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1.
Abstract 1. The present study used the mountain specialist butterfly Parnassius apollo as a model system to investigate how climate change may alter habitat requirements for species at their warm range margins. 2. Larval habitat use was recorded in six P. apollo populations over a 700 m elevation gradient in the Sierra de Guadarrama (central Spain). Larvae used four potential host species (Sedum spp.) growing in open areas amongst shrubs. 3. Parnassius apollo host‐plant and habitat use changed as elevation increased: the primary host shifted from Sedum amplexicaule to Sedum brevifolium, and larvae selected more open microhabitats (increased bare ground and dead vegetation, reduced vegetation height and shrub cover), suggesting that hotter microhabitats are used in cooler environments. 4. Larval microhabitat selection was significantly related to ambient temperature. At temperatures lower than 27 °C, larvae occupied open microhabitats that were warmer than ambient temperature, versus more shaded microhabitats that were cooler than ambient conditions when temperature was higher than 27 °C. 5. Elevational changes in phenology influenced the temperatures experienced by larvae, and could affect local host‐plant favourability. 6. Habitat heterogeneity appears to play an important role in P. apollo larval thermoregulation, and may become increasingly important in buffering populations of this and other insect species against climatic variation.  相似文献   

2.
Ecological responses to climate change may depend on complex patterns of variability in weather and local microclimate that overlay global increases in mean temperature. Here, we show that high‐resolution temporal and spatial variability in temperature drives the dynamics of range expansion for an exemplar species, the butterfly Hesperia comma. Using fine‐resolution (5 m) models of vegetation surface microclimate, we estimate the thermal suitability of 906 habitat patches at the species' range margin for 27 years. Population and metapopulation models that incorporate this dynamic microclimate surface improve predictions of observed annual changes to population density and patch occupancy dynamics during the species' range expansion from 1982 to 2009. Our findings reveal how fine‐scale, short‐term environmental variability drives rates and patterns of range expansion through spatially localised, intermittent episodes of expansion and contraction. Incorporating dynamic microclimates can thus improve models of species range shifts at spatial and temporal scales relevant to conservation interventions.  相似文献   

3.
Devin R. de Zwaan  Kathy Martin 《Ibis》2018,160(4):790-804
Songbird nests are an important life‐history component with multiple functions, including the creation of a suitable microclimate for offspring development. Thus, functional nest characteristics may influence fitness correlates, such as nestling size traits, and may co‐vary with prevailing environmental conditions. We investigated among‐ and within‐female variation in nest substrate, lining and decoration structures with associated fitness consequences (hatching success, nestling size traits, nest survival) across two breeding seasons for an alpine population of Horned Lark Eremophila alpestris. We combined these observations with explicit measures of nest temperature to address the influence of nest characteristics on microclimate. Nests in heather substrate had the coldest microclimates compared with grass and bare‐ground substrate, but also the greatest nest survival rates (68% versus 37–44% in other substrates), indicating the potential for substrate use decisions to reflect a trade‐off between microclimate and nest survival in response to prevailing weather and predation risk conditions. Furthermore, nest lining and nest decoration patterns indicated some support for a thermoregulatory function. Nests that were lined with willow (Salix sp.) seed‐down were associated with larger, heavier nestlings and the use of down lining decreased in frequency as the season warmed up. Nest decoration placed in front of the nest (e.g. stones or dirt clumps varying in mass from 5.3 to 186.6 g) was positively associated with warmer nest microclimates. Females demonstrated high phenotypic flexibility, as 61–94% of the observed variance in nest characteristics was explained by within‐female rather than among‐female differences. Such flexible nesting behaviour suggests the capacity to adjust to changing environmental conditions to maintain vital fitness correlates such as nest survival and nestling size development.  相似文献   

4.
Global change, including habitat isolation and climate change, has both short‐ and long‐term impacts on wildlife populations. For example, genetic drift and inbreeding result in genetic impoverishment in small, isolated populations, while species undergo range shifts or adaptive phenotypic change in response to shifts in environmental temperatures. In this study, we utilize a model system in which Holocene landscape changes have occurred to examine long‐term effects of population isolation. To examine how isolation may constrain responses to climate change, we characterized ecophysiology across land‐bridge island populations of Erhard's wall lizard Podarcis erhardii. We hypothesized that 1) small, isolated populations that are likely genetically depauperate would exhibit lower phenotypic variability; and 2) populations would be adapted to local microhabitat conditions. We compared a population at a low elevation site on the large island of Naxos with two small populations on nearby islets to determine the effects of population fragmentation. We further compared the low elevation Naxos population with two high elevation sites characterized by disparate microclimates to examine the effects of microclimate. To assess the thermal biology and ecophysiological limits of the study species we measured operative body temperatures (Te), field body temperatures (Tb), preferred temperatures (Tp), thermal tolerances (CTmax and CTmin), and evaporative water loss (EWL). Our results indicate that small, isolated populations did not exhibit thermal biology or evaporative water loss, while EWL and thermoregulatory effort varied according to microhabitat characteristics. This study integrates fine‐scale measurements with environmental data to provide a holistic view of the relationships between ecophysiology, fragmentation, and microclimate. Our methods can be applied to other ectotherms to gain a better understanding of potential impacts of global change on natural populations.  相似文献   

5.
6.
Climate warming is likely to shift the range margins of species poleward, but fine‐scale temperature differences near the ground (microclimates) may modify these range shifts. For example, cold‐adapted species may survive in microrefugia when the climate gets warmer. However, it is still largely unknown to what extent cold microclimates govern the local persistence of populations at their warm range margin. We located 99 microrefugia, defined as sites with edge populations of 12 widespread boreal forest understory species (vascular plants, mosses, liverworts and lichens) in an area of ca. 24,000 km2 along the species' southern range margin in central Sweden. Within each population, a logger measured temperature eight times per day during one full year. Using univariate and multivariate analyses, we examined the differences of the populations' microclimates with the mean and range of microclimates in the landscape, and identified the typical climate, vegetation and topographic features of these habitats. Comparison sites were drawn from another logger data set (n = 110), and from high‐resolution microclimate maps. The microrefugia were mainly places characterized by lower summer and autumn maximum temperatures, late snow melt dates and high climate stability. Microrefugia also had higher forest basal area and lower solar radiation in spring and autumn than the landscape average. Although there were common trends across northern species in how microrefugia differed from the landscape average, there were also interspecific differences and some species contributed more than others to the overall results. Our findings provide biologically meaningful criteria to locate and spatially predict potential climate microrefugia in the boreal forest. This opens up the opportunity to protect valuable sites, and adapt forest management, for example, by keeping old‐growth forests at topographically shaded sites. These measures may help to mitigate the loss of genetic and species diversity caused by rear‐edge contractions in a warmer climate.  相似文献   

7.
Microhabitat heterogeneity can lead to fine‐scale local adaptation when gene flow is restricted, which may be important for the maintenance of genetic variation within populations. This study tested whether microhabitat heterogeneity was associated with trait differences in a population of Arabidopsis lyrata and studied its impact on the genetic variance–covariance (G) matrix. Maternal seed families were collected from dune tops and bottoms, two microhabitats known to vary significantly in water availability. In a common garden experiment, replicate individuals per family were raised under wet and dry conditions, and physiological, morphological and life‐history traits were assessed. Plants from the two microenvironments differed in their response to treatment in two performance components, in stomata density and most strongly in flowering time. Under wet conditions, plants originating from dune bottoms flowered 4 weeks earlier than those from dune tops. Only one of three G‐matrix comparisons revealed that habitat heterogeneity and evolutionary potential were positively linked. The number of independent trait dimensions was larger in the entire population than within subpopulations separated by microhabitat under wet conditions. However, the size of the G‐matrix was no larger in the entire population than within subpopulations separated by microhabitat, and trait correlation structure between microhabitats and treatments was not significantly different. These results indicate that fine‐scale habitat heterogeneity likely led to local adaptation, which weakly affected levels of across‐trait genetic variation.  相似文献   

8.
Temperature increases because of climate change are expected to cause expansions at the high latitude margins of species distributions, but, in practice, fragmented landscapes act as barriers to colonization for most species. Understanding how species distributions will shift in response to climate change therefore requires techniques that incorporate the combined effects of climate and landscape‐scale habitat availability on colonization rates. We use a metapopulation model (Incidence Function Model, IFM) to test effects of fine‐scale habitat use on patterns and rates of range expansion by the butterfly Hesperia comma. At its northern range margin in Britain, this species has increased its breadth of microhabitat use because of climate warming, leading to increased colonization rates. We validated the IFM by reconstructing expansions in five habitat networks between 1982 and 2000, before using it to predict metapopulation dynamics over 100 yr, for three scenarios based on observed changes to habitat use. We define the scenarios as “cold‐world” (only hot, south‐facing 150–250° hillsides are deemed warm enough), “warm‐world” in which 100–300° hillsides can be populated, and “hot‐world”, where the background climate is warm enough to enable use of all aspects (as increasingly observed). In the simulations, increased habitat availability in the hot‐world scenario led to faster range expansion rates, and to long‐term differences in distribution size and pattern. Thus, fine‐scale changes in the distribution of suitable microclimates led to landscape‐scale changes in population size and colonization rate, resulting in coarse‐scale changes to the species distribution. Despite use of a wider range of habitats associated with climate change, H. comma is still expected to occupy a small fraction of available habitat in 100 yr. The research shows that metapopulation models represent a potential framework to identify barriers to range expansion, and to predict the effects of environmental change or conservation interventions on species distributions and persistence.  相似文献   

9.
Contrary to assumptions of habitat selection theory, field studies frequently detect ‘ecological traps’, where animals prefer habitats conferring lower fitness than available alternatives. Evidence for traps includes cases where birds prefer breeding habitats associated with relatively high nest predation rates despite the importance of nest survival to avian fitness. Because birds select breeding habitat at multiple spatial scales, the processes underlying traps for birds are likely scale‐dependent. We studied a potential ecological trap for a population of yellow warblers Dendroica petechia while paying specific attention to spatial scale. We quantified nest microhabitat preference by comparing nest‐ versus random‐site microhabitat structure and related preferred microhabitat features with nest survival. Over a nine‐year study period and three study sites, we found a consistently negative relationship between preferred microhabitat patches and nest survival rates. Data from experimental nests described a similar relationship, corroborating the apparent positive relationship between preferred microhabitat and nest predation. As do other songbirds, yellow warblers select breeding habitat in at least two steps at two spatial scales; (1) they select territories at a coarser spatial scale and (2) nest microhabitats at a finer scale from within individual territories. By comparing nest versus random sites within territories, we showed that maladaptive nest microhabitat preferences arose during within‐territory nest site selection (step 2). Furthermore, nest predation rates varied at a fine enough scale to provide individual yellow warblers with lower‐predation alternatives to preferred microhabitats. Given these results, tradeoffs between nest survival and other fitness components are unlikely since fitness components other than nest survival are probably more relevant to territory‐scale habitat selection. Instead, exchanges of individuals among populations facing different predation regimes, the recent proliferation of the parasitic brown‐headed cowbird Molothrus ater, and/or anthropogenic changes to riparian vegetation structure are more likely explanations.  相似文献   

10.
Mitigating the threat of habitat loss requires actions such as restoring and creating new habitat. In order to effectively achieve this, species habitat requirements and use patterns need to be understood. While many studies have been conducted on the habitat choice of species, these generally focused on habitat use during periods of high activity and detection probability without considering seasonal shifts in habitat use. Understanding habitat selection by frogs during the winter season of low activity may be crucial since it may differ from that used during the summer and may be overlooked as important for population success. We describe the microhabitat use of the threatened green and golden bell frog (Litoria aurea) using radio tracking methods during winter when detection is low and knowledge is limited. We followed 26 individuals between May and July, 2011 to determine whether they selected specific overwintering microhabitats and related this to levels of individual exposure to predators, distance from the edge of the water and temperature of microhabitats. We found that overwintering bell frogs inhabited reeds and rock gabions more frequently than expected and that females used a reduced subset of microhabitats compared to males. Additionally, microhabitats used were more likely to conceal an individual from view, and the majority of overwintering sites were located within 5 m of the edge of the water which may be important for reducing the risk of predation and desiccation. Rock gabions had significantly warmer (1.2°C–1.8°C) mean temperatures than the other microhabitats used. The information presented here can be used in habitat creation and reintroduction programmes to provide habitat which is suitable during both the breeding and non‐breeding season for the conservation of other populations.  相似文献   

11.
Ectotherms can attain preferred body temperatures by selecting specific temperature microhabitats within a varied thermal environment. The side‐blotched lizard, Uta stansburiana may employ microhabitat selection to thermoregulate behaviorally. It is unknown to what degree habitat structural complexity provides thermal microhabitats for thermoregulation. Thermal microhabitat structure, lizard temperature, and substrate preference were simultaneously evaluated using thermal imaging. A broad range of microhabitat temperatures was available (mean range of 11°C within 1–2 m2) while mean lizard temperature was between 36°C and 38°C. Lizards selected sites that differed significantly from the mean environmental temperature, indicating behavioral thermoregulation, and maintained a temperature significantly above that of their perch (mean difference of 2.6°C). Uta's thermoregulatory potential within a complex thermal microhabitat structure suggests that a warming trend may prove advantageous, rather than detrimental for this population.  相似文献   

12.
Habitat-specialist species may be restricted to a narrower range of microhabitats than habitat-generalist species. We addressed this hypothesis by comparing microhabitats of two pairs of congeners that differ in habitat specificity and co-occur in one distinct habitat type, Florida rosemary scrub. We characterized microhabitats of rosemary scrub specialists, Polygonella basiramia and Lechea cernua, their habitat-generalist congeners, Polygonella robusta and Lechea deckertii, and random points in the rosemary scrub habitat. Plants of both habitat specialists occurred in microhabitats with significantly more bare sand than plants of habitat-generalist species and random points. Plants of all four species occurred in microhabitats that were farther from dominant shrubs, Ceratiola and Quercus spp., than random points. Seedlings of both habitat specialists grew larger in bare sand microhabitats, whereas ground lichens and litter did not affect seedling growth of the habitat generalists. As the time since fire increases, bare sand cover decreases, Ceratiola density increases, Quercus density remains constant, and shrubs become taller. Physical characteristics, such as soil temperature, soil carbon, and soil moisture, differ slightly with respect to microhabitat. Our results suggest that P. basiramia and L. cernua are specialized on bare sand microhabitats that characterize their preferred habitat, rosemary scrub. Microhabitat specialization may limit the distribution of these rare species.  相似文献   

13.
Microrefuges provide microclimates decoupled from inhospitable regional climate regimes that enable range‐peripheral populations to persist and are important to cold‐adapted species in an era of accelerated climate change. However, identifying and describing the thermal characteristics of microrefuge habitats is challenging, particularly for mobile organisms in cryptic, patchy habitats. We examined variation in subsurface thermal conditions of microrefuge habitats among different rock substrate types used by the American pika (Ochotona princeps ), a climate‐sensitive, rock‐dwelling Lagomorph. We compared subsurface temperatures in talus and lava substrates in pika survey sites in two US national park units; one park study area on the range periphery and the other in the range core. We deployed paired sensors to examine within‐site temperature variation. We hypothesized that subsurface temperatures within occupied sites and structurally complex substrates would be cooler in summer and warmer in winter than unoccupied and less complex sites. Although within‐site variability was high, with correlations between paired sensors as low as 47%, we found compelling evidence that pikas occupy microrefuge habitats where subsurface conditions provide more thermal stability than in unoccupied microhabitats. The percentage of days in which microhabitat temperatures were between ?2.5 and 25.5°C was significantly higher in occupied sites. Interestingly, thermal conditions were substantially more stable (p  < .05) in the lava substrate type identified to be preferentially used by pikas (pahoehoe vs. a'a) in a previous study. Our study and others suggest that thermal stability appears to be the defining characteristic of subsurface microrefuges used by American pikas and is a likely explanation for enigmatic population persistence at the range periphery. Our study exemplifies an integrated approach for studying complex microhabitat conditions, paired with site use surveys and contextualized with information about gene flow provided by complementary studies.  相似文献   

14.
An animal's microhabitat requirements can impact its ability to colonize restored areas, particularly species requiring slow developing microhabitats, such as logs and woody debris piles. Introduction of these microhabitats may be required to facilitate colonization by some species. Restored bauxite mine‐pits in the Jarrah (Eucalyptus marginata) forest of south‐western Australia contain introduced log piles at densities of 1 ha?1. However, these have not facilitated colonization by Napoleon's skink (Egernia napoleonis), which rely on logs for habitat and are largely absent from restored sites. We radio‐tracked 12 skinks in unmined forest to determine their microhabitat preferences and examined differences in vegetation structure, and microhabitat and food availability, between restored and unmined forests to identify reasons for their absence. Restored and unmined forests differed in canopy, mid‐ and understory cover and ground substrates, which were all potential barriers to colonization. Food availability was similar between restored and unmined forest, thus not a barrier to colonization. Skinks primarily utilized long logs, large woody debris piles, and large trees; microhabitats that were scarce or absent in restored sites and, therefore, potential barriers to colonization. Using this information, we introduced small woody debris piles into restored sites in close proximity to unmined areas containing skinks to facilitate skink colonization. This showed early signs of success and suggested that the lack of logs and woody debris were barriers to colonization. However, further monitoring is required to accurately determine the long‐term value of woody debris piles in facilitating skink colonization.  相似文献   

15.
16.
Predicting habitat suitability under climate change is vital to conserving biodiversity. However, current species distribution models rely on coarse scale climate data, whereas fine scale microclimate data may be necessary to assess habitat suitability and generate predictive models. Here, we evaluate disparities between temperature data at the coarse scale from weather stations versus fine-scale data measured in microhabitats required for a climate-sensitive mammal, the American pika (Ochotona princeps). We collected two years of temperature data in occupied talus habitats predicted to be suitable (high elevation) and unsuitable (low elevation) by the bioclimatic envelope approach. At low elevations, talus surface and interstitial microclimates drastically differed from ambient temperatures measured on-site and at a nearby weather station. Interstitial talus temperatures were frequently decoupled from high ambient temperatures, resulting in instantaneous disparities of over 30°C between these two measurements. Microhabitat temperatures were also highly heterogeneous, such that temperature measurements within the same patch of talus were not more correlated than measurements at distant patches. An experimental manipulation revealed that vegetation cover may cool the talus surface by up to 10°C during the summer, which may contribute to this spatial heterogeneity. Finally, low elevation microclimates were milder and less variable than typical alpine habitat, suggesting that, counter to species distribution model predictions, these seemingly unsuitable habitats may actually be better refugia for this species under climate change. These results highlight the importance of fine-scale microhabitat data in habitat assessments and underscore the notion that some critical refugia may be counterintuitive.  相似文献   

17.
A replicated pattern of habitat‐associated morphology among different lineages may represent adaptive convergence. Deviation from the replicated (shared) pattern of diversification reflects unique (e.g. species specific) effects resulting from site‐ or species‐specific selection, intrinsic factors (e.g. G matrix differences) or chance historical events (e.g. genetic drift). For two distantly‐related estuarine fishes [Lagodon rhomboides (Sparidae; Linnaeus) and Leiostomus xanthurus (Sciaenidae; Lacepède)], we examined shared and unique instances of body shape variation between seagrass (complex) and sand (simple) microhabitats at four sites. We found extensive shape variation between microhabitats for both species. As a shared response, both species from sand had subterminal snouts and long caudal peduncles, whereas those from seagrass had terminal snouts and deep bodies. Unique responses involved a greater difference in Lagodon rhomboides head shape between microhabitats compared to L. xanthurus. Patterns of shape variation fit ecomorphological predictions for foraging in the respective microhabitats (simple versus complex) because deep bodies are expected for fish that must negotiate complex habitats and subterminal snouts facilitate benthic foraging common in barren habitats. Parallel differentiation between microhabitats simultaneously suggests that individuals of each species use a particular microhabitat within estuaries for development and the differentiation in shape represents adaptive convergence. Spatial variation in the magnitude of shape differences between microhabitats was an unexpected finding and suggests that phenotypic variation operates at multiple scales within estuaries. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 147–158.  相似文献   

18.
We may expect butterflies as ectotherms to have particularly active life‐history stages that occur in the warmest and lightest times of the year; however, there are temperate species that are active when climatic conditions seem unfavourable and photoperiod short, such as the Taylor's checkerspot (Euphydryas editha taylori). For such species, studies suggest that even subtle changes to microclimate can potentially impact populations. Thus, understanding how in situ variations in microclimate influence the Taylor's checkerspot butterfly could provide much needed insights into more effective management. We conducted a series of surveys that explored (i) adult habitat use, (ii) final instar larval distribution and (iii) adult movement up to and across site boundaries at two sites in Oregon, USA, in 2010 and 2011. We found that in situ habitat use by the Taylor's checkerspot butterfly was strongly influenced by microclimate. Both adult activities and final instar larvae distribution were clustered within the warmest areas of the sites. Moreover, adults did not use up to 59% and larva up to 90% of their sites, despite vegetation structure and composition being uniform. More specifically, butterfly habitat use increased with increasing ground temperatures, and we found that areas with the highest ground temperatures were more exposed to direct sunlight. Similarly, we found that butterflies tended to only move through sunlit site boundaries. We conclude that the Taylor's checkerspot is sensitive to changes in its thermal environment at fine spatial scales. Our results highlight the importance of microclimate as an indicator of habitat quality, and establishing the thermal criteria in which species of concern exists may provide valuable insights into the implications of climate change.  相似文献   

19.
Rugged topography affects species distributions and community composition by creating contrasting mesic (cool, moist) and xeric (warm, dry) microclimates on adjacent slopes. This microclimatic heterogeneity is thought to have contributed to species survival during past climate fluctuations. Within a rugged and botanically rich region, we asked what functional, distributional, and/or biogeographic traits distinguished the species significantly associated with xeric or mesic microclimates. For each of 236 species in 4773 plots in the Klamath‐Siskiyou Mountains, we tested for significant associations with mesic or xeric topographic microclimates inferred from high‐resolution topographic variables. For the subset of species showing significant associations, we then compared their functional traits, biogeographic origins, and macroclimatic attributes to those of other species. We also tested the dependence of topographic associations on elevation, canopy cover, and soil type. Many species in the region (40%) showed significant tendencies to be found only in either mesic or xeric topography. ‘Mesic’ species tended to be of northern biogeographic origin and to have geographic ranges with higher mean precipitation; ‘xeric’ species had the opposite attributes. Species occurred more often in mesic microclimates when they occurred on low‐nutrient serpentine soils, and were more often found in xeric microclimates at high elevations. Functional traits such as specific leaf area were not significant predictors of species association with topographic microclimate. Biogeographic origins and the mean precipitation (rather than temperature) of species geographic ranges are the best indicators of species that are found in cool/moist northerly or hot/dry southerly microclimates.  相似文献   

20.
Aim This study addresses how species resolve environmental differences into biological habitats at multiple, interacting spatial scales. How do patterns of local habitat use change along an elevation gradient? How do patterns of local habitat partitioning interact with partitioning at a landscape scale? Location Northern and southern Lesser Antilles islands, West Indies. Methods We document how Anolis Daudin, 1802 lizards partition habitat locally at sites along a landscape‐scale elevation gradient. We examine habitat partitioning both with and without interspecific interactions in the predominately flat northern Lesser Antilles islands and in the more mountainous southern islands. Results Anoles partition local habitat along perch‐height and microclimate axes. Northern‐group sympatric anoles partition local habitat by perch height and have overlapping distributions at the landscape scale. Southern‐group sympatric anoles partition local habitat by microclimate and specialize in particular habitats at the landscape scale. In both the northern and southern groups, species use different perch heights and microclimates only in areas of species overlap along the elevation gradient. Main conclusions We demonstrate the interaction between local‐ and landscape‐scale habitat partitioning. In the case of microclimate partitioning, the interaction results from the use of thermal physiology to partition habitat at multiple scales. This interaction prompts the question of whether habitat partitioning developed ‘local‐out’ or ‘landscape‐in’. We pose this dichotomy and present a framework for its resolution.  相似文献   

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