Ecological Monographs最新文献

{"title":"Climate-driven thermal opportunities and risks for leaf miners in aspen canopies","authors":"H. Arthur Woods,&nbsp;Geoffrey Legault,&nbsp;Joel G. Kingsolver,&nbsp;Sylvain Pincebourde,&nbsp;Alisha A. Shah,&nbsp;Beau G. Larkin","doi":"10.1002/ecm.1544","DOIUrl":"10.1002/ecm.1544","url":null,"abstract":"<p>In tree canopies, incoming solar radiation interacts with leaves and branches to generate temperature differences within and among leaves, presenting thermal opportunities and risks for leaf-dwelling ectotherms. Although leaf biophysics and insect thermal ecology are well understood, few studies have examined them together in single systems. We examined temperature variability in aspen canopies, <i>Populus tremuloides</i>, and its consequences for a common herbivore, the leaf-mining caterpillar <i>Phyllocnistis populiella</i>. We shaded leaves in the field and measured effects on leaf temperature and larval growth and survival. We also estimated larval thermal performance curves for feeding and growth and measured upper lethal temperatures. Sunlit leaves directly facing the incoming rays reached the highest temperatures, typically 3–8°C above ambient air temperature. Irradiance-driven increases in temperature, however, were transient enough that they did not alter observed growth rates of leaf miners. Incubator and ramping experiments suggested that larval performance peaks between 25 and 32°C and declines to zero between 35 and 40°C, depending on the duration of temperature exposure. Upper lethal temperatures during 1-h heat shocks were 42–43°C. When larvae were active in early spring, temperatures generally were low enough to depress rates of feeding and growth below their maxima, and only rarely did estimated mine temperatures rise beyond optimal temperatures. Observed leaf or mine temperatures never approached larval upper lethal temperatures. At this site during our experiments, larvae thus appeared to have a significant thermal safety margin; the more pressing problem was inadequate heat. Detailed information on mine temperatures and larval performance curves, however, allowed us to leverage long-term data sets on air temperature to estimate potential future shifts in performance and longer-term risks to larvae from lethally high temperatures. This analysis suggests that, in the past 20 years, larval performance has often been limited by cold and that the risk of heat stress has been low. Future warming will raise mean rates of feeding and growth but also the risk of exposure to injuriously or lethally high temperatures.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44337153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of a half century of warming and fire exclusion on montane forests of the Klamath Mountains, California, USA","authors":"Erik S. Jules,&nbsp;Melissa H. DeSiervo,&nbsp;Matthew J. Reilly,&nbsp;Drew S. Bost,&nbsp;Ramona J. Butz","doi":"10.1002/ecm.1543","DOIUrl":"10.1002/ecm.1543","url":null,"abstract":"<p>Climate warming and altered disturbance regimes are changing forest composition and structure worldwide. Given that species often exhibit individualistic responses to change, making predictions about the cumulative effects of multiple stressors across environmental gradients is challenging, especially in diverse communities. For example, warming temperatures are predicted to drive species upslope, whereas fire exclusion promotes the expansion of species at lower elevations where fire was historically frequent. We resampled 148 vegetation plots to assess 46 years (1969–2015) of species and community-level response to warming and fire exclusion in a topographically complex landscape in the Klamath Mountains, California, USA, a diverse region that served as a climate refugia throughout the Holocene. We compared cover and assessed change in the elevational distributions of 12 conifer species at different life stages (i.e., seedlings, saplings, canopy). We observed consistent but non-significant shifts upward in elevation for eight species, and a significant shift upward for one species, all of which were far less than expectations based on recent warming. Six species declined in total cover and another five declined in at least one life stage, whereas the drought- and fire-intolerant <i>Abies concolor</i> increased by 30.7%. The largest declines were at lower elevations in drought-tolerant, early-seral species (<i>Pinus lambertiana</i> and <i>Pinus ponderosa</i>) and at higher elevations for the shade-tolerant <i>Abies magnifica</i> var<i>. shastensis</i> and the regionally rare <i>Abies lasiocarpa.</i> Regionally rare (<i>Picea engelmannii</i>) and endemic (<i>Picea breweriana</i>) species had reductions in early life stages, portending future declines. Multivariate analyses revealed a high degree of inertia with a minor, but significant, shift in composition and a slight decrease in species turnover along the elevation gradient driven by the expansion of <i>A. concolor</i>. Our results indicate that most species are declining, especially at lower and mid-elevations where fire exclusion has increased the cover of shade-tolerant species and reduced the recruitment for fire-adapted species. Collectively, declines in most species, insufficient upward movement to track warming, reductions in drought- and fire-tolerant early-seral species, and an increase in a single, shade-tolerant species will leave these communities maladapted to projected climate scenarios and questions the potential for future climate refugia in this region.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49602715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shorebird food energy shortfalls and the effectiveness of habitat incentive programs in record wet, dry, and warm years","authors":"Gregory H. Golet,&nbsp;Kristen E. Dybala,&nbsp;Matthew E. Reiter,&nbsp;Kristin A. Sesser,&nbsp;Mark Reynolds,&nbsp;Rodd Kelsey","doi":"10.1002/ecm.1541","DOIUrl":"10.1002/ecm.1541","url":null,"abstract":"<p>Programs that incentivize private landowners to create habitats that offset losses due to conversion and climate change are increasingly being used to bolster sensitive wildlife populations. In the Central Valley of California, shorebird habitat incentive programs pay landowners to create additional habitat during the non-breeding season by flooding their fields. However, it remains unclear how successful these programs have been in supporting baseline shorebird population needs or meeting established population goals, particularly in the face of changing environmental conditions. To address these questions, we used bioenergetics modeling to estimate shorebird food energy needs over four consecutive years that had the highest annual mean air temperatures ever recorded in California, and included years of extreme drought, as well as the second wettest winter on record. Our objectives were to (1) characterize annual variability in the timing and magnitude of shorebird food energy shortfalls, (2) estimate the contributions that incentive programs made to meeting these needs, and (3) develop recommendations for implementation of future habitat programs to advance shorebird conservation in the region. Overall, we found a high level of consistency in the timing and magnitude of habitat shortfalls, especially in fall, despite large differences in annual rainfall, a result that was unexpected, but that emphasizes how highly managed the hydrological system is in the Central Valley. We also found that the magnitude of both fall and spring energy shortfalls increased, relative to recent (2007–2014) estimates, perhaps due to aberrantly warm conditions. Incentive programs implemented to provide supplemental habitat were somewhat effective in reducing shortfalls for the assumed baseline population, but there were consistent unmet habitat needs when there were not enough shallow open water foraging areas available. Strategies to offset these remaining food energy deficits include scaling up habitat investments, adjusting the timing of habitat programs to better match the migration patterns of the birds, and adapting programs to new geographies. To the extent that there is variability in annual habitat need we recommend implementing a dynamic conservation approach. This involves scaling the amount of additional habitat created to match the shifting needs of the birds to maximize return on investment.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecm.1541","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51638030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying eco-evolutionary contributions to trait divergence in spatially structured systems","authors":"Lynn Govaert,&nbsp;Jelena H. Pantel,&nbsp;Luc De Meester","doi":"10.1002/ecm.1531","DOIUrl":"10.1002/ecm.1531","url":null,"abstract":"<p>Ecological and evolutionary processes can occur at similar time scales and, hence, influence one another. There has been much progress in developing metrics that quantify contributions of ecological and evolutionary components to trait change over time. However, many empirical evolutionary ecology studies document trait differentiation among populations structured in space. In both time and space, the observed differentiation in trait values among populations and communities can be the result of interactions between nonevolutionary (phenotypic plasticity, changes in the relative abundance of species) and evolutionary (genetic differentiation among populations) processes. However, the tools developed so far to quantify ecological and evolutionary contributions to trait changes are implicitly addressing temporal dynamics because they require directionality of change from an ancestral to a derived state. Identifying directionality from one site to another in spatial studies of eco-evolutionary dynamics is not always possible and often not meaningful. We suggest three modifications to existing partitioning metrics so they allow quantifying ecological and evolutionary contributions to changes in population and community trait values across spatial locations in landscapes. Applying these spatially modified metrics to published empirical examples shows how these metrics can be used to generate new empirical insights and to facilitate future comparative analyses. The possibility of applying eco-evolutionary partitioning metrics to populations and communities in natural landscapes is critical as it will broaden our capacity to quantify eco-evolutionary interactions as they occur in nature.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecm.1531","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48608544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate drove the fire cycle and humans influenced fire occurrence in the East European boreal forest","authors":"N. Ryzhkova,&nbsp;A. Kryshen,&nbsp;M. Niklasson,&nbsp;G. Pinto,&nbsp;A. Aleinikov,&nbsp;I. Kutyavin,&nbsp;Y. Bergeron,&nbsp;Adam A. Ali,&nbsp;I. Drobyshev","doi":"10.1002/ecm.1530","DOIUrl":"10.1002/ecm.1530","url":null,"abstract":"<p>Understanding long-term forest fire histories of boreal landscapes is instrumental for parameterizing climate–fire interactions and the role of humans affecting natural fire regimes. The eastern sections of the European boreal zone currently lack a network of annually resolved and centuries-long forest fire histories. To fill in this knowledge gap, we dendrochronologically reconstructed the 600-year fire history of a middle boreal pine-dominated landscape of the southern part of the Republic of Komi, Russia. We combined the reconstruction of fire cycle (FC) and fire occurrence with the data on the village establishment and climate proxies and discussed the relative contribution of climate versus human land use in shaping historic fire regimes. Over the 1340–1610 <span>ce</span> period, the territory had a FC of 66 years (with the 90% confidence envelope of 56.8 and 78.6 years). Fire activity increased during the 1620–1730 <span>ce</span> period, with the FC reaching 32 years (31.0–34.7 years). Between 1740–1950, the FC increased to 47 years (41.9–52.0). The most recent period, 1960–2010, marks FC's historic maximum, with the mean of 153 years (102.5–270.3). Establishment of the villages, often as small harbors on the Pechora River, was associated with a non-significant increase in fire occurrence in the sites nearest the villages (<i>p</i> = 0.07–0.20). We, however, observed a temporal association between village establishment and fire occurrence at the scale of the whole studied landscape. There was no positive association between the former and the FC. In fact, we documented a decline in the area burned, following the wave of village establishment during the second half of the 1600s and the first half of the 1700s. The lack of association between the dynamics of FC and the dates of village establishments, and the significant association between large fire years and the early and latewood pine chronologies, used as historic drought proxy, indirectly suggests that the climate was the primary control of the landscape-level FCs in the studied forests. Pine-dominated forests of the Komi Republic may hold a unique position as the ecosystem with the shortest history of human-related shifts in fire cycles across the European boreal region.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecm.1530","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42509420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal dynamics of range expander and congeneric native plant responses during and after extreme drought events","authors":"Qiang Yang,&nbsp;G. F. (Ciska) Veen,&nbsp;Roel Wagenaar,&nbsp;Marta Manrubia,&nbsp;Freddy C. ten Hooven,&nbsp;Wim H. van der Putten","doi":"10.1002/ecm.1529","DOIUrl":"10.1002/ecm.1529","url":null,"abstract":"<p>Climate change is causing range shifts of many species to higher latitudes and altitudes and increasing their exposure to extreme weather events. It has been shown that range-shifting plant species may perform differently in new soil than related natives; however, little is known about how extreme weather events affect range-expanding plants compared to related natives. In this study we used outdoor mesocosms to study how range-expanding plant species responded to extreme drought in live soil from a habitat in a new range with and without live soil from a habitat in the original range (Hungary). During summer drought, the shoot biomass of the range-expanding plant community declined. In spite of this, in the mixed community, range expanders produced more shoot biomass than congeneric natives. In mesocosms with a history of range expanders in the previous year, native plants produced less biomass. Plant legacy or soil origin effects did not change the response of natives or range expanders to summer drought. During rewetting, range expanders had less biomass than congeneric natives but higher drought resilience (survival) in soils from the new range where in the previous year native plant species had grown. The biomass patterns of the mixed plant communities were dominated by <i>Centaurea</i> spp.; however, not all plant species within the groups of natives and of range expanders showed the general pattern. Drought reduced the litter decomposition, microbial biomass, and abundances of bacterivorous, fungivorous, and carnivorous nematodes. Their abundances recovered during rewetting. There was less microbial and fungal biomass, and there were fewer fungivorous nematodes in soils from the original range where range expanders had grown in the previous year. We concluded that in mixed plant communities of range expanders and congeneric natives, range expanders performed better, under both ambient and drought conditions, than congeneric natives. However, when considering the responses of individual species, we observed variations among pairs of congenerics, so that under the present mixed-community conditions there was no uniformity in responses to drought of range expanders versus congeneric natives. Range-expanding plant species reduced soil fungal biomass and the numbers of soil fungivorous nematodes, suggesting that the effects of range-expanding plant species can trickle up in the soil food web.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/64/a6/ECM-92-e1529.PMC9787952.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10817433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Climate change weakens the impact of disturbance interval on the growth rate of natural populations of Venus flytrap","authors":"Allison M. Louthan,&nbsp;Melina Keighron,&nbsp;Elsita Kiekebusch,&nbsp;Heather Cayton,&nbsp;Adam Terando,&nbsp;William F. Morris","doi":"10.1002/ecm.1528","DOIUrl":"10.1002/ecm.1528","url":null,"abstract":"<p>Disturbances elicit both positive and negative effects on organisms; these effects vary in their strength and their timing. Effects of disturbance interval (i.e., the length of time between disturbances) on population growth will depend on both the timing and strength of positive and negative effects of disturbances. Climate change can modify the relative strengths of these positive and negative effects, leading to altered optimal disturbance intervals (the disturbance interval at which population growth rate is highest) and changes in the sensitivity of population growth rate to disturbance interval. While we know that climate may alter impacts of disturbance in some systems, we have a poor understanding of which effects of disturbance and which vital rates might drive an altered response to disturbance interval in a changing climate. We use demographic monitoring of natural populations of <i>Dionaea muscipula</i>, the Venus flytrap, that have experienced natural and managed fires, combined with realistic past and future climate projections, to construct climate- and fire-driven integral projection models (IPMs). We use these IPMs to compare the effect of fire return interval (FRI) on population growth rate in past and future climates. To dissect the mechanisms driving FRI response, we then construct IPMs with demographic data from an experimental manipulation of fire effects (ash addition, neighbor removal) and an accidental fire. Our results show that an FRI of 10 years is optimal for <i>D. muscipula</i> in past climate conditions, but a longer FRI (12 years) is optimal in future climate conditions. Further, deviations from optimal FRI reduce population growth rate dramatically in the past climate, but this reduction is muted in a future climate (future minus past sensitivity = 0.006, 95% CI [0.002, 0.011]). Finally, our experimental work suggests that fire effects are driven in part by positive, additive effects of competitor removal and ash addition immediately following a fire; for one population, both these treatments significantly increased population growth rate. Our work suggests that climate change can alter the response of populations to disturbance, highlighting the need to consider the interacting effects of multiple abiotic drivers when projecting future population growth and geographical distributions.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45574302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accidental epiphytes: Ecological insights and evolutionary implications","authors":"Vincent Hoeber,&nbsp;Gerhard Zotz","doi":"10.1002/ecm.1527","DOIUrl":"10.1002/ecm.1527","url":null,"abstract":"<p>Vascular epiphytes are an important component of many ecosystems and constitute a substantial part of global plant diversity. In this context, accidental epiphytism, that is, the opportunistic epiphytic growth of typically terrestrial species, deserves special attention because it provides crucial insights into the global distribution of vascular epiphytes and the initial evolution of epiphytic lineages. Even though accidental epiphytes have been mentioned in the literature for more than a century, they have been neglected in most epiphyte studies. Only recently has accidental epiphytism been investigated more thoroughly. Therefore, the aim of this article is to provide a comprehensive review of the ecological basis and evolutionary relevance of this common but largely neglected phenomenon and to highlight open questions and promising research directions. Our central statement—that any species has the potential to grow epiphytically given the availability of suitable microhabitats and successful dispersal—is backed up by a compilation of observations of accidental epiphytes from numerous ecosystems with diverse climates, even including semiarid Mediterranean ones. A variety of arboreal microhabitats and environmental conditions conform to the ecological niche of typical terrestrial species, with the availability of such microhabitats depending on the interaction of local climate conditions, host tree age, and host species identity. Whenever suitable microhabitats are available in tree crowns, accidental epiphytism is limited primarily by dispersal. In an evolutionary context, the conquest of forest canopy represents an ecological opportunity where accidental epiphytes act as links between terrestrial and epiphytic life forms. We discuss two fundamental scenarios with sympatric speciation, selective pressure, autopolyploidy, and allopatric speciation as underlying mechanisms in the transition from terrestrial to epiphytic growth. In conclusion, we argue that accidental epiphytism is a substrate and dispersal-dependent phenomenon and that, both from an individual perspective and an evolutionary perspective, epiphytism reflects the occupation of suitable but previously unexploited arboreal microhabitats. Acknowledging the fundamental principles that plant growth is opportunistic and that dispersal is a stochastic process can decisively improve our understanding of species distributions and other ecological patterns, as in the case of accidental epiphytism.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecm.1527","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51637975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental drivers of biseasonal anthrax outbreak dynamics in two multihost savanna systems","authors":"Yen-Hua Huang,&nbsp;Kyrre Kausrud,&nbsp;Ayesha Hassim,&nbsp;Sunday O. Ochai,&nbsp;O. Louis van Schalkwyk,&nbsp;Edgar H. Dekker,&nbsp;Alexander Buyantuev,&nbsp;Claudine C. Cloete,&nbsp;J. Werner Kilian,&nbsp;John K. E. Mfune,&nbsp;Pauline L. Kamath,&nbsp;Henriette van Heerden,&nbsp;Wendy C. Turner","doi":"10.1002/ecm.1526","DOIUrl":"10.1002/ecm.1526","url":null,"abstract":"<p>Environmental factors are common forces driving infectious disease dynamics. We compared interannual and seasonal patterns of anthrax infections in two multihost systems in southern Africa: Etosha National Park, Namibia, and Kruger National Park, South Africa. Using several decades of mortality data from each system, we assessed possible transmission mechanisms behind anthrax dynamics, examining (1) within- and between-species temporal case correlations and (2) associations between anthrax mortalities and environmental factors, specifically rainfall and the Normalized Difference Vegetation Index (NDVI), with empirical dynamic modeling. Anthrax cases in Kruger had wide interannual variation in case numbers, and large outbreaks seemed to follow a roughly decadal cycle. In contrast, outbreaks in Etosha were smaller in magnitude and occurred annually. In Etosha, the host species commonly affected remained consistent over several decades, although plains zebra (<i>Equus quagga</i>) became relatively more dominant. In Kruger, turnover of the main host species occurred after the 1990s, where the previously dominant host species, greater kudu (<i>Tragelaphus strepsiceros</i>), was replaced by impala (<i>Aepyceros melampus</i>). In both parks, anthrax infections showed two seasonal peaks, with each species having only one peak in a year. Zebra, springbok (<i>Antidorcas marsupialis</i>), wildebeest (<i>Connochaetes taurinus</i>), and impala cases peaked in wet seasons, while elephant (<i>Loxodonta africana</i>), kudu, and buffalo (<i>Syncerus caffer</i>) cases peaked in dry seasons. For common host species shared between the two parks, anthrax mortalities peaked in the same season in both systems. Among host species with cases peaking in the same season, anthrax mortalities were mostly synchronized, which implies similar transmission mechanisms or shared sources of exposure. Between seasons, outbreaks in one species may contribute to more cases in another species in the following season. Higher vegetation greenness was associated with more zebra and springbok anthrax mortalities in Etosha but fewer elephant cases in Kruger. These results suggest that host behavioral responses to changing environmental conditions may affect anthrax transmission risk, with differences in transmission mechanisms leading to multihost biseasonal outbreaks. This study reveals the dynamics and potential environmental drivers of anthrax in two savanna systems, providing a better understanding of factors driving biseasonal dynamics and outbreak variation among locations.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 4","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecm.1526","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44967517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of increased competitive ability may explain dominance of introduced species in ruderal communities","authors":"José L. Hierro,&nbsp;Özkan Eren,&nbsp;Jan Čuda,&nbsp;Laura A. Meyerson","doi":"10.1002/ecm.1524","DOIUrl":"10.1002/ecm.1524","url":null,"abstract":"<p>The evolution of increased competitive ability (EICA) hypothesis encapsulates the importance of evolution and ecology for biological invasions. According to this proposition, leaving specialist herbivores at home frees introduced plant species from investing limited resources in defense to instead use those resources for growth, selecting for individuals with reduced defense, enhanced growth, and, consequently, increased competitive ability. We took a multispecies approach, including ancestral and non-native populations of seven weeds, as well as seven coexisting local weeds, to explore all three predictions (i.e., lower defense, greater growth, and better ability to compete in non-native than ancestral populations), the generality as an invasion mechanism for a given system, and community-level consequences of EICA. We assessed plant defenses by conducting herbivory trials with a generalist herbivore. Therefore, finding that non-native populations are better defended than ancestral populations would lend support to the shifting defense (SD) hypothesis, an extension of EICA that incorporates the observation that introduced species escape specialists, but encounter generalists. We also manipulated water additions to evaluate how resource availability influences competition in the context of EICA and plant plasticity in our semiarid system. We found that non-native populations of one study species, <i>Centaurea solstitialis</i>, were better defended, grew faster, and exerted stronger suppression on locals than ancestral populations, offering support to EICA through the SD hypothesis. The other species also displayed variation in trait attributes between ancestral and non-native populations, but they did not fully comply with the three predictions of EICA. Notably, differences between those populations generally favored the non-natives. Moreover, non-native populations were, overall, superior at suppressing locals relative to ancestral populations under low water conditions. There were no differences in plasticity among all three groups. These results suggest that evolutionary change between ancestral and non-native populations is widespread and could have facilitated invasion in our system. Additionally, although trading growth for shifted defense does not seem to be the main operational path for evolutionary change, it may explain the dominance of some introduced species in ruderal communities. Because introduced species dominate communities in disturbed environments around the world, our results are likely generalizable to other systems.</p>","PeriodicalId":11505,"journal":{"name":"Ecological Monographs","volume":"92 3","pages":""},"PeriodicalIF":6.1,"publicationDate":"2022-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48695616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}