Wallace lines in eastern Gondwana : palaeobiogeography of Australasian permian brachipoda

The present Australian continent was a major component of the north eastern peninsula of Gondwana, itself the southern region of Pangaea, during the Permian period. Surrounding what is now Australia, were additional elements of north eastern Gondwana that are now incorporated into the tectonically complex regions of New Zealand, New Caledonia, the island of New Guinea, Timor, south east Asia, the Himalaya and southern Tibet. India was to the west and south west and Antarctica to the south. Marine water temperatures ranged from cold to temperate and tropical as Permian global climates ameliorated, global surface ocean circulation systems warmed, and due to rifting and northward drifting of some terranes.

Provincialism of global marine faunas was pronounced during the Permian and hence refined biostratigraphical correlations are often fraught with difficulty. The 'middle' Permian stratotypes approved by the International Subcommission on the Permian System have little direct relevance to correlations within the Gondwanan Region at the level of operational biostratigraphical zonal schemes. Brachiopoda are a dominant marine benthonic faunal element of Permian Gondwanan faunas and they provide refined correlations between marine basins within a specific faunal province. Modem faunal provinces are recognised by the distribution patterns of species and genera belonging to a single family or superfamily such as the Papilionoidea within the Insecta. This review provides an example from Permian Brachiopoda, using the distribution data of genera and subgenera of the superfamily Ingelarelloidea, in order to demonstrate the ability to define provinces and their 'Wallace lines' of demarcation between provinces in the geological past.

Reciprocal natural selection on host‐parasite phenotypes

Coevolution is evolution in one species in response to selection imposed by a second species, followed by evolution in the second species in response to reciprocal selection imposed by the first species. Although reciprocal selection is a prerequisite of coevolution, it has seldom been documented in natural populations. We examined the feasibility of reciprocal selection in a simple host‐parasite system consisting of feral pigeons (Columba livia) and their Ischnoceran feather lice (Phthiraptera: Insecta). We tested for a selective effect of parasites on hosts with experimentally altered defenses and for a selective effect of host defense on a component of parasite escape. Previous work indicates that pigeons control lice through efficient preening, while lice escape from preening using complex avoidance behavior. Our results show that feral pigeons with impaired preening, owing to slight bill deformities, have higher louse loads than pigeons with normal bills. We use a controlled experiment to show that high louse loads reduce the survival of pigeons, suggesting that lice select for efficient preening and against bill deformities. In a reciprocal experiment, we demonstrate that preening with a normal bill selects for small body size in lice, which may facilitate their escape from preening. The results of this study verify a crucial element of coevolutionary theory by identifying likely targets of reciprocal phenotypic selection between host and parasite.