First of all I understand that not all features in a species have evolutionary advantage. Some features are just random mutations.
With that foreground, here are my two questions :
The jackfruit has all the fruits on the trunk or on a few thick branches near the trunk which is unlike other trees. Is there any evolutionary advantage to this ?
The fruit to tree weight ratio is probably the highest for jackfruit. Any evolutionary advantage for this ?
Is the modern jackfruit tree a result of human selection or is it natural ?
The fruit are so large that if they developed at the ends of the branches they would break off from the sheer weight.
The large size of the fruit is possibly related to the animals that feed on the fruit and thence spread the seeds. As a data point: elephantslovejackfruit. In relation to #1, growing the fruit closer to the trunks prevents damage to the tree itself not only due to the weight of the fruit but also due to the weight of the animals that feed on the fruit. Look at what happens when elephants feed on mango trees.
A little bit of both. Jackfruit are native to India and you can still find them growing in the wild there (Cf. elephants). It’s cultivated throughout South and Southeast Asia.
Mine, too, mainly because I have one of these in my banknote collection. And seeing the redbud on the list made me realize that forsythia is, too. I have a large one in my yard, admire the flowers every year, but until this it never crossed my mind to think of the flowering method to be especially unusual.