Soundings: Competition helps drive the world on every level
It’s a dog-eat-dog world out there – the competition’s unreal.
Competition, not just between individuals – dog vs. dog, cat vs. cat – but also between species – insects vs. humans, for instance – both eat the same grains, fruits, vegetables.
There’s even competition among organs in our bodies.
We can eat and digest only so much food, providing only so much energy and raw materials for construction and repair. The brain hogs a fourth of the available energy; our other organs and muscles split up what’s left.
To avoid internecine (mutually destructive) competition, the body apportions its resources, shutting systems down when shortages arise. Women runners, for instance, may stop menstruating – burning so much energy, they lack enough resources to both nurture a fetus and keep themselves healthy.
Summers at Bridgeport State Park are graced by a charcoal-gray butterfly that flashes a blue iridescence on its hind wings. Even as she flits from one type flower to another for nectar, the female Pipevine Swallowtail lays her eggs on just one plant: Dutchman’s Pipe (its flowers resemble old-fashioned pipes), aka California Pipevine.
California pipevine is inedible to most animals – it’s toxic. Not only can the Pipevine Swallowtail caterpillar tolerate this toxin (allowing it to eat the plant without competition), it sequesters the toxin, and itself becomes inedible.
Pipevine Swallowtails lays their eggs on California Pipevine, and Pipevine only.
California Pipevine grows where it does – central and Northern California, into southern Oregon – because it “likes” the climate.
Suppose the climate were to change – grow warmer, or drier, or both. Pipevines in the southern parts of its range – the warmest and driest parts – might succumb.
Fortunately, plants can migrate – not by pulling out their roots and walking, but by spreading their seeds hither and yon. With a warming and drying climate, plants germinating to the north of their usual range may find the new lands more to their liking.
Dependent on the plant for food, Pipevine Swallowtails would need to follow.
A butterfly’s body, like that of all insects, is divided into three parts. The head explores the environment, finds food, solves problems.
Behind the head is the thorax – the “belly.” Attached to the thorax are the legs and wings. The thorax (“belly”) also houses the muscles that move the legs and wings.
Rear-most is the abdomen – the “butt” – housing the critter’s reproductive organs.
Insects “want” to lay lots of eggs – to have lots of offspring. Allocating resources to the abdomen – growing a large “butt” – enables a female to lay lots of eggs.
Insects also need to put their offspring where they can survive. Allocating resources to the thorax – the flight muscles – enables the female to keep up with the migration of the food plants her offspring need.
Over the past decades, entomologists (insect scientists) have been watching insect populations migrating north, following their food plants.
Measured the belly-to-butt ratios of the “pioneers” – the insects leading the migration – they find these animals are putting a large proportion of their resources into flight … meaning they’re not laying as many eggs as they would otherwise.
They’re keeping up with their food plants. But there’s a catch.
Because they’re focusing so much on flight – and on the genes that bestow good flight capabilities – the pioneers are not bringing all the genes of their species with them.
The pioneer population is less biodiverse … and a diversity of genes is the best defense against future change … change that might not require flight, but some other capability … a capability that might have been lost in the course of this forced migration.
Alan Stahler trained as a biologist and is an amateur astronomer. He teaches private enrichment classes for students of all ages. His science programs can be heard at noon on alternate Tuesdays on KVMR-FM (89.5).
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