Habitat Occupancy Research Articles

Spatial dynamic and spillover of the polyphagous pest Bemisia tabaci is influenced by differences in farmland habitats on tropical organic farms

The interplay between natural, non-cropped, and cropped habitats affects insect movement in the landscape. Polyphagous, highly mobile pests are more likely to cross habitat-edges and colonize crops. However, local differences within habitats can affect pest populations and modulate their broad response to the landscape. We investigated how different habitat types influence the spatiotemporal dynamics and spillover of a polyphagous pest on tropical organic vegetable farms. We simultaneously sampled the abundance of the worldwide pest Bemisia tabaci (Hemiptera: Aleyrodidae) on crops, fallow areas, agroforests, and forests fragments on five farms for two years. This whitefly species achieved higher population growth rates in open-field habitats (mostly crops), where resources are more easily found and concentrated. The lack of density dependence on population growth suggests that migration drives habitat occupancy. Crops were the main source of individuals to other habitat types, while agroforests and forest fragments (both sink and stepping-stones habitats) are most likely temporary habitats for whiteflies where they face a populational bottleneck. Regardless of habitat features, higher precipitation and low temperatures independently regulated population densities throughout seasons. Fragmented agricultural landscapes reduced bottom-up effects of forests and facilitated whitefly infestation on crops due to edge effects. In summary, the source-sink dynamics of whiteflies was largely determined by sink habitats that differ in local characteristics and management but was also influenced by landscape type. These findings indicate that the farmland habitat scale was adequate to integrate the scale-dependent processes operating on different spatial (local and landscape) and temporal (seasonality) scales on pest populations.

How many years of acoustic monitoring are needed to accommodate for anuran species turnover and detection?

Anuran species are threatened by a range of anthropogenically induced disturbances, highlighting the need for robust and reliable monitoring programs to detect trends in species occupancy. Anuran species experience not only differences in seasonal distributions of breeding activity, but also interannual variations in habitat occupancy which are dependent on stochastic environmental processes. Acoustic calling surveys are a widely used and reportedly reliable technique for detecting a range of anuran species in Southern Ontario. Short-term applications of this technique may be challenged to detect species which are temporarily absent from suitable habitats due to natural extirpation processes. In this paper, I analyzed anuran occupancy data from 67 long-term acoustic monitoring sites across Southern Ontario to determine the relationship between accumulated species occupancy and number of monitoring years. Data was taken from Birds Canada's Marsh Monitoring Protocol database for amphibians and filtered to extract sites which were monitored for at least 8years and recorded at least 4 anuran species. Species accumulation curves were created using EstimateS. Results suggest that there may be detectability issues for some species such as the pickerel frog, wood frog, and western chorus frog. Interannual detection rates and species accumulation curves point to the need for long-term (> 5years) monitoring programs to reliably detect on average more than 90% of anuran species occupying a monitoring site. They also reflect well-documented reports of high species turnover in anuran metapopulations, suggesting that extirpation-recolonization processes are widespread and frequent. Monitoring programs should address this issue by lengthening monitoring programs, particularly those that aim to document changes to species occupancy before and after major habitat disturbances.

Winter Flounder Navigate the Postsettlement Gauntlet with a Bet‐Hedging Strategy

AbstractWinter FlounderPseudopleuronectes americanus, a coastal flatfish species of historically economic and cultural importance, have declined throughout the past few decades within the southern New England and mid‐Atlantic region of the United States, reaching a low point of less than 9% of their historic biomass in 2009. Unusually high postsettlement mortality is thought to impose a critical recruitment bottleneck on the population, potentially stalling recovery of Winter Flounder populations despite management measures. Survival and growth during early life history play a key role in the recruitment dynamics of marine fishes. Spatiotemporal differences in these vital rates from young‐of‐the‐year (i.e., age‐0) Winter Flounder have been variously linked to environmental gradients, anthropogenic stressors, differences in the timing of settlement, and location. To better understand local declines in recruitment productivity, we assessed vital rates of age‐0 Winter Flounder in five different bays in Long Island, New York. A weekly or biweekly beam‐trawl survey targeting age‐0 Winter Flounder was implemented over five summers. We compared survey‐based estimates of age‐0 mortality and growth, finding significant differences between locations in growth but not mortality. A consistently high abundance of age‐0 Winter Flounder in Shinnecock Bay and Mattituck Creek was prolonged by a secondary settlement pulse later in the season. Hypothesizing that multiple settlement pulses are a bet‐hedging strategy against temporally varying environmental conditions, we compared mortality, growth, and occupied habitat conditions between settlement pulses (cohorts), finding differences in growth and habitat occupancy that varied across years.

Seasonal variation in sexual readiness in a facultatively sexual freshwater cnidarian with diapausing eggs

AbstractFacultative sexuality combines clonal propagation with sexual reproduction within a single life cycle. Clonal propagation enables quick population growth and the occupancy of favorable habitats. Sex, on the contrary, results in the production of offspring that are more likely to survive adverse conditions (such as the resting eggs of many freshwater invertebrates). In seasonal environments, the timing of sex is often triggered by environmental cues signaling the onset of winter (e.g., temperature drop or changes in photoperiod). Organisms switching to sex to produce resting eggs under these conditions face a trade‐off: Responding too early to an environmental cue increases the chances of missing out in clonal propagation, while having a delayed response to deteriorating conditions entails the risk of parental mortality before sexual reproduction could be completed. To mitigate these risks, increased sensitivity toward environmental cues with the onset of the winter might be an adaptive strategy. To test this hypothesis, we investigated sexual propensity and time to gonadogenesis in clonal strains derived from spring‐ and autumn‐collected polyps of Hydra oligactis, a facultatively sexual freshwater cnidarian where sex only occurs prior to the onset of winter. We show that autumn‐collected individuals and their asexual offspring have a higher propensity for sex and require less time for gonad development compared with strains established from spring‐collected individuals that were kept under similar conditions in the laboratory. To see whether the above results can be explained by phenotypic plasticity in sexual readiness, we exposed cold‐adapted laboratory strains to different lengths of warm periods. We found that sexual propensity increases with warm exposure. Our results suggest that reciprocal cold and warm periods are required for sex induction in H. oligactis, which would ensure proper timing of sex in this species. Increased sensitivity to environmental deterioration might help maximize fitness in environments that have both a predictable (seasonal) and an unpredictable component.

Finding a lost species in the ‘Lost World’: predicted habitat occupancy by an endemic butterfly in a Neotropical sky‐island archipelago

Abstract Pantepui is a Neotropical archipelago of remote sky islands (tepuis) that harbours a unique and poorly known biota, such as the endemic butterfly Antirrhea ulei. The Vicariance‐Migration hypothesis argues that Pantepui biota originated from a complex succession of climatic shifts, causing up‐and‐down migrations of cool‐adapted species from the last glacial maximum (LGM) to the present. We evaluated how environmental gradients affect A. ulei habitat occupancy and predict its distribution across the Eastern Pantepui. We also test whether the species had a broader distribution during the LGM, following the Vicariance‐Migration hypothesis. We surveyed for butterflies across 14 plots at Uei tepui, following an elevational gradient. We used Bayesian occupancy modelling to evaluate how environmental gradients affect A. ulei occurrence and to predict the current and past species distribution. Species habitat occupancy was strongly associated with environmental gradients. Our model correctly predicted the species occurrence at all localities previously reported to be occupied by the species, and also predicted the potential species occurrence on other tepuis. Our historical prediction of species distribution showed that the species likely had a broader distribution during the LGM, in comparison with its current restricted distribution. Our historical predictions suggest that the species may have spread across the Eastern Pantepui during LGM and migrated up the tepuis during the Holocene warming, in accordance with the Vicariance‐Migration hypothesis. Our study shows how data from local standardised surveys can be useful to estimate the distribution pattern of other little‐studied species of the Pantepui biota.

Habitat occupancy by semi‐aquatic reptiles on an aridity gradient in the western Mediterranean

AbstractThe influence of aquatic and riparian habitats on the composition of the local herpetofauna has not been studied extensively. We used redundancy analysis and multivariate ordination methods to evaluate the occurrence of semi‐aquatic reptiles in south‐eastern France, the Iberian Peninsula, and Morocco where the climate transitions from humid temperate to subtropical desert. All the semi‐aquatic reptile species present in this region were studied, including two native turtles (Emys orbicularis and Mauremys leprosa), three native snakes (Natrix astreptophora, N. helvetica, and N. maura), and one introduced turtle (Trachemys scripta). We hypothesized that these species will vary in their responses to differences in the composition of riparian habitats (vegetative community and relative proportion of trees, shrubs, grasses, water and bare ground surface) along the aridity gradient in the region. We found that the habitat niche marginality and niche breadth varied widely across species and climatic regions, although most of the species display a greater habitat niche breadth in the transitional semi‐arid belt. Mauremys leprosa and N. maura were the more generalist species, occupying a wide range of freshwater habitats, including streams associated with impoverished vegetation communities, characteristic of the arid southern Mediterranean region.

Community eDNA metabarcoding as a detection tool for documenting freshwater mussel (Unionidae) species assemblages

AbstractDocumenting species occurrences and habitat occupancy of unionid mussels can often be challenging. Environmental DNA (eDNA) has been shown to be a reliable tool for detecting unionids with comparable or greater sensitivity than conventional sampling and has the added advantages of not disturbing individuals or occupied habitats. However, single‐species eDNA assays are limited to targeting individual species of interest and are functionally blind to the presence of other species. Community eDNA assays have the potential to characterize local species assemblages simultaneously but are currently less extensively developed and implemented than single‐species eDNA testing. We tested the effectiveness of community eDNA markers to identify unionid species assemblages, using two overlapping conserved primers that target the maternal mitochondrial 16S rDNA region. Both primer sets were optimized using three mock communities and successfully amplified 62.5%–81.6% of species with largely consistent results between the primer sets. Following optimization, eDNA from water samples from 24 reference sites with known mussel communities was amplified and sequenced to quantify species richness and diversity within and among sites. Metabarcoding results from the monitoring sites largely mirrored those from the mock communities, with >80% of species detections identified by both assays. The results were broadly consistent with species data from quadrat‐based manual field surveys, although both community eDNA and conventional sampling detected some species that the other method did not. These results demonstrate that community eDNA assays using conserved primers and next‐generation sequencing have the potential to simultaneously target eDNA from multiple unionid species and provide a powerful tool for complementing or augmenting conventional field surveys to characterize and monitor unionid species assemblages.

Where three snail species attach while emersed in relation to heterogenous substrate temperatures underneath intertidal boulders.

Mobile intertidal gastropods can employ behavioural thermoregulation to mitigate thermal stress, which may include retreating under boulders when emersed. However, little is known about how gastropod occupancy of under-boulder habitats is associated with any variations in substrate temperature that exist under boulders. Thermal imagery was used to measure the temperature of boulder lower surfaces and investigate how three snail species were associated at low tide with the maximum and average temperatures underneath grey siltstone and quartzite. Lower boulder surfaces had heterogeneous temperatures, with grey siltstone having temperature gradients and quartzite temperature showing mosaics. Temperature differences between the hottest and coolest gradient or mosaic locations were >5 °C; thus there was a range of temperatures that snails could interact with. All three snail species occupied cooler parts of temperature mosaics or gradients, avoiding the hottest areas. Stronger associations were detected on the hotter grey siltstone and for the more-thermally sensitive Nerita atramentosa and Diloma concameratum. Even though snails were associated with cooler areas, some individuals were still exposed to extreme substratum heat (>50 °C). These results suggest that gastropod thermoregulatory behaviour is far more complex than simply retreating underneath boulders at low tide, as there is also a range of under-boulder temperatures that they interact with. Untangling interactions between intertidal gastropods and heterogenous substrate temperatures is important given rocky seashores already represent a thermally-variable and potentially-stressful habitat, which may be exacerbated further given predictions of warming temperatures associated with climate change.

Searching for Function: Reconstructing Adaptive Niche Changes Using Geochemical and Morphological Data in Planktonic Foraminifera

Dead species remain dead. The diversity record of life is littered with examples of declines and radiations, yet no species has ever re-evolved following its true extinction. In contrast, functional traits can transcend diversity declines, often develop iteratively and are taxon-free allowing application across taxa, environments and time. Planktonic foraminifera have an unrivaled, near continuous fossil record for the past 200 million years making them a perfect test organism to understand trait changes through time, but the functional role of morphology in determining habitat occupation has been questioned. Here, we use single specimen stable isotopes to reconstruct the water depth habitat of individual planktonic foraminifera in the genus Subbotina alongside morphological measurements of the tests to understand trait changes through the Middle Eocene Climatic Optimum [MECO: ∼40 Myr ago (mega annum, Ma)]. The MECO is a geologically transient global warming interval that marks the beginning of widespread biotic reorganizations in marine organisms spanning a size spectrum from diatoms to whales. In contrast to other planktonic foraminiferal genera, the subbotinids flourished through this interval despite multiple climatic perturbations superimposed on a changing background climate. Through coupled trait and geochemical analysis, we show that Subbotina survival through this climatically dynamic interval was aided by trait plasticity and a wider ecological niche than previously thought for a subthermocline dwelling genus supporting a generalist life strategy. We also show how individually resolved oxygen isotopes can track shifts in depth occupancy through climatic upheaval. During and following the MECO, temperature changes were substantial in the thermocline and subthermocline in comparison to the muted responses of the surface ocean. In our post-MECO samples, we observe restoration of planktonic foraminifera depth stratification. Despite these changing temperatures and occupied depths, we do not detect a contemporaneous morphological response implying that readily available traits such as test size and shape do not have a clear functional role in this generalist genus. Modern imaging measurement technologies offer a promising route to gather more informative morphological traits for functional analysis, rather than the traditional candidates that are most easily measured.

Hatching date influences winter habitat occupancy: Examining seasonal interactions across the full annual cycle in a migratory songbird.

Birds experience a sequence of critical events during their life cycle, and past events can subsequently determine future performance via carry‐over effects. Events during the non‐breeding season may influence breeding season phenology or productivity. Less is understood about how events during the breeding season affect individuals subsequently in their life cycle. Using stable carbon isotopes, we examined carry‐over effects throughout the annual cycle of prairie warblers (Setophaga discolor), a declining Nearctic–Neotropical migratory passerine bird. In drier winters, juvenile males that hatched earlier at our study site in Massachusetts, USA, occupied wetter, better‐quality winter habitat in the Caribbean, as indicated by depleted carbon isotope signatures. For juveniles that were sampled again as adults, repeatability in isotope signatures indicated similar winter habitat occupancy across years. Thus, hatching date of juvenile males appears to influence lifetime winter habitat occupancy. For adult males, reproductive success did not carry over to influence winter habitat occupancy. We did not find temporally consecutive “domino” effects across the annual cycle (breeding to wintering to breeding) or interseasonal, intergenerational effects. Our finding that a male's hatching date can have a lasting effect on winter habitat occupancy represents an important contribution to our understanding of seasonal interactions in migratory birds.

Topography‐derived variables provide insight into habitat occupancy of a cryptic snake, Bitis atropos

AbstractUnderstanding species’ habitat use is fundamental for conservation and management. However, quantifying habitat use for small cryptic species is limited by imperfect detection during field surveys and the lack of habitat data at meaningful spatial scales. Topographically‐derived habitat variables from digital elevation models (DEMs) have the potential to overcome these limitations. Here we used DEM‐derived topographic variables as fine‐scale proxies for abiotic conditions to study site‐occupancy patterns of the berg adder (Bitis atropos), a small‐bodied cryptic viper. We carried out seven repeated field surveys across 219 hectares in a mountainous protected area in north‐eastern South Africa to estimate snake detection probability and occupancy using maximum likelihood methods. Although snakes occurred across a third of the surveyed habitat, they were only detected 40% of the time during the springtime when detection was highest. Results showed that these snakes preferred north‐west facing, mid and upper slopes, which are exposed to afternoon sun and presumably higher ambient energy. Our results demonstrate the value of using DEM‐derived topographic variables for ecological studies where habitat data are either unavailable or inappropriate, thereby providing valuable insights into habitat use of cryptic and difficult to detect species.

Warming threatens habitat suitability and breeding occupancy of rear‐edge alpine bird specialists

Alpine ecosystems are particularly vulnerable to climate change. For widely distributed alpine specialists, rear‐edge populations are disproportionately important; it is expected that climate change will reduce their occupancy ranges due to the loss of suitable habitats and connectivity among them. Using four alpine bird species inhabiting the southwestern Palearctic as models, we aim to study which and how environmental factors influence habitat suitability, identify mountain areas with suitable habitat, estimate the probabilities of hosting breeding populations for these areas, and predict how habitat suitability and breeding occupancy will change under future climate scenarios. We used a species distribution modeling approach to obtain habitat suitability maps for four biological seasons and assessed the importance and effects of climatic and landscape variables for the studied species. We also assessed the probability of occupancy of potential breeding patches using available systematic distribution data, and projected our habitat suitability and occupancy models to future climate conditions. Our results indicated that the habitat suitability of rear‐edge alpine specialists was limited mainly by climatic factors, restricting their suitable areas to the highest mountains where cold climate persist. The actual occupancy of the potential breeding patches was determined by their size, landscape connectivity and habitat quality. For the period 2041–2060 we predicted a substantial reduction of suitable habitats that varied across seasons and species, and a breeding occupancy range loss that varied across mountain ranges and species. Thus, these alpine bird species, currently not considered as threatened, merit a review of their conservation status. Common distribution patterns and potentially similar responses to climatic change suggest that our findings might be applicable for other rear‐edge alpine species. Our study identified specific mountain systems where research and conservation efforts should focus for the conservation of alpine biodiversity in the southwestern Palearctic.

Climate and land‐use change drive habitat loss in a mountain bird species

Mountain areas still feature remnants of traditional land use and consequently constitute a large proportion of the remaining species‐rich habitats in Central Europe. However, their biodiversity is increasingly threatened by changes in climate and land use. The Alpine Ring Ouzel Turdus torquatus alpestris is a typical mountain bird that has recently declined in most of its breeding range. In this study we compared the historical (1986–1987) and recent (2017) distribution of breeding Ring Ouzels in 62 randomly selected 750 × 750 ‐m plots and analysed local colonization and extinction patterns in 558 subunits (= ‘grid cells’) in the southern Black Forest (south‐western Germany). Our study revealed that habitat occupancy has decreased by about one‐third, mainly at lower elevations and in depressed landforms, during the past three decades. Local colonization amounted to 25% and extinction to 66% of the previously vacant or occupied grid cells, respectively. Habitat occupancy and local colonization and extinction were driven by climate and habitat parameters. The Ring Ouzel preferred convex landscape formations such as mountain peaks and ridges with long snow‐cover duration for breeding. Sites with high proportions of deciduous forest and abandoned pasture were avoided. Local colonization was higher at convex landscape formations and by high coniferous forest coverage and forest‐edge length. Local extinction, on the other hand, was lower at convex landscape formations and high‐elevation sites. Our results suggest that shorter persistence of snow fields caused by climate change and degradation of feeding grounds through land‐use abandonment might severely deteriorate food availability for the species, which is likely to have contributed to the observed decline. For conservation of the Alpine Ring Ouzel, we recommend adopting measures to mitigate the negative effects of climate warming and improve habitat quality. The creation of small‐scale mosaics of sparse conifer forests and regularly grazed pastures, especially on north‐ and east‐facing slopes on the lee sides of hills, mountain peaks or ridges, should be supported.

Remarkable Population Resilience in a North African Endemic Damselfly in the Face of Rapid Agricultural Transformation.

Simple SummaryThere has been a rapid expansion of agricultural area worldwide, resulting in a substantial change in the physical structure, biodiversity, and ecosystem functioning of various natural habitats. In North Africa, many natural habitats have been transformed into agricultural lands, especially in the North, where biodiversity is the highest, to meet the food security and economic development of a rapidly growing population. We estimated the agricultural expansion in North African region between the 1990s and 2000s and found that the percentage of agriculture-free area within the species range declined from 79.5% to 26.2%. Knowing that agroecosystems near lotic environments simplify the structural complexity of habitats (from heterogeneous to homogenous ecological communities) of amphibiotic species such as odonates, we estimated the geographic range of an endemic damselfly and quantified the temporal change in the overlap between agriculture and species occurrence. Our results showed the overlap more than tripled between 1992 and 2005, suggesting that the species experienced a radical change in its terrestrial habitats. We conducted capture–mark–recapture to confirm that the species survives by frequently using croplands and grasslands.Agriculture can be pervasive in its effect on wild nature, affecting various types of natural habitats, including lotic ecosystems. Here, we assess the extent of agricultural expansion on lotic systems in Northern Africa (Algeria, Tunisia, and Morocco) and document its overlap with the distribution of an endemic damselfly, Platycnemis subdilatata Selys, using species distribution modeling. We found that agricultural land cover increased by 321% in the region between 1992 and 2005, and, in particular, the main watercourses experienced an increase in agricultural land cover from 21.4% in 1992 to 78.1% in 2005, together with an increase in the intensity of 226% in agricultural practices. We used capture–mark–recapture (CMR) surveys in terrestrial habitats surrounding a stream bordered by grassland and cropland in northeastern Algeria to determine demographic parameters and population size, as well as cropland occupancy. CMR modeling showed that the recapture and survival probabilities had an average of 0.14 (95%CI: 0.14–0.17) and 0.86 (0.85–0.87), respectively. We estimated a relatively large population of P. subdilatata (~1750 individuals) in terrestrial habitats. The occupancy of terrestrial habitats by adults was spatially structured by age. Our data suggest that P. subdilatata has survived agricultural expansion and intensification better than other local odonate species, mainly because it can occupy transformed landscapes, such as croplands and grasslands.

Potential mammalian species for investigating the past connections between Amazonia and the Atlantic Forest.

Much evidence suggests that Amazonia and the Atlantic Forest were connected through at least three dispersion routes in the past: the Eastern route, the central route, and the Western route. However, few studies have assessed the use of these routes based on multiple species. Here we present a compilation of mammal species that potentially have dispersed between the two forest regions and which may serve to investigate these connections. We evaluate the present-day geographic distributions of mammals occurring in both Amazonia and the Atlantic Forest and the likely connective routes between these forests. We classified the species per habitat occupancy (strict forest specialists, species that prefer forest habitat, or generalists) and compiled the genetic data available for each species. We found 127 mammalian species presently occurring in both Amazonia and the Atlantic Forest for which, substantial genetic data was available. Hence, highlighting their potential for phylogeographic studies investigating the past connections between the two forests. Differently from what was previously proposed, the present-day geographic distribution of mammal species found in both Amazonia and the Atlantic Forest points to more species in the eastern portion of the dry diagonal (and adjoining forested habitats). The Central route was associated with the second most species. Although it remains to be seen how this present-day geography reflects the paleo dispersal routes, our results show the potential of using mammal species to investigate and bring new insights about the past connections between Amazonia and the Atlantic Forest.

Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) summer thermal habitat use in streams with sympatric populations

This study addresses the need to examine the thermally mediated interactions of fish with their natural environment by investigating the shift in thermal habitat occupation for sympatric Brook and Brown Trout populations. We observed upstream Brook Trout and Brown Trout population shifts during the summer, with thermal habitats showing an increased number of Brown Trout, while some sites also displayed a decrease in the number of Brook Trout. Overall, there was an increased incidence of overlapping habitat occupation at the end of the summer. Brown Trout occupied optimal resting and feeding thermal habitat locations, which can potentially affect growth rates and Brook Trout's survival. Population shifts did not occur at elevated water temperatures as expected but seem driven by temperatures that are optimal for growth. Observed population shifts can lead to increased interactions between the two species throughout the summer. The results provide a better understanding of how future, longer-term, thermal habitat modifications may modify species interactions, which are critical for salmonid conservation efforts.

Dynamic multistate occupancy modeling to evaluate population dynamics under a scenario of preferential sampling

AbstractEffective conservation of animal populations depends on the availability of reliable data derived from rigorous monitoring protocols, which allows us to assess trends and understand the processes they are governed by. Nevertheless, population monitoring schemes are hampered by multiple sources of errors resulting from specific logistical and survey constraints. Two common complications are the non‐visitation of some sites in certain years and preferential sampling (PS), that is, the tendency to survey “better” sites disproportionately more often. Both factors can lead to serious biases unless accommodated into models. We used 22 yr of nest‐monitoring data to develop a dynamic multistate occupancy model, including a PS component to investigate occupancy and reproduction dynamics in a peripheral Black Stork (Ciconia nigra) population in Spain. We analyzed the effects of climate and nesting substrate (tree vs. cliff) on population dynamics and accounted for PS and non‐visitation biases using a model that distinguished three territorial states: unoccupied, occupied without, or occupied with successful reproduction. We found strong evidence for positive PS, and when accounting for this bias, lower population size estimates were generated. Black stork nests had a high probability of remaining in the same state from one year to the next, with successful nests more likely to be occupied again and to be successful the following year than occupied but unsuccessful or unoccupied nests. Nesting substrate and spring precipitation did not influence state transition probabilities or the probability of reproductive success; nevertheless, cliff nest occupancy was overall higher than tree nest occupancy. Our results highlight the importance of correcting for non‐visitation and PS in habitat occupancy models. If these potential biasing effects are not accounted for, inferences of population size may be overestimate. Multistate occupancy models with correction for PS offer a powerful analytical framework for data collected as part of population studies of unmarked animals. These models compensate for common methodological biases in biological surveys and can help implement efficient conservation strategies based on robust population dynamics estimates.

Pollinator interaction flexibility across scales affects patch colonization and occupancy.

Global change alters ecological communities and may disrupt ecological interactions and the provision of ecosystem functions. As ecological communities respond to global change, species may either go locally extinct or form novel interactions. To date, few studies have assessed how flexible species are in their interaction patterns, mainly due to the scarcity of data spanning long time series. Using a ten-year species-level dataset on the assembly of mutualistic networks from the Central Valley in California, we test whether interaction flexibility affects pollinators' colonization and persistence and their resulting habitat occupancy in a highly modified landscape. We propose three metrics of interaction flexibility associated with different scales of organization within ecological communities and explore which species' traits affect them. Our results provide empirical evidence linking species' ability to colonize habitat patches across a landscape to the role they play in networks. Phenological breadth and body size had contrasting effects on interaction flexibility. We demonstrate the relationship between mutualistic networks and species' ability to colonize and persist in the landscape, suggesting interaction flexibility as a potential mechanism for communities to maintain ecosystem function despite changes in community composition.

Habitat Specificity, Host Plants and Areas of Endemism for the Genera-Group Blepharida s.l. in the Afrotropical Region (Coleoptera, Chrysomelidae, Galerucinae, Alticini).

Simple SummaryKnowledge of the processes that generate biodiversity is a core-issue of any conservation strategy because it allows predicting the effects of environmental changes in the number and distribution of target taxa. Some phytophagous insects can be good potential indicators of such processes, thanks to their wide distribution and their sensitivity to climate change, due to the association with specific environments and host plants. Unfortunately, this ecological information is often lacking. However, statistical tools allow reconstructing the ecological features of interest, based on the presence–absence data of the taxa, the climatic and vegetational features of their distributional areas, and the available data about their host plants. In this paper, we apply some geostatistical methods to identify processes and patterns of biodiversity at a continental scale, focusing on a group of phytophagous insects widespread in sub-Saharan Africa.The genus Calotheca Heyden (Chrysomelidae) is mainly distributed in the eastern and southern parts of sub-Saharan Africa, with some extensions northward, while Blepharidina Bechyné occurs in the intertropical zone of Africa, with two subgenera, Blepharidina s. str. and Blepharidina (Afroblepharida) Biondi and D’Alessandro. These genera show different ecological preferences. Through an up-to-date presence–absence dataset, in the light of the terrestrial ecoregions of sub-Saharan Africa and the distribution of their possible host plants, we interpreted the pattern of occurrence of these three supraspecific taxa, by geostatistical analyses in GIS and R environments. The separation of Blepharidina from Calotheca was probably driven by changes in climate as adaptation to more xeric and warm environments with a major occupancy of semidesert and savannah habitats, especially in the Afroblepharida species. Based on our data and analyses, Calotheca is mainly associated with Searsia (Anacardiaceae), and Blepharidina is likely associated with Commiphora (Burseraceae). This hypothesis is also corroborated by the widespread and even dominance of the Commiphora plants in the ecoregions where both Blepharidina s.str. and, above all, Afroblepharida, are more common. The main areas of endemism of the two genera are also differently located: Calotheca in the temperate zone; Blepharidina within the intertropical belt.

Fine-scale analysis of habitat occupancy by Kura lizard (Darevskia portschinskii) and its daughter parthenogenetic form (Darevskia dahli)

Two species of rock lizards, the parthenogenetic D. dahli and the sexually reproducing D. portschinskii, coexist in a rocky outcrop in an area of ca. 1 ha, in the vicinity of Tbilisi, Georgia; the location has been well-known since the middle 1960s. The population density of the parthenogenetic lizard is five times higher than that of the sexual breeder. We studied the distribution of active lizards in space and time over three consecutive years, during the spring and autumn activity periods, to explore spatial and temporal differences between the species on a fine spatial scale. We studied the influence of temperature, humidity, and quantitative characteristics of the surface and the distance from permanent water source on the spatial distribution of D. dahli and D. portschinskii. Darevskia portschinskii was less dependent on the distance from the water source and more evenly distributed in space and time than D. dahli. Despite potential competitive interactions, the species did not avoid each other on the microhabitat scale, suggesting that the observed ecological differences are not caused by a niche shift. More individuals of the sexual breeder than individuals of the parthenogen were found in suboptimal habitats. This feature may increase the evolutionary success of D. portschinskii in a long-term perspective.