Historical biogeography and modes of speciation across high-latitude seas of the Holarctic: concepts for host – parasite coevolution among the Phocini (Phocidae) and Tetrabothriidae (Eucestoda)

Abstract

Species of Anophryocephalus are host-specific parasites of pinnipeds in the Holarctic. Phylogenetic analysis of 7 species postulates A. anophrys as the basal taxon and A. inuitorum as basal to A. skrjabini; A. arcticensis is basal to A. nunivakensis and A. eumetopii + A. ochotensis (single tree; consistency index = 74.4%; homoplasy slope ratio = 36.45%). Evaluation of host and geographic distributions postulates ringed seals of the Atlantic-Arctic as ancestral hosts, and the Arctic basin as a paraphyletic area with respect to the North Pacific. Cospeciation within this assemblage was dependent on intense isolation of small effective populations of definitive hosts during the late Tertiary and Pleistocene glacial stages. Rapid modes of parasite speciation, compatible with microallopatry and peripheral isolation, appear to have been associated with isolation of pinniped populations in refugial habitats of the Arctic basin and Beringia. The biogeography of host -parasite assemblages among pinnipeds and Alcidae (Charadriiformes) during the Pliocene and Quaternary contrasts in part with the history elucidated for some free-living invertebrate taxa in the Arctic basin.

A Phylogenetic Hypothesis for Species of the Genus Taenia (Eucestoda: Taeniidae)

“…Consequently, speciation is likely to be driven by definitive hosts, whereas ecological continuity and predictability are limited by transmission dynamics linked to the intermediate hosts (Hoberg et al, 1999). This observation and prediction parallels that developed for patterns and processes of speciation within the marine assemblage represented by tetrabothriid cestodes of the genus Anophryocephalus and their pinniped hosts (see Hoberg, 1992Hoberg, , 1995Hoberg, , 1997.…”

The Beringian Coevolution Project: holistic collections of mammals and associated parasites reveal novel perspectives on evolutionary and environmental change in the North

“…Parasites are elegant proxies for understanding contemporary and historical community ecology, biogeography, and the complexity of evolutionary diversification (e.g., Hoberg 1997;Hoberg and Klassen 2002;Nieberding and Olivieri 2007;Hoberg et al 2012aHoberg et al , 2012b. For example, parasites often reveal "cryptic events" that are not apparent from host genetic signatures alone (Hoberg 1995;Wickström et al 2003;Koehler et al 2009a). Processes that unfolded across Beringia through the Quaternary contribute to a general model for exploring the impact of recurrent expansion, geographic colonization, faunal mixing, and host switching in the development and persistence of complex biotas (e.g., Brooks 2008, 2015;Araujo et al 2015;Galbreath and Hoberg 2015).…”

Patterns and processes influencing helminth parasites of Arctic coastal communities during climate change

“…Seabirds and marine mammals that accumulated in these refugia fed on the same available foods. Hoberg (1992Hoberg ( , 1995 and Hoberg & Adams (1992, 2000 suggested that such a situation opened new vistas for colonization of new hosts and thus accelerated speciation via host switching (the Arctic refugium hypothesis). In a way, the present-day conditions of parasites' transmission in the high Arctic are comparable with those in the glacial refugia.…”

“…The modern parasitic fauna of marine mammals and birds of the Arctic areas of the Atlantic and the Pacific formed in the course of the Pleistocene glacial cycles, numbering c. 20 events (Hoberg, 1992(Hoberg, , 1995Hoberg & Adams, 1992, 2000Waltari et al, 2007;Hoberg & Brooks, 2008). The exchange between the faunas of the North Atlantic (NA) and North Pacific (NP) was interrupted during glacials/stadials, but was resumed to some extent during warm interstadials/interglacials.…”

“…In this way, the modern composition of the cestode fauna of marine mammals and birds of NA and NP was determined by transarctic migrations of these hosts. These migrations became possible during some interstadials/interglacials of the Pleistocene (Hoberg, 1992(Hoberg, , 1995Hoberg & Adams, 1992, 2000. Two other factors contributed to this process: the lack of narrow specificity of cestodes to their intermediate hosts, crustaceans and fish (if they serve as second intermediate or paratenic hosts) and the broad transarctic distribution of many of these host species.…”