# Shared Flashcard Set

## Details

NEU Ecology Fall 2013 Lec set 7
Lec set 7 flashcards
23
Environmental Studies
11/06/2013

Term
 Predation, competition, herbivory and disease are all species interactions which can influence what?
Definition
 Population growth
Term
 For a specific generation type, we say that each female has a life span of 1 year and 1 viable breeding season and that they produce R0 female offspring that survive to breed the following year. What is this generation subtype called?
Definition
 Discrete generation
Term
 R0Nt = what?
Definition
 Nt+1 (the net reproductive rate, or number of female offspring produced per female per generation, times the population size of females at a generation t when mutliplied give the population size of females at generation t+1)
Term
 What is important about R0 being greater than or less than 1?
Definition
 If R0 is less than one, the population will decrease in size and will eventually go extinct
Term
 What is so important to note about the equilibrium point, where R0=1.0?
Definition
 The birth rate equals the death rate (the population is perfectly stable)
Term
 The deviation from the equilibrium plot can be expressed as z=N-Neq. What do these values mean?
Definition
 z: deviation from equilibrium density N: observed population size Neq: equilibrium population size
Term
 1-Bzt (where B equals the slope of the deviation line and z equals the deviation from equilibrium density at a given time t) is another way to express what?
Definition
 R0
Term
 This value (obtained from multiplying B and Neq) tells us what type of population growth we can expect with discrete generations and certain values of B and Neq
Definition
 L -If 0
Term
 What is the instantaneous rate of population growth?
Definition
 r=b-d where r = per-capita rate of population growth
Term
 What does the equation rN=(b-d)N express and what are its components?
Definition
 It is the curve of geometric increase. N: population size r: per-capita rate of population growth b: instantaneous birth rate d: instantaneous death rate
Term
 Because the presence of other organisms can limit the fertility and longevity of others, what do we often see in population growth graphs?
Definition
 We often see a sigmoid (S-shaped) or logistic curve
Term
 What does the equation dN/dt=rN((K-N)/K) calculate and what do its terms mean?
Definition
 It produces a logistic curve and takes into account the carrying capacity, K, of the organism
Term
 What is the key distinction between geometric and logistic growth?
Definition
 There is no resource limitation in the case of geometric growth
Term
 What did Gause show with his Paramecium studies with respect to the logistical growth model?
Definition
 He showed that under a stable environment, the paramecium species follow a generally good logistical growth pattern
Term
 What was a key issue in Pearl's (1927) argument that logistic growth is a law? (Hint: he studied Drosophilia which were fed by yeast)
Definition
 Sang (1950) criticized his use of yeast since yeast is itself a growing and changing organism so the food source for the flies was not kept constant. He also only counted grown adults whereas both adults and larvae feed on yeast
Term
 What interesting theory did Pearl and Reed generate in 1920 regarding the US population?
Definition
 It would reach a carrying capacity of about 197 million people around 2060
Term
 What is the theta logistic model and how does it theoretically operate?
Definition
 It relaxes the assumption that population growth rate decreases linearly as density increases; rN((K-N)/K) becomes r(1-(N/K)theta)
Term
 Under the theta logistic model, 78% of population growth curve had a theta value less than 1. What does this mean?
Definition
 When populations are below K, their growth rate is low and is also low relative to that predicted by normal logistic curves
Term
 What do time-lag models say about animals and their population growth models?
Definition
 R0 at a generation t may not depend on density in that generation but in the generation before that (t = -1)
Term
 In the time-lag model, how is the equation Nt+1=R0Nt impacted?
Definition
 This equation now becomes Nt+1=(1-Bzt-1)Nt
Term
 How do the L values change for time-lag models of population growth?
Definition
 If 01.0, the stable limit cycles or there is divergent oscillation to the point of extinction
Term
 What interesting facet has been discovered from experiments on the zooplankton Daphnia with regards to time delay models?
Definition
 Daphnia raised at high temperatures showed continuous over and undershooting of its equilibrium density
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