Elephant tales

I received email alerts for two stories from CNN.com today that taken together present an almost paradoxical picture of humanity’s effect on the natural world as manifested through the biology and ecology of one of Earth’s most intelligent, most unique, and certainly its largest land animal. The first was an almost humorous account of an elephant in India that effectively robs motorists at tusk-point for food as they pass its stretch of highway (I say “almost” humorous because such regular and close encounters between large animals and people rarely end up well for one if not both). This situation really captures the continual encroachment of civilization upon the wildlife habitat, and the adaptations that animals must make if they are to survive that encroachment. However, the second story reported the discovery of an intact, isolated elephant population on an island in the swamps of southern Sudan, where they have avoided poaching and other disturbance during Sudan’s long civil war, reminding us that pockets of true wildness do still exist.

This pair of elephant stories reminded me of a superb article I’d read a few months ago in the New York Times magazine about the profound psychological and behavioral changes being induced in elephants by drastic disruption of the age structure, sex ratio, and social hierarchy of the herd. The article reveals shockingly complex capacity for teaching, learning and emotional responses in these amazing animals. And this raises an important point about the impacts we are having on the natural world: There is far more to animal conservation than simply population size and extinction risk. Elephants show us that beyond simple numbers of individuals, population structure and behavior are key determinants of success, and those are not the only key factors.

Australian researchers have recently shown that climate change is altering the fundamental demographic processes underlying the dynamics of marine fish populations (I had to get back to fishes somehow...), with deep-dwelling species exhibiting slower growth and species in shallower waters exhibiting faster growth. Neither fast growth nor slow growth is inherently better or worse, as growth is tied in with a wide array of other demographic traits (mortality rate, maturation, fecundity, spawning frequency, etc) and ecological factors to maximize the reproductive success of a species. Whether these alterations to the growth of fishes will compromise reproduction remains to be seen. But if these effects primarily represent a response to temperature, then they should not be permanent, or at least the species should retain the genetic resilience to adapt to changing conditions. That is, as long as we are not also draining the genetic gene pool. Sadly, it appears that we may be doing just that: Researchers at Stony Brook University have shown how fishing pressure can act as a remarkably strong agent of (non-)natural selection, potentially causing an irreversible loss of genes that reduce the adaptability of a population. Eroding the foundational genetic basis for the ecological success of a species is a truly frightening prospect.