Desert Habitats Research Articles

Physiological characterisation of coprophilous fungal isolates that behave as plant root associates

Different fungal isolates closely related to Zopfiella erostrata and Cercophora caudata have been found to colonise plant root tissues in an asymptomatic way in the Monte Desert biome of La Rioja Province, Argentina. This interaction has been newly discovered, and the role of these fungi in their desert habitat has never been studied in detail. The objective of this study was to evaluate eight fungal isolates by means of specific physiological traits that could have implications for their interaction with the host plant. The selected isolates, four endophytic and four rhizospheric, were characterised for their ability to produce indole acetic acid, solubilise and mineralise phosphorus (P), and utilise different nitrogen sources. In addition, we evaluated organic acid production and phosphatase activities as mechanisms of P recycling. These analyses revealed that most isolates produced indole acetic acid, and that all isolates could solubilise and mineralise P, although to different degrees. Furthermore, the production of organic acids correlated with P solubilisation levels, which may enhance P availability in soils. Nitrogen utilisation was variable among the isolates, without specific patterns concerning the different sources and fungal isolates tested. Our results demonstrated that the fungal isolates had great variability, probably because they complete their teleomorphic phase in their habitats, generating viable meiotic spores, in addition to the active dispersion of these fungi by the underground rodent Ctenomys aff. knightii from which they were isolated. Although the isolates were variable, the endophytic isolates exhibited improvement in all the P parameters measured. This can be explained by the ability of these isolates to intimately colonise root tissues, while the colonisation by rhizospheric isolates is produced superficially in the rhizoplane. The high occurrence of this interaction, as well as the physiological traits detected, suggest that this kind of fungi could play an important ecological role in the Monte Desert environment, benefiting the establishment and growth of new seedlings in areas occupied by the rodents.

Quantifying development to inform management of Mojave and Sonoran desert tortoise habitat in the American southwest

Two tortoise species native to the American southwest have experienced significant habitat loss from development and are vulnerable to ongoing threats associated with continued development. Mojave desert tortoises Gopherus agassizii are listed as threatened under the US Endangered Species Act, and Sonoran desert tortoises G. morafkai are protected in Arizona (USA) and Mexico. Substantial habitat for both species occurs on multiple-use public lands, where development associated with traditional and renewable energy production, recreation, and other activities is likely to continue. Our goal was to quantify development to inform and evaluate actions implemented to protect and manage desert tortoise habitat. We quantified a landscape-level index of development across the Mojave and Sonoran desert tortoise ranges using models of potential habitat for each species (152485 total observations). We used 13 years of Mojave desert tortoise monitoring data (4732 observations) to inform the levels and spatial scales at which tortoises may be affected by development. Most (66-70%) desert tortoise habitat has some development within 1 km. Development levels on desert tortoise habitat are lower inside versus outside areas protected by actions at national, state, and local levels, suggesting that protection efforts may be having the desired effects and providing a needed baseline for future effectiveness evaluations. Of the relatively undeveloped desert tortoise habitat, 43% (74030 km2) occurs outside of existing protections. These lands are managed by multiple federal, state, and local entities and private landowners, and may provide opportunities for future land acquisition or protection, including as mitigation for energy development on public lands.

Effects of light, temperature, salinity, and maternal habitat on seed germination of Aeluropus lagopoides (Poaceae): an economically important halophyte of arid Arabian deserts

In this study, salt tolerance during germination of Aeluropus lagopoides (L.) Trin. was tested using fresh seeds collected from three different maternal habitats under three thermoperiods and two light regimes. Additionally, we tested the ability of non-germinated seeds that had been exposed to different concentrations of NaCl to recover their germination in distilled water. The results showed a significant effect of seed source, temperature, and salinity, and some of their two- and three-way interactions on final germination and recovery percentage. The seeds from non-saline provenances had the highest percentages for germination (ca. 79%) under the 35/25 °C temperature regime, whereas the lowest percentages for germination (ca. 21%) was recorded for seeds from saline conditions under the 25/15 °C treatment. Additionally, percent germination was significantly lower for the seeds incubated in the saline solutions (100, 200, 400, and 600 mmol/L NaCl) and germinated under colder conditions (15/25 °C), compared with the seeds incubated in non-saline solutions (control group, 0 mmol/L NaCl) and germinated under warmer conditions (35/25 °C). The highest recovery percentage was recorded for seeds of the hyper-saline habitat incubated at 35/25 °C. Thus, seeds maintained their viability despite experiencing a range of saline conditions and were able to germinate upon the arrival of suitable conditions, which can be an adaptation to its saline arid desert habitat.

Life history response of Echinops gmelinii Turcz. to variation in the rainfall pattern in a temperate desert.

BackgroundCurrent and future changes in rainfall amount and frequency may particularly impact annual plants in desert ecosystems. The winter annual Echinops gmelinii Turcz. is widely distributed in the desert habitats of northern China and is a dominant pioneer annual plant following sand stabilization in the Tengger Desert. This species plays a vital role in dune stabilization during spring and early summer, when wind erosion is the most severe and frequent. However, seedling emergence and regeneration in sandy soil are mainly determined by rainfall patterns. Therefore, understanding the life history response of this species to rainfall variation is necessary for understanding the change of population dynamics under the future climate change.MethodsA field simulation rainfall pot experiment using rainout shelter was conducted that included five amounts and five frequencies of rainfall based on historical and predicted values to monitor the life history responses of E. gmelinii in a near-natural habitat.ResultsWe found that rainfall amount and frequency significantly affected seedling survival, growth and reproduction. The plant height, biomass, capitula number, seed number, seed mass and reproductive effort, but not the root/shoot ratio, significantly increased with increasing rainfall. Further, these traits exhibited the greatest response to low-frequency and larger rainfall events, especially the optimal rainfall frequency of 10-day intervals. Offspring seed germination showed increasing trends with decreasing rainfall, suggesting that the maternal effects may have occurred.ConclusionsOur study shows that the plasticity in growth and reproduction of E. gmelinii in response to rainfall variations may help it to gain dominance in the harsh and unpredictable desert environment. Furthermore, population development of this winter annual species should be promoted under the likely future scenarios of large rainfall events and increasing cool-season precipitation in temperate desert.

Evolution of phenotypic plasticity: Genetic differentiation and additive genetic variation for induced plant defence in wild arugula Eruca sativa.

Phenotypic plasticity is the primary mechanism of organismal resilience to abiotic and biotic stress, and genetic differentiation in plasticity can evolve if stresses differ among populations. Inducible defence is a common form of adaptive phenotypic plasticity, and long-standing theory predicts that its evolution is shaped by costs of the defensive traits, costs of plasticity and a trade-off in allocation to constitutive versus induced traits. We used a common garden to study the evolution of defence in two native populations of wild arugula Eruca sativa (Brassicaceae) from contrasting desert and Mediterranean habitats that differ in attack by caterpillars and aphids. We report genetic differentiation and additive genetic variance for phenology, growth and three defensive traits (toxic glucosinolates, anti-nutritive protease inhibitors and physical trichome barriers) as well their inducibility in response to the plant hormone jasmonic acid. The two populations were strongly differentiated for plasticity in nearly all traits. There was little evidence for costs of defence or plasticity, but constitutive and induced traits showed a consistent additive genetic trade-off within each population for the three defensive traits. We conclude that these populations have evolutionarily diverged in inducible defence and retain ample potential for the future evolution of phenotypic plasticity in defence.

Transcriptome responses to different herbivores reveal differences in defense strategies between populations of Eruca sativa

BackgroundIntraspecific variations among induced responses might lead to understanding of adaptive variations in defense strategies against insects. We employed RNA-Seq transcriptome screening to elucidate the molecular basis for phenotypic differences between two populations of Eruca sativa (Brassicaceae), in defense against larvae of the generalist and specialist insects, Spodoptera littoralis and Pieris brassicae, respectively. The E. sativa populations originated from desert and Mediterranean sites, where the plants grow in distinct habitats.ResultsResponses to elicitation of the plants’ defenses against wounding and insect herbivory resulted in more upregulated transcripts in plants of the Mediterranean population than in those of the desert. PCA analysis differentiated between the two populations and between the elicitation treatments. Comprehensive analysis indicated that defense responses involved induction of the salicylic acid and jasmonic acid pathways in plants of the desert and Mediterranean populations, respectively. In general, the defense response involved upregulation of the aliphatic glucosinolates pathway in plants of the Mediterranean population, whereas herbivory caused downregulation of this pathway in desert plants. Further quantitative RT-PCR analysis indicated that defense response in the desert plants involved higher expression of nitrile-specifier protein (NSP) than in the Mediterranean plants, suggesting that in the desert plants glucosinolates breakdown products are directed to simple-nitriles rather than to the more toxic isothiocyanates. In addition, the defense response in plants of the desert population involved upregulation of flavonoid synthesis and sclerophylly.ConclusionsThe results indicated that differing defense responses in plants of the two populations are governed by different signaling cascades. We suggest that adaptive ecotypic differentiation in defense strategies could result from generalist and specialist herbivore pressures in the Mediterranean and desert populations, respectively. Moreover, the defense responses in plants of the desert habitat, which include upregulation of mechanical defenses, also could be associated with their dual role in defense against both biotic and abiotic stresses.

Predicting how seed-eating passerines respond to cattle grazing in a semi-arid grassland using seed preferences and diet

Numerical responses of animals to habitat perturbation often seem inconsistent, spreading skepticism about the predictive capacity of applied ecology. Domestic grazing changes several habitat variables that can affect seed-eating birds. Birds, in turn, show adaptations (e.g. in their feeding behavior) that could allow them to overcome habitat perturbations. Here we modelled habitat variables (e.g. cover of different plants, panicles, soil seed bank) in grazed and ungrazed (or lightly grazed) habitats of the central Monte desert, Argentina, to detect those affected by grazing activity. There was no effect of grazing on shrub and tree cover, but grazing reduced the abundance mostly of large grass seeds but also of small grass and forb seeds. Then, we used model’s outputs and knowledge of feeding preferences of the five most common seed-eating passerines in the Monte to make species-specific predictions: changes in abundance of grass seed specialists (Saltatricula multicolor, Microspingus torquatus and Porphyrospiza carbonaria) due to grazing activity should be consistent and should depend on large grass seeds (i.e. preferred seeds), whereas changes in abundance of more generalist species (Zonotrichia capensis and Diuca diuca) should be less consistent and explained also by the abundance of other seeds. The abundance of large grass seeds was sufficient to predict the abundances of S. multicolor, M. torquatus and P. carbonaria. The best model for predicting the abundance of Z. capensis included large grass seeds as well as small grass or forb seeds. No model including the abundance of seeds predicted the abundance of D. diuca. Therefore, feeding behavior explained the abundance of four out of the five bird species. A review of the literature showed that feeding behavior is also a good predictor of habitat use in other desert grasslands. Conservative range management should consider, and even manipulate, the level of the seeds preferred by wildlife. Grazed grasslands should be rested from grazing on a rotational basis so that grasses, especially those whose seeds are preferred by birds, can seed.

Germination asynchrony is increased by dual seed bank presence in two desert perennial halophytes

Maintaining a viable seed bank throughout the germination season is considered very important for plant recruitment in desert environments, where environmental conditions are unpredictable. Seeds from fully matured Seidlitzia rosmarinus Bunge ex Boiss and Halothamnus iraqensis Botsch. were collected in December 2016, then April, June, and September 2017 from both soil-surface and aerial seed banks. Both of the species were selected mainly by their capacity to rehabilitate saline coastal sites. Germination was analyzed under two photoperiods (0 or 12 h light per day), with winged or dewinged perianths. Seidlitzia rosmarinus had a shorter seasonal range in comparison with H. iraqensis (6 and 9 months, respectively), and the presence of a winged perianth reduced the germination rate of both species. A permanent winged perianth significantly inhibited the germination rate in both species. In the absence of perianth, the germination registered in December 2016 was mostly 100%, but declined to around 20% in September 2017. Seeds are thus more likely to germinate after scarification from wind mobilization, and do not require burial. Our results show that seeds of both the aerial and soil banks are transitory, and viable only during the winter months. Taken together, the combination of aerial and soil seed banks has greatly facilitated germination asynchrony in their environmentally unpredictable desert habitat.

Evaporative water loss in Kuhl's pipistrelles declines along an environmental gradient, from mesic to hyperarid

Intraspecific variation in animal energy and water balances may play an important role in local adaptation of populations to specific habitats such as deserts. We examined Kuhl's pipistrelle (Pipistrellus kuhlii), a common bat in Israel that ranges in distribution from mesic Mediterranean to hyperarid desert habitats, for intraspecific differences in metabolic rate (MR) and evaporative water loss (EWL) among populations along a climatic gradient. We tested the prediction that EWL, especially at high ambient temperatures is lower in Kuhl's pipistrelles from desert habitats than from mesic habitats. We measured MR and total evaporative water loss (TEWL) at four ambient temperatures (10 °C, 20 °C, 30 °C and 35 °C) in three groups of bats using open-flow respirometry. We fitted the bats with a mask to separate cutaneous water loss (CWL) from respiratory water loss (RWL) at 35 °C. At 35 °C, mean TEWL in the southernmost group, from the hyperarid location, was significantly lower than in the other two groups, with no apparent difference in mean MR. The source of difference TEWL was that the southern group had significantly lower CWL than the other two groups; RWL did not differ among them. This suggests that there are mechanisms that reduce EWL from the skin of the bats; a likely candidate is modification of the lipids in the outer layer of the dermis that make the skin possibly less permeable to water as has been described in birds and a few other species of bat.

Identification of drought response genes by digital gene expression (DGE) analysis in Caragana korshinskii Kom.

Caragana korshinskii Kom. is a legume shrub that is widely distributed across desert habitats with gravely, sandy, and saline soils in Asia and Africa. C. korshinskii has highly developed roots and a strong tolerance to abiotic stress. At present, there are few genetic studies of C. korshinskii because of the limited availability of genomic resources. To understand the comprehensive mechanisms that are associated with drought tolerance, we used RNA-seq to survey the differentially expressed genes (DEGs) in comparisons of drought-treated and control plants. After analysing the sequencing results, we found 440 differentially expressed genes existing in drought-treated and control plants. Among the DEGs, 39 unigenes showed up-regulated expression after drought treatment, while 401 unigenes were down-regulated. We used the KEGG database to annotate these drought-induced genes; 126 unigenes were identified by KEGG pathway annotation, and approximately 28% of the unigenes with known function fell into categories related to fatty acid metabolism, starch, sucrose metabolism, and nitrogen metabolism, suggesting that these pathways or processes may be involved in the drought response. Finally, we confirmed that one gene has a potential function in drought tolerance.Our study is the first to provide transcriptomic resources for Caragana korshinskii and to determine its digital gene expression profile under conditions of drought stress using the assembled transcriptomic data for reference. These data provide a valuable resource for genetic and genomic studies of desert plants under abiotic stress conditions.

GPS tracking and population genomics suggest itinerant breeding across drastically different habitats in the Phainopepla

Abstract Migratory birds generally divide the annual cycle between discrete breeding and nonbreeding ranges. Itinerant breeders, however, reproduce twice at different geographic locations, migrating between them. This unusual flexibility in movement ecology and breeding biology suggests that some species can rapidly modulate the conflicting physiological and behavioral traits required for migration and reproduction. The Phainopepla (Phainopepla nitens), a songbird of the southwestern USA, has long been suspected to breed first in desert habitats in spring, then migrate to woodland habitats to breed again in summer. However, direct evaluation of movement and gene flow among individuals breeding in different locations has previously been logistically intractable. We deployed GPS tags on free-flying Phainopeplas in southern California, all of which migrated to hypothesized woodland breeding habitats after desert breeding (an average distance of 232 km). GPS data also revealed previously unknown fall and spring stopover sites. Population genomic analyses revealed no genetic differentiation among desert and woodland breeding populations, indicating significant movement and gene flow across the region. Finally, we used random forest analyses to quantify substantial environmental differences among temporal stages. Our results provide direct evidence that individual Phainopeplas do indeed move between 2 drastically different breeding habitats in the same year, representing a rare and extreme example of life-history flexibility.

Urban heat island conditions experienced by the Western black widow spider (Latrodectus hesperus): Extreme heat slows development but results in behavioral accommodations.

While shifts in organismal biology stemming from climate change are receiving increased attention, we know relatively little about how organisms respond to other forms of anthropogenic disturbance. The urban heat island (UHI) effect describes the capture of heat by built structures (e.g. asphalt), resulting in elevated urban temperatures. The UHI is a well-studied phenomenon, but only a handful of studies have investigated trait-based shifts resulting from the UHI, and even fewer have attempted to quantify the magnitude of the UHI experienced at the microclimate scale. Here, using a common urban exploiter, the Western black widow spider (Latrodectus hesperus), we show that the UHI experienced by spiders in July in their urban Phoenix, AZ refuges is 6°C hotter (33°C) than conditions in the refuges of spiders from Sonoran Desert habitat outside of Phoenix’s development (27°C). We then use this field microclimate UHI estimate to compare the development speed, mass gain and mortality of replicate siblings from 36 urban lineages reared at ‘urban’ and ‘desert’ temperatures. We show that extreme heat is slowing the growth of spiderlings and increasing mortality. In contrast, we show that development of male spiders to their penultimate moult is accelerated by 2 weeks. Lastly, in terms of behavioral shifts, UHI temperatures caused late-stage juvenile male spiders to heighten their foraging voracity and late-stage juvenile female spiders to curtail their web-building behavior. Trait-based approaches like the one presented herein help us better understand the mechanisms that lead to the explosive population growth of urban (sometimes invasive) species, possibly at the expense of urban biodiversity. Studies of organismal responses to the present day UHI can be used as informative surrogates that help us grasp the impact that projected climate change will have on biodiversity.

Vegetation Ecology Associated with Some Species of Family Zygophyllaceae in Different Regions of Egyptian Desert

The Zygophyllaceae is a widespread family of common existence in arid and semi-arid habitats of the Old and New Worlds, especially in seasonally dry deserts. Various members of this family are characterized by high efficient potential for the treatment of broad spectrum health disorders and well known in scientific and folk literature for their medicinal uses. TWINSPAN cluster for the 38 stands yielded four vegetation groups (A, B, C and D) at the 3rd level of classification. These groups were identified after the first dominant species that attained the highest importance value (IV). Group A: Zygophyllum aegyptium, group B: Fagonia cretica, group C: Zygophyllum coccineum and group D: Pulicaria undulata. The vegetation group A characterized sand formation habitats along Deltaic Mediterranean coastal desert, while group B represented roadside habitats of the western Mediterranean coastal desert, group C dominated Wadi Hagul bed and gravel desert habitats of Suez. Furthermore, group D inhabited wadi bed and roadside habitats in Ismailia. Ordination of the vegetation groups along 2 axes was performed using Detrended Correspondence Analysis (DCA), while Canonical Correspondence Analysis (CCA) was utilized to determine the relation between the community types and soil factors.

Size dependency of patch departure behavior: evidence from granivorous rodents.

Individual size is a major determinant of mobile organisms’ ecology and behavior. This study aims to explore whether allometric scaling principles can provide an underlying framework for general patterns of resource patch use. To this end, we used giving‐up densities (GUDs), that is, the amount of resources remaining in a patch after a forager has quit feeding, as a comparative measure of the amount of resources exploited by a forager of any given size. We specifically tested the hypothesis that size‐dependent responses to both internal (energy requirement) and external (risk management) forces may have an effect on GUDs. We addressed this topic by conducting an extensive meta‐analysis of published data on granivorous rodents, including 292 GUD measurements reported in 25 papers. The data set includes data on 22 granivorous rodent species belonging to three taxonomic suborders (Castorimorpha, Myomorpha, and Sciuromorpha) and spans three habitat types (desert, grassland, and forest). The observations refer to both patches subject to predation risk and safe patches. Pooling all data, we observed positive allometric scaling of GUDs with average forager size (scaling exponent = 0.45), which explained 15% of overall variance in individual GUDs. Perceived predation risk during foraging led to an increase in GUDs independently of forager size and taxonomy and of habitat type, which explained an additional 12% of overall GUD variance. The size scaling exponent of GUDs is positive across habitat types and taxonomic suborders of rodents. Some variation was observed, however. The scaling coefficients in grassland and forest habitat types were significantly higher than in the desert habitat type. In addition, Sciuromorpha and Myomorpha exhibited a more pronounced size scaling of GUDs than Castorimorpha. This suggests that different adaptive behaviors may be used in different contexts and/or from different foragers. With body size being a fundamental ecological descriptor, research into size scaling of GUDs may help to place patch‐use observations in a broader allometric framework.

Rodent burrow network dynamics under human-induced landscape transformation from desert to steppe in Kalmykian rangelands.

Rodents play an important role in rangelands through the engineering of extensive burrow systems, which provides key habitats for many animal and plant species. We have analyzed the long-term variation in the abundance and distribution of rodent burrows in grazing ecosystems of southern Russia (Kalmykia) under the landscape change from desert to steppe caused by the drastic reduction of livestock after the collapse of the USSR in the early 1990s. We conducted burrow surveys in the "desert" (1980) and "steppe" (2017) periods on 19 3-km transects. We found considerable changes in burrow abundance and distribution, as well as evidence of desert habitat fragmentation and isolation caused by the expansion of tall-grass communities. Burrows of the open-dwelling diurnal ground squirrel (Spermophilus pygmaeus), the dominant and the keystone species during the "desert" period, almost completely disappeared from the rodent burrow network by 2017, indicating significant habitat loss. In contrast, the burrows of the folivorous social vole (Microtus socialis) which was rare in the 1980s, became abundant and ubiquitously distributed. The burrow density of the desert-dwelling psammophilous midday gerbil (Meriones meridianus) decreased, while the distances between occupied patches increased, indicating desert habitat fragmentation and loss of population connectivity. Burrows of the folivorous tamarisk gerbils (M. tamariscinus) were recorded only sporadically in both 1980 and 2017. The observed changes in the rodent burrow network, the key component of grazing ecosystems, correlate with rodent species ecology and can have long-term and important consequences for ecosystem functioning.

The on‐ground feasibility of a waterless barrier to stop the spread of invasive cane toads in Western Australia

AbstractModeling suggests that excluding invasive cane toads from artificial water points (e.g., pastoral dams) along an arid coastal corridor in Western Australia would create a “waterless barrier” halting their spread. In this study, we explored one critical assumption of these models: that toads cannot persist in the corridor during the dry season without access to artificial water points. We explicitly tested this assumption by translocating and radio‐tracking 78 male cane toads in the proposed barrier region during the dry season. Telemetered toads moved substantial distances (maximum distance >2.5 km/night) and were adept at finding shelter. Nonetheless, toads experienced high water loss rates (1.89%/hr) and rapid mortality in both desert (mean ± SD = 43.6 hr ±1.4) and coastal (24.5 hr ±1.2) habitats. Survival analysis suggested that toads could survive a maximum of 5 days without access to surface water and would move a maximum of 5.35 km in this time. Our results confirm that artificial water points are a critical resource for toads in the proposed barrier region and provide further evidence that the waterless barrier could successfully halt toad expansion in Western Australia.

Natural Variation in Flower Color and Scent in Populations of Eruca sativa (Brassicaceae) Affects Pollination Behavior of Honey Bees.

Plants of Eruca sativa Mill. (Brassicaceae) from desert and Mediterranean populations in Israel differ in flower color and size. In the desert habitat, the population has higher abundance of flowers with cream color and longer petals, whereas in the Mediterranean habitat, the population has higher abundance of flowers with yellow and shorter petals. Choice experiments with honey bee foragers (Apis mellifera Linn., Apidae, Hymenoptera), the main pollinator in the natural habitat in Israel, confirmed that they are more attracted to the yellow flower morph than to the cream one. A proboscis extension response test indicated that honey bees are able to discriminate between flower scents of the desert and Mediterranean populations. Considering the advantage of plants of the yellow morph in attracting pollinators, we further tested in a common garden experiment whether these possess higher fitness than plants of the desert population. Indeed, a significant association was found between flower color and fruit set, and seed mass. In general, our results provide evidence for ecotypic differentiation between populations imposed by pollinators. The advantage of the yellow color morph in attracting pollinators may explain its dominance among plants of the Mediterranean population. We discuss why the cream color morph may be dominant in the desert habitat, considering the possibility of different pollinators, tradeoffs between traits, or pleiotropy.

Precocious Torpor in an Altricial Mammal and the Functional Implications of Heterothermy During Development.

Most mammals and birds are altricial, small and naked at birth/hatching. They attain endothermic thermoregulation at a fraction of their adult size at a vulnerable stage with high heat loss when many could profit from using torpor for energy conservation. Nevertheless, detailed data on the interrelations between torpor expression and development of endothermic thermoregulation are currently restricted to <0.1% of extant endotherms. We investigated at what age and body mass (BM) desert hamsters (Phodopus roborovskii), wild-caught in Inner Mongolia and born in autumn/early winter when environmental temperatures in the wild begin to decrease, are able to defend their body temperature (Tb) at an ambient temperature (Ta) of ∼21°C and how soon thereafter they could express torpor. Measurements of surface temperatures via infrared thermometer and thermal camera show that although neonate hamsters (BM 0.9 ± 0.1 g) cooled rapidly to near Ta, already on day 15 (BM 5.5 ± 0.2 g) they could defend a high and constant Tb. As soon as day 16 (BM 5.8 ± 0.2 g), when their maximum activity metabolism (measured as oxygen consumption) approached maxima measured in vertebrates, animals were able to enter torpor for several hours with a reduction of metabolism by >90%, followed by endothermic arousal. Over the next weeks, torpor depth and duration decreased together with a reduction in resting metabolic rate at Ta 30–32°C. Our data show that development of endothermy and torpor expression in this altricial hamster is extremely fast. The results suggest that precocious torpor by juvenile hamsters in autumn and winter is an important survival tool in their vast and harsh Asian desert habitats, but likely also for many other small mammals and birds worldwide.

Introduction of Fire Ant Biological Control Agents into the Coachella Valley of California

The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), is a stinging, invasive ant from South America that has plagued the southern US since the 1930s. It is currently established in parts of California, including the Coachella Valley. We introduced and established the fire ant decapitating phorid flies, Pseudacteon curvatus Borgmeier and Pseudacteon obtusus Borgmeier (Diptera: Phoridae); Solenopsis invicta virus 3 (Picornavirales: Solinviviridae) (SINV-3); and the microsporidian fire ant pathogen Kneallhazia solenopsae Knell, Allan, & Hazard (Microsporida: Thelohaniidae) for the biological control of fire ants in this region of California. This is the first establishment of fire ant decapitating phorid flies in California. In addition, we demonstrated human-mediated establishment of SINV-3 and K. solenopsae in hot, dry, but irrigated, urban desert habitat.

Low genetic diversity in the vulnerable Goitred Gazelle, Gazella subgutturosa (Cetartiodactyla: Bovidae), in Iran: potential genetic consequence of recent population declines

The Goitered Gazelle, Gazella subgutturosa, is the most widespread gazelle species in the Middle East and central Asia inhabiting desert and semi-desert habitats. Today it is threatened and its geographic range and population size have experienced significant decline in the last decades. In Iran, the remnant populations are confined to fragmented habitats. We aimed to characterise genetic diversity and phylogenetic status of the populations of Goitered Gazelle in Central Iran and to evaluate the potential effect of a historic population bottleneck on the genetic variation of today’s population. We used noninvasive sampling to uncover structure and level of genetic variation in a fragment of the cytochrome-b gene from 170 samples. Genealogical analyses were performed using HKY+I model and phylogenetic trees reconstructed using Bayesian inference and maximum likelihood. We found extremely low levels of genetic variation, with altogether only five haplotypes in samples from different populations. Overall haplotype diversity was 0.081 and nucleotide diversity 0.0003. The mean observed mismatch between any two sequences was 0.093 with the largest peak for small numbers. The mismatch distribution fit the model of population expansion and suggested that gazelles had experienced a sudden expansion. An unrooted median-joining network analysis of mtDNA haplotypes showed a star-like structure which few mutations steps separating the haplotypes from other regions. Our findings strengthen the urgency of preserving the species’ genetic diversity to prevent local extinction.