Rock hyrax

Procavia capensis

Our primary model is the wild rock hyrax (Procavia capensis) in the Ein Gedi Nature Reserve, which Lee has studied since 1998. Hyraxes are highly social, living in groups that consist of both sexes, with female dominance. Female testosterone is as high as males’, yet they reproduce annually, nursing multiple offspring for up to a year. Hyraxes are diurnal, facilitating behavioral observations. As a graduate student, Lee developed tools to visually mark hyrax and record their social, agonistic, maternal, and vocal behaviors. Projects in this system have involved sexual selection, social status and stress, social and sexual networks, maternal behavior, and acoustic communication. Prof. Eli Geffen (Tel Aviv University) and Dr. Amiyaal Ilany (Bar Ilan University) are collaborators in this system.

Baluchistan gerbil

Gerbillus nanus

We study the wild Baluchistan gerbil (Gerbillus nanus) in the Sheizaf Nature Reserve in the Arava Valley. Gerbils were live-trapped, individually marked, measured, and filmed. Molecular tools are used to quantify parentage, hair-testing to measure steroids, immunological tools to quantify infections, and behavioral methods to mark and observe this nocturnal species in the wild. These tools allow us to address multiple ecological, immunological, and endocrinological questions. Our collaborators on the different projects are Prof. Allan Degen, Dr. Michael Kam, Prof. Burt Kotler, Prof. Boris Krasnov, Dr. Irina Khokhlova (Ben Gurion University), Prof. Eli Geffen (Tel Aviv University), Prof. Aharon Friedman, Dr. Enav Bar-Shira (Hebrew University).

Nutria

Myocastor coypus

Nutria (Myocastor coypus) are invasive in the Hula valley. They show fluctuating sex ratios across groups and years, with males bigger than females throughout life. Females in good condition selectively abort small litters that are predominantly female, and quickly reconceive a litter bearing numerous small females or a few large males. The current culling program allows us to collect a large number of pregnant females, and through detailed necropsies examine the relationship between maternal hair testosterone and offspring sex ratios. We also measure fetal steroids using hair samples grown in utero during the second trimester, to study the contribution of maternal and sibling steroid levels to individual fetuses, and the effects of testosterone on reproduction and fetal survival. The nutria projects are in collaboration with Dr. Yoni Vortman (Tel-Hai Academic College) and Prof. Uri Shanas (University of Haifa - Oranim).

Humans

Homo sapiens

Although difficult to monitor and study, we have several projects on human sociality, reproduction, and sex ratios. Human hair grows at an average rate of 1cm per month. This allows hair segmentation, and measurement of steroid levels backdating to the time targeted by the study (e.g., fetal conception, war, exams, etc.). Through collaborations with psychologists, sociologists, medical doctors, and hospitals at large, we address key questions in behavioral ecology and sociobiology, such as the effect of steroids on birth sex ratios and fetal outcomes, social behaviour, learning, attention, maternal, and attachment behaviors.

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