Biology Reference
In-Depth Information
next chapter. For now, it is simply enough to note that ecological interactions in the New
Guinean rain forests seem to keep many species scarce.
In further conversations with Bruce, I turned to a behavioral trait that intrigued me: the
lack of shyness shown by the wildlife. Could it be a result of evolving in a region with no
large terrestrial predators to stalk them or humans to hunt them? Bruce confirmed my guess
of the relative dearth of predators in this upland forest. So, if large and midsized spotted cats
never cross Wallace's Line and aerial predators are uncommon, then looking up or around is
a distraction from dancing. Bruce concluded, “It makes the forests of New Guinea something
of a peaceable kingdom, friendly to the birds of paradise and bowerbirds.” It may seem as if
Bruce slipped back into sound bite mode again, but not entirely. Nature is replete with star-
vation, disease, intense parasitism, and death from typhoons or drought, even in the Fojas.
His point was simply that here was a place where fierce predators of these birds had less of
an ecological and perhaps evolutionary influence.
In the Foja Mountains, the birds seemed to be common within their narrow range and
tame, whereas the mammals appeared neither common nor tame. Perhaps the explanation
is that some traits selected for in response to encounters with human hunters had persisted
even when such wildlife populations dispersed into new areas. The range of these species of
mammals included areas hunters frequented. Some, such as the six-wired bird of paradise,
changed, reverting to natural boldness in isolation from humans; others, such as tree
kangaroos, which remain shy, seem to have been more resistant to evolving to take advantage
of the absence of human predators. Bruce had invoked what scientists call “the ghost of evol-
ution,” that is, in this instance, the “echo” of past influence of New Guinea-wide hunting
pressure continuing to resound through time, even in the absence of the original hunting pres-
sure, at least for some of the mammals. “What we are actually observing is natural selection
on the local scale in real time, not over thousands of years. Only the stealthy or wary species
survive the hunter's bow, snare, or shotgun when wildlife meets humans for the first time.
It's why some birds of paradise disappear right away near villages.”
Further analysis of some of the other taxa supported the findings on birds of paradise,
bowerbirds, and tree kangaroos. New Guinea is one of the global centers of diversity of
palms, with about 145 species plus 5 new ones discovered by the Beehler team. What were
the patterns of rarity and abundance among palms or orchids or other vascular plants? Was
the pattern here similar to what we expect in other tropical forests: a few abundant tree and
understory shrub species and many other species represented by a few individuals? Was this
true for butterflies as well? Brother Henk van Mastrigt confirmed that for the groups of but-
terflies and moths he collected, the pattern held. Many frogs, too, showed the same basic
pattern as the birds and mammals of the Fojas: a few common species with very limited dis-
tributions, with a number of other frogs that were range limited and had low population dens-
