Biology Reference
In-Depth Information
which began in 1958, constitute the longest continuous record of changing atmospheric CO
2
concentrations. Earth's atmosphere mixes globally so that the CO
2
component at Mauna Loa,
where there are few local inputs to the atmosphere, is a good gauge of the overall fraction.
The methods and equipment used to obtain these measurements have remained essentially
unchanged during the five-decade monitoring program. The Mauna Loa record shows a ma-
jor increase in the mean annual concentration of CO
2
, from 316 parts per million by volume
(ppmv) of dry air in 1959 to 385 ppmv in 2010. In short, the increasing amounts of CO
2
in
Earth's atmosphere are real and serious.
Many scientists have warned about the spread of tropical diseases with shifts in climate,
but few have considered its impact on particular species of wildlife, especially rarities. This
is an issue that extends far beyond Hawaii. Species are beginning to head uphill to find cooler
and often wetter refuges, and as the climate warms further, their chances of success are likely
to decline. Shifting one's range up a mountain is especially problematic for organisms other
than birds because of limited mobility options.
We returned to Hilo in time for the opening plenary lecture by David Steadman, an authority
on extinctions in the Pacific region. Part-time comedian and full-time paleontologist, anthro-
pologist, and evolutionary biologist, he related an ecological history that captivated many in
the audience who were new to the region. Steadman projected a map of the Pacific Ocean on
the screen. Pointing out the island groups in the order that they were discovered by Polyne-
sian sailors, he showed that the Hawaiian Islands were among the last. Anthropologists gen-
erally date the first landing on Hawaii by the Polynesians (who hailed from the Marque-
sas Islands) around AD 1200-1300, although some experts set their arrival more than 800
years earlier. The prevailing winds, which skirt the Hawaiian archipelago, had discouraged
human settlement longer than had been the case anywhere else except New Zealand and
Easter Island. After the initial discoveries, several more migrations to the Hawaiian Islands
occurred from Tahiti and elsewhere. Along with them came the normal passengers for colon-
ization and exploration—taro root, bananas, coconut palms, dogs, hogs, and chickens—and
the stowaways, the Polynesian rats.
When Captain James Cook arrived in 1778, the total human population was less than 1
million. But by then the biological effects of the Polynesian invasion were well established
in Hawaii, just as they were wherever else the Polynesians had landed across the Pacific.
Polynesian farming practices involved widespread clearing and burning of the lowlands,
a process that wiped out those species adapted to life along the coast. New information sug-
gests, however, that the Polynesian rat may have played a bigger role in the demise of the
native birds than did land clearing. The naïveté of native birds that had evolved in the ab-
