older sheep are susceptible to predators due to less agility—adults steeply die off later in life; this is also true for humans! Type 2: individuals in a population with type 2 die at equal rates, regardless of age; the slope is a constant which suggests that the mortality is constant over time —each class has same probability of dying o Birds: (the sparrow and robin): you see steady decline in survivorship overtime until they are all gone by age 6; Ground finches o Mud turtle Type 3: individuals showing type 3 die at a high rate as juveniles and then at much lower rates later in life—an example would be the sea turtles (loggerhead) o Desert shrub: after out of seedling stage, there are very little shrubs left. Then at about 30 years old they have high survivorship until the end o Darwin’s Ground Finch (ex of life table): display type 2 survivorship First 3 bullets points on slide 31 would be given info on test L0 could be subbed for 1 2. Age-Specific Fecundity:
o Fecundity = reproductive capability and is age dependent o Potential fecundity: ignores survivorship o Net Reproductive Rate (R0) : expected # of female offspring produced per female per generation o Complete Life Table o Generation Time (T): mean period of time elapsing between birth of parents and all offspring T= average across all families within the population
The larger the organism, the longer the generation time and vice versa - Predicting Population Growth o R0 = expected number of female offspring produced per female per generation ( net replacement rate); it is the multiplicative growth per generation - R0 is an indicator of growth R0=1 no change; the mother is replacing herself exactly once in her lifetime, so the population will not grow R0 > 1 increase R0 < 1 decrease - N(t+1) = NtR0 - If R0=2, the population would double each generation, known as geometric growth. o Predicting population size at any time in the future: - Lx and bx do not change over time - Scotch pine, black noddy, global human population: examples of J shaped curve (exponential) o Modeling Accelerating Growth - Non-Overlapping Generations: No age structure Annual species Exhibit geometric growth : Nt = NoRo^t - Overlapping Generations: Age structure Exhibit exponential growth : Nt = Noe^rt o r = intrinsic rate of increase, per capita rate of exponential growth. The bigger the r the steeper the curve. o r determines rate of increase; r is also max rate of population growth (r max ) r < 0 exponential decline r = 0 stable r > 0 exponential increase r = ln(R0) --------- T o Intrinsic rate of increase (r) declines predictably with increasing size
Finite rate of per-capita growth: lambda o r is constant through time: No change in vital rates No change in biotic interactions No major change in weather o There are no limiting resources (unlimited resources) o The growth rate of population (r) doesn’t depend on age structure (in the long term) The bigger your size, the longer your generation time and vice versa R0 is multiplicative growth per generation, also known as geometric growth We do we assume when predicting population size? Lx
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