Population Demography

Life history tradeoffs.
• Reproductive female red deer on Scottish island have lower survival rates than non-reproductive females of same age

•Adult kestrels (sparrow hawks) have better survival if their broods are artificially reduced, and poorer survival if the broods are artificially enlarged. Fig 52.6, Campbell 6 Fig. 52.7, Campbell 7

Demography and Population Dynamics
November 17 2006 Announcements • we’re now 1 lecture behind; I hope to catch up next time
by combining two lectures on species interactions • No class Friday Dec. 8. Review session scheduled for Monday Dec. 11, 6-7:30 pm 2050 VLSB--come with questions

See Fig 52.5 Campbell 6

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Population biology
• Demography: study of how the vital rate of individuals (birth, death, growth) affect structure and dynamics of populations • Population: group of potentially interbreeding individuals (same species, co-occur in time and space) – Properties of populations: • Density: number of individuals per area or volume • Size structure: proportion of individuals in various size categories • Age distribution: proportion of individuals in various age categories 3 • Sex ratio: number Males: number Females

Life Tables
• Life (and reproductive) table—summary of age (or size) specific rates of survival and fecundity (progeny per individual) • Constructed by following cohort: a group of individuals of the same age, from birth until they all die (or by other methods that approximate this ideal approach) .

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Cohort life table (assume all are reproductive): ax - number surviving at time x lx – proportion original cohort alive at time x mx – fecundity of individual at age x lx mx – number of progeny contributed per original individual at time x

•Survivorship curve: proportion of numbers in a cohort still alive at age X. (Fig. 52.3, Campbell)
1000 Number of survivors
Type II. Squirrels, birds Type I. Humans

Basic Reproductive Rate Ro = ! lx mx Ro is sum of progeny produced per original...