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Climate drying could have transformed ecosystems in southern Madagascar during recent millennia by contributing to the extinction of endemic megafauna. However, the extent of regional aridification during the past 2000 years is poorly known, as are the responses of endemic animals and economically important livestock to drying. We inferred ~1600 years of climate change around Lake Ranobe, SW Madagascar, using oxygen isotope analyses of monospecific freshwater ostracods (Bradleystrandesia cf. fuscata) and elemental analyses of lake core sediment. We inferred past changes in habitat and diet of introduced and extinct endemic megaherbivores using bone collagen stable isotope and 14C datasets (n = 63). Extinct pygmy hippos and multiple giant lemur species disappeared from the vicinity of Ranobe during a dry interval ~1000–700 cal yr BP, but the simultaneous appearance of introduced cattle, high charcoal concentrations, and other evidence of human activity confound inference of drought-driven extirpations. Unlike the endemic megafauna, relatively low collagen stable nitrogen isotope values among cattle suggest they survived dry intervals by exploiting patches of wet habitat. Although megafaunal extirpations coincided with drought in SW Madagascar, coupled data from bone and lake sediments do not support the hypothesis that extinct megafauna populations collapsed solely because of drought. Given that the reliance of livestock on mesic patches will become more important in the face of projected climate drying, we argue that sustainable conservation of spiny forests in SW Madagascar should support local livelihoods by ensuring that zebu have access to mesic habitat. Additionally, the current interactions between pastoralism and riparian habitats should be studied to help conserve the island’s biodiversity.

The nuclear 2C DNA content and ploidy level determination of five indigenous coffee species from India was carried out using flow cytometry and by assessing the stomatal characteristics. The nuclear DNA content (2C/pg) analyzed varied from 1.29 pg in Coffea wightiana Wall. ex Wight & Arn. to 1.48 pg in Coffea jenkinsii Hook.f. Based on the genome size, all five species were divided into two groups. The first group comprises Coffea travancorensis Wight & Arn and C. wightiana with lower genome size (2C DNA 1.29–1.30 pg), and the second group consists of Coffea bengalensis Roxb.ex Schult, Coffea khasiana (Korth.) Hook.f and C. jenkinsii with larger genome size (2C DNA 1.45–1.48 pg). The species included in the first group were inhabited in dry environmental conditions in contrast to the species included in the second group which was predominantly from mesic habitat. Among the stomatal characteristics, no significant variation in stomatal density was observed among the species, although stomatal guard cell length and stomatal chloroplast number recorded significant variation among some species. Based on flow cytometry and stomatal characteristics, all five endangered coffee species analyzed in the study were identified as diploids. The study revealed that stomatal guard cell length and stomatal chloroplast number could be fast, inexpensive, and reliable methods for determining the ploidy status of indigenous coffee species.

Capsule: Breeding success in female Pied Flycatchers Ficedula hypoleuca is related to isotopic signature of feathers grown in Africa, suggesting wintering habitat links to breeding performance 5000km away.\ud Aims: Better understanding of interseasonal carry-over effects is a research priority, especially for declining migrants. We use stable isotope analysis to relate Pied Flycatcher winter habitat to summer reproductive success.\ud Methods: Flycatchers were captured in three UK woodlands in 2013-2015. An Africa-grown tertial was trimmed and analysed using Isotope Ratio Mass Spectrometry to quantify Nitrogen-15 (δ15N) and Carbon-13 (δ13C). In total, 135 samples were taken from 80 individuals.\ud Results: Wintering δ15N and δ13C differed significantly between years. δ13C correlated with lay date, such that birds with lower carbon levels (indicative of more mesic habitat) bred earlier. There was a significant correlation between wintering δ13C and productivity after allowing for year, site, and lay date; birds with low δ13C were more successful. This suggests δ13C links productivity directly as well as indirectly through phenological effects. δ15N did not relate to phenology or productivity.\ud Conclusion: This is the first evidence of carry-over effects between geographical regions for a European passerine. Conservation measures should focus on all aspects of seasonal cycles, not just breeding grounds.

The Texas Horned Lizard (Phrynosoma cornutum) is found in a variety of habitats. Although several studies have been conducted on habitat use by this species, none have been performed in central Texas, a more mesic habitat than most of those previously studied. This area is of special interest because horned lizard populations have been experiencing sharp declines in central Texas over the last approximately 50 years. We collected habitat data at two sites in central Texas, Camp Bowie and Blue Mountain Peak Ranch. Microhabitat data included canopy cover and ground cover from digitized photographs of Daubenmire quadrats; macrohabitat variables included vegetation height and length, cactus height, soil penetrability, woody plant species richness, tree density, tree diameter at breast height (DBH), and density of ant mounds collected along 100-m by 2-m transects. Similar patterns of habitat use were observed between the two sites. At Blue Mountain Peak Ranch, lizards appeared to be located in areas with a diversity of ground cover types, as observed in previous studies. At Camp Bowie, vegetation encroachment limited lizards in some areas to the use of roads and road margins. Implementation of prescribed burns or other vegetation management could create the preferred ground cover mosaic at such sites.

Geographical variation among contiguous populations is frequently attributed to ecological divergence or historical isolation followed by secondary contact. Distinguishing between these effects is key to studies of incipient speciation and could be revealed by different genomic signatures. We used RAD-seq analyses to examine morphologically divergent populations of the endemic lizard (Gallotia galloti) from the volcanic island of Tenerife. Previous analyses have suggested ecological and historical causes to explain the morphological diversity. Analyses of 276,483 single nucleotide polymorphisms (SNPs) from >20 Mbp of the genome revealed one genetically divergent population from Anaga, a region associated with divergent mtDNA lineages in other Tenerife endemics. This population also has a high number of private alleles, and its divergence can be explained by historical isolation. Bayesian outlier analyses identified a small proportion of SNPs as candidates for selection (0.04%) which were strongly differentiated between xeric and mesic habitat types. Individual testing for specific xeric-mesic selection using an alternative approach also supported ecological divergence in a similarly small proportion of SNPs. The study indicates the roles of both historical isolation and ecological divergence in shaping genomic diversity in G. galloti. However, north-south morphological divergence appears solely associated with the latter and likely involves a relatively small proportion of the genome.

In southern Florida, Gopher Tortoises (Gopherus polyphemus) occupy mesic flatwoods and Florida scrub communities where habitat and climatic conditions differ from other portions of the species' range. Both of these habitats appear suboptimal for tortoises due to saturated soils in mesic flatwoods and low forage abundance in scrub. Nonetheless, these habitats support large numbers of tortoises in southern Florida, albeit at low intensities. We assessed influences of elevation and microtopography on the spatial distributions of tortoise burrows and examined burrow use patterns within six sites at Avon Park Air Force Range in south-central Florida. The six sites differed in dominant soil types and vegetation communities, allowing comparisons of burrow distributions among mesic flatwoods, Florida scrub, and mixed flatwoods-scrub habitats (two replicate sites each). Point-process modeling identified significant influences of microtopography on burrow intensities that superseded the effects of site-wide elevation trends in five of the six sites. The effects of microtopography were most pronounced in flatwoods, suggesting greater reliance on areas of slightly higher elevation in mesic habitat, presumably in response to saturated soils and frequent flooding. Burrow use patterns during an exceedingly wet year also suggested that tortoises respond behaviorally to unsuitable hydrology by moving frequently among burrows that were flooded with groundwater. Microtopographic variation may be an important predictor of small-scale habitat use for fossorial reptiles, especially in mesic soils, which could be readily explored using increasingly available LiDAR-derived elevation data combined with the modeling approach demonstrated here.

We describe a new species of Rhadinella from the dry forest and thorn scrub of Valle del Motagua, Guatemala, a region and habitat where the congeners were previously unrecorded. This species is related to the group of Rhadinella that have dark dorsal coloration, which mostly or completely obscures a pattern of longitudinal striping characteristic of the majority of species of Rhadinella. The new species has dark gray, almost black, dorsal coloration with barely discernible slightly darker striping. Top of the head is mostly blackish with irregular auburn-orange markings on the internasals, prefrontals, frontal, parietals, loreals, postoculars, temporals, and two ultimate supralabials. Most conspicuous features are an orange-auburn Y-shaped marking along frontal-parietal and interparietal sutures, followed by an orange nuchal collar. The closest relative of the new species, based on morphological similarities, appears to be Rhadinella pilonaorum, which occurs in a relatively mesic habitat of pine-oak forest located about 90 km southwest from the type-locality of the new species.

The research was conducted to investigate the persistent soil seed bank composition and its relation to the above-ground vegetation of upland area (piedmont) to low land area (alluvial) landscape from arid to mesic region of Dera Ghazi Khan. A transact of 40 kilometers was laid down from arid to mesic habitat. At each 2 km a quadrate of 1 m−2sizes was thrown in the field to collect a soil sample of 2kg from soil cores ranging 0-15 cm deep for the analysis of soil seed bank. Twenty different sites were sampled by throwing 6 quadrates at each site making a total of 120 samples. Three thousand seeds were obtained of 50 different species from all the collected samples. Soil seed bank density m−2was higher in the alluvial plains of Dera Ghazi Khan. Most of the perennial species, which were xerophytic in nature such asAerua persica, Calotropis procera, Fagonia indica, Leptadaenia pyrotechnica, Peganum hermala, Rhazya strictaandSuaeda fructicosawere found in the piedmont (arid) soil habitat and the soil seed bank relatively less than the species found in the alluvial (Mesic) soil habitat, which were mostly of annual life span such asChenopodium murale, Euphorbia prostrata, Medicago denticulata, Fumaria indica, andWithania somnifera. From this study it is concluded that the similarity found between soil seed bank and above ground vegetation of both historic types of habitats piedmont (arid) and alluvial (mesic) of Dera Ghazi Khan

We examined how conditions prior to migration influenced migration performance of two breeding populations of black-and-white warblers Mniotilta varia by linking information on the migrant's winter habitat quality, measured via stable carbon isotopes, with information on their breeding destination, measured via stable hydrogen isotopes. The quality of winter habitat strongly influenced the timing of migration when we accounted for differential timing of migration between breeding populations. Among birds migrating to the same breeding destination, males and females arriving early to the stopover site originated from more mesic habitat than later arriving birds, suggesting that the benefits of occupying high-quality mesic habitat during the winter positively influence the timing of migration. However, male warblers arriving early to the stopover site were not in better migratory condition than later arriving conspecifics that originated from poor-quality xeric winter habitat, regardless of breeding destination. The two breeding populations stopover at the study site during different time periods, suggesting that the lower migratory condition of early birds is not a function of the time of season, but potentially a migrant's migration strategy. Strong selection pressures to arrive early on the breeding grounds to secure high-quality breeding territories may drive males from high-quality winter habitat to minimize time at the expense of energy. This migration strategy would result in a smaller margin of safety to buffer the effects of adverse weather or scarcity of food, increasing the risk of mortality. The migratory condition of females was the same regardless of the timing of migration or breeding destination, suggesting that females adopt a strategy that conserves energy during migration. This study fills an important gap in our understanding of the linkages between winter habitat quality and factors that influence the performance of migration, the phase of the annual cycle thought to be limiting most migratory bird populations.

Capsule Territory density of the Dusky Orange-crowned Warbler Oreothlypis celata sordida, endemic to the California Channel Islands, USA, varied with vegetation greenness and oak coverage on Santa Catalina Island.Aims To model factors affecting territory density of warblers on Santa Catalina Island.Methods Breeding warblers were monitored in a dry and a more mesic habitat on the island in 2006–2008 and modelled using a GIS tool to predict territory density. Data of three-year territory boundaries with ecological covariates were used to develop a regression tree and project the distribution of territory density on an island-wide scale. The fitted model was indirectly evaluated using the island-wide point counts.Results The territory density of warblers differed between mesic and xeric habitats in response to oak coverage and food abundance in oaks. In the model, Normalized Difference Vegetation Index and oak coverage were the best predictors. Individual density estimates from distance sampling were compara...

Topography exerts strong control on microclimate, resulting in distinctive vegetation patterns in areas of moderate to high relief. Using the Thornthwaite approach to account for hydrologic cycle components, a GIS-based Water Balance Toolset is presented as a means to address fine-scale species−site relationships. For each pixel within a study area, the toolset assesses inter-annual variations in moisture demand (governed by temperature and radiation) and availability (precipitation, soil storage). These in turn enable computation of climatic water deficit, the amount by which available moisture fails to meet demand. Summer deficit computed by the model correlates highly with the Standardized Precipitation−Evapotranspiration Index (SPEI) for drought at several sites across the eastern U.S. Yet the strength of the approach is its ability to model fine-scale patterns. For a 25-ha study site in central Indiana, individual tree locations were linked to summer deficit under different historical conditions: using average monthly climatic variables for 1998−2017, and for the drought year of 2012. In addition, future baseline and drought-year projections were modeled based on downscaled GCM data for 2071−2100. Although small deficits are observed under average conditions (historical or future), strong patterns linked to topography emerge during drought years. The modeled moisture patterns capture vegetation distributions described for the region, with beech and maple preferentially occurring in low-deficit settings, and oak and hickory dominating more xeric positions. End-of-century projections suggest severe deficit, which should favor oak and hickory over more mesic species. Pockets of smaller deficit persist on the landscape, but only when a fine-resolution Light Detection and Ranging (LiDAR)-derived Digital Elevation Model (DEM) is used; a coarse-resolution DEM masks fine-scale variability and compresses the range of observed values. Identification of mesic habitat microrefugia has important implications for retreating species under altered climate. Using readily available data to evaluate fine-scale patterns of moisture demand and availability, the Water Balance Toolset provides a useful approach to explore species−environment linkages.

Variation in mating system traits can have important consequences for plant populations by affecting reproductive assurance, the expression of inbreeding depression, and the colonization of and persistence in new or altered habitats. Environmental stressors, such as drought, have been hypothesized to induce higher rates of self-fertilization, yet this hypothesis has rarely been tested. Here we measure the response of two sister species of self-compatible annual herbs from contrasting habitats, Clarkia breweri and C. concinna, to an experimentally imposed greenhouse drought treatment. We find that the species differ in their baseline per-flower autogamy rates and the degree of spatial and temporal separation of male and female function within their flowers. Both species show a reduction in temporal separation of anthesis and stigma receptivity with the drought treatment. However, the species from the more mesic habitat, C. concinna, increases its low autogamy rate under drought conditions, whereas the species from the more xeric habitat, C. breweri, decreases its high autogamy rate under drought conditions. Neither species showed a response to drought in flower size or anther-stigma distance. Our results demonstrate that the induction of selfing under environmental stress cannot be assumed and that, in this case, the developmental timing of flower maturation is more plastic than floral morphology.

Summary 1. Rising global temperatures are predicted to impact organisms in diverse ways. For ectotherms, recent broad-scale analyses have predicted global patterns of vulnerability to warming, with tropical species at higher risk of detrimental effects than temperate species. However, vulnerability results from complex interactions between environment, physiology and behaviour. For species that inhabit a diversity of habitat types, these interactions may change across their range. 2. We measured operative thermal environments (Te) and body temperatures (Tb) of the tropical Caribbean lizard Anolis cristatellus at nine sites representing two habitat types: mesic and xeric forest. The thermal sensitivity of whole-organism physiological performance (i.e. sprint speed) of one mesic and one xeric population was also measured. Thermal and performance data were integrated to determine how habitat thermal variation, behavioural thermoregulation and thermal physiology influence current physiological performance capacity in the field. We then evaluate if habitat suitability and physiological capacity would change assuming climate warming of 3 ! C over the next century. 3. The mean Te of the xeric habitat was 4AE5 ! C warmer than that of the mesic habitat. However, behavioural thermoregulation by xeric lizards led to lesser differences in Tb (3AE5 ! C) between habitat types. The thermal sensitivity of sprint performance was similar for mesic and xeric lizards, and lizards from both habitats maintain sprint capacities near 100%. Climate warming is predicted to influence mesic and xeric lizards differently. Xeric lizards currently live in a thermal environment near their upper temperature threshold, while mesic lizards do not. As a result, the number of suitable perch sites is predicted to decrease dramatically in the xeric but not the mesic habitat. In addition, the physiological capacity of mesic lizards is predicted to increase by approximately 4%, whereas a decrease of approximately 30% is predicted for xeric lizards. 4. We characterized variation in the current biophysical and ecophysiological conditions experienced by A. cristatellus by integrating fine-scale measurements of thermal microhabitats with data on body temperatures and physiological performance capacities. These data allowed us to explicitly demonstrate how variation in these parameters can influence population susceptibility to climate warming across a species range and highlight the utility of a mechanistic approach in studies of global climate change.

We tested two hypotheses that investigated the pattern of attack by a gall-inducing insect on its host plant Astronium fraxinifolium (Anacardiaceae) in two contrasting habitats: cerrado (a savannic formation that indicates harsh conditions) and gallery forest (indicating moist conditions): (i) that galling female preference and larval performance are higher in xeric than mesic habitats; (ii) that vigorous modules are more attacked by the galling female insects where their larvae achieve higher performance independent of the habitat. The attack preference by the female galling did not differ between habitats. However, the larval performance was higher in the xeric habitat (cerrado) (76%) compared to the mesic habitat (gallery forest) (24%), partially supporting the first hypothesis. In general, bottom-up and top-down forces controlling the gall-inducing insect were higher in the mesic habitat. Shoot size of A. fraxinifolium did not influence the selection by the females for oviposition in any of ...

Few studies link habitat to grizzly bear Ursus arctos abundance and these have not accounted for the variation in detection or spatial autocorrelation. We collected and genotyped bear hair in and around Glacier National Park in northwestern Montana during the summer of 2000. We developed a hierarchical Markov chain Monte Carlo model that extends the existing occupancy and count models by accounting for (1) spatially explicit variables that we hypothesized might influence abundance; (2) separate sub-models of detection probability for two distinct sampling methods (hair traps and rub trees) targeting different segments of the population; (3) covariates to explain variation in each sub-model of detection; (4) a conditional autoregressive term to account for spatial autocorrelation; (5) weights to identify most important variables. Road density and per cent mesic habitat best explained variation in female grizzly bear abundance; spatial autocorrelation was not supported. More female bears were predicted in places with lower road density and with more mesic habitat. Detection rates of females increased with rub tree sampling effort. Road density best explained variation in male grizzly bear abundance and spatial autocorrelation was supported. More male bears were predicted in areas of low road density. Detection rates of males increased with rub tree and hair trap sampling effort and decreased over the sampling period. We provide a new method to (1) incorporate multiple detection methods into hierarchical models of abundance; (2) determine whether spatial autocorrelation should be included in final models. Our results suggest that the influence of landscape variables is consistent between habitat selection and abundance in this system.

Aim: The mesic biome, encompassing both rain forest and open sclerophyllous forests, is central to understanding the evolution of Australia’s terrestrial biota and has long been considered the ancestral biome of the continent. Our aims are to review and refine key hypotheses derived from palaeoclimatic data and the fossil record that are critical to understanding the evolution of the Australian mesic biota. We examine predictions arising from these hypotheses using available molecular phylogenetic and phylogeographical data. In doing so, we increase understanding of the mesic biota and highlight data deficiencies and fruitful areas for future research. Location: The mesic biome of Australia, along the eastern coast of Australia, and in the south-east and south-west, including its rain forest and sclerophyllous, often eucalypt-dominated, habitats. Methods: We derived five hypotheses based on palaeoclimatic and fossil data regarding the evolution of the Australian mesic biota, particularly as it relates to the mesic biome. We evaluated predictions formulated from these hypotheses using suitable molecular phylogenies of terrestrial plants and animals and freshwater invertebrates. Results: There was support for the ancestral position of mesic habitat in most clades, with support for rain forest habitat ancestry in some groups, while evidence of ancestry in mesic sclerophyllous habitats was also demonstrated for some plants and herpetofauna. Contraction of mesic habitats has led to extinction of numerous lineages in many clades and this is particularly evident in the rain forest component. Species richness was generally higher in sclerophyllous clades than in rain forest clades, probably due to higher rates of net speciation in the former and extinction in the latter. Although extinction has been prominent in rain forest communities, tropical rain forests appear to have experienced extensive immigration from northern neighbours. Pleistocene climatic oscillations have left genetic signatures at multiple levels of divergence and with complex geographical structuring, even in areas with low topographical relief and few obvious geographical barriers. Main conclusions: Our review confirms long-held views of the ancestral position of the Australian mesic biome but also reveals new insights into the complexity of the processes of contraction, fragmentation, extinction and invasion during the evolution of this biome.

Ecologists and evolutionary biologists must develop theories that can predict the consequences of global warming and other impacts on Earth's biota. Theories of adaptive habitat selection are particularly promising because they link distribution and density with fitness. The evolutionarily stable strategy that emerges from adaptive habitat choice is given by the system's habitat isodar, the graph of densities in pairs of habitats such that the expectation of fitness is the same in each. We illustrate how isodars can be converted into adaptive landscapes of habitat selection that display the density- and frequency-dependent fitness of competing strategies of habitat use. The adaptive landscape varies with the abundance of habitats and can thus be used to predict future adaptive distributions of individuals under competing scenarios of habitat change. Application of the theory to three species of Arctic rodents living on Herschel Island in the Beaufort Sea predicts changes in selection gradients as xeric upland increases in frequency with global warming. Selection gradients will become more shallow for brown lemming (Lemmus trimucronatus) and tundra vole (Microtus oeconomus) strategies that preferentially exploit mesic habitat. Climate change will cause selection gradients for the alternative strategy of using mostly xeric habitat to become much steeper. Meanwhile, the adaptive landscape for collared lemmings (Dicrostonyx groenlandicus), which specialize on xeric Dryas-covered upland, will become increasingly convex. Changes in the adaptive landscapes thus predict expanding niches for Lemmus and Microtus, and a narrower niche for Dicrostonyx. The ability to draw adaptive landscapes from current patterns of distribution represents one of the few methods available to forecast the consequences of climate change on the future distribution and evolution of affected species.

Population substructure has important implications for both basic and applied genetic research. We used 10 microsatellite markers to characterize population substructure in two ecologically and demographically contrasting populations of the model tree Populus trichocarpa. The Marchel site was a continuous stand growing in a mesic habitat in western Oregon, whereas the Vinson site consisted of three disjunct and isolated stands in the high desert of eastern Oregon. A previous study revealed that pollen-mediated gene flow is extensive in both populations. Surprisingly, model-based clustering, principal components analysis and analyses of molecular variance provided overwhelming support for the existence of at least two intermingled sub-populations within the continuous Marchel population (F(ST)=0.026, P0.001), which occupied an area with a radius of only about 250 m. Genets in these two sub-populations appeared to have different relative clone ages and phenologies, leading us to hypothesize that they correspond to different seedling cohorts, each established from seeds produced by relatively few mothers. As expected, substructure was stronger in the fragmented Vinson population (F(ST)=0.071, P=0.001), and this difference appeared to result from the more extensive family structure in this population. Using group-likelihood methods, we reconstructed multiple interconnected half-sib families in the Vinson population, with some genets having as many as eight putative siblings. Researchers involved in ongoing and future association studies in P. trichocarpa should account for the likely presence of subtle but practically significant substructure in populations throughout the range of this species.

The chuditch is a large carnivorous dasyurid marsupial. Historically it had one of the widest geographical distributions of all marsupials, encompassing much of arid Australia, but it is now restricted to the mesic south-west of Western Australia. It is therefore of interest to determine if its physiology better reflects adaptation to its historically arid or present mesic habitat. The basic physiological parameters of the chuditch conform to other marsupials. Body mass of males (1385 g) was400% of that predicted by phylogeny and this may be related to its carnivorous diet. Body temperature was 33.9 degrees C at ambient temperaturesor = thermoneutrality, with hyperthermia occurring above thermoneutrality. Basal metabolic rate was 0.361 mL O(2) g(-1) h(-1) at an ambient temperature of 31 degrees C. Metabolic rate increased below the thermoneutral zone by 0.038 mL O(2) g(-1) h(-1) degrees C(-1), and above the thermoneutral zone to 0.444+/-0.059 mL O(2) g(-1) h(-1) at 33.3 degrees C. Standard evaporative water loss was 0.498+/-0.071 mg g(-1) h(-1) at an ambient temperature of 26.0 degrees C, and increased at higher ambient temperatures due to panting and licking. Changes in wet thermal conductance largely reflected changes in evaporative heat loss, and dry thermal conductance increased at high ambient temperature due in part to posture change. Ventilatory parameters were consistent with metabolic demands in and below thermoneutrality, and suggested augmented evaporative heat loss above the thermoneutral zone. Chuditch had a high point of relative water economy of 22.6 degrees C, indicating favourable water economy at even moderate ambient temperatures, due to its low evaporative water loss rather than high metabolic water production. Chuditch were physiologically more similar to marsupials from arid rather than mesic habitats, better reflecting their historical distribution than their current geographical range.

The honey possum is the only non-volant mammal to feed exclusively on a diet of nectar and pollen. Like other mammalian and avian nectarivores, previous studies indicated that the honey possum's basal metabolic rate was higher than predicted for a marsupial of equivalent body mass. However, these early measurements have been questioned. We re-examined the basal metabolic rate (2.52 +/- 0.222 ml O(2) g(-1) h(-1)) of the honey possum and confirm that it is indeed higher (162%) than predicted for other marsupials both before and after accounting for phylogenetic history. This, together with its small body mass (5.4 +/- 0.14 g; 1.3% of that predicted by phylogeny) may be attributed to its nectarivorous diet and mesic distribution. Its high-basal metabolic rate is associated with a high-standard body temperature (36.6 +/- 0.48 degrees C) and oxygen extraction (19.4%), but interestingly the honey possum has a high point of relative water economy (17.0 degrees C) and its standard evaporative water loss (4.33 +/- 0.394 mg H(2)O g(-1) h(-1)) is not elevated above that of other marsupials, despite its mesic habitat and high dietary water intake.

Death Valley, California is today the hottest hyperarid area in the western Hemisphere with temperatures of 57 °C (134 °F) recorded. During the late Quaternary, pluvial Lake Manly covered much of the Valley and contributed to a much more moderate climate. The abrupt draining of Lake Manly in the mid-Holocene and coincident dramatic shifts in temperature and aridity exerted substantial selection pressure on organisms living in this area. Our research investigates the adaptive response of Neotoma (woodrats) to temperature change over the late Quaternary along a steep elevational and environmental gradient. By combining fieldwork, examination of museum specimens, and collection of paleomiddens, our project reconstructs the divergent evolutionary histories of animals from the valley floor and nearby mountain gradients (− 84 to > 3400 m). We report on recent paleomidden work investigating a transition zone in the Grapevine Mountains (Amargosa Range) for two species of woodrats differing significantly in size and habitat preferences: N. lepida, the desert woodrat, and N. cinerea, the bushy-tailed woodrat. Here, at the limits of these species' thermal and ecological thresholds, we demonstrate dramatic fluctuations in the range boundaries over the Holocene as climate shifted. Moreover, we find fundamental differences in the adaptive response of these two species related to the elevation of the site and local microclimate. Results indicate that although N. cinerea are currently extirpated in this area, they were ubiquitous throughout the late Pleistocene and into the middle Holocene. They adapted to climate shifts over this period by phenotypic changes in body mass, as has been demonstrated for other areas within their range; during colder episodes they were larger, and during warmer intervals, animals were smaller. Their presence may have been tied into a much more widespread historical distribution of juniper (Juniperus sp.); we document a downward displacement of approximately 1000 m relative to juniper's modern extent in the Amargosa Range. These results suggest a cooler and more mesic habitat association persisting for longer and at lower elevations than previously reported.

Herbivory may be an important factor affecting seedling survival of exotic species invading new habitats. We evaluated the effect of vertebrate herbivory on the seedling survival of two widely planted and invasive tree species (Pinus radiata and Eucalyptus globulus), in a Mediterranean-type ecosystem of central Chile. An important role of herbivory on seedling survival of these two species in their introduced ranges has previously been documented. However, this has mainly been evaluated in forest plantations where habitat and vegetation conditions differ from wild habitats in which invasion occurs. We planted seedlings with and without protection against vertebrate herbivores in different aspects (a mesic south-facing slope and a xeric north-facing slope) and vegetation cover (open sites and sites with patchy tree cover). We found that regardless of aspect or vegetation cover, herbivory, in this case mainly caused by exotic vertebrates, significantly and negatively affected seedling survival of both species. However, while the effect of herbivory on P. radiata was significant in every vegetation and habitat condition, for E. globulus, the effect of herbivory was significant only for open sites in the mesic habitat. These results suggest that, as observed in forestry plantations, vertebrate herbivory may constrain seedling establishment of these two exotic trees and potentially impede the invasion. However, the importance of herbivory in controlling exotic species may vary depending on the vegetation and habitat conditions in some species such as E. globulus.

Trypoxylon(Trypargilum)tridentatum tridentatumPackard (Hymenoptera: Crabronidae) is a spider-hunting wasp in mesic and xeric habitats in the arid Baja California peninsula of Mexico. Spider (Araneae) prey were collected every 2 weeks from wasp trap nests. Individuals of the family Araneidae were the most abundant prey (60.9%), followed by Theridiidae and Mimetidae. Dictynidae, Anyphaenidae, Salticidae, Uloboridae, Tetragnathidae, Miturgidae, and Philodromidae were captured only in the mesic habitat. An unidentified species ofEriophoraSimon (Araneidae) was the most frequently collected spider in the xeric habitat (29.0%), followed byTheridion submissumGertsch and Davis (Theridiidae) (24.0%), which was the commonest prey species in the mesic habitat (21.1%), andMetepeira crassipesChamberlin and Ivie (Araneidae) (16.5%). Nineteen species and three families are newly recorded as prey. The araneidsAraneus lineatipes(O.P.-Cambridge) andKaira alba(Hentz) and the uloboridsPhiloponella arizonica(Gertsch) andUloborus segregatusGertsch are new records for Baja California.

Leaf litter decomposition of dominant woody perennial species in the three most common habitats of the southern Sonoran Desert was studied using the litter-bag method. Our objective was to assess the influence of litter quality on decomposition rates in three contrasting desert environments. The hypotheses were: (1) decomposition rates within the same litter type are faster in more mesic habitats, (2) decomposition rates are lower in higher lignin content or lower nutrient quality substrates, and (3) species-rich substrates enhance decomposition rates. For all litter types and habitats, a rapid loss of mass occurred during the summer rains at the start of the experiment, but total loss within the same litter type differed significantly among habitats. Decay rates were not higher in the more mesic habitat, but in the dry plains where solar irradiance and termite activity were highest. While termite activity was less important in the arroyos and absent in the hillsides habitats, proliferation of fungal mycelium in these sites was much higher than in the plains, suggesting that biotic and abiotic factors act both independently of litter richness. Lignin content seems to be an important factor controlling the loss of litter, because decay rates were inversely related to litter initial lignin content in all three habitats. Leaf litter diversity did not enhance rates of decomposition. The leaf litter mixture had k-values similar to the most recalcitrant monospecific litter in all three habitats, indicating a neutral or even antagonistic role of species-specific compounds in decomposition rates.

Irrigation in desert ecosystems can either reduce or increase species diversity. Groundwater pumping often lowers water tables and reduces natural wetlands, whereas canal irrigation often creates mesic habitat, resulting in great increases in avian diversity from irrigation. Here we compare a dataset of potential natural vegetation to recent datasets from areal and satellite imagery to show that 60% of the land in the coastal plain of southern Sonora and northern Sinaloa lying below 200 m elevation has been converted by irrigation to more mesic habitats. We then use the record of bird specimens in the world’s museums from this same region of Mexico to examine the avian community before and after the development of extensive irrigation. In general these museum records show an increase in the abundance and diversity of breeding birds associated with mesic habitats. Although thorn forest birds have likely decreased in total numbers, most are common enough in the remaining thorn forest that collection records did not indicate their probable decline. Four migrants having most of their breeding ranges in the US or Canada, Yellow-billed Cuckoo, Cliff Swallow, Bell’s Vireo, and Orchard Oriole, apparently have increased dramatically as breeders in irrigated habitats of NW Mexico. Because these species have decreased or even largely disappeared as breeding birds in parts of the US or Canada, further research should assess whether their increases in new mesic habitats of NW Mexico are linked to their declines as breeding birds in Canada and the US For Bell’s Vireo recent specimens from Sinaloa suggest its new breeding population in NW Mexico may be composed partly of the endangered Least Bell’s Vireo.

Terrestrial ecosystems are heterogeneous habitatmosaics of varying vegetation types that are differentiallyaffected by climate change. Arctic plant communities, for example, are changing faster in moist habitats than in dry habitats and abiotic changes likesnowmelt vary locally among habitats. Such differences between habitats may influence the effects of climate changes on animals and this could be especially true in low-mobility species. Suitable model systems to test thisidea, however, are rare. We examined how proxies of reproductive success (body size, juvenile/female ratios) and sex ratios have changed in low-mobility crab spiders collected systematically over a 17-year period (1996–2012)from two distinct habitats (mesic and arid dwarf shrub heath) at Zackenberg in northeast Greenland. We identified all adults in the collection to confirm that they represented just one species (Xysticus deichmanni Sørensen) based onmorphology. This provided a unique opportunity to measure recruitment potential because we could assume that all juvenile crab spiders belonged to that species. We determined sex, stage, and size of all specimens (n = 2,115).Body size variation was significantly related to the timing of snowmelt and differed significantly between the sexes and habitats with the spiders in the mesic habitat showing a stronger temporal response to later snowmelt. Juvenile/female ratios also differed significantly between habitats; as did the overall abundance of individuals. We found significant main effects of snowmelt and habitat on sex ratio with the proportion of females decreasing significantlyin response to later snowmelt only in the mesic sites. Effects of climate change may be masked by habitat differences and have implications for future range changes of species at both small and large spatial extents. We recommendthat local habitat differences are included in analyses of species responses to climate change.

We investigated relationships between whole-tree hydrau- lic architecture and stomatal conductance in Pinus palus- tris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio ( A S : A L ) than trees in a mesic habitat. The soil-leaf water potential gradient ( Ψ Ψ S − Ψ L ) and leaf-specific hydraulic conductance ( k L ) were similar between sites, as was tissue- specific hydraulic conductivity ( K S ) of roots. Leaf and can- opy stomatal conductance ( g S and G S , respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit ( D ) was low. A hydraulic model incorpo- rating tree height, A S : A L and Ψ S − Ψ L accurately described the observed variation in individual tree G Sref ( G S at D = 1 kPa) across sites and indicated that tree height was an important determinant of G Sref across sites. This, com- bined with a 42% higher root-to-leaf area ratio ( A R : A L ) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal - and sometimes higher - potential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees sug- gests that this potential for higher conductance may only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.

SUMMARYThe relative role of the mesothoracic and abdominal spiracles in respiration was examined using flow-through respirometry in four dung beetle species from different habitats. Two species of flightless beetles, Scarabaeus (Pachysoma) gariepinus and Scarabaeus (Pachysoma) striatum, from the arid western region of southern Africa and a large flighted species, Pachylomerus femoralis, from a more mesic habitat were compared with Circellium bacchus, a flightless beetle from a low rainfall eastern area. All species showed a form of the discontinuous gas exchange pattern at rest. The mesic flighted species used a closed, flutter, open, cycle (CFO)while those species from more arid habitats used a closed, ventilation, cycle(CV) or a closed, burst cycle (CB). The relative importance of the mesothoracic spiracles in CO2 emission varied between the species,even between those from the same genus and habitat. C. bacchus and P. femoralis represent extremes of CO2 emission from the mesothoracic spiracles; from almost total to almost none, respectively. Overall, mesothoracic CO2 emission and convection were more pronounced in the dry habitat species, supporting the hypothesis that both strategies aid in the reduction of water loss.

Forests of Southern Appalachia are critical habitats with respect to biodiversity, with a large portion of these forests residing on public multiuse lands. With pressure to extract timber from maturing forests, there is a need to identify the relative importance of forest types within the larger forest matrix. We examined small-mammal populations at 350 sample points across 157 km 2 of forested habitat in the George Washington and Jefferson National Forests, Virginia, to determine landscape and habitat correlates of species abundance and richness. A total of 3,955 individuals representing 20 species were captured using live trap and pitfall sampling at each point during 1996 and 1997. Nine species were sufficiently common to examine their abundance relative to landscape and habitat features. We found species abundance and richness to be highest in mesic deciduous forest types, with the exception of Peromyscus leucopus. Soil moisture capacity and the proportion of mesic habitat within 100 m of the sample point were also important for several species. If mesic deciduous forest can be considered patches within a matrix of xeric forest, then the abundance of 4 species and species richness could be predicted based on the distance of the sample point to the nearest mesic patch and the abundance of 3 species inside mesic patches was related to patch size. At least 73% of mesic patches within this forest were ,25 ha and separated from other patches by .100 m. Our results indicate that mesic forest patches contain the bulk of the species richness for small mammals in the Southern Appalachian ecotype. Designing timber harvests that minimize use of mesic deciduous forest type and that does not decrease patch numbers would achieve the largest benefits to small mammals within the region.

Summary The feeding habits of two carnivorous opportunists, red fox ( Vulpes vulpes ) and stone marten ( Martes foina ), have been compared in two Mediterranean mountain habitats (mesic and xeric), located in the Sierra Nevada National Park (SE Spain), between April 1997 and March 1998. The analysis of scats revealed a very important interspecific trophic niche overlap in the mesic habitat. In the xeric habitat the differences were significant and the overlap moderate. Seasonal variations existed in the degree of overlap, which reached its highest level in winter in the mesic habitat and in spring in the xeric habitat. The results indicated that the availability of food in each habitat was important in determining the divergence of the diets. Thus, in the mesic habitat, competition could be possible, although it was not important enough to cause a habitat segregation. Martens seemed to be more adaptive than foxes, probably due to their smaller size and arboreal life, allowing them to exploit fruit which is not as profitable for the fox. Foxes based their diet on small mammals, carrion and cultivated fruit in both habitats. Rabbits were also seasonally important in the xeric habitat. The trophic niche breadth of foxes was higher in the mesic habitat. The inter-habitat comparison showed significant differences in the diet of martens. In the xeric habitat, martens centred their diet on small mammals and fruit of Juniperus phoenicea , Morus ulmifolius and Amelanchier ovalis , while in the mesic habitat their diet was very similar to that of foxes. The trophic niche breadth was higher in the xeric habitat than in the mesic. The habitat conditions particulary influenced the overlap of the diets and these variations were fundamentally caused by the different availability of small fruit.

In ecology, expert knowledge on habitat characteristics is often used to define sampling units such as study sites. Ecologists are especially prone to such approaches when prior sampling frames are not accessible. Here we ask to what extent can different approaches to the definition of sampling units influence the conclusions that are drawn from an ecological study? We do this by comparing a formal versus a subjective definition of sampling units within a study design which is based on well-articulated objectives and proper methodology. Both approaches are applied to tundra plant communities in mesic and snowbed habitats. For the formal approach, sampling units were first defined for each habitat in concave terrain of suitable slope using GIS. In the field, these units were only accepted as the targeted habitats if additional criteria for vegetation cover were fulfilled. For the subjective approach, sampling units were defined visually in the field, based on typical plant communities of mesic and snowbed habitats. For each approach, we collected information about plant community characteristics within a total of 11 mesic and seven snowbed units distributed between two herding districts of contrasting reindeer density. Results from the two approaches differed significantly in several plant community characteristics in both mesic and snowbed habitats. Furthermore, differences between the two approaches were not consistent because their magnitude and direction differed both between the two habitats and the two reindeer herding districts. Consequently, we could draw different conclusions on how plant diversity and relative abundance of functional groups are differentiated between the two habitats depending on the approach used. We therefore challenge ecologists to formalize the expert knowledge applied to define sampling units through a set of well-articulated rules, rather than applying it subjectively. We see this as instrumental for progress in ecology as only rules based on expert knowledge are transparent and lead to results reproducible by other ecologists.

Population divergence and speciation are often explained by geographical isolation, but may also be possible under high gene flow due to strong ecology-related differences in selection pressures. This study combines coalescent analyses of genetic data (11 microsatellite loci and 1 Kbp of mtDNA) and ecological modelling to examine the relative contributions of isolation and ecology to incipient speciation in the scincid lizard Chalcides sexlineatus within the volcanic island of Gran Canaria. Bayesian multispecies coalescent dating of within-island genetic divergence of northern and southern populations showed correspondence with the timing of volcanic activity in the north of the island 1.5–3.0 Ma ago. Coalescent estimates of demographic changes reveal historical size increases in northern populations, consistent with expansions from a volcanic refuge. Nevertheless, ecological divergence is also supported. First, the two morphs showed non-equivalence of ecological niches and species distribution modelling associated the northern morph with mesic habitat types and the southern morph with xeric habitat types. It seems likely that the colour morphs are associated with different antipredator strategies in the different habitats. Second, coalescent estimation of gene copy migration (based on microsatellites and mtDNA) suggest high rates from northern to southern morphs demonstrating the strength of ecology-mediated selection pressures that maintain the divergent southern morph. Together, these findings underline the complexity of the speciation process by providing evidence for the combined effects of ecological divergence and ancient divergence in allopatry.

By the methods of morphological anatomy and investigation in the sample fields, the main studies were carried out such as morphological anatomy of reproductive organs, birch population’s reproductive ages, reproductive allotment value and seed behavior. The relationship between birch population and their surroundings was studied. The results showed that birch’s flower organs and its seeds were suitable well for spreading by wind. The seeds by wind can fly far away in a short time. The quantity of seed spreading greatly varied with different communities. Birch’s reproduction age can be changed in different ecological surroundings. The reproductive allotment value of birch was obviously different at different reproductive stages. In the mesic habitat, birch can grow well. The lowest reproductive age of them was 12, average age 15. In most cases the age of branches to bearing fruits was more than 18. The order of reproductive allotment values was as follows: a flowering phase > flower bud phase > fruit phase.

Feral asses have been studied in the arid habitats of the southwestern United States [Moehlman, P.D., 1974. Behavior and ecology of feral asses ( Equus asinus ). PhD dissertation, University of Wisconsin, Madison, 251 pp.; Moehlman, P.D., 1979. Behavior and ecology of feral asses ( Equus asinus ). Nat. Geogr. Soc. Res. Reports 1970, 405–411.; Woodward, S.L., 1979. The social system of feral asses ( Equus asinus ). Z. Tierpsychol. 49, 304–316] and in the mesic habitat of Ossabaw Island, Georgia [Moehlman, P.D., 1979, ibid; McCort, W.D., 1980. The feral asses ( Equus asinus ) of Ossabaw Island, Georgia. PhD dissertation, Pennsylvania State University, University Park, 219 pp]. The feral ass populations in these two locales exhibited intraspecific variation in polygynous mating systems and social organization which were consistent with the ecological classification of mating systems of Emlen and Oring (1977) [Emlen, S.T., Oring, S.W., 1977. Ecology, sexual selection, and the evolution of mating systems. Science 197 (4300), 215–223]. Feral asses in the arid environment have a `resource defense' polygynous mating system, and those in the mesic habitat exhibit `female (harem) defense' polygyny. The intraspecific variation observed in feral asses encompasses the interspecific variation observed in the family Equidae.

Vegetation growing in irrigation canals has been postulated to furnish an important mesic habitat within arid landscapes. Some canal designs now incorporate plastic (PVC) liners to reduce seepage, and vegetation could be incidentally affected. We tested the hypothesis that PVC lining has no long-term effect on bank vegetation by comparing vegetation on interior banks of a reach of an 88-km long irrigation canal (47 m 3 s −1 capacity) lined 6–8 years earlier, with vegetation along unlined reaches of the same canal. The lined reach generally had lower values for cover, biomass, and richness than unlined reaches to the east. However, an east–west gradient in biomass noted within a 32-km long unlined reach suggested that the lower values of the lined-reach were at least partially due to factors unrelated to lining. Butterfly communities using the sampled reaches were surveyed to assess habitat quality. No significant differences were detected among the reaches, although the butterfly assemblage in the westmost lined reach tended to differ from those in unlined reaches. Pre- and post-lining surveys conducted on the same reach, as well as natural history data, indicated that canal butterflies were derived from surrounding habitats, rather than the canal itself. Vegetation management practices (e.g. periodic burning) limit the study canal's value as a habitat for butterflies and probably other species.

Habitat specialization is an effective mechanism of coexistence among com- peting species. But many communities also include generalized species whose habitat use overlaps that of the specialists. Two hypotheses seem most likely to account for the pattern: (1) Habitat generalists may coexist in competitively structured communities by exploiting habitats unused, or underused, by habitat specialists. (2) Population densities of the spe- cialized species may be limited (e.g., by predation) below levels where the specialists can competitively exclude habitat generalists. I evaluated these ideas in a community of small mammals occupying mesic and xeric habitats at nine different locations in the Rocky Mountains of southern Alberta, Canada. A chipmunk generalist coexists with two specialists, one with a distinct preference for xeric habitat (deer mouse), and another with a similar preference for mesic habitat (red-backed vole). Habitat selection appeared to depend pri- marily on the density of conspecifics. The generalist coexisted by responding to habitat at a larger scale than did the specialists. Shared predators, whose habitat selection operates on a larger scale than that of their prey, may augment coexistence of all species by rein- forcing habitat selection by the specialists.

Galls are morphological changes caused by endoparasites on plants, mainly related to insects. Several hypotheses have been proposed to explain the patterns of gall richness. In this study, we tested the harsh environment hypothesis, which suggests higher galling richness in xeric habitats when compared to mesic habitats. In addition, we describe the richness of gall induced-insects on their host plants in a transition Cerrado-Caatinga, Brazil. Sampling was performed along of five trajectory of an “imaginary line,” traveled at a natural walking pace over the course of one hour in each of the three adjacent habitats (cerrado, dry forest and riparian forest). We found 98 different morphospecies of galling insects on 70 plant species belonging to 20 families. Gall richness was higher in the xeric habitats (cerrado and dry forest) when compared to mesic habitat (riparian forest). Gall richness differed significantly among the gall-inducing taxa; most galls morphospecies were induced by the Diptera (Cecidomyiidae). In general, richness of all gall-inducing taxa was higher in the xeric habitats than in the mesic habitat. The highest gall richness was found on leaves of the host plants of the riparian forest and cerrado, while the stem represented the organ most attacked in the dry forest. Although there is lower availability of sites for oviposition by female galling in the dry forest during the dry season, we found higher gall richness in this environment when compared to riparian forest. In this way, confirming the harsh environment hypothesis despite the absence of leaves. Likely, there was high gall irradiation on organ exposed continuously to gall attack during ecological time in dry forest. However, further studies are needed to clarify the forces related to differential gall performance among habitats, particularly in threatened Cerrado-Caatinga transition. Key words: Cerrado, seasonally dry tropical forests, harsh environment hypothesis, galling insects, host plants.

BackgroundBalancing animal conservation and human use of the landscape is an ongoing scientific and practical challenge throughout the world. We investigated reproductive success in female greater sage-grouse (Centrocercus urophasianus) relative to seasonal patterns of resource selection, with the larger goal of developing a spatially-explicit framework for managing human activity and sage-grouse conservation at the landscape level.Methodology/principal findingsWe integrated field-observation, Global Positioning Systems telemetry, and statistical modeling to quantify the spatial pattern of occurrence and risk during nesting and brood-rearing. We linked occurrence and risk models to provide spatially-explicit indices of habitat-performance relationships. As part of the analysis, we offer novel biological information on resource selection during egg-laying, incubation, and night. The spatial pattern of occurrence during all reproductive phases was driven largely by selection or avoidance of terrain features and vegetation, with little variation explained by anthropogenic features. Specifically, sage-grouse consistently avoided rough terrain, selected for moderate shrub cover at the patch level (within 90 m(2)), and selected for mesic habitat in mid and late brood-rearing phases. In contrast, risk of nest and brood failure was structured by proximity to anthropogenic features including natural gas wells and human-created mesic areas, as well as vegetation features such as shrub cover.Conclusions/significanceRisk in this and perhaps other human-modified landscapes is a top-down (i.e., human-mediated) process that would most effectively be minimized by developing a better understanding of specific mechanisms (e.g., predator subsidization) driving observed patterns, and using habitat-performance indices such as those developed herein for spatially-explicit guidance of conservation intervention. Working under the hypothesis that industrial activity structures risk by enhancing predator abundance or effectiveness, we offer specific recommendations for maintaining high-performance habitat and reducing low-performance habitat, particularly relative to the nesting phase, by managing key high-risk anthropogenic features such as industrial infrastructure and water developments.