Emerging climate‐driven disturbance processes: widespread mortality associated with snow‐to‐rain transitions across 10° of latitude and half the range of a climate‐threatened conifer

Climate change is causing rapid changes to forest disturbance regimes worldwide. While the consequences of climate change for existing disturbance processes, like fires, are relatively well studied, emerging drivers of disturbance such as snow loss and subsequent mortality are much less documented. As the climate warms, a transition from winter snow to rain in high latitudes will cause significant changes in environmental conditions such as soil temperatures, historically buffered by snow cover. The Pacific coast of North America is an excellent test case, as mean winter temperatures are currently at the snow–rain threshold and have been warming for approximately 100 years post‐Little Ice Age. Increased mortality in a widespread tree species in the region has been linked to warmer winters and snow loss. Here, we present the first high‐resolution range map of this climate‐sensitive species, Callitropsis nootkatensis (yellow‐cedar), and document the magnitude and location of observed mortality across Canada and the United States. Snow cover loss related mortality spans approximately 10° latitude (half the native range of the species) and 7% of the overall species range and appears linked to this snow–rain transition across its range. Mortality is commonly >70% of basal area in affected areas, and more common where mean winter temperatures is at or above the snow–rain threshold (>0 °C mean winter temperature). Approximately 50% of areas with a currently suitable climate for the species (相似文献   

Winter feeding of ptarmigan (<Emphasis Type="Italic">Lacopus lacopus</Emphasis>, Galliformes,Tetraonidae) in Yakutia

This paper presents the results of long-term studies on winter feeding of ptarmigan in Yakutia. This territory of the species habitat is characterized by the longest snow period and low ambient temperatures. Like in the predominant part of the range, the basis of winter feeding of birds is made up here of the vegetative parts of willow and birch. The period of winter feeding lasts 230–250 days in individuals of the northern populations and 170–180 days in individuals of the southern population. It was found that the preference for birch by ptarmigan changed to a preference for willow with advancement to the north and to the mountains. In addition to birch and willow, the diet of the birds includes up to 23 plant species. Among them, horsetail, chosenia, and larch can serve as the main food due to both biotic factors (the presence of animal excavations) and abiotic factors (thin snow cover, long-term severe frosts). In severe frosts, ptarmigans mainly feed on the ground using almost all the plants including those they do not prefer in warmer days. Two peaks of the craw fullness were observed in birds at average daily air temperatures below–50°C, and four peaks were noted in warmer days. The first peak is obviously due to the need to be in shelter for most of the daytime.     

Evidence of climate change effects on within‐winter movements of European Mallards Anas platyrhynchos

Other than during periods of migration, animal movement tends to be poorly described, despite the potential importance of such movements, which may prove crucial for surviving periods of bad weather and low food availability. We analysed within‐winter (December–February) movements of Mallard using the EURING Data Bank. Most movements were directed towards the south or southwest during all three winter months. Distances covered increased with winter harshness and generally decreased from 1952 to 2004. Mallards appear to move less than other duck species during winter. Long‐distance movements of Mallards seem to be related to cold weather, birds only moving long distances in large numbers during the very coldest winters. Movements are not restricted during midwinter, but occur throughout the winter. The decreasing within‐winter movement over time (1952–2004) could be explained by decreasing reporting probabilities and/or warmer winters in recent decades. However, the first is only true if the decrease in reporting probability increases with distance moved, for which we found no indication in our study. Therefore, we suggest that the pattern found is evidence of long‐term winter warming reducing the distance of within‐winter movements in this species.     

Estimating age‐dependent survival when juveniles resemble females: Invasive ring‐necked parakeets as an example

Many species only show sexual dimorphism at the age of maturity, such that juveniles typically resemble females. Under these circumstances, estimating accurate age‐specific demographic parameters is challenging. Here, we propose a multievent model parameterization able to estimate age‐dependent survival using capture–recapture data with uncertainty in age and sex assignment of individuals. We illustrate this modeling approach with capture–recapture data from the ring‐necked parakeet Psittacula krameri. We analyzed capture, recapture, and resighting data (439 recaptures/resightings) of 156 ring‐necked parakeets tagged with neck collars in Barcelona city from 2003 to 2016 to estimate the juvenile and adult survival rate. Our models successfully estimated the survival probabilities of the different age classes considered. Survival probability was similar between adults (0.83, 95% CI = 0.77–0.87) and juveniles during their second (0.79, 95% CI = 0.58–0.87) and third winter (0.83, 95% CI = 0.65–0.88). The youngest juveniles (1st winter) showed a slightly lower survival (0.57, 95% CI = 0.37–0.79). Among adults, females showed a slightly higher survival than males (0.87, 95% CI = 0.78–0.93; and 0.80, 95% CI = 0.73–0.86, respectively). These high survival figures predict high population persistence in this species and urge management policies. The analysis also stresses the usefulness of multievent models to estimate juvenile survival when age cannot be fully ascertained.     

Immediate and short‐term responses of bird and mammal assemblages to a subalpine wildfire in the Snowy Mountains,Australia

Abstract Over 35 days in January–February 2003, wildfires burnt across much of the subalpine/alpine landscape of south‐eastern Australia, including about 70% of the land above 1500 m in the Snowy Mountains. At the time of the fire, studies of two subalpine faunal assemblages were being undertaken. The opportunity to resurvey the assemblages was taken in order to examine the immediate impact of fire in an environment where it is uncommon but predicted to occur increasingly with global warming. A study area in the Whites River Valley, where the number of bird species was counted monthly from 1996 to 2003, and weekly in late winter–spring from 2000 to 2003, was burnt in one fire. As well as the expected decrease in the number of individual birds, the fire resulted in an immediate decrease in the number of bird species, unlike in previously studied montane forest, with only the regularly wintering species plus the olive whistler and the ground‐feeding flame robin remaining. During the post‐winter avian immigration, few regular spring migrants appeared on burnt sites despite their nearby presence on the unburnt side of the valley. Five of six small mammal trapping grids were burnt. As with fires at lower altitudes, there was an immediate reduction in mammal numbers on burnt grids following the fire, but in addition, one species, Mastacomys fuscus, declined further in the ensuing 2 months both on burnt and unburnt sites. Numbers of Antechinus swainsonii and Rattus fuscipes stabilized until autumn/winter when there was a further decline due to the unavailability of subnivean space to allow winter foraging, allied with a concentration of fox predation on areas still carrying populations of small mammals.     

The fluctuating world of a tundra predator guild: bottom‐up constraints overrule top‐down species interactions in winter

Global warming is predicted to change ecosystem functioning and structure in Arctic ecosystems by strengthening top‐down species interactions, i.e. predation pressure on small herbivores and interference between predators. Yet, previous research is biased towards the summer season. Due to greater abiotic constraints, Arctic ecosystem characteristics might be more pronounced in winter. Here we test the hypothesis that top‐down species interactions prevail over bottom‐up effects in Scandinavian mountain tundra (Northern Sweden) where effects of climate warming have been observed and top‐down interactions are expected to strengthen. But we test this ‘a priori’ hypothesis in winter and throughout the 3–4 yr rodent cycle, which imposes additional pulsed resource constraints. We used snowtracking data recorded in 12 winters (2004–2015) to analyse the spatial patterns of a tundra predator guild (arctic fox Vulpes lagopus, red fox Vulpes vulpes, wolverine Gulo gulo) and small prey (ptarmigan, Lagopus spp). The a priori top‐down hypothesis was then tested through structural equation modelling, for each phase of the rodent cycle. There was weak support for this hypothesis, with top‐down effects only discerned on arctic fox (weakly, by wolverine) and ptarmigan (by arctic fox) at intermediate and high rodent availability respectively. Overall, bottom‐up constraints appeared more influential on the winter community structure. Cold specialist predators (arctic fox and wolverine) showed variable landscape associations, while the boreal predator (red fox) appeared strongly dependent on productive habitats and ptarmigan abundance. Thus, we suggest that the unpredictability of food resources determines the winter ecology of the cold specialist predators, while the boreal predator relies on resource‐rich habitats. The constraints imposed by winters and temporary resource lows should therefore counteract productivity‐driven ecosystem change and have a stabilising effect on community structure. Hence, the interplay between summer and winter conditions should determine the rate of Arctic ecosystem change in the context of global warming.     

Cold-hardiness of the most common soil invertebrates in Northeast Asia. 1. Cold-hardiness and its mechanisms

Cold-hardiness of soil-dwelling invertebrates (37 species of insect and 27 species from other taxa) was studied in the continental parts of Northeast Asia, which represent a region with winter temperatures extreme for the Northern Hemisphere. Insects belonging to 34 species overwinter in the supercooled state, whereby they withstand temperatures of–12...–35°C. Thirteen species (insects, myriapods, slugs, earthworms, and an amphipod) spend winter in the frozen state and survive temperatures from–5 to–45°C. Cryoprotective dehydration is typical of slug eggs, earthworm cocoons, and certain click beetle larvae, which survive temperatures ranging from–20 to–40°C, down to the record value of–196°C. The majority of the studied organisms tolerate cooling to–25...–30°C, which corresponds to average temperature minima in the upper soil horizons of most biotopes in the continental parts of the Asian Northeast.     

Climate anomalies affect annual survival rates of swifts wintering in sub‐Saharan Africa

Several species of migratory swifts breed in the Western Palearctic, but they differ in reproductive traits and nonbreeding areas explored in Africa. We examined survival and recapture probabilities of two species of swifts by capture–mark–recapture data collected in northern Italy (Pallid Swift Apus pallidus in Carmagnola, Turin, and Common Swift Apus apus in Guiglia, Modena) in the breeding season (May–July). Apparent survival rates were relatively high (>71%), comparable to other studies of European swifts, but showed marked annual variations. We used geolocators to establish the exact wintering areas of birds breeding in our study colonies. Common Swifts explored the Sahel zone during migration and spent the winter in SE Africa, while the Pallid Swifts remained in the Sahel zone for a longer time, shifting locations southeast down to Cameroun and Nigeria later in winter. These movements followed the seasonal rains from north to south (October to December). In both species, we found large yearly differences in survival probabilities related to different climatic indices. In the Pallid Swift, wintering in Western Africa, the Sahel rainfall index best explained survival, with driest seasons associated with reduced survival. In the Common Swift, wintering in SE Africa, the El Niño–Southern Oscillation (ENSO) cycle performed significantly better than Sahel rainfall or North Atlantic Oscillation (NAO). Extreme events and precipitation anomalies in Eastern Africa during La Niña events resulted in reduced survival probabilities in Common Swifts. Our study shows that the two species of swifts have similar average annual survival, but their survival varies between years and is strongly affected by different climatic drivers associated with their respective wintering areas. This finding could suggest important ecological diversification that should be taken into account when comparing survival and area use of similar species that migrate between temperate breeding areas and tropical wintering areas.     

Testing agri‐environment delivery for farmland birds at the farm scale: the Hillesden experiment

The Hillesden experiment, established in 2005/2006 to test the delivery of biodiversity benefits under Environmental Stewardship, covers c. 1000 ha of arable farmland in central lowland England. It is a randomized block experiment with five replicates of three treatments: (1) CC: cross compliance, the control; (2) ELS: 1% of land removed from production for wildlife habitat provision; and (3) ELS‐X: 5% of land used for wildlife habitat, each treatment being applied to contiguous areas of 70–80 ha. Bird usage of winter food patches, comprising three different seed mixes, was monitored through the winter and was also related to seed yield. Winter and breeding season bird/territory abundance was recorded before and after the provision of the winter food patches. Bird use of the patches differed between seed mixes. There was large variation between individual patches in both seed yield and bird numbers and between individual bird species in their use of different seed mixes, suggesting that the availability of a range of patch types would be beneficial. Use of all patch types declined sharply in late January to February, indicating depletion and/or inability of birds to access shed seed. Winter bird abundance at a farm scale for all species combined, granivorous species and nine individual species increased for all monitored species when seed patches were available. At a treatment level, the increases tended to be greater in ELS‐X, where most of the patches were located. In the breeding season at a farm scale, the numbers of territories for all species combined and granivorous species increased significantly when seed patches had been available in the previous winter. There was little evidence of a treatment‐scale response. The provision of winter food appeared to increase winter bird abundance and to follow on into an overall increase in the breeding population, but if the latter effect is to be reflected elsewhere, this requires that sufficient breeding habitat is available to accommodate an increase.     

Winter ecology of Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) and brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) in a subarctic lake,Norway

We studied habitat choice, diet, food consumption and somatic growth of Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) during the ice-covered winter period of a subarctic lake in northern Norway. Both Arctic charr and brown trout predominantly used the littoral zone during winter time. Despite very cold winter conditions (water temperature <1°C) and poor light conditions, both fish species fed continuously during the ice-covered period, although at a much lower rate than during the summer season. No somatic growth could be detected during the ice-covered winter period and the condition factor of both species significantly declined, suggesting that the winter feeding rates were similar to or below the maintenance requirements. Also, the species richness and diversity of ingested prey largely decreased from summer to winter for both fish species. The winter diet of Arctic charr <20 cm was dominated by benthic insect larvae, chironomids in particular, and Gammarus lacustris, but zooplankton was also important in December. G. lacustris was the dominant prey of charr >20 cm. The winter diet of brown trout <20 cm was dominated by insect larvae, whereas large-sized trout mainly was piscivorous, feeding on juvenile Arctic charr. Piscivorous feeding behaviour of trout was in contrast rarely seen during the summer months when their encounter with potential fish prey was rare as the small-sized charr mainly inhabited the profundal. The study demonstrated large differences in the ecology and interactions of Arctic charr and brown trout between the winter and summer seasons.     

The biology, ecology, and harmfulness of the flea-beetle Chaetocnema aridula Gill (Coleoptera, Chrysomelidae) in the forest-steppe of the middle Volga Area

In the forest-steppe of Samara Province, Chaetocnema aridula Gill. dominates among all the species of Chaetocnema Steph. found in cereal crops. The species develops mainly on winter wheat, and, to a lesser extent, on spring wheat and barley. In autumn, adult beetles aggregate on millet for pre-hibernation feeding. The highest population density of Ch. aridula was observed in the humid and warm 1997 and the lowest one, in the extremely dry 1998. In late April-the first third of May, adults begin oviposition after wintering. Larvae appear in winter and spring wheat in mid-May and in late May-early June, respectively. Larvae pupate in winter wheat, beginning from mid-June; in spring crops, pupation begins in mid-June. Adults of a new generation emerge between the middle of June and the middle of July. In spring crops, development of Ch. aridula finishes 2–3 weeks later than in winter crops. Larvae penetrate shoots in the upper soil level in the tillering zone. 50–80% of wheat and barley plants are damaged by larvae. In damaged plants, the number of shoots increases by 1.2–5.8 times, and the number of productive shoots decreases to 17–68%. In plants damaged by flea-beetles, harvest losses constitute 62–90% and 5–20% in winter and spring wheat crops, respectively, and the total harvest loss constitutes 0.3–3.9 and 1–15%, respectively.     

Dependency of Antarctic zooplankton species on ice algae‐produced carbon suggests a sea ice‐driven pelagic ecosystem during winter

How the abundant pelagic life of the Southern Ocean survives winter darkness, when the sea is covered by pack ice and phytoplankton production is nearly zero, is poorly understood. Ice‐associated (“sympagic”) microalgae could serve as a high‐quality carbon source during winter, but their significance in the food web is so far unquantified. To better understand the importance of ice algae‐produced carbon for the overwintering of Antarctic organisms, we investigated fatty acid (FA) and stable isotope compositions of 10 zooplankton species, and their potential sympagic and pelagic carbon sources. FA‐specific carbon stable isotope compositions were used in stable isotope mixing models to quantify the contribution of ice algae‐produced carbon (α_Ice) to the body carbon of each species. Mean α_Ice estimates ranged from 4% to 67%, with large variations between species and depending on the FA used for the modelling. Integrating the α_Ice estimates from all models, the sympagic amphipod Eusirus laticarpus was the most dependent on ice algal carbon (α_Ice: 54%–67%), and the salp Salpa thompsoni showed the least dependency on ice algal carbon (α_Ice: 8%–40%). Differences in α_Ice estimates between FAs associated with short‐term vs. long‐term lipid pools suggested an increasing importance of ice algal carbon for many species as the winter season progressed. In the abundant winter‐active copepod Calanus propinquus, mean α_Ice reached more than 50% in late winter. The trophic carbon flux from ice algae into this copepod was between 3 and 5 mg C m^?2 day^?1. This indicates that copepods and other ice‐dependent zooplankton species transfer significant amounts of carbon from ice algae into the pelagic system, where it fuels the food web, the biological carbon pump and elemental cycling. Understanding the role of ice algae‐produced carbon in these processes will be the key to predictions of the impact of future sea ice decline on Antarctic ecosystem functioning.     

Climate‐driven diversity change in annual grasslands: Drought plus deluge does not equal normal

Climate forecasts agree that increased variability and extremes will tend to reduce the availability of water in many terrestrial ecosystems. Increasingly severe droughts may be exacerbated both by warmer temperatures and by the relative unavailability of water that arrives in more sporadic and intense rainfall events. Using long‐term data and an experimental water manipulation, we examined the resilience of a heterogeneous annual grassland community to a prolonged series of dry winters that led to a decline in plant species richness (2000–2014), followed by a near‐record wet winter (2016–2017), a climatic sequence that broadly resembles the predicted future in its high variability. In our 80, 5‐m² observational plots, species richness did not recover in response to the wet winter, and the positive relationship of richness to annual winter rainfall thus showed a significant weakening trend over the 18‐year time period. In experiments on 100, 1‐m² plots, wintertime water supplementation increased and drought shelters decreased the seedling survival and final individual biomass of native annual forbs, the main functional group contributing to the observed long‐term decline in richness. Water supplementation also increased the total cover of native annual forbs, but only increased richness within nested subplots to which seeds were also added. We conclude that prolonged dry winters, by increasing seedling mortality and reducing growth of native forbs, may have diminished the seedbank and thus the recovery potential of diversity in this community. However, the wet winter and the watering treatment did cause recovery of the community mean values of a key functional trait (specific leaf area, an indicator of drought intolerance), suggesting that some aggregate community properties may be stabilized by functional redundancy among species.     

Eelgrass,Zostera marina,as essential fish habitat for young‐of‐the‐year winter flounder,Pseudopleuronectes americanus (Walbaum, 1792) in Maine estuaries

Distribution and density by habitat for age‐0, young‐of‐the‐year (YOY) winter flounder, Pseudopleuronectes americanus (Walbaum, 1792), were compared for two Maine estuaries to help define essential fish habitat for this life history stage. Two estuaries (Weskeag River and Penobscot Bay) along Mid‐coast Maine were sampled monthly with daytime 1.0 m² fixed‐frame throw traps around neap low tide, May–December over two consecutive years (2003–2004). Both eelgrass and adjacent sand/mud (20–60 cm deep) were randomly sampled with equal effort (4–12 samples per month) at two sites in both the Weskeag River and Penobscot Bay. Significantly higher densities of YOY winter flounder (2–9 cm TL) occurred in eelgrass relative to sand/mud. Density increased significantly in both habitats in 2004, and was higher in Penobscot Bay relative to the Weskeag River. YOY densities compared by eelgrass coverage within throw traps were found to be significantly higher in eelgrass that exceeded 30% coverage when compared with adjacent sand/mud areas and eelgrass coverage of 10–20%. YOY occurred in all months sampled (May–December); no density differences existed by month. These results indicate that very shallow (<0.6 m) eelgrass habitat is of key importance to YOY winter flounder in Maine estuaries and should be viewed as essential fish habitat (EFH) for this species and life stage.     

Response diversity of wild bees to overwintering temperatures

Biodiversity can provide insurance against environmental change, but only if species differ in their response to environmental conditions (response diversity). Wild bees provide pollination services to wild and crop plants, and response diversity might insure this function against changing climate. To experimentally test the hypothesis that bee species differ in their response to increasing winter temperature, we stored cocoons of nine bee species at different temperatures during the winter (1.5–9.5 °C). Bee species differed significantly in their responses (weight loss, weight at emergence and emergence date). The developmental stage during the winter explained some of these differences. Bee species overwintering as adults generally showed decreased weight and earlier emergence with increasing temperature, whereas bee species overwintering in pre-imaginal stages showed weaker or even opposite responses. This means that winter warming will likely affect some bee species negatively by increasing energy expenditure, while others are less sensitive presumably due to different physiology. Likewise, species phenologies will respond differently to winter warming, potentially affecting plant–pollinator interactions. Responses are not independent of current flight periods: bees active in spring will likely show the strongest phenological advances. Taken together, wild bee diversity provides response diversity to climate change, which may be the basis for an insurance effect.     

Length–weight relationships for 19 headwater fish species from streams in the Sinos River basin,southern Brazil

This study reports the length–weight relationship estimates (LWRs) for 19 fish species inhabiting low order headwater streams in the Sinos River basin of southern Brazil. Between 2010 and 2014, 19 species at 47 sites were sampled in 10 sub‐basins by electrofishing in winter and summer. For two species, Bryconamericus iheringii and Phalloceros caudimaculatus, the estimates in this study offer new maximum size ranges compared to previous studies.     

Winter ecology of the Arunachal macaque Macaca munzala in Pangchen Valley,western Arunachal Pradesh,northeastern India

The newly described Arunachal macaque Macaca munzala occurs largely in sub‐tropical to temperate environments at elevations of c. 1,800–3,000 m in Arunachal Pradesh, northeastern India. We studied its over‐wintering strategy by comparing the diet, ranging, and behavior of a troop of 24 individuals during winter and spring (December 2005 to May 2006) through instantaneous scan sampling (3,002 records, 448 scans, 112 hr of observation). We also monitored the phenology of food plants. The macaques spent more time (41–66%) feeding in the winter than in spring (33–51%), whereas time spent moving and resting was greater in spring. The diet composed largely of plants, with animal matter being eaten rarely. The number of plant species in the diet increased from 18 to 25 whereas food types rose from 18 to 36 from winter to spring, respectively. Although only two species formed 75% of the winter diet, seven species comprised this proportion in spring. Availability of fruits and young leaves increased in spring; the troop moved more and utilized a larger part of its range during this time. Seasonal changes in behavior could be explained by the scarcity of food and the costs of thermoregulation in winter. Our study suggests that the Arunachal macaque inhabits a highly seasonal environment and has an over‐wintering strategy that includes subsisting on a high‐fiber diet by increasing the time spent feeding, and minimizing energy expenditure by reducing the time spent moving. Am. J. Primatol. 71:939–947, 2009. © 2009 Wiley‐Liss, Inc.     

Length–weight and length–length relationships of three Blenny species from the Persian Gulf and the Gulf of Oman

The present study provides the length–weight and length–length relationships information (LWR & LLR) for three Blenny species; Antennablennius adenensis from the coast of Larak Island in the Persian Gulf and Istiblennius pox and Omobranchus mekranensis, which were captured in the coasts of Chabahar city in the Gulf of Oman, Iran. Total length (TL) and standard length (SL) were determined as well as weight. Specimens were collected occasionally in summer 2017 and winter 2018 by Hand net. The length–weight parameter b for these species was 2.84, 3.29 and 3.06 respectively with a high coefficient of determination (r² ≥ 0.95). All LLRs were highly correlated (r² > 0.99). All three species had no previous report for LWR and LLR estimates in FishBase.     

Timing of diapause induction and its life‐history consequences in Nezara viridula: is it costly to expand the distribution range?

Abstract. 1. From the early 1960s to 2000 Nezara viridula (Heteroptera: Pentatomidae) expanded its range northwards in Japan and reached Osaka following climate warming recorded in the region. 2. The timing of diapause induction and its effect on life‐history traits were studied under quasi‐natural conditions in Osaka. Egg masses were placed outdoors in six series in July–November 1999. Developmental events were monitored until September 2000. 3. Adult diapause was induced in September–October in agreement with the photoperiodic response obtained under laboratory conditions. Induction of diapause in early October ensured the highest winter survival. Nymphs that hatched after late September died by December–April showing that the species cannot survive winter in the nymphal stage. 4. Life‐history traits varied between the early (non‐diapause reproduction) and late (post‐diapause reproduction) series. Thus, non‐diapause females produced significantly fewer egg masses than did females that reproduced only after diapause. The timing of diapause induction strongly affected overwintering success and post‐diapause performance: females that became adults and entered diapause in October lived longer, had a longer period of oviposition, and produced more eggs in larger egg masses than females that attained adulthood and entered diapause in September. 5. Females from the early series reproduced until late November, although progeny from the late September eggs were destined to die during the winter. Pre‐winter reproduction of adults that emerged in mid‐September or later was a result of the imperfect timing of diapause induction. It is an ineffective allocation of resources and may be considered the ecological cost of range expansion. 6. To establish in the region, N. viridula will probably evolve a lengthening of the critical photoperiod of the diapause induction response. This will allow the species to enter diapause earlier and, thus, avoid maladaptive late‐autumn reproduction but, perhaps, increase the cost of diapause because of a possible adverse impact of pre‐winter high temperature conditions on overwintering.