(ORDO NEWS) — When a hungry year is issued, a cautious animal should bring as few offspring as possible in order to successfully feed them and not lose resources.
However, red squirrels seem to go against this logic by playing the “evolutionary lottery”.
Every four to seven years, forests in Canada experience a bountiful year when spruce branches burst with cones full of nourishing seeds.
At this time, there is enough food for everyone. And a few months before the “spruce boom” begins, red squirrels bring offspring that can feed on spruce seeds and prepare for a harsh winter.
However, having studied the breeding strategies of several dozen female squirrels, the researchers found that among these animals there are “optimists” and “pessimists”.
“Optimists” bring numerous offspring every year, regardless of the amount of food in the environment, and “pessimists”, on the contrary, are cautious and leave few squirrels.
It would seem that the “pessimists” have more chances to survive, because the “spruce boom” happens quite rarely, but a long-term study showed that this is not the case.
Although in rare cases red squirrels live up to seven years, their average lifespan is three and a half years, so the optimistic animal may not live to see the next spruce boom.
However, if the female refuses to bring numerous offspring every year, she may miss the chance to “hit the jackpot” when the “boom” does happen and there is enough food for all the squirrels.
In other words, despite the risk of losing offspring every year and remaining in poor physical shape after costly reproduction, in the long run, “optimistic” proteins turn out to be more successful than their “pessimistic” relatives.
Nevertheless, the persistence of two alternative breeding strategies in the populations of these animals proves that in the event of unforeseen changes in the environment (for example, when the “spruce boom” does not come for a long time), the “pessimists” may also have a chance to win back.
So far, scientists cannot say how squirrels choose one or another breeding strategy, but they suspect that this is due to their feeding on spruce shoots throughout the year.
Since squirrels cannot bear offspring immediately after the “boom” (they need a month to bear squirrels, and for almost two more months the babies will feed on their mother’s milk), they “monitor” the condition of the trees so that a few months before the possible abundance begins to risk for the jackpot or beware of high stakes.
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