My dissertation research was on natal dispersal in the desert isopod, Hemilepistus reaumuri, carried out at the Mitrani Center for Desert Ecology, in the Negev, Israel. Desert isopods are monogamous, annual crustaceans, which exhibit parental care in the form of feeding and guarding young. Their life cycle is centered around a single-family burrow, which the parents guard and develop, and which provide shelter and access to moist air during Summer days, allowing the isopods to regain the moisture lost during above ground activity. When the young are large enough, they help in digging and guarding the burrow. The parents die late in the Summer, and every Spring, the young from the previous year emerge from their family burrows and travel long distances in search of new sites to start burrows, or to join others in already established burrows. For my dissertation I examined the costs of dispersal, habitat selection, dispersal and orientation behavior, and, as presented in my Allee paper, the role of learning in dispersal and settling behavior in these desert isopods.

A primary goal of the study of natal dispersal is to predict how individual and population dispersal patterns might change as a consequence of habitat loss or change. I wrote a dynamic programming model with and without the use of Bayesian learning to improve estimates of habitat parameters to find (1) the dispersal strategies and (2) the fitnesses of individuals who disperse with and without learning. I then used the model to simulate the dispersal patterns of populations with and without learning in years with different means and variabilities in habitat quality. Whether or not animals learn about habitat quality during natal dispersal can lead to opposite predictions about the population dispersal response to habitat loss or change. Specifically, in the absence of learning, dispersal should increase, as animals search longer distances to locate habitat that they are less likely to find. If animals learn (or have perfect knowledge) they should respond to habitat loss or decline with a reduction in selectivity and reduction in their willingness to disperse. In a manipulative experiment, I showed that Desert isopods do use previous experience to influence their settling decisions. Isopods are more likely to settle in a specific area the greater the perceived improvement in habitat quality. My dissertation research was conducted with the guidance of Hugh Dingle.

In addition to dispersal and animal movement, I am interested in life history evolution and parental investment. I usually combine experimental and modeling approaches to answer behavioral questions. Modeling has led to collaborations with others, involving me with diverse natural systems and questions, such as the decision to forego later reproduction by spiders that care for their young by letting themselves be eaten, the foraging costs of group living in Namib dune spiders that live in aggregations of burrows and trap ants on the surface, and the evaluation of different hypotheses to explain differential migration in birds.

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email: mbbaker@ucdavis.edu