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


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.