Power5_LifeHistories - 1 Ectotherms rely on external...

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Unformatted text preview: 1 Ectotherms: rely on external sources of heat to regulate temperature; Endotherms: use their own metabolic heat production to regulate their body temperature. Heterotherms 2 Temperature-Time “Degree Days” • Temperature governs rates of development and growth in ectotherms (microbes, invertebrates, plants, amphibians, reptiles, fish) – Insect hatches – Tree bud burst and flowering, fruiting times • Temperature may serve as a cue for seasonal life cycle events (e.g. emergence of aquatic insects, flowering, migration ). 3 The life history bottleneck for both fish is whether the young of the year can grow large enough to survive their first winter. Northern limit with high food Northern limit with low food Where starvation presently affects bass population Current range perch bass Northern range expansion of bass and perch predicted under climate warming scenarios 4 Phenology Phenology : the study of periodic plant and animal life cycle events that are influenced by environmental changes, especially seasonal variations in temperature and precipitation driven by weather and climate. http://www.windows.ucar.edu/citizen_science/budburst 5 Ecological Significance of Body Size Homeostasis : maintaining an internal state with a narrower (and physiologically more favorable) range of conditions than the external environment Surface:Volume ratios decrease with size, so less heat or water loss, osmoregulation (maintaining salinity balance) easier More metabolic reserves in larger organisms, so can maintain homeostasis longer through periods of stress or resource deprivation 6 Velocity (cm s-1 ) Depth (cm) Boundary layer Free-...
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This note was uploaded on 04/01/2008 for the course BIO 1B taught by Professor Carlson,mischel,power during the Fall '07 term at Berkeley.

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Power5_LifeHistories - 1 Ectotherms rely on external...

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