Effects of Habitat Fragmentation and Patch Alteration on Desert Lizards
Investigators (most current known information)
The main goal of the study was to evaluate the effects of changing patchiness in arid ecosystems on lizard species. The main specific objectives were to: 1) assess the impact of adding rich patches (created by the Jewish National Fund by harvesting runoff for plantations) on the structure of a lizard assemblage and 2) assess how densities of lizards change across a gradient of human impact that includes habitat fragmentation through suburban development. These objectives were achieved by studying the problem at two different scales: medium (in the Negev Desert, Israel) and large (in New Mexico, U.S.A.).
The number of lizards in the two study areas is similar ¿ 11 in Israel and 10 species of lizards in New Mexico. In both countries, there seemed to be little differences between the treatments in the number of lizard species found. The composition of the species changed though, in both arid zones, when they were subject to anthropogenic activities. In the Negev desert, in Israel, the abundance of the desert species is lower in the enriched patches and that of the Mediterranean species ¿ higher. In New Mexico, the most common lizards found in disturbed sites were the side-blotched lizard and the New Mexico whiptail. The first lizard is widely distributed and does not require a great amount of vegetative cover. The whiptail is a parthenogenetic species (females breed without males) known to occur in a variety of disturbed habitats. Seven out of the 10 species recorded in New Mexico inhabited the Jornada Experimental Range. Some of the species found in this area have very specific habitat requirements such as high amounts of vegetative cover.
In the Negev, the most common species were affected by the perennial cover. In New Mexico, the greatest number of lizards detected was in one of the undeveloped sites, the Jornada experimental range. The lowest number of lizards detected was in the recently developed areas. The trend seems to be that areas having the highest amount of percent plant coverage (but not woody plants) had the greatest number of lizards present. The Jornada had the highest amount of percent plant coverage while the recently developed area had the lowest. Nevertheless, it appears that there was no relation found between plant species diversity and lizard abundance.
Human impacts in both sites do not affect species richness, but they alter species composition. These changes need to be carefully evaluated, because for example, one of the species in the Negev Desert, A. beershebensis, is an endemic and endangered species. This lizard requires special considerations to ensure its survival. It is not found in the planted plots, only in natural ones, and its habitat requirements need to be studied thoroughly.
Articles in Journals
Hawlena, D. and A. Bouskila. 2006. “Land management practices for combating desertification cause species replacement of desert lizards.” Journal of Applied Ecology 43:701-709.
Hawlena, D., R. Boochnik, Z. Abramsky, and A. Bouskila. 2006. “Blue tail and striped body: why do lizards change their infant costume when growing up?” Behavioral Ecology http://dx.doi.org/10.1093/beheco/arl023 Advance Access publication 13 July 2006.
Hawlena, D. A, Bouskila and Z. Abramsky. 2005. Bird's predation or ectoparasite infestation: Manipulative field experiment assessing increased predation effects on parasite infestation. (in press).
Hawlena, D. A, Bouskila and Z. Abramsky. To be eaten or to be parasitised- possible relationship between predation and infestation. (in review).
Hawlena, D. & A. Bouskila. Effects of large scale land management practices on the lizard assemblage in an arid landscape. (in review).
Bouskila, A. and R. Boochnick. 2005. The risk associated with foraging modes: a comparison between Lacertid foragers. Proc. of the Fifth World Congress of Herpetology June 2005. Stellenbosch, Republic of South Africa.
Hawlena, D., A. Bouskila, and Z. Abramsky. 2005. Foraging mode may indicate why growing-up lizards lose their infant costume of blue tail and striped body. Proc. of the Fifth World Congress of Herpetology June 2005. Stellenbosch, Republic of South Africa.
Boochnik, R. and A. Bouskila. 2000. "Resource partitioning between adults and juveniles of the desert lizard Acanthodactylus boskianus" In Proceedings of the joint herpetological meeting of ASIH, HL and SSAR, July. La Paz, Mexico.
Hawlena, D. and A. Bouskila. 2000. "Effect of habitat fragmentation and patch alteration on the northern Negev lizards assemblage" In Proceedings of the joint herpetological meeting of ASIH, HL and SSAR, July. La Paz, Mexico.
Annual meeting of the Zoological Society of Israel. 2000. Effect of anthropogenic patch alteration on the lizard assemblage in arid landscape, December. Ben-Gurion University of the Negev, Beer-Sheva, Israel.
80th annual meeting American Society of Ichthyologists and Herpetologists. 2000. Effects of large scale land management practices on the lizard assemblage in an arid landscape, June. Universidad Autonoms de Baja California Sur, La Paz, Mexico.
Biological Society of Ethiopia and the Linnean Society of London, Ethiopia: A biodiversity challenge. 2000. "Effect of habitat alteration on the lizard assemblage in arid landscape," February. Addis Ababa University, Ethiopia.
Hawlena, D. and A. Bouskila. 2000. "Estimation of the importance of the Hirbet Hasif area for the conservation of the endangered lizard, Acanthodactylus beershebensis." Report prepared for the Forestry Department of the Jewish National Fund, Southern District. Israel. (in Hebrew).
Boochnik, R. 2001. Title? M.S. Thesis. Ben-Gurion University of the Negev. Sede Boker, Israel.
Hawlena, D. 2000. Title? M. S. Thesis. Ben-Gurion University of the Negev. Sede Boker, Israel.
Projects of Third-year Undergraduate Students
Adout, A. 2001. Ben-Gurion University of the Negev. Sede Boker, Israel.
Hawlena, D. 1998. Ben-Gurion University of the Negev. Sede Boker, Israel.
Gil, P. 2000. Ben-Gurion University of the Negev. Sede Boker, Israel.
Salomon, M. 2000. Ben-Gurion University of the Negev. Sede Boker, Israel.
Hawlena, D. 1998. Yoav Livne Award, for the Best Research Project, Department of Life Sciences, Ben-Gurion University of the Negev, June. Israel.