Biology Reference
In-Depth Information
cold for malaria to complete its life cycle in time, even though a competent vector—this new
species of mosquito—is there.” But if temperatures warm up the mountainsides, the malarial
parasites could survive and infect the birds that used to live above the zone.
New studies show that at least one of the native forest birds is holding its own with the
local strain of avian malaria. A 2007 paper by Bethany Woodworth and colleagues documen-
ted, for the first time, that the 'amakihi seems to be developing some resistance to malaria.
Another, yet untested hypothesis is that the disease is becoming less virulent, a phenomenon
of natural selection that leads some variants of the pathogen to persist and continue to infect
the host. This finding was the result of a large project about ten years ago that found, quite
unexpectedly, that 'amakihis were abundant at some low-elevation sites. Before this study,
the conventional wisdom was that most native birds could not really persist below the “dis-
ease line” due to avian malaria. 'Apapanes also seem to be increasing in abundance at low
elevations. The fecund 'apapane, which can have multiple broods of two or three chicks in a
season—as compared with the 'aki, which typically has one at best—may be evolving faster
to adapt to surviving the disease. Extinction may lurk in the shadow of rarity, but natural
resistance to avian malaria, as is being seen in some species, gives more hope for growing
resilience in others, if it is selected for soon enough. That is a lot to hope for.
On one of our last nights in Hawaii in 2001, David Wilcove and I approached the active
flows of Kilauea to watch the stream of lava rolling into the sea. Under a full moon, we wit-
nessed Kilauea in its fiery adolescence. We hopped over the black, twisted ropes of long-
cooled
pāhoehoe
lava. There was nothing else—everything had been incinerated or buried in
its wake. Many of the tourists scrambling about the lava field, headed for the same destina-
tion, were here for the spectacle—the sight of pieces of lava like fiery ingots dropping into a
cooling sea. A few biologists were also about, snapping photographs, probably for future lec-
tures on plant succession. In a crack in the lava bed, the presumed lecturers gathered around
a pioneer—an
'ōhelo
, a kind of huckleberry—and nearby was a
kūkaenēnē
, whose fruit is a
mainstay of the Hawaiian goose. These plants were establishing themselves in a barren land-
scape, giving organic life a toehold for expansion.
On volcanic islands in the species-rich tropics, a single eruption can wipe out millions
of years of evolution in one moment of frenzy. But without lava flows, there would be no
Hawaiian Islands. The hillside above us bore the scars of old lava streams, some ancient and
long since revegetated, while others were still fresh and simmering. We have no control over
the timetable for the next eruption of Kilauea, or Mauna Loa, or Mauna Kea. But we have
considerable leverage over the timetable for the fate of the remaining honeycreepers, land
snails, and lobelias and for the rest of wild Hawaii. It is in our hands, not just at the mercy of
the gods of the mountains.
