Friday, December 9, 2011

Survival Strategies

Six inches of rain fell during two days of steady showers leaving considerable surface flooding across the flat Arkansas Delta. Broad fields, harvested recently, became shallow lakes. The North wind blew crop debris of twigs, stems, and leaves to form long bands of floating vegetative matter. Numerous dinner plate sized masses of fire ants floated on these rafts of ground-up soybean plants shown in today’s photo. Fire ant colonies, which live underground, were being transported to dry ground on floating crop debris. Not only were the fire ants being saved from drowning by their huddling on floating matter, they were also expanding their range across open fields.

Honey bees expand their range through swarming, usually in the spring but to a lesser extent in the summer and fall. When the bees swarm, the colony divides; half of the bees stay behind, and half of the bees fly away. Sometimes all of the bees in a colony abandon their hive and fly away in a move called “absconding.” Bees will abandon their hive if the nest gets badly damaged, as when flooded or overrun and “slimed” by small hive beetles. At times, bees abscond during times of extreme dearth. Honey bees in the tropics tend to abscond more often than bees in more temperate areas. Tropical bees don’t have the need to store great amounts of honey to survive the winter. Seasonal changes in tropical nectar and pollen flows vary with rain and drought. During a dearth of nectar, tropical bees will abscond and move to areas where flowers are blooming. Honey bees in temperate areas survive by hoarding honey to provide food and energy for the winter. Each of these behaviors by ants or bees illustrates a heritable survival strategy which allows the insects to survive in a changing environment. Two studies hint at the mechanisms for the inheritance of survival traits: looks at methods of fighting viruses, and reveals how lizards learn to avoid fire ants.

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