Cophylogeny and disparate rates of evolution in sympatric lineages of chewing lice on pocket gophers

Constraining the Deep Origin of Parasitic Flatworms and Host-Interactions with Fossil Evidence

“…Ituarte et al (2001Ituarte et al ( , 2005) demonstrated a link between igloo-shaped concretions and gymnophallid digenean flatworms, which these authors traced back to 6400 years in the Holocene. Superficially, similar igloo-shaped concretions have, however, also been reported from the Upper Silurian (Liljedahl, 1985(Liljedahl, , 1994Figure 2(d)), but the Paleozoic occurrence of this structure is not consistent with extant host associations of Gymnophallidae, which typically have shorebirds (Charadriiformes) as final hosts (Ching, 1995), although some forms also infest humans as final hosts (Lee and Chai, 2001). The earliest fossils that can be confidently assigned to extant lineages of charadriiform birds are stem-group representative of Alcidae from the Upper Eocene of North America (Mayr, 2011), although older charadriiform-like fossils have been reported from the Lower Eocene of Denmark (Bertelli et al, 2010(Bertelli et al, , 2013.…”

“…Ksepka et al, 2014). The appearance of shorebirds in the Cretaceous or Early Paleogene suggests that the Paleozoic structures were probably caused by a different group of parasites or even epizoa (Liljedahl, 1985(Liljedahl, , 1994 with similar behaviour, although we cannot rule out the possibility that gymnophallids, or closely related (now potentially extinct) taxa or their ancestors, had different life cycles and host associations in the past. Shell pits have so far been traced back only to the Eocene (Ruiz and Lindberg, 1989;Todd and Harper, 2011;Huntley and De Baets, 2015), which is more or less consistent with the presence of gymnophallideshorebird associations ( Figure 2).…”

“…As (blister) pearls and volcano-to igloo-shaped concretions can be induced by intermediate stages of parasitic flatworms (G€ otting, 1974, 1979Lauckner, 1983;Campbell, 1985;Ituarte et al, 2001Ituarte et al, , 2005, their first occurrence in the Silurian (K rí z, 1979;Liljedahl, 1985Liljedahl, , 1994De Baets et al, 2011) might already indicate the presence of derived parasitic flatworms in the Silurian. Pearls and blisters can, however, be caused by a variety of irritants, including other parasites, shell burrowing organisms and inorganic particles (G€ otting, 1974;Lauckner, 1983).…”

“…Pearls and blisters can, however, be caused by a variety of irritants, including other parasites, shell burrowing organisms and inorganic particles (G€ otting, 1974;Lauckner, 1983). The earliest known fossil blister pearls from the Silurian (K rí z, 1979;Liljedahl, 1985Liljedahl, , 1994 and earliest known free pearls from Triassic (Kutassy, 1937;Conway Morris, 1981;Combes, 2001;Geyer et al, 2005;Rouse, 2005;Boucot and Poinar, 2010) are therefore not characteristic for parasitism unless parasitic remains can be found inside of them (De Baets et al, 2011). This is not straightforward since it has been demonstrated that the remains of soft-bodied helminths can be destroyed during the pearl formation process (Lauckner, 1983).…”

“…Shell pits have so far been traced back only to the Eocene (Ruiz and Lindberg, 1989;Todd and Harper, 2011;Huntley and De Baets, 2015), which is more or less consistent with the presence of gymnophallideshorebird associations ( Figure 2). Age: The Silurian occurrence of an igloo-shaped concretion was found in the silicified M€ ollboss 1 fauna from the Halla Formation (previously Halla Beds) of Gotland (Liljedahl, 1985(Liljedahl, , 1994. Jeppsson et al (2006) correlated M€ ollboss 1 with the parvus graptolite biozone and the Ozarkodina bohemica longa conodont subzone 2 as defined by Calner and Jeppsson (2003).…”