Evolution, 4th Edition

SUGGESTioNS FoR FURTHER READiNG

The Evolution of Life Histories, by S. C. Stearns

(oxford University Press, oxford, 1992), and

Life History Evolution, by D. A. Roff (Sinauer

Associates, Sunderland, MA, 2002), are com-

prehensive treatments of the topics discussed

in this chapter. Among theoretical treatments,

Evolution in Age-structured Populations, by

Brian Charlesworth (Cambridge University

Press, Cambridge, UK, 1994, is a key reference.

See Robert D. Holt, “Evolution of the ecological

niche” (pp. 288–297 in The Princeton Guide to

Evolution, edited by J. B. Losos, Princeton Uni-

versity Press, Princeton, NJ, 2014) for an out-

standing introduction to this topic. The most

comprehensive treatment of the evolution of

niche width is by D. J. Futuyma and G. More-

no, “Evolution of ecological specialization”

(Annu. Rev. Ecol. Systemat. 19: 207–233, 1988).

A more recent review, focused mostly on her-

bivorous insects, is “Revisiting the evolution

of ecological specialization, with emphasis on

insect-plant interactions,” by M. L. Forister and

colleagues (Ecology 93: 981–991, 2012).

PRoBLEMS AND DiSCUSSioN ToPiCS

1. Female parasitoid wasps search for insect hosts
   in which to lay eggs, and they can often dis-
   criminate among individual hosts that are more
   or less suitable for their offspring. Behavioral
   ecologists have asked whether or not the wasps’
   willingness to lay eggs in less suitable hosts var-
   ies with the female’s age. on the basis of life his-
   tory theory, what pattern of change would you
   predict? Does life history theory make any other
   predictions about animal behavior?


2. Suppose that a mutation in a species of annual
   plant increases allocation to chemical defenses
   against herbivores, but decreases production
   of flowers and seeds (i.e., there is an allocation
   trade-off). what would you have to measure in a
   field study in order to predict whether or not the
   frequency of the mutation will increase?


3. in many species of birds and mammals, clutch
   size is larger in populations at high latitudes than
   in populations at low latitudes. Species of lizards
   and snakes at high latitudes often have smaller
   clutches, however, and are more frequently
   viviparous (bear live young rather than lay eggs)
   than are low-latitude species. what selective fac-
   tors might be responsible for these patterns?


4. Compared with most other mammals, primates
   and bats have lower fecundity and a later age at
   first reproduction. why might that be?
   5. Shrimps of the genus Pandalus mature as males
   but later in life change into females. The shrimps
   are commonly fished with nets that tend to
   capture large individuals. How do you predict
   that these shrimps will evolve in response to the
   selective removal of the largest and oldest indi-
   viduals in their populations?
   6. Suppose you are studying an organism that
   shows strong signs of declining health and
   reproduction late in its life. what are two
   hypotheses that could explain this drop in fit-
   ness? How might you distinguish between them
   experimentally?
   7. why are species of weedy plants more likely to
   be r-selected than K-selected? why are most
   species with large body size K-selected? what
   other general patterns of lifestyle are associated
   with either r- or K-selection?

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