Birds of paradise, biogeography and ecology in New Guinea: a review

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896 M. Heads anomaly¼ nowhere else in the world is there, over a similar distance, so great a difference in plant and animal life'. Of the 906 Àustralo-Papuan' bird species, 566 occur in the New Guinea region and 531 in Australia (Keast, 1961), although the latter is ten times greater in size. In a similar way, tectonically complex Colombia has as many bird species and subspecies as Brazil, although Brazil is 7.5 times the area of Colombia (Dugand, 1948). Rallidae, Columbidae, Psittacidae, Alcedinidae, Muscicapidae and Pachycephalidae all have roughly 50% more genera in New Guinea than in Queensland (Pratt, 1982), for example, there are eight genera of parrots in New Guinea that are not in Queensland. Likewise Ziegler (1982) wrote that it is `surprising' just how few of the many indigenous New Guinea mammals also occur in Australia. Conversely, Ziegler observed that the bat family Megadermatidae is in Australia and the Moluccas, but is ìnexplicably' absent on the New Guinea mainland. The apparent absence of birds of paradise from most of Australia and Indonesia is complemented by the concentration there of the families Sibley & Ahlquist (1990) proposed as the relatives of Paradisaeidae: Artamidae (including Cracticidae and Grallinidae) (wood swallows and butcherbirds) range from India to Australia (most species), New Guinea, New Britain and Fiji. Oriolidae (orioles) occur in Africa and Eurasia (Oriolus), and Australia and PNG (Oriolus and Sphecotheres). New Guinea has four species, but three are restricted to the south coast and only one is widespread. Campephagidae (cuckoo-shrikes; included with Oriolidae by Sibley & Ahlquist) are distributed from Africa through southern Asia to the Paci®c, with the main bulk of the seventy-two species occurring west of New Guinea: Indonesia west of Irian Jaya has twenty-seven species, New Guinea ®fteen, and Australia four. The Corvidae (crows and jays; twenty-six genera) are notably poorly represented in Australia (only ®ve species of Corvus L.) and New Guinea (only three species of Corvus), again indicating vicariance of a global ancestor. There are as many as six genera of Corvidae in Indonesia. The Callaeidae, a relic New Zealand group with three monotypic genera, has often been placed with these families, although Sibley & Ahlquist (1990) listed it as ìncertae sedis'. In a similar, well-known example, the order Casuariiformes comprises two families, Casuariidae (cassowaries) mainly in New Guinea, and Dromaiidae (emus) in Australia. Casuariidae has thirteen subspecies in New Guinea, three on the Aru Islands, two on Japen Island and one on each of Moluccas, New Britain, and northern Queensland. Fossils are known from the Northern Territory. Dromaiidae has one subspecies in each of NW and W Australia, SW Australia and E Australia. There is no need to invoke any dispersal by migration from Australia to New Guinea or vice versa to explain the distribution of Paradisaeidae and Artamidae, or Casuariidae and Dromaiidae, only simple vicariance around a Torres Strait node (Heads, 1990). As Mayr (1953) noted: `The independence of birds from habitat restrictions leads to the remarkable phenomenon that the nearest relatives of many birds of the central Australian brush savannas and semi-deserts are found in the steaming lowland or the misty mountain forest of New Guinea¼'. Similarly, Taylor (1972) described Australia and New Guinea as `separate evolutionary epicentres' for insects. The two faunas are strongly autochthonous at species level, and Àustralia may be viewed as a producer of semi-arid adapted species, New Guinea as a producer of moist-adapted species'. Again, in this vicariance model there is no need to invoke any dispersal by physical movement between Australia and New Guinea to explain the main pattern. Schodde & Calaby (1972) summarized the history of biogeographical ideas on the region, writing that: Ìn recent years [in fact since the time of Wallace and Matthew] there has been an almost universal preoccupation with successive waves of colonization to explain the present composition and distribution of the whole Australo-Papuan land bird and mammal fauna'. Schodde & Calaby were highly critical of what they called this `simplistic' idea ± they suggested that it has resulted from the `super®cial ease' with which immigration can be invoked, and rests on the `shaky notion' that biotas `must have moved because the continents could not'. Instead, Schodde & Calaby cited data favouring the view that the elements of the great arc of rainforest ¯ora and fauna stretching through montane New Guinea and E Australia are òld, autochthonous and co-inherited by Australia and New Guinea' (cf. Webb et al., 1986). The age of the profound Australia/New Guinea difference is as controversial as the mode of its origin. Discussing the tree family Sapindaceae, Turner (1995) wrote that the basal split between taxa of E Australia and New Guinea `suggests that the vicariance between these two regions may be older than the often suggested period of post-Pleistocene rise in sea-level¼'. Likewise, Zweifel (1985) saw `no reason' for assuming that the initial vicariant event separating Australian and New Guinea microhylid frogs occurred as recently as the Pleistocene. Torres Strait has traditionally been seen as either a bridge for, or a barrier to dispersal, and has caused confusion as it seems to be a `bridge' in some groups but a `barrier' in others with similar ecology and means of dispersal. However, if `dispersal' in the broadest sense of àny change in position' is often a result of evolution, rather than physical movement, the Torres Strait region is neither bridge nor barrier, but a zone of biogeographical articulation and a centre of endemism in its own right. In the same way, the Weyland Mountains/Wissel Lakes in the west of New Guinea and the Bismarck Fault Zone/Kratke Mountains in the east are not bridges or barriers to dispersal for birds of paradise and others, but represent areas around which allopatric evolution has taken place. Similarly, birds of paradise and bowerbirds (traditionally, but probably incorrectly, allied with Paradisaeidae) are absent from the northern islands fringing New Guinea (Biak, Manam, Karkar and the Bismarck Archipelago), not because they are unable to ¯y there, or were there and went extinct, but because their early Tertiary ancestors did not live in the region. Instead, these Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925
Biogeography of birds of paradise 897 ancestors were concentrated on the lands and islands around the craton margin which later became consolidated and uplifted as the New Guinea orogen. The different regions of the orogen are discussed next, starting in the west. The northern Moluccas Terranes in the Moluccas may form a western extension of the New Guinea orogen (Pigram & Davies, 1987). Birds of paradise are represented in the northern Moluccas by two unrelated monospeci®c genera, Lycocorax Bonaparte and Semioptera Gray. This outpost of the family is à bit of an anomaly' for Frith & Beehler (1998) who explained it as the result of overwater dispersal. However, although Frith & Beehler (1998) wrote that Manucodia Boddaert, sister group of Lycocorax, shows a `propensity for colonizing islands', they immediately followed this by writing `We hypothesize that Lycocorax is an island vicariant that evolved from what was a widespread form that gave rise to both Lycocorax and the genus Manucodia'. This second view is supported here; there is no need to propose `colonizing ¯ights' across modern geography by birds already recognizable as Manucodia or Lycocorax. The pre-Lycocorax + Manucodia widespread ancestral complex may itself have `reached' the Moluccas, again, not by physical movement but by vicariant evolution out of a more or less global assemblage of pre-Corvidae/Paradaisaeidae/Artamidae/Oriolidae. For the `very aberrant' Semioptera, Frith & Beehler (1998) suggested that its weirdness and remarkable morphological divergency are `deceptive', and might simply be the result of à very small founding population'. Nevertheless, according to Frith & Beehler it has one set of characters linking it to Ptiloris Swainson and another linking it to the Paradisaea lineage. Stochastic òver-water dispersal', even with `founder effects', is hardly likely to result in this arrangement ± it would more likely result in Semioptera having one obvious ancestor. It is simpler to account for the distribution by a vicariance event in which the characters of a widespread ancestral complex have been recombined to give Semioptera in the Moluccas, and the Paradisaea and Ptiloris lineages further east. Despite their presence in the northern Moluccas, birds of paradise are absent from the southern Moluccas. In fact the fauna of the southern Moluccas is quite different from that of the northern islands ± many widespread Indonesian species occur on the southern islands without being in the north, while many New Guinea groups such as Paradisaeidae are represented in the northern islands only (White & Bruce, 1986). Likewise, Michaux (1994) cited four mammal species in the northern Moluccas and New Guinea, but not in the southern Moluccas. Many taxa show differentiation between the northern and southern Moluccas, in the marsupials for example, Phalanger orientalis (Pallas) is in the southern Moluccas (and Timor ± New Guinea), while P. ornatus (Gray) and P. rothschildii Thomas are endemic in the northern Moluccas (Flannery, 1994). It is striking that there are only two genera of Paradisaeidae in the Moluccas and that they are so distinctive, unlike the Australian species which all have congeners in New Guinea. Geological and biological evolution focused along the New Guinea orogen may have been responsible. The following birds, like the two endemic bird of paradise genera, illustrate the status of the Moluccas as a biogeographically independent centre: In Megapodiidae, Megapodius wallacei Gray, sometimes treated as a monotypic genus Eulipoa Ogilvie-Grant, is a Moluccas endemic (Fig. 5), vicariant with Macrocephalon MuÈ ller to the west and Aepypodius Salvadori in the east to the Huon and Papuan Peninsulas. Similarly, Ninox squamipila (Bonaparte) (Fig. 6) of the Moluccas and Tanimbar Islands (with a disjunct race on Christmas Island south of Java, 3000 km to the west) is sandwiched between N. perversa Stresemann in the west and N. theomacha Bonaparte to the east. The cuckoo shrikes Coracina papuensis Gmelin, C. parvula (Salvadori) and C. atriceps (MuÈ ller) (Campephagidae) (Fig. 7) form a concentric series of species around Halmahera (cf. Lycocorax enclosing Semioptera, which is not on Morotai or Obi Islands). The Moluccas are also interesting as a centre of absence. Acanthizidae, for example, are widespread from Malaysia and the Philippines to New Zealand (with Gerygone, etc.) and while they closely surround the Moluccas, they do not occur there (Ford, 1986). Other taxa present in both Indonesia and New Guinea but not on the Moluccas include the pigeon Gallicolumba, the tree Stemonurus Bl. and the liane Phytocrene Wall. (Sleumer, 1971). The western limit of birds of paradise on the Moluccas is far from being an ànomaly' (Frith & Beehler, 1998). The Moluccas show very clear faunistic links with New Guinea and form the north-western limit of many New Guinea/ Australasian taxa. Casuariidae reach their western limit in the southern Moluccas (Seram), while birds with a western Figure 5 Three genera of Megapodiidae: Macrocephalon, Megapodius wallacei Gray ( ˆ the monotypic Eulipoa): Moluccas, Misol; and Aepypodius (east to the Saruwaged and Owen Stanley Mountains). Ó Blackwell Science Ltd 2001, Journal of Biogeography, 28, 893±925
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Birds of paradise, biogeography and ecology in New Guinea: a review

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