Molecular Panbiogeography of the Tropics

Jurassic primates, immobile ducks and other oddities: a reply to Heads’ review of The Monkey’s Voyage

“…Emphasising the implausibility of Heads' approach even further, Swenson et al (2012, p. 530) noted that the point estimate derived from the tectonic calibration for Abrotanella places the origin of Asteraceae 'at a time when the biosphere was nearly exclusively populated by microscopic marine organisms. ' Similarly, Heads' scenario for the historical biogeography of primates (Heads 2010(Heads , 2012a; see Goswami and Upchurch 2010 for a detailed critique) assumes that crown-group primates are c. 180 million years old, more than 120 million years older than the oldest fossils for the group (O'Leary et al 2013;Benton et al 2015), and this, again, renders the correlation between first appearance and branching order for primates and deeper branches coincidental. For instance, in Heads' scenario, the fact that several early branches in the mammalian tree, such as monotremes and marsupials, are represented by fossils much older than any primate fossil has nothing to do with the actual ages of the involved groups, because all of them were already in existence at the time.…”

“…289). Here, and for the ancestors of oceanic island taxa in general, Heads (2011Heads ( , 2012a envisioned ancestral metapopulations in which the individual populations may be on separated islands, but are connected to each other by normal dispersal. When islands become too widely separated, for example, because of submergence of some of them, metapopulations are fragmented and the now truly isolated parts are free to diverge.…”

“…However, the old Hawaiian groups just mentioned are estimated to have separated from continental relatives between 10 million years ago and 30 million years ago (Garb and Gillespie 2009;Givnish et al 2009;Russo et al 2013;Haines et al 2014), thus refuting the involvement of Mesozoic or Early Tertiary islands. Heads (2011Heads ( , 2012a) also invoked terranes accreted to or subducted beneath North America, but these areas are substantially older than even those just mentioned, and, thus, are even less plausibly tied to the current Hawaiian biota.…”

“…A key point is that the nearby former lands that are the appropriate age to account for the origins of these various old Hawaiian lineages are much fewer and farther between than Heads (2011Heads ( , 2012aHeads ( , 2014c would have people believe. These possible source areas include the older islands in the Hawaiian chain, the Line Islands, and hypothetical islands within the formations mentioned above that formed after the main volcanic events had created the bulk of those formations.…”

“…Heads is among a minority of biogeographers who believe, on the one hand, that LDD is not an important process, and, on the other hand, that all or nearly all disjunctions must be explained by some form of vicariance (Heads 1985(Heads , 2005(Heads , 2009(Heads , 2010(Heads , 2011(Heads , 2012a(Heads , 2014b. In Heads' case, these beliefs derive directly from the panbiogeography of Croizat (1958Croizat ( , 1962, and, especially, the claim that an objective examination of distribution patterns reveals the dominance of the fragmentation and conglomeration of areas as biogeographic processes.…”