Conservation genetics of a rare Gerbil species: a comparison of the population genetic structures and demographic histories of the locally rare Pygmy Gerbil and the common Anderson's Gerbil

<p>Abstract</p> <p>Background</p> <p>One of the major challenges in evolutionary biology is identifying rare species and devising management plans to protect them while also sustaining their genetic diversity. However, in attempting a broad understanding of rarity, single-species studies provide limited insights because they do not reveal whether the factors that affect rare species differ from those that affect more common species. To illustrate this important concept and to arrive at a better understanding of the form of rarity characterizing the rare <it>Gerbillus henleyi</it>, we explored its population genetic structure alongside that of the locally common <it>Gerbillus andersoni allenbyi</it>. We trapped gerbils in several locations in Israel's western and inner Negev sand dunes. We then extracted DNA from ear samples, and amplified two mitochondrial sequences: the control region (CR) and the <it>cytochrome oxidase 2 </it>gene (CO2).</p> <p>Results</p> <p>Nucleotide diversity was low for all sequences, especially for the CR of <it>G. a. allenbyi</it>, which showed no diversity. We could not detect any significant population genetic structure in <it>G. henleyi</it>. In contrast, <it>G. a. allenbyi</it>'s CO2 sequence showed significant population genetic structure. Pairwise PhiPT comparisons showed low values for <it>G. henleyi </it>but high values for <it>G. a. allenbyi</it>. Analysis of the species' demographic history indicated that <it>G. henleyi</it>'s population size has not changed recently, and is under the influence of an ongoing bottleneck. The same analysis for <it>G. a. allenbyi </it>showed that this species has undergone a recent population expansion.</p> <p>Conclusions</p> <p>Comparing the two species, the populations of <it>G. a. allenbyi </it>are more isolated from each other, likely due to the high habitat specificity characterizing this species. The bottleneck pattern found in <it>G. henleyi </it>may be the result of competition with larger gerbil species. This result, together with the broad habitat use and high turnover rate characterizing <it>G. henleyi</it>, may explain the low level of differentiation among its populations. The evidence for a recent population expansion of <it>G. a. allenbyi </it>fits well with known geomorphological data about the formation of the Negev sand dunes and paleontological data about this species' expansion throughout the Levant. In conclusion, we suggest that adopting a comparative approach as presented here can markedly improve our understanding of the causes and effects of rarity, which in turn can allow us to better protect biodiversity patterns.</p

Jack of All Trades, Master of All: A Positive Association between Habitat Niche Breadth and Foraging Performance in Pit-Building Antlion Larvae

Species utilizing a wide range of resources are intuitively expected to be less efficient in exploiting each resource type compared to species which have developed an optimal phenotype for utilizing only one or a few resources. We report here the results of an empirical study whose aim was to test for a negative association between habitat niche breadth and foraging performance. As a model system to address this question, we used two highly abundant species of pit-building antlions varying in their habitat niche breadth: the habitat generalist Myrmeleon hyalinus, which inhabits a variety of soil types but occurs mainly in sandy soils, and the habitat specialist Cueta lineosa, which is restricted to light soils such as loess. Both species were able to discriminate between the two soils, with each showing a distinct and higher preference to the soil type providing higher prey capture success and characterizing its primary habitat-of-origin. As expected, only small differences in the foraging performances of the habitat generalist were evident between the two soils, while the performance of the habitat specialist was markedly reduced in the alternative sandy soil. Remarkably, in both soil types, the habitat generalist constructed pits and responded to prey faster than the habitat specialist, at least under the temperature range of this study. Furthermore, prey capture success of the habitat generalist was higher than that of the habitat specialist irrespective of the soil type or prey ant species encountered, implying a positive association between habitat niche-breadth and foraging performance. Alternatively, C. lineosa specialization to light soils does not necessarily confer upon its superiority in utilizing such habitats. We thus suggest that habitat specialization in C. lineosa is either an evolutionary dead-end, or, more likely, that this species' superiority in light soils can only be evident when considering additional niche axes

Small mammal studies in natural and manipulated shortgrass prairie

Reports contain information of a preliminary nature, prepared primarily for the internal use of the IBP Grassland Biome Program.January 1977.On cover: Grassland Biome, Ecosystem analysis studies, U.S. International Biological Program.Includes bibliographical references