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rmax, generation time and body size Exponential population growth Demographic and environmental stochasticity Optimal reproductive tactics Semelparity versus iteroparity Reproductive effort (parental investment) Expenditure per progeny Parent-offspring conflict Patterns in Avian Clutch Sizes Altrical versus Precocial Nidicolous vs. Nidifugous Determinant vs. Indeterminant Layers Open Ground Nesters Open Bush Nesters Open Tree Nesters Hole Nesters Nest attentiveness and male feeding Flicker egg removal experiment Lecture # 15 8 March 2016 N = 5290 Species Trade-offs between present progeny and expectation of future offspring Iteroparous organism Semelparous organism Patterns in Avian Clutch Sizes Altrical versus Precocial Patterns in Avian Clutch Sizes Altrical versus Precocial Nidicolous vs. Nidifugous Determinant vs. Indeterminant Layers N = 5290 Species Patterns in Avian Clutch Sizes Open Ground Nesters Open Bush Nesters Open Tree Nesters Hole Nesters MALE (From: Martin and Ghalambor 1999) Patterns in Avian Clutch Sizes Classic Experiment: Flickers usually lay 7-8 eggs, but in an egg removal experiment, a female flicker laid 61 eggs in 63 days Great Tit Parus major David Lack Parus major European Starling, Sturnus vulgaris Chimney Swift, Apus apus Seabirds (N. Philip Ashmole) Boobies, Gannets, Gulls, Petrels, Skuas, Terns, Albatrosses Delayed sexual maturity, Small clutch size, Parental care Boobies, Gannets, Gulls, Petrels, Skuas, Terns, Albatrosses Delayed sexual maturity, Small clutch size, Parental care Albatross Egg Addition Experiment An extra chick added to each of 18 nests a few days after hatching. These nests with two chicks were compared to 18 other natural “control” nests with only one chick. Three months later, only 5 of the 36 experimental chicks survived from the nests with 2 chicks, whereas 12 of the 18 chicks from single chick nests were still alive. Parents could not find food enough to feed two chicks and most starved to death. Diomedea immutabilis Latitudinal Gradients in Avian Clutch Size Latitudinal Gradients in Avian Clutch Size Daylength Hypothesis Prey Diversity Hypothesis Spring Bloom or Competition Hypothesis Latitudinal Gradients in Avian Clutch Size Nest Predation Hypothesis Alexander Skutch ––––––> Latitudinal Gradients in Avian Clutch Size Hazards of Migration Hypothesis Falco eleonora Varanus giganteus Evolution of Death Rates Senescence, old age, genetic dustbin Medawar’s Test Tube Model p(surviving one month) = 0.9 p(surviving two months) = 0.92 p(surviving x months) = 0.9x Peter Medawar recession of time of expression of overt effects of a detrimental allele precession of time of expression of the effects of a beneficial allele Age Distribution of Medawar’s test tubes recession of time of expression of overt effects of a detrimental allele precession of time of expression of the effects of a beneficial allele