Research Outputs

Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2

Browse

Filters

2019 - 201912020 - 202424

Advanced Search

Filter by

Settings

Full Text: YesSubject: search.filters.subject.Ecology

Search Results

Now showing 1 - 10 of 25
  • Thumbnail Image
    PublicationOpen Access
    Aggression and multi-modal signaling in noise in a common urban songbird
    (Springer, 2022) Department of Media and Visual Arts; Department of Psychology; Akçay, Çağlar; Yelimlieş, Alper; Önsal, Çağla; Faculty Member; Department of Media and Visual Arts; Department of Psychology; College of Social Sciences and Humanities; 272053; N/A; N/A
    Anthropogenic noise may disrupt signals used to mediate aggressive interactions, leading to more physical aggression between opponents. One solution to this problem is to switch signaling effort to a less noisy modality (e.g., the visual modality). In the present study, we investigate aggressive behaviors and signaling in urban and rural male European robins (Erithacus rubecula) in response to simulated intrusions with or without experimental noise. First, we predicted that urban birds, living in noisier habitats, would be generally more aggressive than rural birds. We also predicted that during simulated intrusions with experimental noise, robins would increase their physical aggression and show a multi-modal shift, i.e., respond with more visual threat displays and sing fewer songs. Finally, we expected the multi-modal shift in response to noise to be stronger in urban birds compared to rural birds. The results showed that urban birds were more aggressive than rural robins, but an increase in aggression with experimental noise was seen only in the rural birds. Urban but not rural birds decreased their song rate in response to noise. Contrary to the multi-modal shift hypothesis, however, there was no evidence of a concurrent increase in visual signals. These results point to a complex role of immediate plasticity and longer-term processes in affecting communication during aggressive interactions under anthropogenic noise. Significance statement Human activity has an enormous effect on wildlife, including on their social behavior. Animals living in urban areas often tend to be more aggressive than those living in rural areas, which may be due to urban acoustic noise making communication between individuals more difficult. In a study with a common songbird, the European robin, we investigated the role of urban acoustic noise in aggression and territorial communication. Urban robins were more aggressive than rural robins, and additional noise in the territory increased aggression in rural but not urban robins. While urban robins decreased their singing effort with additional noise, they did not increase visual signals concurrently. These results suggest that noise can indeed make animals behave more aggressively although the effect may depend on how noisy it is already. These results further our understanding of how human-made noise changes animal communication and social behavior.
  • Thumbnail Image
    PublicationOpen Access
    Avian use of agricultural areas as migration stopover sites: a review of crop management practices and ecological correlates
    (Frontiers, 2021) Blount, J. David; Horns, Joshua J.; Kittelberger, Kyle D.; Neate-Clegg, Montague H. C.; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences; 327589
    An estimated 17% of migratory bird species are threatened or near threatened with extinction. This represents an enormous potential loss of biodiversity and cost to human societies due to the economic benefits that birds provide through ecosystem services and ecotourism. Conservation of migratory bird species presents many unique challenges, as these birds rely on multiple geographically distinct habitats, including breeding grounds, non-breeding grounds, and stopover sites during migration. In particular, stopover habitats are seldom studied relative to breeding and non-breeding habitats, despite their importance as refueling stations for migratory birds. In this study, we summarize the current research on the use of temporary primary crops by birds during migration and we assess the species characteristics and agricultural practices most often associated with the use of cropland as stopover habitat. First, we conducted a systematic review of the literature to document the effects various farming practices and crop types have on the abundance and diversity of migratory birds using agricultural areas for stopovers. Second, we analyzed the ecological correlates of bird species in the Northern Hemisphere that predict which species may use these areas while migrating. We ran a GLMM to test whether primary diet, diet breadth, primary habitat, habitat breadth, or realm predicted stopover use of agricultural areas. Our review suggests that particular crop types (principally rice, corn, and sunflower), as well as farming practices that result in higher non-cultivated plant diversity, encourage the use of agricultural areas by migrating birds. We found that cropland is used as stopover habitat by bird species that can utilize a large breadth of habitats, as well as species with preferences for habitat similar in structure to agricultural areas.
  • Thumbnail Image
    PublicationOpen Access
    Biological correlates of extinction risk in resident Philippine avifauna
    (Frontiers, 2021) Kittelberger, Kyle D.; Neate Clegg, Montague H. C.; Blount, J. David; Posa, Mary Rose C.; McLaughlin, John; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences; 327589
    The majority of the world's biodiversity occurs in the tropics, but human actions in these regions have precipitated an extinction crisis due to habitat degradation, overexploitation, and climate change. Understanding which ecological, biogeographical, and life-history traits predict extinction risk is critical for conserving species. The Philippines is a hotspot of biodiversity and endemism, but it is a region that also suffers from an extremely high level of deforestation, habitat degradation, and wildlife exploitation. We investigated the biological correlates of extinction risk based on the IUCN Red List threat status among resident Philippine birds using a broad range of ecological, biogeographical, and life history traits previously identified as correlates of extinction risk in birds. We found strong support across competing models for endemism, narrower elevational ranges, high forest dependency, and larger body size as correlates significantly associated with extinction risk. Additionally, we compared observed threat status with threat status fitted by our model, finding fourteen species that are not currently recognized by the IUCN Red List as threatened that may be more threatened than currently believed and therefore warrant heightened conservation focus, and predicted threat statuses for the four Philippine Data Deficient bird species. We also assessed species described in recent taxonomic splits that are recognized by BirdLife International, finding 12 species that have a fitted threat status more severe than their IUCN-designated ones. Our findings provide a framework for avian conservation efforts to identify birds with specific biological correlates that increase a species' vulnerability to extinction both in the Philippine Archipelago and elsewhere on other tropical islands.
  • Thumbnail Image
    PublicationOpen Access
    Combining models of environment, behavior, and physiology to predict tissue hydrogen and oxygen isotope variance among individual terrestrial animals
    (Frontiers, 2020) Magozzi, Sarah; Vander Zanden, Hannah B.; Wunder, Michael B.; Trueman, Clive N.; Pinney, Kailee; Peers, Dori; Dennison, Philip E.; Horns, Joshua J.; Bowen, Gabriel J.; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences
    Variations in stable hydrogen and oxygen isotope ratios in terrestrial animal tissues are used to reconstruct origin and movement. An underlying assumption of these applications is that tissues grown at the same site share a similar isotopic signal, representative of the location of their origin. However, large variations in tissue isotopic compositions often exist even among conspecific individuals within local populations, which complicates origin and migration inferences. Field-data and correlation analyses have provided hints about the underlying mechanisms of within-site among-individual isotopic variance, but a theory explaining the causes and magnitude of such variance has not been established. Here we develop a mechanistic modeling framework that provides explicit predictions of the magnitude, patterns, and drivers of isotopic variation among individuals living in a common but environmentally heterogeneous habitat. The model toolbox includes isoscape models of environmental isotopic variability, an agent-based model of behavior and movement, and a physiology-biochemistry model of isotopic incorporation into tissues. We compare model predictions against observed variation in hatch-year individuals of the songbird Spotted Towhee (Pipilo maculatus) in Red Butte Canyon, Utah, and evaluate the ability of the model to reproduce this variation under different sets of assumptions. Only models that account for environmental isotopic variability predict a similar magnitude of isotopic variation as observed. Within the modeling framework, behavioral rules and properties govern how animals nesting in different locations acquire resources from different habitats, and birds nesting in or near riparian habitat preferentially access isotopically lighter resources than those associated with the meadow and slope habitats, which results in more negative body water and tissue isotope values. Riparian nesters also have faster body water turnover and acquire more water from drinking (vs. from food), which exerts a secondary influence on their isotope ratios. Thus, the model predicts that local among-individual isotopic variance is linked first to isotopic heterogeneity in the local habitat, and second to how animals sample this habitat during foraging. Model predictions provide insight into the fundamental mechanisms of small-scale isotopic variance and can be used to predict the utility of isotope-based methods for specific groups or environments in ecological and forensic research.
  • Thumbnail Image
    PublicationOpen Access
    Counter-interception and counter-exploitation features of noise radar technology
    (Multidisciplinary Digital Publishing Institute (MDPI), 2021) Galati, Gaspare; Pavan, Gabriele; Wasserzier, Christoph; Department of Electrical and Electronics Engineering; Savcı, Kubilay; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering
    In defense applications, the main features of radars are the Low Probability of Intercept (LPI) and the Low Probability of Exploitation (LPE). The counterpart uses more and more capable intercept receivers and signal processors thanks to the ongoing technological progress. Noise Radar Technology (NRT) is probably a very effective answer to the increasing demand for operational LPI/LPE radars. The design and selection of the radiated waveforms, while respecting the prescribed spectrum occupancy, has to comply with the contrasting requirements of LPI/LPE and of a favorable shape of the ambiguity function. Information theory seems to be a “technologically agnostic” tool to attempt to quantify the LPI/LPE capability of noise waveforms with little, or absent, a priori knowledge of the means and the strategies used by the counterpart. An information theoretical analysis can lead to practical results in the design and selection of NRT waveforms.
  • Thumbnail Image
    PublicationRestricted
    Determining demographic and genetic structure of sedentary and migratory bears (ursus arctos) within Eastern Anatolia using genome-wide genetic markers
    (Koç University, 2022) Kemahlı Aytekin, Mübeccel Çisel; Kavaklı, İbrahim Halil; 0000-0001-6624-3505; Koç University Graduate School of Sciences and Engineering; Molecular Biology and Genetics; 40319
  • Thumbnail Image
    PublicationOpen Access
    Ecological correlates of elevational range shifts in tropical birds
    (Frontiers, 2021) Neate-Clegg, Montague H. C.; Jones, Samuel E., I; Tobias, Joseph A.; Newmark, William D.; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences; 327589
    Globally, birds have been shown to respond to climate change by shifting their elevational distributions. This phenomenon is especially prevalent in the tropics, where elevational gradients are often hotspots of diversity and endemism. Empirical evidence has suggested that elevational range shifts are far from uniform across species, varying greatly in the direction (upslope vs. downslope) and rate of change (speed of elevational shift). However, little is known about the drivers of these variable responses to climate change, limiting our ability to accurately project changes in the future. Here, we compile empirical estimates of elevational shift rates (m/yr) for 421 bird species from eight study sites across the tropics. On average, species shifted their mean elevations upslope by 1.63 +/- 0.30 m/yr, their upper limits by 1.62 m +/- 0.38 m/yr, and their lower limits by 2.81 +/- 0.42 m/yr. Upslope shift rates increased in smaller-bodied, less territorial species, whereas larger species were more likely to shift downslope. When considering absolute shift rates, rates were fastest for species with high dispersal ability, low foraging strata, and wide elevational ranges. Our results indicate that elevational shift rates are associated with species' traits, particularly body size, dispersal ability, and territoriality. However, these effects vary substantially across sites, suggesting that responses of tropical montane bird communities to climate change are complex and best predicted within the local or regional context.
  • Thumbnail Image
    PublicationRestricted
    Ecological niche modeling and genetic structure of brown bear (ursus arctos) in Türkiye
    (Koç University, 2024) Sıkdokur, Ercan; Şekercioğlu, Çağan Hakkı; 0000-0003-3193-0377; Koç University Graduate School of Sciences and Engineering; Molecular Biology and Genetics; 327589
  • Thumbnail Image
    PublicationOpen Access
    Existence of SARS-Cov-2 RNA on ambient particulate matter samples: a nationwide study in Turkey
    (Elsevier, 2021) Arı, Akif; Şahin, A. Ülkü; Gaga, O. Eftade; Kuzu, S. Levent; Arı Ertürk, Pelin; Odabaşı, Mustafa; Taşdemir, Yücel; Cindoruk, S. Sıddık; Esen, Fatma; Çalışkan, Burak; Sakin, Egemen; Tecer, H. Lokman; Fıçıcı, Merve; Altın, Ahmet; Onat, Burcu; Ayvaz, Coşkun; Uzun, Burcu; Saral, Arslan; Döğeroğlu, Tuncay; Malkoç, Semra; Üzmez, Ö. Özlem; Kunt, Fatma; Aydın, Senar; Kara, Melik; Yaman, Barış; Doğan, Güray; Olgun, Bihter; Dokumacı, N. Ebru; Güllü, Gülen; Uzunpınar, S. Elif; Kayalar, Özgecan; Konyalılar, Nur; Doğan, Özlem; Can, Füsun; Babuççu, Gizem; Bayram, Hasan; Researcher; PhD Student; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); School of Medicine; Graduate School of Health Sciences; N/A; N/A; 170418; 103165; N/A; 4890
    Coronavirus disease 2019 (COVID-19) is caused by the SARS-CoV-2 virus and has been affecting the world since the end of 2019. The disease led to significant mortality and morbidity in Turkey, since the first case was reported on March 11th, 2020. Studies suggest a positive association between air pollution and SARS-CoV-2 infection. The aim of the present study was to investigate the role of ambient particulate matters (PM), as potential carriers for SARS-CoV-2. Ambient PM samples in various size ranges were collected from 13 sites including urban and urban-background locations and hospital gardens in 10 cities across Turkey between 13th of May and 14th of June 2020 to investigate the possible presence of SARS-CoV-2 RNA on ambient PM. A total of 203 daily samples (TSP, n = 80; PM2.5, n = 33; PM2.5-10, n = 23; PM10?m, n = 19; and 6 size segregated PM, n = 48) were collected using various samplers. The N1 gene and RdRP gene expressions were analyzed for the presence of SARS-CoV-2, as suggested by the Centers for Disease Control and Prevention (CDC). According to real time (RT)-PCR and three-dimensional (3D) digital (d) PCR analysis, dual RdRP and N1 gene positivity were detected in 20 (9.8%) samples. Ambient PM-bound SARS-CoV-2 was analyzed quantitatively and the air concentrations of the virus ranged from 0.1 copies/m3 to 23 copies/m3. The highest percentages of virus detection on PM samples were from hospital gardens in Tekirdağ, Zonguldak, and Istanbul, especially in PM2.5 mode. Findings of this study have suggested that SARS-CoV-2 may be transported by ambient particles, especially at sites close to the infection hot-spots. However, whether this has an impact on the spread of the virus infection remains to be determined.
  • Thumbnail Image
    PublicationOpen Access
    How COVID-19 financially hit urban refugees: evidence from mixed-method research with citizens and Syrian refugees in Turkey
    (Wiley, 2021) Kirişçioğlu, Eda; Department of International Relations; Elçi, Ezgi; Faculty Member; Department of International Relations; College of Administrative Sciences and Economics; Graduate School of Social Sciences and Humanities; 238439; N/A
    Peering through a lens of disasters and inequalities, this article measures the financial impacts of Covid-19 on citizens and refugee communities in Turkey during a relatively early phase of the global pandemic. Our data comes from an online survey (N = 1749) conducted simultaneously with Turkish citizens and Syrian refugees living in Turkey, followed by in-depth online interviews with Syrian refugees. Our findings indicate that the initial Covid-19 measures had a higher financial impact on Syrians than on citizens when controlled for employment, wealth, and education, among other variables. In line with the literature, our research confirms that disasters' socio-economic effects disproportionally burden minority communities. We additionally discuss how Covid-19 measures have significantly accelerated effects on refugees compared to the local population, mainly due to the structural and policy context within which forcibly displaced Syrians have been received in Turkey.