International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.1, 1-9 http://ecoevopublisher.com/index.php/ijmeb 5 spoiling. Scientists can also find some special genes from wild durian, such as those that are drought-resistant and disease-resistant. Then use genetic technology to transfer these good genes to common cultivated varieties. The durian grown in this way is more resistant to climate change and easier to grow. This kind of durian is sometimes called “climate-smart durian” and is a very popular research direction now. 5 Case Study: Gene Flow in Southeast Asia 5.1 Historical background of durian cultivation in Southeast Asia Durian is not uncommon in Southeast Asia. In countries like Malaysia, Thailand, Indonesia, the Philippines, and Vietnam, you can find it everywhere, on the roadside, in markets, and in orchards (Van Hau et al., 2023). In fact, durian has been grown by local people for a long time, but it was not spread at that time. Later, it was slowly spread to other places and became a fruit that everyone eats. The durian in Malaysia is particularly diverse, with more than 100 officially registered varieties, specifically 126 (Siew et al., 2018). This is only the registered varieties, and there may be more varieties circulating among the people. For the people there, durian is not only eaten, but also a part of culture in many cases. Speaking of genes, durian is not simple either. It has an astonishing number of genes, about 46,000, which is twice that of humans. How did this number come from? In fact, it did not increase all at once, but was the result of the accumulation of climate, environment, human selection, and cultivation methods. However, if there is one reason for the big changes, it has to be “gene flow”. Simply put, wild durian and human-grown durian are genetically intermixed (Mursyidin et al., 2024). This interbreeding has resulted in more species and characteristics of durian, making it more adaptable to different places. 5.2 Genetic analysis of local durian varieties and wild relatives Although they look similar, durian in different countries and regions actually has quite different genes. Take Thailand as an example. There are several common varieties - Kradumthong, Monthong, and Puangmanee. Researchers used “gene resequencing” to analyze them and found that the genes of these durians are very different from those of Malaysia’s “Musang King” (Nawae et al., 2023). Judging from the results, their ancestors probably did not come from the same place, and their development paths were also different. Similar studies have also been done in Indonesia. Prakoso and Retnoningsih (2021), and Mursyidin (2022), used the “molecular marker” method to analyze several local Indonesian varieties. The results showed that durians in places like Blongko, Semarang, and South Kalimantan may not be particularly exaggerated in appearance, but they are quite different at the genetic level (Figure 2). Basically, durians in every place have a bit of “their own bloodline”. So, don’t just think that durians look similar. If you check their genes, you can tell which ones are not very related to each other. 5.3 Implications for future conservation and breeding strategies In the final analysis, for durian to continue to develop, it must rely on protection and breeding. Some of these durians in Southeast Asia are wild, and some are artificially grown. There will be gene exchange between them. You may not think that this kind of “give and take” is particularly useful for breeding. Different genes can bring different benefits. For example, some are insect-resistant, some are drought-resistant, some are afraid of water but can still grow well, and some taste particularly good or have a lot of flesh (Lin et al., 2022). Some genes don't seem to matter on the surface, but in years with extreme weather or many diseases, they are very useful. Although wild durian may not taste very good, they often have some “backup options” hidden in their genes. When the climate really changes, we may have to rely on them for help. So now protecting these wild resources is not just “saving seeds”, but more like leaving more ways for the future. Scientists now have a lot of tools, such as “molecular markers” and “genetic analysis”. Using these methods, we can find suitable varieties for breeding more quickly. There is also a method called “marker-assisted selection (MAS)”, which simply means using molecular information to help select seeds. The durian selected in this way not only tastes good, but also better meets market requirements and sells well (Khaksar et al., 2024). 6 Challenges and Future Directions 6.1 Threats to durian germplasm conservation Protecting durian genetic resources is easy to say, but it is difficult to do. One of the most troublesome problems is called “genetic erosion” - in fact, there is no need to be too professional, that is, everyone only grows the
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