Oh, where do I begin? I tend to fixate on a particular species that catches my fancy for some reason, and try to learn everything about it. If a species has no economic value – positive or negative – and isn’t of conservation concern, there is seldom very much research on it. I’m probably an expert on several such species, to the extent that “expert” can apply to a species that has been neglected due to lack of interest, but I doubt that I will ever know which ones.
One bigger question that has come to mind lately is the flipside of invasive species: of all the species transported to new continents and planted out or released, only a relatively small proportion become invasive. There has been considerable research on what characteristics make a species likely to become invasive; but I wonder why don’t most species have those characteristics? To put it another way, why are most species NOT invasive when transported to a new area, even if it has a similar climate to their native range? With all the plantings of oleander, for example, all over California – including different colored cultivars, which must, therefore, be genetically distinct – why don’t we find little wild oleanders popping up in neglected, shrubby spots?
A related question is why do we have genera with a few widespread species and many localized species? The genus Rattus has 64 extant species, but only three – Rattus rattus, Rattus norvegicus, and Rattus exulans – have spread across the world and become pests.