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Sawflies, wasps, bees, and ants. ( EE , pp. 259-275). Eusociality in Hymenoptera ( what role does haplodiploidy play in cooperation?). Half of your genes come from your mother, and half from your father: ( ½ x ½) + (½ x ½) = ½
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Sawflies, wasps, bees, and ants • (EE, pp. 259-275)
Eusociality in Hymenoptera (what role does haplodiploidy play in cooperation?) Half of your genes come from your mother, and half from your father: (½ x ½) + (½ x ½) = ½ You are just as related to your brother or sister as you are to your father or mother. In haplodiploid insects, it's different. The father only has one set of genes to pass along, so the probability that an ant will share the same paternal genes as her sister is 100%. So the degree of relatedness for two sisters is: (1 x ½) + (½ x ½) = ¾ A typical female ant is genetically more closely related to her sister than to her mother or her daughters. Hamilton proposed that this increased the incentive for cooperation, and was one of the factors in leading many of the Hymenoptera down the path to eusociality.
Sex determination (sex determination is by haplodiploidy) • males, produced parthenogenetically from unfertilized eggs, are haploid (path a) • females, produced from fertilized eggs, are diploid (path b) • inseminated females can control the sex of their offspring by withholding sperm - which can result in very biased sex ratios (many more females)
The Formicidae (ants all belong to this single family - first appeared 145-65 mya) • ants are now found everywhere (except Antarctica) and many are major predators, although some are herbivores (e.g. leafcutter ants) • ants are vital in nutrient recycling and plant dispersal - they also move more earth than earthworms • many ants have close associations with plants, which may provide them with homes in the forms of galls or larger domatia (ant homes) an acacia ant (Pseudomyrmex ferruginea) sipping nectar from a bull thorn acacia (Acacia collinsii)
The Apoidea (contains more than 25,000 species of bee, most of which are solitary) • major families include the following... • plasterer and yellow-faced bees (Colletidae) • sweat bees (Halictidae) • mining bees (Adrenidae) • leaf-cutter and mason bees (Megachilidae) • digger, cuckoo, carpenter, bumble and honey bees (Apidae) plasterer bee (Colletes inaequalis) sweat bee (Augochlorini spp.) wool carder bee (Anthidium manicatum)
The Apidae (the bumble and honey bees - about 1,000 species) • bumble bees are hairy and stout-bodied, whereas honey bees are smaller and more slender • females of most species have a specialized pollen carrying apparatus, the corbiculum or pollen basket • members of this family are highly social and live in colonies with a queen, males and sterile worker females European honey bee (Apis mellifera) carpenter bee (Xylocopa spp.)
Bee Defense • many enemies • other insects • vertebrates • pathogens
The waggle dance (conveys information on direction and distance)
The Apidae (early humans collected honey from wild bees) • foragers communicate information about pollen using a round dance (food is nearby) and a waggle dance (farther) • bee keeping goes back to 2000 BC, and the best known honey bee is Apismellifera (now worldwide) • a colony has one queen, 40-80 thousand workers, and a few hundred male or drone bees (they fertilize new queens) European honey bee (Apis mellifera)