Squamate metabolic rates decrease in winter beyond the effect of temperature

The reptilian form of hibernation (brumation) is much less studied than its mammalian and insect equivalents. Hibernation and brumation share some basic features but may differ in others. Evidence for hypometabolism in brumating reptiles beyond the effect of temperature is sporadic and often ignored. We calculated the standard metabolic rates (SMR, oxygen uptake during inactivity), in winter and/or summer, of 156 individuals representing 59 species of Israeli squamates across all 17 local families. For 32 species, we measured the same individuals during both seasons. We measured gas exchange continuously in a dark metabolic chamber, under the average January high and low temperatures (20°C and 12°C), during daytime and nighttime. We examined how SMR changes with season, biome, body size, temperature and time of day, using phylogenetic mixed models. Metabolic rates increased at sunrise in the diurnal species, despite no light or other external cues, while in nocturnal species the metabolic rates did not increase. Cathemeral species shifted from a diurnal-like diel pattern in winter to a nocturnal-like pattern in summer. Regardless of season, Mediterranean species SMRs were 30% higher than similar-sized desert species. Summer SMR of all species together scaled with body size with an exponent of 0.84 but dropped to 0.71 during brumation. Individuals measured during both seasons decreased their SMR between summer and winter by a 47%, on average, at 20°C and by 70% at 12°C. Q10 was 1.75 times higher in winter than in summer, possibly indicating an active suppression of metabolic processes under cold temperatures. Our results challenge the commonly held perception that squamate physiology is mainly shaped by temperature, with little role for intrinsic metabolic regulation. The patterns we describe indicate that seasonal, diel and geographic factors can trigger remarkable shifts in metabolism across squamate species.

The biodiversity of testate amoebae within the Mediteranean region of Israel

The species composition of testate amoebae was studied for the first time in the northern and central parts of Israel. One hundred and eight species and infra-species taxa of Testacea belonging to 18 genera and 10 families were identified in 68 samples. The materials were collected along a transect in the Mediterranean phyto-geographical region of Israel, from Mt. Hermon 2100 m above sea level (part of the Anti-Lebanon Mt. Ridge), to the Sea of Galilee 200 m below sea level to the Mediterranean sea shore near Tel Aviv. All the species identified are Holarctic, most of them cosmopolitan. Some of the sampled testaceans require additional taxonomic studies and are possibly new species endemic to the country. A low α-diversity index was demonstrated for the specimens collected in the humid and swampy habitats, while the majority of the species assemblages, mainly eury-bionts, were similar among habitats.

Environmental effects on molecular and phenotypic variation in populations of Eruca sativa across a steep climatic gradient

In Israel Eruca sativa has a geographically narrow distribution across a steep climatic gradient that ranges from mesic Mediterranean to hot desert environments. These conditions offer an opportunity to study the influence of the environment on intraspecific genetic variation. For this, we combined an analysis of neutral genetic markers with a phenotypic evaluation in common-garden experiments, and environmental characterization of populations that included climatic and edaphic parameters, as well as geographic distribution. A Bayesian clustering of individuals from nine representative populations based on amplified fragment length polymorphism (AFLP) divided the populations into a southern and a northern geographic cluster, with one admixed population at the geographic border between them. Linear mixed models, with cluster added as a grouping factor, revealed no clear effects of environment or geography on genetic distances, but this may be due to a strong association of geography and environment with genetic clusters. However, environmental factors accounted for part of the phenotypic variation observed in the common-garden experiments. In addition, candidate loci for selection were identified by association with environmental parameters and by two outlier methods. One locus, identified by all three methods, also showed an association with trichome density and herbivore damage, in net-house and field experiments, respectively. Accordingly, we propose that because trichomes are directly linked to defense against both herbivores and excess radiation, they could potentially be related to adaptive variation in these populations. These results demonstrate the value of combining environmental and phenotypic data with a detailed genetic survey when studying adaptation in plant populations. This article describes the use of several types of data to estimate the influence of the environment on intraspecific genetic variation in populations originating from a steep climatic gradient. In addition to molecular marker data, we made use of phenotypic evaluation from common garden experiments, and a broad GIS based environmental data with edaphic information gathered in the field. This study, among others, lead to the identification of an outlier locus with an association to trichome formation and herbivore defense, and its ecological adaptive value is discussed.

Holy or Not, Israel is a Palaearctic Biodiversity Hotspot

In their rebuttal to my comment, Roll et al. (2011) defend their original conclusion, by questioning the theoretical framework on which I based my analysis. They stress the importance of the statistical prediction limits and the treatment of latitudinal location as a covariate. They also add an additional grid-cell-based analysis. Here, I claim that even if provincial species-area relationships (SPAR) are not parallel, they are still different. While relying on Roll et al.'s (2011) analyses, I show that for each taxon there is at least one other provincial SPAR that lies considerably above the Palaearctic SPAR, making Palaearctic countries less favorable to be identified as a global biodiversity hotspot. I further claim that prediction limits should not be used to answer the question in focus and that adding latitude as a covariate does not alter the results. Finally, I address the grid-cell analyses of Roll et al. (2011), claiming that Israel's diversity lies mainly in the species turnover between cells (i.e., β diversity) and not on the average species richness within cells (α diversity). Therefore I hold on to my former conclusion that at least for three taxa—birds, mammals, and reptiles—Israel is indeed a Palaearctic provincial hotspot.

Questioning Israel's Great Biodiversity—Relative to Whom? A Comment on Roll et al., 2009

Each evolutionary-independent province has its own mainland species area relationship (SPAR). When using the power law SPAR (S = cAz), separate mainland SPARs are parallel in a log-log space (similar z value), yet they differ in species density per unit area (c value). This implies that there are two main SPAR-based strategies to identify biodiversity hotspots. The first treats all mainland SPARs of all provinces as if they form one global SPAR. This is the strategy employed by Roll et al. (2009) when questioning Israel's high biodiversity. They concluded that Israel is not a global biodiversity hotspot. Their results may arise from the fact that Israel's province, the Palaearctic, is relatively poor. Therefore, countries from richer provinces, whose mainland SPAR lies above the Palaearctic SPAR, are identified as global hotspots. The second strategy is to construct different mainland SPARs for each province and identify the provincial hotspots. In this manuscript I ask whether Israel's biodiversity is high relative to other countries within its province. For six different taxa, I analyzed data for Palaearctic countries. For each taxon, I conducted a linear regression of species richness against the country's area, both log transformed. The studentized residuals were used to explore Israel's rank relative to all other Palaearctic countries. I found that Israel lies above the 95th percentile for reptiles and mammals and above the 90th percentile for birds. Therefore, within the Palaearctic province, Israel is indeed a biodiversity hotspot.

Not so Holy After All

In responses to our paper questioning Israel's great biodiversity, Gavish and Yom-Tov claim that our methods and geographic scope are erroneous, and responsible for our inability to find Israel as diversity hotspot. They maintain that relative to its latitude and realm, Israel is very species-rich. However, our original work corrected for latitude and we highlight the failure of Israel to lie outside the prediction limits of any test in all geographical scopes. We now also analyze richness to test whether realms have parallel slopes in species area curves as Gavish claims and upon which he bases his analysis. We also analyze species richness in the Palearctic realm, calculate prediction limits, and add latitude as a predictor. Moreover, we analyze a new dataset of mammal, bird, and amphibian richness in grid-cells comparing Israeli cell values to the entire world, the Palearctic, and Israel's latitudes. We reject the idea that realms have equal slopes and therefore the Palearctic is not always at a disadvantage compared to other realms. Within the Palearctic realm Israel never lies outside the prediction limits for a country of its area, and adding latitude to this analysis lowered Israel's residual placement. Israel's richness in grid-cells is unexceptional for any taxon at all geographical scopes. In sum, irrespective of the test performed or the geographical region it is compared to, Israel is not a diversity hotspot.