Uri Roll

On the role of phylogeny in determining activity patterns of rodents

Evolutionary plasticity is limited, to a certain extent, by phylogenetic constraints. We asked whether the diel activity patterns of animals reflect their phylogenies by analyzing daily activity patterns in the order Rodentia. We carried out a literature survey of activity patterns of 700 species, placing each in an activity time category: diurnal, nocturnal, or active at both periods (a-rhythmic). The proportion of rodents active at these categories in the entire order, was compared to the activity patterns of species of different families for which we had data for over ten species each: Dipodidae, Echimyidae, Geomyidae, Heteromyidae, Muridae, and Sciuridae. Activity times of rodents from different habitat types were also compared to the ordinal activity time pattern. We also calculated the probability that two random species (from a particular subgroup: family, habitat, etc.) will be active in the same period of the day and compared it to this probability with species drawn from the entire order. Activity patterns at the family level were significantly different from the ordinal pattern, emphasizing the strong relationship between intra-family taxonomic affiliation and daily activity patterns. Large families (Muridae and Sciuridae) analyzed by subfamilies and tribes showed a similar but stronger pattern than that of the family level. Thus it is clear that phylogeny constrains the evolution of activity patterns in rodents, and may limit their ability to use the time niche axis for ecological separation. Rodents living in cold habitats differed significantly from the ordinal pattern, showing more diurnal and a-rhythmic activity patterns, possibly due to physiological constraints. Ground-dwelling rodents differed significantly, showing a high tendency towards a-rhythmic activity, perhaps reflecting their specialized habitat.

The change in genetic diversity down the core-edge gradient in the eastern spadefoot toad (Pelobates syriacus)

Several hypotheses are available to predict change in genetic diversity when approaching peripheral populations. We used the eastern spadefoot toad in Israel as a model system to examine these hypotheses using population genetics analyses and network theory. Our results contradicted most of the predictions from the ‘abundant centre’ model, that edge populations should have lower density and lower genetic diversity than core populations. Furthermore, dispersal rate between core and peripheral populations is expected to be asymmetric, mostly directed outwards from the core population, but we did not detect such a trend. Our data did not support the hypothesis of no change or a non‐linear change in genetic diversity towards the range edge. However, our results did fit the Fisher (The Genetical Theory of Natural Selection, Clarendon Press, Oxford, 1930) hypothesis, which predicts increase in genetic variability from core to edge of distribution. We attributed this finding to the much harsher climatic and abiotic conditions at the edge, which must be tolerated over generations by both tadpoles and post‐metamorphic individuals in this region. Finally, our results have significant conservation implications for the survival of this species in Israel, where it is critically endangered. We identified two distinct communities, which are genetically linked through two specific rain pools in the Upper Galilee. Details on the spatial subdivision of this species are cardinal for future management and restoration of temporary wetlands in Israel.

Characteristics of the introduced fish fauna of Israel.

Fishes have been introduced worldwide with deleterious effects on various native ecosystems. To gain insight into this phenomenon in Israel, we studied the introduced ichthyofauna. There are 27 species of introduced fishes in the freshwater habitats of Israel, a large number for a nation this size. Ten of these species reproduce in the wild. Most of these fishes were introduced for aquaculture; some are constantly restocked. The proportion of restocked versus established species in Israel is high compared to other regions. New fish introductions continue in recent decades, unlike the global trend. In Israel these species are found in the Jordan Basin, Lake Kinneret (Sea of Galilee), and the coastal plain rivers. A few species are widespread, and most are found in Lake Kinneret. Harmful effects of introduced fishes have been suspected and in several cases demonstrated. We encourage further caution when new introductions are contemplated; in some regions eradication should be attempted.

Modelling the initial phase of an epidemic using incidence and infection network data: 2009 H1N1 pandemic in Israel as a case study

This paper presents new computational and modelling tools for studying the dynamics of an epidemic in its initial stages that use both available incidence time series and data describing the populations infection network structure. The work is motivated by data collected at the beginning of the H1N1 pandemic outbreak in Israel in the summer of 2009. We formulated a new discrete-time stochastic epidemic SIR (susceptible-infected-recovered) model that explicitly takes into account the diseases specific generation-time distribution and the intrinsic demographic stochasticity inherent to the infection process. Moreover, in contrast with many other modelling approaches, the model allows direct analytical derivation of estimates for the effective reproductive number (Re) and of their credible intervals, by maximum likelihood and Bayesian methods. The basic model can be extended to include age–class structure, and a maximum likelihood methodology allows us to estimate the models next-generation matrix by combining two types of data: (i) the incidence series of each age group, and (ii) infection network data that provide partial information of ‘who-infected-who’. Unlike other approaches for estimating the next-generation matrix, the method developed here does not require making a priori assumptions about the structure of the next-generation matrix. We show, using a simulation study, that even a relatively small amount of information about the infection network greatly improves the accuracy of estimation of the next-generation matrix. The method is applied in practice to estimate the next-generation matrix from the Israeli H1N1 pandemic data. The tools developed here should be of practical importance for future investigations of epidemics during their initial stages. However, they require the availability of data which represent a random sample of the real epidemic process. We discuss the conditions under which reporting rates may or may not influence our estimated quantities and the effects of bias.

Modeling and statistical analysis of the spatio-temporal patterns of seasonal influenza in Israel

Background Seasonal influenza outbreaks are a serious burden for public health worldwide and cause morbidity to millions of people each year. In the temperate zone influenza is predominantly seasonal, with epidemics occurring every winter, but the severity of the outbreaks vary substantially between years. In this study we used a highly detailed database, which gave us both temporal and spatial information of influenza dynamics in Israel in the years 1998–2009. We use a discrete-time stochastic epidemic SIR model to find estimates and credible confidence intervals of key epidemiological parameters. Findings Despite the biological complexity of the disease we found that a simple SIR-type model can be fitted successfully to the seasonal influenza data. This was true at both the national levels and at the scale of single cities.The effective reproductive number Re varies between the different years both nationally and among Israeli cities. However, we did not find differences in Re between different Israeli cities within a year. R e was positively correlated to the strength of the spatial synchronization in Israel. For those years in which the disease was more “infectious”, then outbreaks in different cities tended to occur with smaller time lags. Our spatial analysis demonstrates that both the timing and the strength of the outbreak within a year are highly synchronized between the Israeli cities. We extend the spatial analysis to demonstrate the existence of high synchrony between Israeli and French influenza outbreaks. Conclusions The data analysis combined with mathematical modeling provided a better understanding of the spatio-temporal and synchronization dynamics of influenza in Israel and between Israel and France. Altogether, we show that despite major differences in demography and weather conditions intra-annual influenza epidemics are tightly synchronized in both their timing and magnitude, while they may vary greatly between years. The predominance of a similar main strain of influenza, combined with population mixing serve to enhance local and global influenza synchronization within an influenza season.

Onset of a pandemic: characterizing the initial phase of the swine flu (H1N1) epidemic in Israel

BackgroundThe swine influenza H1N1 first identified in Mexico, spread rapidly across the globe and is considered the fastest moving pandemic in history. The early phase of an outbreak, in which data is relatively scarce, presents scientific challenges on key issues such as: scale, severity and immunity which are fundamental for establishing sound and rapid policy schemes. Our analysis of an Israeli dataset aims at understanding the spatio-temporal dynamics of H1N1 in its initial phase.MethodsWe constructed and analyzed a unique dataset from Israel on all confirmed cases (between April 26 to July 7, 2009), representing most swine flu cases in this period. We estimated and characterized fundamental epidemiological features of the pandemic in Israel (e.g. effective reproductive number, age-class distribution, at-risk social groups, infections between sexes, and spatial dynamics). Contact data collected during this stage was used to estimate the generation time distribution of the pandemic.ResultsWe found a low effective reproductive number (Re= 1.06), an age-class distribution of infected individuals (skewed towards ages 18-25), at-risk social groups (soldiers and ultra Orthodox Jews), and significant differences in infections between sexes (skewed towards males). In terms of spatial dynamics, the pandemic spread from the central coastal plain of Israel to other regions, with higher infection rates in more densely populated sub-districts with higher income households.ConclusionsAnalysis of high quality data holds much promise in reducing uncertainty regarding fundamental aspects of the initial phase of an outbreak (e.g. the effective reproductive number Re, age-class distribution, at-risk social groups). The formulation for determining the effective reproductive number Reused here has many advantages for studying the initial phase of the outbreak since it neither assumes exponential growth of infectives and is independent of the reporting rate. The finding of a low Re(close to unity threshold), combined with identification of social groups with high transmission rates would have enabled the containment of swine flu during the summer in Israel. Our unique use of contact data provided new insights into the differential dynamics of influenza in different ages and sexes, and should be promoted in future epidemiological studies. Thus our work highlights the importance of conducting a comprehensive study of the initial stage of a pandemic in real time.

Non-indigenous terrestrial vertebrates in Israel and adjacent areas

We investigated characteristics of established non-indigenous (ENI) terrestrial vertebrates in Israel and adjacent areas, as well as attributes of areas they occupy. Eighteen non-indigenous birds have established populations in this region since 1850. A database of their attributes was compiled, analyzed, and compared to works from elsewhere. Most ENI bird species are established locally; a few are spreading or widespread. There has been a recent large increase in establishment. All ENI birds are of tropical origin, mostly from the Ethiopian and Oriental regions; the main families are Sturnidae, Psittacidae, Anatidae, and Columbidae. Most species have been deliberately brought to Israel in captivity and subsequently released or escaped. Most of these birds are commensal with humans to some degree, are not typically migratory, and have mean body mass larger than that of the entire order. ENI birds are not distributed randomly. There are centers in the Tel-Aviv area and along the Rift Valley, which is also a corridor of spread. Positive correlations were found between ENI bird richness and mean annual temperature and urbanization. Mediterranean forests and desert regions have fewer ENI species than expected. Apart from birds we report on non-indigenous species of reptiles (2) and mammals (2) in this region.

The global distribution of tetrapods reveals a need for targeted reptile conservation

The distributions of amphibians, birds and mammals have underpinned global and local conservation priorities, and have been fundamental to our understanding of the determinants of global biodiversity. In contrast, the global distributions of reptiles, representing a third of terrestrial vertebrate diversity, have been unavailable. This prevented the incorporation of reptiles into conservation planning and biased our understanding of the underlying processes governing global vertebrate biodiversity. Here, we present and analyse the global distribution of 10,064 reptile species (99% of extant terrestrial species). We show that richness patterns of the other three tetrapod classes are good spatial surrogates for species richness of all reptiles combined and of snakes, but characterize diversity patterns of lizards and turtles poorly. Hotspots of total and endemic lizard richness overlap very little with those of other taxa. Moreover, existing protected areas, sites of biodiversity significance and global conservation schemes represent birds and mammals better than reptiles. We show that additional conservation actions are needed to effectively protect reptiles, particularly lizards and turtles. Adding reptile knowledge to a global complementarity conservation priority scheme identifies many locations that consequently become important. Notably, investing resources in some of the world’s arid, grassland and savannah habitats might be necessary to represent all terrestrial vertebrates efficiently.The global distribution of nearly all extant reptile species reveals richness patterns that differ spatially from that of other taxa. Conservation prioritization should specifically consider reptile distributions, particularly lizards and turtles.

Bats of a Gender Flock Together: Sexual Segregation in a Subtropical Bat

Competition has long been assumed to be a major driver in regulating ecological communities. Intra-specific competition is considered to be maximal as members of the same species use the same ecological niches in a similar way. Many species of animals exhibit great physiological, behavioral, and morphological differences between sexes (sexual dimorphism). Here we report an extreme geographical segregation between the sexes in the greater mouse-tailed bat (Rhinopoma microphyllum). To gain insight into the driving mechanisms of sexual segregation outside the mating season, we collected and integrated environmental, behavioral, physiological, and spatial information. We found that both sexes choose roosts with similar characteristics and the same food type, but use different habitats for different durations. Males forage around cliffs at higher and cooler elevations while females forage in lowlands around a river delta. We suggest that it is their different physiological and social needs, and not competition, that drives sexual segregation in this species.

Non-indigenous land and freshwater gastropods in Israel

Few comprehensive works have investigated non-indigenous snails and slugs as a group. We compiled a database of non-indigenous gastropods in Israel to explore how they arrived and spread, characteristics of their introduction, and their biological traits. Fifty-two species of introduced gastropods are known from Israel (of which nine species subsequently went extinct): 19 species of freshwater snails and 33 species of terrestrial gastropods. The majority of these species are found only in human-dominated habitats. Most of those found in natural habitats are aquatic species. Most snails are introduced unintentionally from various parts of the Holoarctic region, reaching Israel as stowaways with horticultural imports and the aquarium trade, but some are brought intentionally to be used as pets or for food. Because the study of this group in Israel is very limited, information regarding their distribution in the country and their effects on other species is incomplete. Though only nine species of non-indigenous snails have been found to date in natural habitats, some of these are very abundant. More information and research is required to enable effective management schemes.