence frequency of the _TPS_ genes during the receptive stage of male syconia, we scanned two known genomes of _F. microcarpa_ and _F. hispida_ and compared their _TPS_ number at a genome-wide level to the number identified in our study. We identified 33 and 59 _TPS_ genes in the two genomes and found that only 39% (13) and 13% (eight) _TPS_ genes of two species occurred during the receptive stage (Table 1). This result suggests that the number and occurrence frequency of _TPS_ genes in the receptive stage of male syconia largely depend on the species in _Ficus_. This situation is consistent with the hypothesis that different species of _Ficus_ release specific volatiles to attract specific pollinating waps [34].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Gene** & **Clade** & **Models Compared** & **np** & \(p\)**-Value 1 ** & **InL** & **\(\omega\) Values** & **Positive Sites** (BEB) 2 ** \\ \hline _FtPS3_ & fimon & Model A & 38 & \(1.490\times 10^{-2}\) 1  & \(-5595.802\) & \(p_{0}=0.023\) & \(\omega 1=1.000\) \\  & & Model A null & 37 & & \(-5598.162\) & \(p_{0}=0.023\) & \(\omega 1=1.000\) \\  & fipyr & Model A & 38 & \(6.105\times 10^{-4}\) 1  & \(-5490.893\) & \(p_{0}=0.015\) & \(\omega 2=315.194\) \\  & & Model A null & 37 & & \(-5496.038\) & \(p_{0}=0.018\) & \(\omega 1=1.000\) \\  & & Model A null & 37 & & \(-5496.038\) & \(p_{0}=0.001\) & \(\omega 1=1.000\) \\ _FtPS4_ & fhiir-fitri & Model A & 34 & 0.051 & \(-4860.385\) & \(p_{0}=0.000\) & \(\omega 1=1.000\) \\  & & Model A null & 33 & & \(-4861.730\) & \(p_{0}=0.000\) & \(\omega 1=1.000\) \\ _FtPS8_ & fhiet & Model A & 26 & 0.059 & \(-5773.442\) & \(p_{0}=0.047\) & \(\omega 1=1.000\) \\  & & Model A null & 25 & & \(-5776.607\) & \(p_{0}=0.047\) & \(\omega 1=1.000\) \\  & & Model A null & 25 & & \(-5776.607\) & \(p_{0}=0.047\) & \(\omega 1=1.000\) \\  & & Model A null & 13 & \(1.129\times 10^{-3}\) 1  & \(-5776.607\) & \(p_{0}=0.002\) & \(\omega 2=1.000\) \\ _FtPS16_ & fffis & Model A & 13 & \(1.129\times 10^{-3}\) 1  & \(-3118.162\) & \(p_{0}=0.047\) & \(\omega 2=314.584\) \\  & & Model A null & 12 & & \(-3122.826\) & \(p_{0}=0.408\) & \(\omega 1=1.000\) \\  & & Model A null & 16 & \(6.005\times 10^{-7}\) 1  & \(-3399.251\) & \(p_{0}=0.588\) & \(\omega 1=1.000\) \\  & & Model A null & 15 & & \(-3427.039\) & \(p_{0}=0.626\) & \(\omega 1=1.000\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Positive selection analysis of _FTPS_ genes occurred in more than four species under branch site model test.