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How Organisms Work Microevolution Adaptations are considered “microevolution” : Change driven by natural selection in terms of shifting environmental conditions. Regulation of water Water moves by osmosis Remember – water follows the salt !! Lets look at Osmoregulation (a Very Big Deal) Balloon in water brackish (neutral) Balloon in salt water Balloon in fresh water Osmolarity 1. Ocean water has about 35 g NaCl per liter of water (and lots of other ions as well) 2. Marine invertebrates & cartilaginous fish have internal osmolarity = surroundings 1. Stenohaline: Lives in a narrow range of salinity variations large changes 2. Euyhaline: Tolerates large salinity changes Osmoregulators: Organisms that maintain Hypoosmotic pressure • Worms and amphibians use the surface of the skin to maintain osmoic pressure • Marine fish teleost (boney) fish are hypoosmotic (lower osmoic pressure inside) – The chloride cells in the gills export Na+ and Cl- ions – Marine mammals produce urine that is more concentrated than their blood Physiological systems Evolve Gills active uptake of ions from cells Skin absorbs water, transport salt out Salt glands expedite the excretion and defecation of salt • Active Transport: transport of a substance against a gradient – Primary ATP dependent mechanism – Secondary ATP generated electrical gradient • Substance is moving down its own concentration gradient • The Sodium and Potassium pump is the most familiar primary active transport system Active transport Terrestrial Animals • Intake of Gas • Water Loss • The water in exhaled air is recovered using countercurrent circulatory systems (cool air holds less moister) Heat Flow In the Gills Countercurrent conserves heat Warm venous blood from muscles provides heat to the cold arterial blood. This limits the amount of heat lost in the extremities. Counter current O2 Exchange 1. Unoxygenated blood from the heart is pumped into the gills 2. Oxygen diffuses from the water to the bloodstream 3. The fish also moves water through the gills in the opposite flow Diffusion is Slow Ram ventilation Water must move continually bringing fresh water with high levels of oxygen to the gills Lungs 1 Lungs 2 • A lung is an invagination of skin to form a respiratory surface • In humans the total surface of are of the lungs is 100 m2 = a tennis court • Counter current exchange works for the flow of oxygen and carbon A fish with fingers? “Fishapod” • It had the scales, teeth and gills of a fish, but also a big, curved rib cage that suggests the creature had lungs as well. • The ribs interlock, moreover, unlike a fish's, implying they were able to bear fishapod's weight—an unnecessary trait in a fish. • It had a neck—most unfishlike. • its pectoral fins included bones that look a primitive wrist and fingers • Lived about 383 million years ago. “Fishapod” from about 383 million years ago. Link • Potassium ions move out of the vacuole and out of the cells, Water moves out of the vacuoles, and the guard cells shrink in size. The stoma closes. • Potassium ions move into the vacuoles, water moves into the vacuoles, guard cells expand • Evaporation of water from the stomata creates a positive pressure upward • The forces of Cohesion & adhesion are central to the effective movement of water through the xylem Transpiration in plants 90-95% water loss is through leaves. Animals transport fluids • Open circulatory systems: • A system in which the circulating fluid is not enclosed in vessels at all times; found in insects, crayfish, some mollusks, and other invertebrates Closed circulatory System • In a Closed circulatory system, gas exchange takes place across thin walls of capillaries – the blood never mixes in a “hemocoel” Physiological systems evolve Evolution of Lungs It is all about surfactants and surface area Surfactants & surface area Evolution: Desiccation • 9000 adults 1000 survivors after 20-60 hours without food or water • After many generations of selection, the fruit flies lost water at 50% of the rate of the controls • Survivors had greater amount of bulk water • Survivors had Increased amounts of long chain hydrocarbons in the epicutical Desicattion 1. Bulk water storage 2. Water resistant outer covering 3. Root system 4. Life history modification Nitrogen Tolerance and waste • Elimination of waste is provides a “peak” at evolution What else can we do to fruit flies? Ammonia adaped fruit flies had more glutamate dehydrogenase Feed more slowly, and were less vigorous foregers Fat is beautiful when starvation is part of life history 1. Starvation resistant flies develop larger reserves of fat in the first four days of adult life. 2. The starvation resistant flies grew faster, and had 40% mass that was lipid (as compared to the 16% lipid in the control group) 3. There is also an association with starvation resistance and longevity. These traits may be genetically connected Energy production Terminology • Catabolism (break down) – Anaerobic metabolism (no oxygen) • Glucose + 2 ADP + Pi 2ATP + Lactate – Aerobic metabolism (with oxygen) • Glucose + 36 ADP 36ATP + 6CO2 + 6H2O • Anabolism (The building up of tissue or fat reserves) Energy Production and Utilization • Ectotherms: The rate of energy intake and loss increases as ambient temperature increases • There is an “optimal temperature for growth” If maintenance costs are lowered, then more energy is used for growth How does one lower maintenance cost in a muscle? • Basal Metabolic rate (BMR): – stable rate of metabolism measured under conditions of minimal stress – At rest, at normal temperature, after fasting • Standard metabolic rate (SMR): – Animals resting and fasting metabolism at a specific temperature (also known as the RMR – resting metabolic rate) • Maximum metabolic rate: – Highest measurable rate under stress and exertion – The ratio of maximum metabolic rate to basal metabolic rate is the factorial aerobic scope • Vertebrates 5-12 • Invertebrates 2-10 (insects are higher) Metabolic rates • Is Longevity related to metabolic rate? Experimental fruit flies population were selected for longevity • There was no difference in metabolic rate • Correlation does not mean cause and effect Cost of transport Part of maintenance is the need for movement. 1. Foraging 2. Escape from predation 3. Mating 4. Raising young 5. Seeking shelter Animals instinctively adjust speed and gait for maximum energy conservation Energy cost is dependent on lifestyle • Aquatic • • • Aerial • • Animals that swim in water spend little or no energy supporting their own weight The high density of water does produce a high drag Flying animals must overcome gravity, making use of aerodynamic lift Terrestrial • The most costly locomotion • The Physiology of Birds • The Pectoral Muscles: The Mechanics of Flight: • The Strategy of Size and Flying Energy and Life Trade offs • Birds in high latitudes lay many egg per clutch. • They spend more energy on fecundity than on competition, • Birds in low latitudes lay fewer eggs per clutch • They spend more energy on competition than on fecundity Chapter 6 • Species concept • Factors that lead to speciation & the types of speciation • Concept of punctuated equilibrium • Concept of extinction • Allopatry • Sympatry • Extinction & mass extinction • Hybridization • Reproductive isolation • Burgess shale • Isolating mechanism Chapter 7 • Life history concept • Semelparous vs iteroparous • Univoltine • Fitness and definitions of fitness • Age structure • Trade off in survival and reproduction • Evolution and aging • Fecundity • Senescence • viability Chapter 8 Physical ecology Temperature and light Q10 Ectotherms and endotherms Limitations of size in terms heat, and gas exchange