This is an interesting piece of research but it is also coloured by mainstream assumptions based on theory. For example, the fact that in the Late Pleistocene the islands were more extensive is assumed to be the result of lower sea levels rather than a redistribution of the ocean waters. The position of the equatorial bulge, for example, may have differed. This is a problem for Ice Age theory that is never mentioned out loud, or only in the inner cloisters. It is known that very little ice was locked up in Siberia and Alaska and a land bridge existed in the Bering Straits. There was a lot of ice in North America and NW Europe south of where it is today but that does not necessarily imply global sea levels were universally lower.
Apart from that the thrust of the research article is that in different situations, when the Phillippines were composed of larger land masses, species evolved that were common to all the islands but during periods when the islands were much smaller they evolved in local ways that differed from island to island. In that respect, species were responding to catastrophic changes in their environments, and appear to have been able to adapt to new situations within a short span of time. One theory of course is that evolution has always done this, evolving into new life forms in response to change in the environment, quickly rather than slowly as in a uniformitarian manner. An interesting read. Go to https://phys.org/news/2022-07-idea-ice-age-species-philippines.html …