Flocks fl fl herds herds of herbivorous mammals

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Unformatted text preview: conspecifics conspecifics Bi Birds form feeding flocks, migrating flocks fl fl Herds Herds of herbivorous mammals Schools Schools of fish Insect Insect aggregations (e.g., monarch butterflies) What What determines group size? What What are benefits and costs? Major benefits of group living Major benefits of group living Improved foraging success Improved foraging success Improved Improved defense against enemies Improved ability to cope with the physical th environment environment Case Case Study – Sonoran Desert Cicadas Cicadas Ta 46 Ta = 46°C – higher than upper lethal than upper lethal Tground = 70°C Tb = 37°C Actively calling during hottest part of day Hyp1 – use microclimates effectively Hyp2 – use evaporative cooling evaporative cooling Feeds on xylem from Feeds on xylem from Mesquite trees Found capable of evaporative cooling Placed in Env Chambers – no access to cool microclimates microclimates Ta = 45.5°C 45.5 Tb = 37 - 42°C 1. Relative Humidity 100% Ta = 45.5°C Tb = 45.5°C 2. Relative Humidity 0% Ta = 45.5°C Tb = 41°C How are results consistent with How are results consistent with evaporative cooling? 2nd group of experiments -Placed humidity sensors above cuticle - As Ta increased rate of water movement increased movement increased - Rate of water loss highest ever of water loss highest ever reported for insect Sonoran desert cicada. Pores 7X size of pore canals located on dorsal located on dorsal mesonotum + connected to special dermal glands via cuticular ducts are involved in water transport to the surface. Cooling of 2-5oC below ambient of 42-45oC....
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