Biology Reference
In-Depth Information
rats arrived on their island. We realized that we had to consider all the different causes of rar-
ity to better understand which species would be likely to persist without much conservation
effort. We needed to know which species had always been rare but were now facing even
lower numbers, a more limited range, or a new invader.
Some of the more promising places to look for the causes of rarity and of patterns of rarity
and abundance are where there are no people. A remote mountainous region of New Guinea
with no history of human visitation, the locale of chapter 2, offers a good venue to investig-
ate the extent of rarity under natural conditions. By comparing what we discover there with
what is found in other ranges where local tribes have access, we can begin to answer sever-
al fundamental questions about how rarity is created and what pattern exists where humans
have had no perceivable influence. New Guinea also offers a rewarding glimpse of how ex-
treme isolation and active geology can lead to rarity and a narrow range of resident species.
In contrast, another area with low human activity, the Peruvian region of Madre de Dios, the
locale of chapter 3, illustrates a condition that exists for many tropical rarities, from jaguars
to canopy trees—a wide range of species living at extremely low densities.
The string of insults to nature brought about by human activities covers a staggering range
including habitat loss, poaching and the consumption of body parts of rare creatures, intro-
duction of diseases and invasive predators, expansion of agriculture to feed a growing human
population, and the horrors of war. In this topic I examine these human-induced causes of
rarity, along with many natural influences, in a journey that spans most continents. In the nat-
ural world, the causes of rarity are often difficult to pin down or isolate to a single source. To
untangle these strands, in each chapter that follows I sample different manifestations of rarity
and consider probable causes and consequences for species and the ecosystems they inhab-
it. Much can be done in the short term to preserve species populations. Ultimately, though,
the future of many species depends on our ability to live in greater harmony with the rare
creatures among us. In Bhutan, the setting of chapter 9, where Tibetan Buddhism is the dom-
inant religion and cultural conservation is part of the fabric of society, we see how rare spe-
cies can persist and recover when humans coexist peacefully with wildlife and treat rare spe-
cies with respect and compassion.
What is in store for rare species? Looking backward and examining evolution's finger-
prints may provide some clues. The renowned ecologist Gordon Orians has noted that natural
selection, as an evolutionary process, lacks foresight. It can't look ahead to help a species
best adapt to a threat to its future survival, be it next year or several centuries or millen-
nia hence. Thus, all the current traits and behavioral responses we see in such species as the
maned wolf, the giant anteater, the rhinoceroses, and the Kirtland's warbler—all protagon-
ists in this story—were shaped in their predecessors' environments. Yet some of those traits,
even if selected for other reasons, may enhance persistence when a species becomes rare or,
if it has always been rare, faces even more dramatic threats to its survival. Phrased another
