Dynamic State Variable Models in Ecology

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   You can order Dynamic State Variable Models in Ecology (C.W. Clark and M. Mangel)
   from Oxford University Press (1 800 451 7556).

   What follows are:

     •Excerpts from reviews

     •Table of contents

     •Examples of student projects done at Florida State Univesity in Winter
     2000, in a course taught by Don Levitan and Alice Winn, when I was the Mote
     Eminent Scholar in Fisheries Ecology at FSU and the Mote Marine Laboratory. I
     had the great pleasure of helping the students formulate the models and
     interpret the results.

   Excerpts from Reviews

   "...[this book] aims to demonstrate the breadth of problems that can be addressed
   by the state-dependent approach, covering such diverse topics as parasitoid
   oviposition, human behavioural ecology, conservation biology, agroecology and
   information models...Over the past 15 years SDM [stochastic dynamic modeling] has
   become an indispensable tool for behavioural ecologists and has been shown to be
   useful in related fields, such as conservation biology and agroecology. It is a
   necessity for scientists to be able to read and understand papers that make use
   of these techniques. Scientists who cannot do this are missing out on significant
   contributions to their field. For those wishing to gain such ability, I
   enthusiastically recommend Clark and Mangel's new book - it is an excellent
   self-teaching text and is highly suitable for students of all abilities"

   Jonathan Newman, Trends in Ecology and Evolution 15:385-386

   Contents

     1 The Basics, 3

     2 Some Details of Technique, 49

     3 Using the Model, 71

     4 Oviposition Behavior of Insect Parasitoids, 82

     5 Winter Survival Strategies, 108

     6 Avian Migration, 139

     7 Human Behavioral Ecology, 161

     8 Conservation Biology, 173

     9 Agroecology, 192

     10 Population-Level Models, 212

     11 Stochasticity, Uncertainty, and Information as a State Variable, 232

     12 Measures of Fitness, 248

     Appendix: Programs available at the

     OUP Web site, 265

     References, 267

     Index, 287

   Student Projects from FSU, Winter 2000

   The Timing of Open (Out-crossed) and Closed (Selfed) Flowers in Violets

   Elizabeth Boyd

   Viola septemloba is a perennial plant with a specialized breeding system in which
   it produces two distinct flower types. The chasmogamous flowers are typical
   flowers that open and have attractive structures and rewards for pollinators. The
   cleistogamous flowers are much smaller flowers that self fertilize without ever
   opening. Previous work has shown that the cleitogamous flowers are much less
   expensive to produce then the chasmogamous flowers and that the progeny of the
   cleistogamous flowers do not suffer from inbreeding depression. Knowing this, the
   question is why does the plant maintain a mixed breeding system that includes
   chasmogamous flowers? There must be some fitness advantage associated with the
   seeds produced by chasmogamous flowers. This fitness advantage may be achieved
   through one of two routes. The short termselection hypothesis is that seeds from
   chasmogamous flowers have an immediate fitness payoff in terms of better
   performance than their cleistogamous counterparts. The long term selection
   hypothesis is that seeds from chasmogamous flowers have more variation in
   genotype than seeds from cleistogamous flowers (which, resulting from selfing,
   are identical),and this variation will allow them to perform better than their
   cleistogamous counterparts in situations of environmental variability.The model
   predicts the values of the fitness advantage of chasmogamous flowers that are
   necessary to maintain mixed breeding for given probabilities of these two types
   of selection.

   Models for Invasion

   Jean Burns

   Models of species invasion have frequently focused on either characteristics of
   the habitat subject to invasion or characteristics of the potentially invasive
   species. Few models have taken both characteristics of the environment and
   characteristics of the invader into account. In this model, I attempt to predict
   what species will become invasive (i.e. persist), given certain characteristics
   of the invader species and certain environmental conditions. I determine optimal
   biomass allocations to reproductive or non-reproductive tissue using backward
   iteration, given a plant's photosynthetic rate as a function of time of year and
   current vegetative biomass. Curves were fit based on data from Baruch and Bilbao
   (1999). Fitness is a product of the vegetative biomass and the photosynthetic
   function, and thus varies with time. The fitness value of allocating to growth is
   dependent on vegetative biomass increasing as a function of some growth constant
   multiplied by the photosynthates produced in a given time step. The value of
   allocating to reproduction is a product of the photosynthates produced and the
   proportion of seeds that are viable plus the fitness value at the given
   vegetative biomass. Determine the optimal decision, grow or reproduce, for each
   month and each possible vegetative biomass. Then use Monte Carlo forward
   iterations to predict fitness (reproductive output) over time, given a
   probability of disturbance, p. Reproductive output depends not only on the
   probability of disturbance (e.g. grazing) but also on the amount of vegetative
   biomass lost in a given disturbance event. Assume that the habitat is homogeneous
   (that there is no spatial variability that you must take into account) and that
   all plants in a given species behave the same way (no genetic variance). Use the
   forward iterations to predict what species will persist in the environment under
   different disturbance pressures (vary p).

   Leaf Structures in Violets

   Ken Moriuchi

   Viola septemloba is a perennial plant that can produce both cordate leaves and
   lobed leaves. The two leaf shapes have different photosynthetic capabilities
   during the different times of the year, because of their capabilities to maintain
   a leaf at the optimal temperature for photosynthesis . Cordate leaves are better
   at conserving heat, and are thus better at maintaining the optimal temperature
   for photosynthesis during the winter. Lobed leaves, in contrast, are better at
   dissipating heat, and are thus better at maintaining the optimal temperature for
   photosynthesis during the summer. Thus, the trade-off is quite clear in that an
   individual plant that maximizes the amount of photosynthates for the current
   environmental condition will do so at the expense of a lower amount of
   photosynthates in the future. I used a dynamic state variable model to determine
   the optimal number and proportion of cordate and lobed leaves produced by an
   individual. Furthermore, plants were given the opportunity to store the resources
   gained during each time step to storage tissue. The effects of leaf turnover and
   herbivory were also investigated. The proportion and number of cordate leaves,
   lobed leaves and units of storage affect the decision to produce a leaf or to add
   the resources to storage. Individuals used the storage option only when the
   maximum number of cordate and lobed leaves was achieved. Leaf turnover did not
   have a large effect on the optimal decisions made. However, herbivory did have a
   large effect on the optimal switch date. With the addition of herbivory, there
   was a general trend to not produce all of one type of leaf or another during the
   time of year when one leaf type would be advantageous over the production of both
   leaf types. The implications of these results are discussed in this paper.

   Environmentally controlled sociality and optimal sex ratios in a facultatively
   social bee

   Sheryl Soucy

   Socially polymorphic bee species, those that exhibit both social and solitary
   behaviors, are important systems for studying the intrinsic and extrinsic factors
   that promote the evolution of sociality. It has been suggested elsewhere that
   sociality in some bee species is facultative, with social behavior induced in
   warm climates, and solitary behavior in cold climates. In this paper, I test the
   idea that a species employing a single algorithm of egg-laying behavior can
   exhibit different social behaviors in response to varying environmental
   conditions. I used a dynamic state variable model to demonstrate that the
   difference between social and solitary behaviors is the ratio of males to females
   in the first brood of the season. Excess females in the first brood will act as
   helpers to increase a gyne's reproductive output in the second brood. If a gyne
   perceives adverse conditions she will produce more males in the first brood. In
   doing so, she forfeits potential high future returns in favor of immediate payoff
   (mated daughters). According to the results of this model, populations that
   experience a short growing season, high mortality, or high incidence of rain
   produce fewer helpers in the first brood than populations experiencing more
   favorable conditions. In areas with a growing season below a critical length, all
   nests exhibit solitary behavior. In short, the facultative nature of sociality
   results from the potential to eliminate the worker brood in favor of producing
   reproductives early in the season under adverse environmental conditions.

   Egg-laying decisions of a molluscan communal breeder

   Cheryl Swanson

   Breeding site selection is an important aspect of life history because it can
   directly affect fitness in terms of offspring survival. Where an organism decides
   to reproduce often depends on a variety of factors. The presence of conspecifics
   may alert individuals to a good quality site, but at high densities, site quality
   may diminish. The apple murex snail, Phyllonotus pomum, is one of a handful of
   marine snails that deposit egg capsules in communal masses. In this extreme form
   of communal breeding, numerous females aggregate to simultaneously lay clutches
   of egg capsules in a single mass. One clutch contains hundreds of egg capsules
   with each capsule averaging 574 eggs (unpublished data). Of these, approximately
   12 develop into juveniles, the rest remain nutritive eggs (unpublished data). The
   3-dimensional communal masses can reach volumes of up to 2.3L (unpublished data).
   Site selection for depositing these capsules, clutches, and masses therefore
   plays a fundamental role in offspring success. A dynamic state variable model may
   be used to examine the tradeoffs associated with egg-laying decisions of communal
   breeders such as Phyllonotus pomum. Site availability is a great concern for a
   sandy bottom habitat dwelling snail that requires hard substrates upon which to
   deposit capsules. P. pomum most commonly uses dead pen shells Atrina rigida or A.
   serrata which are also used for reproduction and shelter by other species of
   fish, snails, and crabs (unpublished data). P. pomum, however, will not deposit
   clutches on inhabited substrate. Encountering uninhabited or non-communal
   substrates may therefore decrease as the season progresses. The presence of
   conspecifics determines opportunities for communal laying as well as the size of
   the masses. Laying clutches in communal masses may be beneficial in diluting the
   risk of predation either to the adult, developing embryos, or both. Because of
   the properties of water flow and oxygen transfer, communal egg-laying may impose
   an added costly tradeoff between the size of a communal mass and successful
   embryo development. The number of clutches a female carries and the time
   remaining in the season will effect the decision of whether to delay, deposit, or
   continue to deposit clutches in the same location with regards to the type of
   substrate encountered. A model incorporating these tradeoffs provides theoretical
   insight on when and how a female apple murex snail should deposit her clutches to
   maximize offspring success.

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References

   1. http://www.soe.ucsc.edu/~msmangel/index.html
   2. http://www.soe.ucsc.edu/~msmangel/pubs1.html
   3. http://www.soe.ucsc.edu/~msmangel/research.htm
   4. http://www.soe.ucsc.edu/~msmangel/cv.htm
   5. http://www.soe.ucsc.edu/~msmangel/training.htm
   6. http://www.soe.ucsc.edu/~msmangel/CSTAR.html
   7. http://www.soe.ucsc.edu/~msmangel/course.htm
   8. http://www.soe.ucsc.edu/~msmangel/religion.htm
   9. http://www.soe.ucsc.edu/~msmangel/consulting.htm
  10. http://www.soe.ucsc.edu/~msmangel/books.htm
  11. http://www.soe.ucsc.edu/~msmangel/miscellaneous.html
  12. http://www.soe.ucsc.edu/~msmangel/index.html
  13. http://www.soe.ucsc.edu/~msmangel/pubs1.html
  14. http://www.soe.ucsc.edu/~msmangel/research.htm
  15. http://www.soe.ucsc.edu/~msmangel/cv.htm
  16. http://www.soe.ucsc.edu/~msmangel/training.htm
  17. http://www.soe.ucsc.edu/~msmangel/CSTAR.html
  18. http://www.soe.ucsc.edu/~msmangel/course.htm
  19. http://www.soe.ucsc.edu/~msmangel/religion.htm
  20. http://www.soe.ucsc.edu/~msmangel/consulting.htm
  21. http://www.soe.ucsc.edu/~msmangel/books.htm
  22. http://www.soe.ucsc.edu/~msmangel/miscellaneous.html