Competition experiments estimating the relative effects of inter- and intraspecific competition can help to resolve whether interspecific competition results in coexistence or exclusion. For mosquitoes, most such experiments have focused on invasive Aedes albopictus and its interactions with resident Aedes. A meta-analysis of such experiments tested whether the effect of interspecific competition is greater than, less than, or equal to that of intraspecific competition, and whether competitive outcomes are dependent on food quality. For A. albopictus and A. aegypti, there was significant context dependence, with interspecific competitive advantage for A. albopictus with low food quality, and competitive equivalence with high food quality. Meta-analysis of survivorship yielded more significant effects than did estimated rate of increase. Competitive effects and competitive responses of each species yielded similar results. This meta-analysis suggests competitive exclusion of A. aegypti by A. albopictus, and is thus consistent with field sampling, qualitative reviews, and interpretations from individual publications. For A. albopictus and A. triseriatus, most results indicated competitive equivalence and no context dependence, and are thus contrary to previous qualitative reviews and to interpretations from individual publications. For both pairs of species, published results suitable for meta-analysis remain scarce, and better experimental designs and improved analysis and reporting of statistical results are needed. Greater emphasis needs to be placed on estimating species' inter- and intra-specific competitive effects, rather than the more common, but theoretically less interesting, competitive responses. Experiments without low-density controls (i.e., replacement series) are inadequate for comparing competitive effects and responses.
Many mosquito-borne arboviruses have more than one competent vector. These vectors may or may not overlap in space and time, and may interact differently with vertebrate hosts. The presence of multiple vectors for a particular virus at one location over time will influence the epidemiology of the system, and could be important in the design of intervention strategies to protect particular hosts. A simulation model previously developed for West Nile and St. Louis encephalitis viruses and Culex nigripalpus was expanded to consider two vector species. These vectors differed in their abundance through the year, but were otherwise similar. The model was used to examine the consequences of different combinations of abundance patterns on the transmission dynamics of the virus. The abundance pattern based on Cx. nigripalpus dominated the system and was a key factor in generating epidemics in the wild bird population. The presence of two vectors often resulted in multiple epidemic peaks of transmission. A species which was active in the winter could enable virus persistence until another vector became active in the spring, summer, or fall. The day the virus was introduced into the system was critical in determining how many epidemic peaks were observed and when the first peak occurred. The number of epidemic peaks influenced the overall proportion of birds infected. The implications of these results for assessing the relative importance of different vector species are discussed.
Life sciences became Biology, like Physics and Chemistry, only in the 19th century, when researchers turned to reductive, determinist experimental methodologies. Whereas theories like that of the cell and that of Faktoren-of-inheritance provided the elementary units of life, Darwinism provided the framework for the diversity of life and its evolution. Only towards the second half of the 20th century did biologists realize that once living systems were constructed, it was systems analysis that became the focus of understanding living structures and functions.
Our current understanding of the mechanisms that lead to successful biological invasions is limited. Although local adaptation plays a central role in biological invasions, genetic studies have failed to produce a unified theory so far. The bluespotted cornetfish, a recent invader of the Mediterranean Sea from the Red Sea via the Suez Canal, provides an ideal case study to research the mechanisms of invasive genetics. Previous genetic work based on mitochondrial markers has shown the genetic diversity of the Mediterranean population was greatly reduced in comparison to the natural population in the Red Sea. In the current study, we expand upon these studies by adding mitochondrial and nuclear markers. Mitochondrial results confirm previous findings. The nuclear marker, however, does not show evidence of reduction in diversity. We interpret these results as either a differential dispersal capability in males and females, or the presence of selection on the invading Mediterranean population.
Food caching allows foraging decisions to include both present and future food value. We developed and tested a conceptual framework for measuring animals’ perceptions of future vs. present food value. Fox squirrels (sciurus niger) are well-known caching animals in North America. We measured giving-up densities (GUDs) of fox squirrels to test the following hypotheses: (1) all else equal, animals should prefer cacheable to non-cacheable foods, and (2) the option value of a cacheable food should change seasonally and be highest preceding lean periods. We presented squirrels with experimental food patches containing either shelled hazelnuts, hazelnuts with their shells intact (to affect cacheability) or both kinds. Our data support both hypotheses. Squirrels exploited food patches with cacheable nuts more thoroughly and left them at lower GUDs. The squirrels’ perception of the future value of hazelnuts with their shells intact was found to be 32% higher than their present value. GUDs also varied by season, fall > spring >winter > summer, likely corresponding to food availability. Season and food cacheability interacted to further determine GUDs. The difference in GUDs between cacheable and non-cacheable nuts varied similarly: fall > spring > winter > summer, likely corresponding to changing food availability, reproductive opportunities and pending energetic shortfalls.
Measures of animal behavior can be used in a variety of situations to make inferences about the environment and population status. Work by our research group shows that migratory shorebirds adjust their usage of, and behavior at, stopover sites in response to environmental conditions. Motivated by this, we built an individual-based model of migrating shorebirds moving through a sequence of alternating small and large stopover sites. Birds at larger sites are safer from predators, but we assumed that less food is available than at small sites. In the model, both predation risk and food intake are densitydependent, and the behavior of migrants is controlled by two rules: one that determines whether a bird will depart a stopover site, and one that controls the individual's foraging versus vigilance intensity. The optimal behavior is calculated by maximizing a payoff function that depends on arrival date and arrival energy stores at the final site. We used this model to predict mass gain, foraging intensity, and usage by migrants of small and large sites under various conditions. We examined the effects of a flyway-wide reduction in the amount of food, a flyway-wide increase in predation danger, and the effects of lowering the overall population size. The mass action of many individuals, each optimizing its migration timing and routing, leads to the emergence of distinctive patterns of behavior and site choice under these differing environmental conditions. When food availability is reduced throughout the flyway, our model predicts that foraging intensity increases at every stopover site, thereby forcing birds to accept greater danger to maintain the fitness benefit of a timely arrival to the breeding area. A flyway-wide increase in predation danger results in fewer migrants choosing (and/or migrants staying a shorter time at) small stopover sites, balanced by a higher usage of large sites. These effects contrast with what is observed under true population declines, when the usage of both small and large sites declines.
Floral color is an important cue that converged in many ornithophilous flowers and can be used by nectarivorous birds to make foraging decisions. Wild ornithophilous flowers are frequently red, although they are more often yellow in Israel. The Palestine sunbird (Nectarinia osea) is the only nectarivorous bird in Israel and surrounding Mediterranean areas. Given the prevalence of yellow flowers in their habitats (along with sunbirds' expected sensitivity increase in this region of color vision), we predicted that Palestine sunbirds prefer yellow food sources over red. We examined sunbird foraging behavior when they were presented simultaneously with a yellow and red feeder, each containing the same quantity and quality of food. We investigated whether sunbirds had a side bias in the color preference experiment, but also in a separate experiment where both feeders were white. Sunbirds did not exhibit a significant color bias, while they did have a significant preference for a particular side of the cage. Location appears to be a more important cue than color to Palestine sunbirds, likely because location can offer information on the most rewarding plants and recently depleted flowers. However, color may still provide useful information that could influence foraging decisions in different contexts.
Appreciation of ecology as a setting or stage for evolution has a long history, but evolutionary ecology became an identifiable discipline in the 1960's, growing mostly out of efforts to understand the evolution of life history components and to formulate a theory of community ecology based on the evolution of species' niches. Since the 1960's, technological advances and conceptual developments, especially the use of null hypotheses and an appreciation of the effects of evolutionary history and Earth history on current patterns, have altered and expanded evolutionary ecology. Many challenging questions remain poorly answered, especially the pressing question of how successful ongoing and future evolution will be in rescuing species from anthropogenic climate change and other human assaults on the natural world.
The possible influence of geographic range size on speciation remains a controversial subject in evolutionary ecology, with theory and data supporting positive, negative and bell-shaped relationships between speciation probability and ancestor range size. In this study, a surrogate of the speciation-range size relationship of extant European tree species (22 genera, 11 families) is obtained by comparing the range-size distribution of candidate ancestors (i.e. species which are thought to have originated new species) with that of relatives, controlling phylogenetic inertia and macroecological sampling bias. In this comparison, species range size is measured qualitatively using six categories. The candidate ancestors included seem to have speciated mainly through allopatric speciation, with fewer instances of hybridogenesis by allopolyploidy. The results show that speciation is significantly facilitated for species with intermediate range size. In the European tree flora, this pattern could be the result of multiple causes, including intermediate dispersal ability at these ranges. Descendant tree species tend to have narrow geographic ranges, a trend which arguably comes from limited dispersal ability in this case. Low dispersal ability could be common in new species as a consequence of widespread adaptation to stable habitats isolated by geographic barriers (“island habitats”) during allopatric speciation. This mechanism could be widespread among regional biotas and would facilitate narrow ranges in new species. This would provide a simple explanation to the observed abundance of narrow ranges in most macroecological species-range size distributions.
A total of six Red Sea inshore fish species with wide Indo-Pacific distribution, including Lessepsian migrants that reached the Mediterranean Sea via the Suez Canal, were studied and compared genetically to conspecific populations from Japan and the Seychelles. Examination of the cytochrome c oxidase 1 (COI) gene of Apogon cyanosoma, Sargocentron rubrum, Upeneus moluccensis, Spratelloide sdelicatulus, Gerres oyena and Terapon jarbua from Japan, the Red Sea, the Seychelles and the Mediterranean revealed that in five out of six fish species, a difference greater than 4% was found. These results indicate the importance of DNA genetic analysis in revealing possible cryptic species and supplementing classic taxonomic studies, as well as contributing to a reappraisal of the zoogeography and evolution of Indo-Pacific ichthyofauna and enhancing our understanding of fish biodiversity.
A case study of the Lessepsian invasion of the Mediterranean Sea was carried out during the 1970s by a Hebrew University of Jerusalem team that included Uzi Ritte and his research students. The study zoomed on two mollusk “trios” of mytilid bivalves and cerithiid gastropods, each including an invader, a closely related and ecologically similar indigenous Red Sea species and a Mediterranean indigenous competitor. This paper revisits the results, conclusions and projections made by the 1970s study in the context of a recent unified invasion biology framework, and in the view of the dynamic development of the Lessepsian invasion and research into it throughout the more than 30 years since the case study took place. The approach of studying “trios” to detect potential invaders and project the course of invasions has not been repeated in the Lessepsian system since the 1970s case study. But the findings that opportunistic life history traits linked with a match of habitat in the invaded range to a species’ ecological niche make this species a potential invader and enable it to coexist with an encountered competitor remain robust. Recent human-induced and other environmental changes in the Mediterranean have however highlighted a potential significance of propagule pressure in intensifying competitive exclusion and resource monopolization by the invader, to the point of potentially impacting the invaded ecosystem.
In this paper I argue that many sociocultural phenomena are best explained by the comparative (phylogenetic) method, which consists of using information on other species, notably our closest relatives, the nonhuman primates, as a means to understand the evolutionary history and biological underpinnings of human traits. The social phenomena considered here embody the unitary social configuration of humankind, the set of traits common to all human societies. Those traits could not be explained by sociocultural anthropology, or the other social sciences, because even though they have a highly variable cultural content, they are not cultural creations but rather the products of human nature, or natural categories. I argue that some of those traits resulted from the cognitive enhancement of specific primate traits in the course of human evolution and others evolved as by-products of the coalescence of several primate traits, and I illustrate each process with a number of examples. I also show that even though many of those traits are crossculturally universal, they need not be: culture may modulate the expression of primate legacies and produce various sociocultural patterns from the same set of universal biological underpinnings, or biological constants. Finally, I discuss the importance for the social sciences of integrating biological constants in their models and theories even when they seek to explain cultural differences.
State-and-transition language for ecosystem dynamics was articulated in a 1989 paper written by Imanuel Noy-Meir in collaboration with Westoby and Walker. That paper has been surprisingly influential considering that the publication it appeared in, Journal of Range Management, serves a relatively small community of researchers. Here we trace the wider history within which the paper sits, both the context that led up to its being written and its influence subsequently. Our aim is to explain Noy-Meir's distinctive and constructive role, at several points in the history.
Three general factors affect wildfire behavior and outcome: vegetation properties, weather patterns during the wildfire and topography. A heterogeneous landscape emerges from the interactions among these factors in open and natural areas following wildfires. Herein, an attempt is made to analyze the spatial heterogeneity of the Carmel 2010 fire using aerial photographs and fire spread simulation models. Additionally, simulation models were used to assess the sensitivity of fire properties to variations in foliar moisture content and wind speed. Image analysis results indicate that broadleaved communities in the Carmel region are less flammable compared to pine stands, resulting in larger areas of undamaged vegetation within the extent of the burned area. Once a vegetation patch is burned, however, the proportion of the area severely affected by the fire is not fundamentally different, with 64.6% of the trees severely damaged in the pine stands, compared to 60.5% in the broadleaved stands. Simulation results also suggest that flame height and variance is higher in the pine stands compared to other vegetation communities. Further, simulation results indicate that the fire event was more sensitive to wind speed than to foliar moisture content. Increasing wind speed from 8 to 40 km/h resulted in a 2.5-fold average increase in flame heights and a 50% decrease in the coefficient of variation, compared to an irregular response observed following manipulations of foliar moisture content. Consequently, it is suggested that extreme conditions generate more severe damage and result in lower landscape heterogeneity.
The bdelloid rotifer is an important component of freshwater zooplankton, exhibiting the features of parthenogenesis and anhydrobiotic capability. Heat shock proteins (Hsps), acting as molecular chaperones, are a highly conserved, ubiquitously expressed family of stress response proteins. In this study, the thermal optimums for heat-shock response and the levels of Hsp70 in Rotaria rotatoria (bdelloid rotifer) under different stress conditions were evaluated using survival assays and western blotting with fluorescent detection. The results showed that: (1) The survivorship in R. rotatoria were 100% throughout the temperature range of 12°C to 40°C, and the population growth rate reached its culmination at 28°C, suggesting the retardation of growth and reproduction at the other temperatures; (2) While stressed under 40°C, the levels of Hsp70 in R. rotatoria increased significantly over time, correlating with the duration of the stress; (3) As responses to different temperatures, the synthesis of Hsp70 could be induced significantly in R. rotatoria under both of high (40°C) and low (16°C) temperatures; (4) After removal of the thermal stress and recovery at 28°C, the levels of Hsp70 continued to rise for a period of time, peaked at 12 h, and then slowly declined with the extension of recovery duration, until there is no significant difference of Hsp70 levels. Summarily, with the fluctuations of stress duration and temperature, the rotifers could adapt to the environments sensitively by regulating the synthesis of Hsp70.
Most ecological research has hitherto focused more on sea and lake ecosystems than on peatland habitats. The primary objectives of this paper were to analyse the ciliate, rotifer, cladoceran, copepod and insect assemblages in a horizontal lagg and an open peat bog, and to assess the influence of physical and chemical parameters on their communities. Sampling was done in a transitional bog from May to October 2012 in a transect comprising the lagg and the open peatbog. The first two axes of a principal component analysis accounted for 49.8% of the total variance in the composition of the faunal communities studied. The distribution of samples in ordination space suggested that the habitats are distributed along the gradient of water level and the gradients of total organic carbon and nutrients. Assemblages of all groups investigated showed a strong compositional gradient correlated with surface water and phosphates. However, species composition of ciliates and rotifers was explained by conductivity and/or chlorophyll-a concentration. The results suggest that the lagg zone of a bog can function as an ecotone, with significantly greater species richness and abundance of faunal communities.
The physical structures built by animals are considered extended phenotypes that reflect how organisms make decisions and deal with changes in their biotic and abiotic environment. We summarize the results of several studies on Myrmeleon crudelis, a neuropteran larva that digs pit-traps in the soil to capture small arthropods (mostly ants) in the tropical dry forests of Costa Rica. Specifically, we showed how this species responds to varying biotic and abiotic conditions with changes in the design and/or location of its pit traps. Several experiments and field comparisons indicate that: 1) antlions adjust the pit design according to the abundance and type of prey. When prey is scarce, antlions increased trap diameter, an architectural adjustment that enhances the probability of prey encounter. Antlions that experienced high prey abundance, but the prey easily escaped, then increased pit depth, an adjustment that increases the chance of prey retention; 2) soil compaction strongly reduced pit-trap size and abundance; 3) antlions preferred soils with high proportion of fine-particle size to build pits. In fine-grained soil, pit-traps are larger and more efficient to capture prey than traps in coarse-grained soils; and 4) pit-traps may also be affected through indirect effects of soil structure and vegetation cover. Areas with fine-soil presented less plant cover, and plant cover could be beneficial for antlions because it acts as a shelter against direct sunlight and rainfall, or it may represent a cost because it is a source of leaflitter falling in the pits. The works summarized here how trap-building predators can exhibit considerable flexibility in trap construction in response to various biotic and abiotic factors, emphasizing how the study of extended phenotypes can be a useful approach to better understand the flexibility of foraging behaviors.
The present paper focuses on the ability of the European Leaf-toed gecko, Euleptes europaea , an endemic species of the western Mediterranean, to live in low-nutrient habitats. Its distribution is mainly insular and particularly noteworthy is its ability to live on islets and rocks. This work includes data originating from surveys carried out on 111 islands surrounding the island of Corsica (France) in search of herpetofauna. E. europaea is able to survive on the smallest islets, with low habitat complexity, suggesting a pre-adaptation of this species to island life. Moreover, high population densities associated with a low biomass seem to facilitate survival on island.
The Eurasian Jackdaw is thought to be archetypically monogamous, but recent tagging research uncovered extra-pair copulations in the species. Here we examined extra-pair paternity (genetic monogamy) in Eurasian jackdaws breeding in the Judean Hills, Israel, at the global edge of the species range, using a set of highly polymorphic molecular microsatellites. We found roughly a sixth of nests sampled showed deviations from monogamy, more than previously found in DNA fingerprinting studies of jackdaws, suggesting a mixed mating strategy in this population. These findings support the trend of extra-pair paternity in avian species, even when social monogamy remains the rule, and highlight the importance of continued study of species throughout their geographical range.
Heavy metal pollution has become a serious global problem in soil contamination. Cadmium (Cd) is a ubiquitous environmental toxic pollutant to plants, which can greatly affect their growth and development, or even lead to their death. In the present study, we performed a comparative transcriptome analysis to identify the regulators and pathways that were involved in Cd absorption and transportation in the roots, leaves and fruits of wild-type and mutant pepper plants. A total of 883,591,943 million reads were mapped to the reference genome, and 33,927 genes were identified. Sample reads and the reference genome alignment efficiency were between 78.99% to 84.57%. Finally, 798 differentially expressed genes (DEGs) were identified in the roots, leaves and fruits of the mutant and wild-type plants, including 80 up-regulated DEGs and 718 down-regulated DEGs. The DGEs were mostly related to the phenylpropanoid biosynthesis pathway and glyoxylate and dicarboxylate metabolism. In addition, some vital DEGs were identified in absorption/transportation-related pathways, such as ABC transporter and P-type ATPase. The results revealed that several genes were related to the regulation of Cd absorption and transportation. Collectively, our findings provided valuable insights into the molecular mechanism of Cd absorption and transportation in pepper.
The south-facing slopes in canyons, oriented along an east-west axis north of the equator, are often hotter and drier than north-facing slopes, promoting differences in the biotic and abiotic characteristics of the opposing slopes. We studied how diversity and abundance patterns have changed in Oren stream (Carmel Mountains, Israel) during the last 25 years. We tested whether temperature and habitat preferences of reptiles affected observation frequencies, to assess potential effects of global warming on the reptiles. We compared the results of a 1993–1994 survey in Oren stream to a survey we conducted during 2017–2018, using similar methods, survey area and effort. Species composition and abundance in Oren stream did not significantly change between studies, but the proportion of observations differed significantly across slopes for four out of the six most abundant species. The number of observations increased monotonically with increasing temperatures on the south-facing slope, but decreased on the north-facing slope above a temperature of 22°C. The major biome species inhabit globally was unrelated to the number of observations across slopes or studies, but species inhabiting warmer ranges were more frequently observed in the current survey. Our results suggest that as global temperatures rise, reptile species which can tolerate higher temperatures, and those which can avoid the hottest temperatures of the day, may be able to cope better. These results however may also derive from better detection ability of some species over others between study teams.
Rarity of species is often considered to set priorities for biodiversity conservation. Less abundant species are expected to be at higher risk of extinction and make significant contribution to food web functioning. However, the relationship between species abundance and position in food webs is still unclear. Here we tested possible correlations between species abundance and structural position in Prince William Sound food web. Species abundance was inferred from biomass data and structural position was characterized by 13 centrality indices.
We found that less abundant species have higher trophic positions and display more generalist feeding strategies. However, positive correlations link most of the centrality indices to population size. Thus, being locally rare translates into more peripheral food web positions and implies marginal roles in the spread of indirect effects. Species characterized by largest population size are responsible for the transfer of largest amounts of biomass and regulate the transmission of indirect effects. Less abundant species are of marginal structural importance and are exposed to impacts mediated by larger populations. In Prince William Sound ecosystem, rarity is associated with critical food web positions and does not simply reflect a marginal contribution to biodiversity.
We suggest that knowing the food web position of rare species might help to formulate more effective, system-level solutions for their conservation, rather than simply focusing on the direct treatment of symptoms.
The present study explored the evolutionary role of epicarp thickness of Q. variabilis acorns as a defensive mechanism against weevil infestation. Our results, based on two years' study, suggested that length and fresh mass of insect-damaged acorns were not different from those of intact ones, but width did differ. About 2, 18, and 79% of oviposition sites are distributed at the apical end, middle part, and basal end of acorns, respectively. About 5, 49, and 55% of eggs or larvae are infested at the apical end, middle part, and basal end, respectively. Similarly, about 10, 43, and 45% of emergence holes are found at the apical end, middle part, and basal end. Epicarp thickness varied among the three parts of acorns and was significantly negatively correlated with the appearance percentage of oviposition sites, infestation sites, and emergence sites, respectively. However, secondary metabolites and nutrition reserve showed no close correlation with the appearance percentage of oviposition sites, infestation sites, and emergence sites. Acorns with emergence holes at the apical end exhibited significantly lower seedling emergence and survival rates. Therefore, variation in epicarp thickness in individual acorns may be responsible for the weevil's preference for oviposition, infestation, and emergence, and acts as an alternative and important strategy protecting acorn embryos from pre-dispersal larval damage.
Only a few studies have examined responses of grassland functional diversity to management and major environmental gradients, in order to address the question of whether grassland use can promote functional divergence. For five grassland sites in Israel, Portugal, the Czech Republic, Mediterranean France, and the French Alps, where traditional grassland management is being abandoned, we quantified community-weighted means (CWM) and functional divergence (FDvg) for the three Leaf-Height-Seed (LHS) traits, individually and in combination. Responses of CWM and FDvg to land use were analyzed by mixed linear models with aridity, phosphorus, fertility, and the fractions of grasses and annuals as covariates.
Responses of community-weighted traits to land use were consistent with current knowledge. More intense management favored plants with more rapid resource acquisition (high Specific Leaf Area, or SLA), whereas abandonment or less intense grassland management increased the dominance by tall plants with more conservative strategies (low SLA). Seed weight did not respond to land use. For the three traits and their combination, functional divergence decreased in response to land use change overall. Detailed responses, however, varied depending on sites and especially their climate. At the two French sites, traditional site management promoted functional divergence within communities by suppressing dominance by large perennial tussocks, whereas at the two Mediterranean sites it is likely that the drier climate promoted a functionally diverse pool of species tolerant to grazing.
This study demonstrates how simultaneous analyses of variations in community-mean traits and functional divergence for a focused set of traits offer promising avenues to understand mechanisms of community response to environmental change.
Various major evolutionary problems are still open, controversial or unsettled. These include even the basic evolutionary processes of adaptation and speciation. The “Evolution Canyon” model is a microscale natural laboratory that can highlight some of the basic problems requiring clarification (Nevo list of “Evolution Canyon” publications at http://evolution.haifa.ac.il). This is especially true if an interdisciplinary approach is practiced including ecological functional genomics, transcriptomics, proteomics, metabolomics and phenomics. Here I overview and reanalyze the incipient sympatric adaptive ecological speciation of five model organisms at “Evolution Canyon”, across life: the soil bacterium, Bacillus simplex; wild barley, the progenitor of cultivated barley, Hordeum spontaneum; the tiny beetle Oryzaephilus surinamensis; the cosmopolitan fruit-fly, Drosophila melanogaster, and the Africa-originated spiny mouse, Acomys cahirinus. All five models of organisms display evolution in action of microclimatic adaptation and incipient sympatric adaptive ecological speciation on the tropical and temperate abutting slopes, separated on average by only 250 meters. Some distant species converge in their micro-climatic adaptations to the hot and dry “African”, south-facing slope (SFS or AS) and to the cool and humid “European”, north-facing slope (NSF or ES). Natural selection overrules ongoing inter-slope gene-flow between the free interbreeding populations within and between slopes, and leads to adaptive incipient sympatric ecological speciation on the dramatically opposite abutting xeric savannoid and mesic forested slopes.
There is growing evidence for rapid adaptive evolution in response to climate change, including phenological transitions such as earlier flowering with climate warming. The consequences of these evolutionary changes for population dynamics and shifts in species ranges remain, however, quite unexplored. Here, we propose that inter-population differences in patterns of flowering across geographic precipitation gradients can be considered a proxy for changes in flowering time due to variation in rainfall resulting from climate change. To this end, we analyze trends of variation in flowering time across rainfall gradients in the eastern Mediterranean region in three main plant life-forms present in the local vegetation: winter annuals, geophytes, and perennial grasses. These life-forms cope with the hot and dry summer via a drought escape strategy. The analysis is based on published and unpublished data from common-garden experiments in which plants from populations sampled along rainfall gradients were grown under similar conditions, thus allowing detection of genetic differences in flowering time along the gradient. The data clearly indicate that decreasing rainfall across a Mediterranean-desert transect is associated with earlier flowering in winter annual species. In contrast, the limited available data shows no consistent trend of change in flowering time with decreasing rainfall in geophytes and perennial grasses. The phenological shift to early flowering in winter annuals coping with terminal drought appears to be a widespread method for adaptation to arid environments by stress avoidance, diminishing the risk of early death before seed production. However, changes in flowering time associated with the reduction in precipitation predicted by climate change models are relatively small, suggesting that additional traits are involved in the adaptation to increasing aridity. The hypothesis that low water availability is an environmental signal inducing earlier flowering of annual plants under drought conditions is not supported by experimental data.
Abstract Compassionate conservation is an emerging field in conservation that seeks to integrate animal protection and
conservation to achieve either improved conservation outcomes, particularly where conservation priorities and humanwildlife
conflict, or the same outcomes, but with less pain and suffering for wildlife. In the Australian Capital Territory
(ACT), Eastern Grey Kangaroos (EGKs) are culled to reduce grazing pressure on threatened native grasslands and woodlands.
We integrate decision-making criteria about animal protection into planning of wildlife-management to formulate
a compassionate conservation management case study. The management criteria include a series of guiding questions: Is
management necessary? Will intervention (management of EGKs) achieve the desired conservation outcomes? And, if
intervention is necessary, is killing necessary? We found that kangaroos can be managed without culling. The conflict between
conservation goals and kangaroo abundance is likely to be accentuated during extended drought. In the short-term,
methods for improving rates of habitat recovery can include fencing of threatened grassland communities and reduction of
kangaroo density via translocation. Human activity must also be monitored as multiple human-caused biotic and abiotic
disturbances are known to have a strong impact on biodiversity of the native grassland habitats. In the medium to longterm,
Eastern Grey Kangaroos have the potential for maintaining stable populations, and their herbivory is necessary for
grassland function and nutrient cycling. Finally, we suggest that compassionate conservation and adaptive management can
work well together as social values shift towards greater emphasis on animal protection.
Despite a worldwide increase in experience with species protection, few scientific publications are available to assist in deciding how to use ecological knowledge to protect species and how to proceed in the absence of this knowledge. To strengthen the link between science and applied conservation, we suggest an article format that covers all activities towards species protection including both its ecological and its political components. This article is an attempt to provide such a template for publishing conservation case studies. The paper focuses on the experience gained in recent activities to promote butterfly conservation in Israel. It describes the parallel components of these activities: (a) selecting species for protection; (b) studying the species and identifying threats while identifying potential links between these threats and services for ecosystems and humans; and (c) acting to raise public awareness and initiate conservation actions. Special emphasis is given to two components of the process that receive little attention in other publications, namely, interpreting scientific knowledge in terms of biological indicators and eco-system services to humans, giving conservation efforts political leverage; and the practical aspects of raising public awareness. Specifically in this context, we elaborate on the relative contribution of local and international NGOs, political institutions, international law, and, especially, the media. The paper closes with lessons from this process that may be of practical use to scientists and conservationists worldwide.
During the project management actions, a chain of fine-grained events occur, both of bio-ecological and anthropic origin. While some may be expected or planned, others may be unforeseen. This work proposes the drafting of a ‘diary of events’ reporting bio-ecological and anthropogenic events, these last having both negative and positive impacts. This diary can be carried out using a schematic form, aiming to highlight the cause-effect relationships between events, the management responses, and the lessons learned. Analyzing the strengths, weaknesses, opportunities, and threats (i.e., the internal and external conditioning factors) linked to these events (SWOT analysis) to make a case of study from the real world, we applied this approach to a project aimed at protecting nests of two species of conservation interest ( Charadrius alexandrinus and C. dubius ) in a protected coastal area of central Italy.
Desert rodent assemblages from around the world provide convergent, but independent crucibles for testing theory and deducing general ecological principles. The heteromyid rodents of North America and the gerbils of the Middle East and their predators provide such an example. Both sets of rodents face predation from owls and vipers, but the North American species possess unique traits that may represent macroevolutionary breakthroughs: rattlesnakes have infra-red sensitive sensory pits, and heteromyids have cheek pouches. To test their significance, we brought together two gerbils (Middle East), two heteromyid rodents (a kangaroo rat and a pocket mouse; North America) in a common setting (a vivarium in the Negev Desert), and quantified the “opinions” of the rodents towards the North American sidewinder rattlesnake and the Middle Eastern Saharan horned viper and the foraging behavior of each in the face of these snake predators plus owl predators. Gerbils are fairly evenly matched in their anti-predator abilities, while the heteromyids differ widely, and these seem to match well with and may determine the types of mechanisms of species coexistence that operate in the communities of each continent. Evolutionary history, macroevolutionary traits, and risk management therefore combine to determine the characteristics of the organisms and the organization of their communities.
Allelopathic interference is considered an ecologically acceptable and effective means of biological control of invasive weeds, but little is known about phenotypic plasticity and the physiological integration of clonal plants in response to allelopathic interference. We used the clonal invasive aquatic water lettuce as a target for allelopathic control by spraying it with a crofton weed filtrate that contained strong allelochemicals. The growth of single-parent water lettuce was inhibited early on in the experiment when adult leaves gradually faded and new leaves grew slowly. However, as offspring ramets grew, the total number of ramets, leaf coverage, and biomass were all significantly greater in allelopathic treatments than in the control, although individual offspring ramets were smaller on average than in the control. This is an indication that the effects of allelopathic control on the water lettuce are: overcompensation in growth, and a trade-off between average size and the number of offspring. The pressure of allelopathy resulted in the water lettuce producing more small ramets, but total biomass was not different from the control. The water lettuce increased investment in root growth and also the capacity for absorbing resources to counteract growth loss due to allelopathy. This possible trade-off suggests that the clonal traits of invasive species should be considered before using allelopathic control.
We evaluated the suitability of a corticosterone enzyme immunoassay (EIA) to monitor excretion of fecal glucocorticoid metabolites (FGM) in response to Adrenocorticotropic hormone (ACTH) and saline injections in three desert rodent species ( Gerbillus andersoni allenbyi (GA), Gerbillus nanus (GN), and Gerbilis piridium (GP). We exposed 24 gerbils (N = 9 for GA, N = 7 for GN, N = 8 for GP) to an ACTH and a saline injection at different times. Fecal samples were collected hourly for 24 hours after injection. The average starting concentration (baseline) FGM concentration was 797 ng/g for GA, 183 ng/g for GN, and 749 ng/g for GP. The average peak concentration was 2377 ng/g for GA, 589 ng/g for GN, and 1987 ng/g for GP. We were able to provide a physiological validation for the chosen assay in GAs and GPs, however, our results for GNs were less clear. We found an increase in FGM concentrations on average after 5.5 hours in GA, 3.1 hours in GN, and 3.8 hours in GP. We found a peak in FGM concentration on average after 8.8 hours in GA, 5.6 hours in GN, and 10.3 hours in GP. We determined that FGM concentration returned to starting value on average after 14.4 hours in GA, 9.1 hours in GN, and 15.1 hours in GP. The outcomes of this study can help establish trapping protocols and time frames for FGM monitoring of these wild small mammal populations. The time course for excretion of FGM is similar between the species in this study, and comparable to some non-desert rodents. We found high variation in the time course of excretion within species. This variation needs to be taken into account when monitoring stress responses in the field. By assessing adrenocortical activity using FGM monitoring, stress responses to varying ecological and environmental factors can be reliably examined in the field.