Birds of paradise, biogeography and ecology in New Guinea: a review
Birds of paradise, biogeography and ecology in New Guinea: a review
Birds of paradise, biogeography and ecology in New Guinea: a review
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
920 M. Heads<br />
throughout, say, Melanesia <strong>and</strong> Australasia might be the<br />
result <strong>of</strong> a recent range expansion. However, two endemic<br />
genera, each found through the <strong>New</strong> Gu<strong>in</strong>ea mounta<strong>in</strong>s,<br />
but one compris<strong>in</strong>g different species <strong>and</strong> the other not, may<br />
well be the result <strong>of</strong> the same phase <strong>of</strong>, for example, early<br />
Tertiary evolution. Taxonomic diversity or dist<strong>in</strong>ctiveness<br />
is proportional neither to the age <strong>of</strong>, nor the time <strong>in</strong>volved<br />
<strong>in</strong>, the group's orig<strong>in</strong>.<br />
The second factor Frith & Beehler cited <strong>in</strong> expla<strong>in</strong><strong>in</strong>g why<br />
some widespread birds <strong>of</strong> <strong>paradise</strong> are diverse is the dispersal<br />
ability <strong>of</strong> local populations, although no examples are given.<br />
The difference between groups that do speciate <strong>and</strong> those that<br />
do not probably has more to do with the different genetic<br />
potentials <strong>of</strong> the ancestral populations. To be expressed, this<br />
potential may need to be exposed to a phase <strong>of</strong> geological<br />
change <strong>and</strong> physiographic <strong>and</strong> ecological dynamism, for<br />
example a period <strong>of</strong> orogeny or terrane accretion.<br />
If the concept <strong>of</strong> dispersal/migration is de®ned broadly as<br />
`any <strong>and</strong> all changes <strong>of</strong> position', it is clear that evolution<br />
should be <strong>in</strong>cluded as a key component <strong>of</strong> dispersal, as the<br />
evolution <strong>of</strong> a form can by itself br<strong>in</strong>g about the distribution<br />
<strong>of</strong> the form. In periods <strong>of</strong> allopatric evolution dispersal as<br />
physical movement can be replaced with a concept <strong>of</strong><br />
dispersal as evolution. In this view, evolution is not seen as a<br />
morphogenetic <strong>and</strong> biogeographical radiation from a monophyletic<br />
po<strong>in</strong>t centre <strong>of</strong> orig<strong>in</strong>, <strong>and</strong> from a s<strong>in</strong>gle, monomorphic,<br />
ancestral species (or even a parent pair). Rather, it<br />
is a process work<strong>in</strong>g on broad geographical <strong>and</strong> phylogenetic<br />
fronts by phases <strong>of</strong> modernization (cf. Kerr, 1997) <strong>of</strong> already<br />
widespread ancestral complexes. (Mayr, 1982; while not yet<br />
accept<strong>in</strong>g this Croizatian idea, regarded it as a `completely<br />
legitimate hypothesis'.) This view implies that evolution<br />
operates ma<strong>in</strong>ly by parallel development <strong>of</strong> characters,<br />
which is clearly seen <strong>in</strong> the Paradisaeidae ± recomb<strong>in</strong>ation<br />
<strong>of</strong> characters <strong>in</strong> the genera has been referred to <strong>in</strong> Semioptera<br />
<strong>and</strong> Seleucidis. In another case, Frith & Beehler (1998)<br />
referred to the `remarkable phenomenon' <strong>of</strong> geographically<br />
<strong>and</strong> morphologically parallel variation <strong>in</strong> the adult females<br />
<strong>of</strong> Lophor<strong>in</strong>a superba <strong>and</strong> Parotia carolae, with the western<br />
populations <strong>of</strong> the two species be<strong>in</strong>g `extremely similar'<br />
(Beehler et al., 1986). Parallel evolution <strong>of</strong> taxa (which may<br />
be cladistically monophyletic, with `uniquely' derived characters)<br />
means that descendant taxa can have the same range<br />
as an ancestral taxon. The range <strong>of</strong> Paradisaeidae, for<br />
example, could have been <strong>in</strong>herited more or less directly<br />
from a preparadisaeid ancestral complex.<br />
Naturally a degree <strong>of</strong> range expansion <strong>and</strong> contraction is<br />
constantly occurr<strong>in</strong>g, <strong>and</strong> <strong>in</strong> certa<strong>in</strong> periods many taxa enter<br />
a phase <strong>of</strong> mobilism. This may have been the case <strong>in</strong> <strong>New</strong><br />
Gu<strong>in</strong>ea <strong>and</strong> <strong>New</strong> Zeal<strong>and</strong> dur<strong>in</strong>g the Oligocene mar<strong>in</strong>e<br />
transgressions <strong>in</strong> downwarped bas<strong>in</strong>s where many new,<br />
shift<strong>in</strong>g coastl<strong>in</strong>es became available for colonization. However,<br />
there is no evidence <strong>of</strong> this be<strong>in</strong>g important for most<br />
birds <strong>in</strong> geologically recent times. On the contrary, the<br />
current distributions <strong>of</strong> the vast majority <strong>of</strong> <strong>New</strong> Gu<strong>in</strong>ea<br />
birds, <strong>and</strong> all the birds <strong>of</strong> <strong>paradise</strong> <strong>and</strong> bowerbirds, seem to<br />
be the result <strong>of</strong> a phase <strong>of</strong> modernization ma<strong>in</strong>ly <strong>in</strong>volv<strong>in</strong>g<br />
vicariant phylogenesis.<br />
It is suggested that populations <strong>of</strong> birds <strong>of</strong> <strong>paradise</strong>,<br />
sedentary forest dwellers with small home ranges but<br />
tolerant <strong>of</strong> disturbance, have been caught <strong>in</strong> the dramatic<br />
geological uplift <strong>and</strong> downwarp<strong>in</strong>g <strong>of</strong> different parts <strong>of</strong> the<br />
<strong>New</strong> Gu<strong>in</strong>ea orogen, lead<strong>in</strong>g to speciation, distributional<br />
breaks <strong>and</strong> disjunctions, <strong>and</strong> altitud<strong>in</strong>al anomalies. The<br />
ancestral complex <strong>of</strong> Paradisaeidae, Ptilonorhynchidae <strong>and</strong><br />
other Corv<strong>in</strong>ae may have <strong>in</strong>cluded birds <strong>of</strong> the mangrove<br />
<strong>and</strong> associated vegetation (back-mangrove, swamp forest,<br />
drier secondary vegetation) some <strong>of</strong> which have been<br />
str<strong>and</strong>ed <strong>in</strong> central Australia follow<strong>in</strong>g mar<strong>in</strong>e transgressions<br />
(Ptilonorhynchidae) <strong>and</strong> others uplifted <strong>in</strong> <strong>New</strong> Gu<strong>in</strong>ea<br />
dur<strong>in</strong>g Tertiary orogeny (Ptilonorhynchidae <strong>and</strong> Paradisaeidae).<br />
The entire sequence: mangrove ± subalp<strong>in</strong>e forest is<br />
occupied by Manucodia comrii.<br />
Populations currently juxtaposed on very narrow terranes<br />
or sets <strong>of</strong> terranes may not always have been so close<br />
together, as the <strong>in</strong>dividual terranes may have travelled<br />
hundreds or even thous<strong>and</strong>s <strong>of</strong> kilometres before dock<strong>in</strong>g.<br />
Furthermore, <strong>in</strong> <strong>New</strong> Zeal<strong>and</strong> <strong>and</strong> <strong>New</strong> Gu<strong>in</strong>ea several<br />
accreted terranes have been substantially narrowed by<br />
subduction, fault<strong>in</strong>g <strong>and</strong> erosion subsequent to their formation,<br />
some to just slivers, <strong>and</strong> L<strong>and</strong>is & Blake (1987)<br />
suggested that terranes hundreds <strong>of</strong> kilometres wide may<br />
have disappeared from with<strong>in</strong> the <strong>New</strong> Zeal<strong>and</strong> region.<br />
These vanished terranes would have supported liv<strong>in</strong>g communities,<br />
some <strong>of</strong> which would have transferred to<br />
encroach<strong>in</strong>g terranes <strong>and</strong> given rise to modern plants <strong>and</strong><br />
animals. The slight differentiation between Paradisaea r.<br />
rudolphi <strong>and</strong> P. r. margaritae (Fig. 30), for example, may<br />
<strong>in</strong>dicate a deeper structure, a biological <strong>and</strong> geological faultl<strong>in</strong>e<br />
where populations <strong>of</strong> the birds <strong>of</strong> one terrane have been<br />
grafted onto the birds <strong>and</strong> l<strong>and</strong>scapes <strong>of</strong> another.<br />
Simply because a bird is widespread through <strong>New</strong> Gu<strong>in</strong>ea<br />
on many terranes does not mean this is the result <strong>of</strong> dispersal<br />
from one terrane to another after terrane sutur<strong>in</strong>g. The<br />
taxon might have been widespread before the terranes came<br />
together, as even if the terranes were hundreds <strong>of</strong> kilometres<br />
apart they probably already shared some taxa. There are<br />
many questions concern<strong>in</strong>g the biogeographical relationships<br />
among populations <strong>and</strong> taxa <strong>of</strong> terranes such as the<br />
Jimi, F<strong>in</strong>isterre <strong>and</strong> Owen Stanley terranes, or between areas<br />
on the craton such as the Mimika/Setekwa Rivers, <strong>and</strong> the<br />
areas north <strong>of</strong> the craton.<br />
Biogeographical analysis is not concerned primarily with<br />
the terranes as strata, even less as centres <strong>of</strong> orig<strong>in</strong>, but<br />
rather as tectonic <strong>in</strong>dicators. For example, the lithological<br />
differences between the shelf sediments <strong>of</strong> the craton <strong>and</strong> the<br />
deeper water sediments <strong>of</strong> the Aure Trough probably have<br />
little direct effect on the vegetation, but the dist<strong>in</strong>ct tectonic<br />
histories <strong>of</strong> the two regions as revealed by lithology <strong>and</strong><br />
structure are <strong>of</strong> great signi®cance.<br />
Similarly, the currently exposed strata <strong>of</strong> <strong>in</strong>trusive <strong>and</strong><br />
metamorphic terranes were obviously not colonized by<br />
plants <strong>and</strong> animals as they formed, as this happened beneath<br />
the earth's surface. However, these rocks <strong>in</strong>dicate phases <strong>of</strong><br />
revolutionary physiographical change dur<strong>in</strong>g which plants<br />
<strong>and</strong> animals had ample opportunity for evolution. Later, the<br />
Ó Blackwell Science Ltd 2001, Journal <strong>of</strong> Biogeography, 28, 893±925