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Yayın Strategies for the evolution of sex(American Institute of Physics Inc., 2001-12) Tüzel, Erkan; Sevim, Volkan; Erzan, AyşeThe maintenance of a macroscopic sexual population is addressed. As a scenario, the mechanism of random conversion to sex, in the presence of a constant rate of mutation is examined. This scenario is very closely related to "coevolution of cell senescence and diploid sexual reproduction in unicellular organisms." In this work, a "senescence clock" ticks off a finite lifetime for each bit string. Sexual reproduction resets the senescence of clock; unless this happens after a number of generations of cloning, the offspring stop dividing and die.Yayın Quaternary uplift of the northern margin of the Central Anatolian Plateau: New OSL dates of fluvial and delta-terrace deposits of the Kizilirmak River, Black Sea coast, Turkey(Pergamon-Elsevier Science Ltd, 2018-12-01) Berndt, Christopher; Yıldırım, Cengiz; Çiner, Tahsin Attila; Strecker, Manfred R.; Ertunç, Gülgün; Sarıkaya, Mehmet Akif; Özcan, Orkan; Öztürk, Tuğba; Güneç Kıyak, NafiyeWe analysed the interplay between coastal uplift, sea level change in the Black Sea, and incision of the Kizilirmak River in northern Turkey. These processes have created multiple co-genetic fluvial and marine terrace sequences that serve as excellent strain markers to assess the ongoing evolution of the Pontide orogenic wedge and the growth of the northern margin of the Central Anatolian Plateau. We used high-resolution topographic data, OSL ages, and published information on past sea levels to analyse the spatiotemporal evolution of these terraces; we derived a regional uplift model for the northward advancing orogenic wedge that supports the notion of laterally variable uplift rates along the flanks of the Pontides. The best-fit uplift model defines a constant long-term uplift rate of 0.28 +/- 0.07 m/ka for the last 545 ka. This model explains the evolution of the terrace sequence in light of active tectonic processes and superposed cycles of climate-controlled sea-level change. Our new data reveal regional uplift characteristics that are comparable to the inner sectors of the Central Pontides; accordingly, the rate of uplift diminishes with increasing distance from the main strand of the restraining bend of the North Anatolian Fault Zone (NAFZ). This spatial relationship between the regional impact of the restraining bend of the NAFZ and uplift of the Pontide wedge thus suggests a strong link between the activity of the NAFZ, deformation and uplift in the Pontide orogenic wedge, and the sustained lateral growth of the Central Anatolian Plateau flank.Yayın Evolutionary route to diploidy and sex(National Academy of Sciences, 2001-11-20) Tüzel, Erkan; Sevim, Volkan; Erzan, AyşeBy using a bit-string model of evolution, we find a successful route to diploidy and sex in simple organisms. Allowing the sexually reproducing diploid individuals to also perform mitosis, as they do in a haploid-diploid cycle, leads to the complete takeover of the population by sexual diploids. This mechanism is so robust that even the accidental conversion and pairing of only two diploids give rise to a sexual population.Yayın Eolianite and coquinite as evidence of MIS 6 and 5, NW Black Sea coast, Turkey(Elsevier B.V., 2017-04) Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Selim, Hamit Haluk; Bozcu, Mustafa; Öztürk, Muhammed Zeynel; Ekinci, Yunus Levent; Demirci, Alper; Elmas, Elmas Kırcı; Öztürk, Tuğba; Çakır, Çağlar; Karabıyıkoğlu, MustafaThis paper discusses the implications of a lowstand carbonate eolianite and overlying transgressive sequence of coquinite at Şile on the Turkish Black Sea coast based on composition, depositional characteristics and optical age estimations. The cross-bedded eolianite is a mixed ooid quartz grainstone in composition, yielding a depositional age matching MIS 6. It formed at the backshore of the paleobeach with the supply of sediment the from the beach face and offering insights into the drift of mixed shallow marine carbonates and siliciclastics together with radial ooids by onshore winds from a subaerially exposed high- to low-energy ooid shoals and oolitic sand complexes which developed parallel to the shoreline on the shallow shelf margin. During this lowstand, a low-relief dune retaining a record of opposing paleowind directions than that of prevalent northeasterly winds of today appears to have been lithified to form dune rock (aeolinite) under drier conditions compared to the present. Coinciding with MIS 5e, shallow marine coquina beds resting unconformably on the eolianite indicate the occurrence of the Mediterranean transgression during the last interglacial, as confirmed by benthic foraminifera within the high-salinity tolerant coquina shells.Yayın Testing a hypothesis for the evolution of sex(World Scientific Publishing Company, 2000-07-11) Örçal, Bora; Tüzel, Erkan; Sevim, Volkan; Jan, Naeem; Erzan, AyşeAn asexual set of primitive bacteria is simulated with a lit-string Penna model with a Fermi function for survival. A recent hypothesis by Jan, Stauffer, and Moseley on the evolution of sex from asexual cells as a strategy for trying to escape the effects of deleterious mutations is checked. This strategy is found to provide a successful scenario for the evolution of a stable macroscopic sexual population.Yayın Investigation of beachrock using microanalyses and OSL dating: a case study from Bozcaada island, Turkey(Coastal Education & Research Foundation, 2010-03) Erginal, Ahmet Evren; Güneç Kıyak, Nafiye; Öztürk, BeyhanWe investigated the origin and absolute age of beachrock samples on Bozcaada Island, located on the northern Aegean Sea coast of Turkey, using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) analyses and optically stimulated luminescence (OSL) dating. Various types of cements were identified, such as micritic, meniscus, and biologic cements, revealing that the beachrock could have occurred as a result of the combined effects of marine-phreatic and supratidal cementation conditions. Optical dating results showed that the formation of beachrock ranged in age from 5.41 +/- 0.58 ka BP to 0.33 +/- 0.05 ka BP. However, much of the beachrock body (about 3 m in thickness) is drowned or submerged today, suggesting that submerged beachrocks extending to -5 m date to earlier times than the start of the cementation period discussed herein.Yayın Spatial slip behavior of large strike-slip fault belts: Implications for the Holocene slip rates of the eastern termination of the North Anatolian Fault, Turkey(Blackwell Publishing Ltd, 2015-12) Zabcı, Cengiz; Sançar, Taylan; Akyüz, Hüsnü Serdar; Güneç Kıyak, NafiyeWe present new data on Holocene slip rates for the eastern end of the North Anatolian Fault (NAF) by using the optically stimulated luminescence ages of the offset terrace deposits at two sites, where a total of four displaced landforms was studied. Each offset feature was analyzed independently, and three different assumptions were made for all the offsets, depending on whether the age of the upper tread (upper tread reconstruction), the lower tread (lower tread reconstruction), or all bounding surfaces (intermediate solution) were used in dating of the terrace risers. The deflected geometry of the risers strongly suggests the use of either the intermediate solution or the upper tread reconstruction. The joint slip rate distributions for the upper tread reconstructions and the intermediate solutions were modeled as 13.0 + 1.8 / -1.4 and 14.3 + 5.8 / -2.4 mm/yr (2?), respectively. Although the intermediate solution covers the full range of ages for the measured displacements, the curved geometry of the terrace risers suggests that the initiations of the riser offsets are most probably close to the abandonment ages of the upper terrace treads. Therefore, we accepted the joint slip rate of the intermediate solution but suggested that the average rate for the main displacement zone of the eastern NAF should be close to its lower limits. This slower rate with respect to previous estimates suggests that the total deformation is not only accommodated on the main displacement zone but is also distributed along the secondary faults to the south of the easternmost segments of the NAF.Yayın Tectonic and climatic controls on Quaternary fluvial processes and river terrace formation in a Mediterranean setting, the Goksu River, southern Turkey(Cambridge University Press, 2019-03) Avşin Görendağlı, Nurcan; Vandenberghe, Jef; Van Balen, Ronald; Güneç Kıyak, Nafiye; Öztürk, TuğbaClimate and tectonics effect the fluvial evolution of the Mediterranean Mut basin. The basin contains a river terrace staircase of 16 levels (T16-T1) ranging from 365 to 10m above the current Goksu River in its middle and lower sections. These river terraces records tectonic uplift in the Mut basin. Optically stimulated luminescence (OSL) dating of the fluvial sediments of the youngest terrace (T16) provides a chronology for the assessment of the important impacts of climatic changes. The ages from the youngest river terrace deposits in T16 may be subdivided into two intervals: (1) 239-194.7 ka during the later part of Marine Oxygen Isotope Stage (MIS) 7, implying that the aggradation of T16 started in (the final phase of) this warm period; and (2) 187.9-171 ka during much of MIS 6. Thus, it appears that the Goksu River continued depositing sediment from an interglacial into a glacial time. The differences in climate-driven fluvial evolution between this Mediterranean fluvial system and the classical, well-studied temperate-periglacial river systems in Europe may be the result of different vegetation cover and greater thaw of more intense snowfalls.Yayın Yeşilırmak taraçalarında (Orta Kuzey Anadolu) geç pleyistosen iklim değişiklikleri ve düşey yönlü deformasyona akarsu cevabının araştırılması(TMMOB Jeoloji Mühendisleri Odası, 2017) Erturaç, Mehmet Korhan; Güneç Kıyak, NafiyeFosilleşmiş taşkın ovası çökelleri olarak da tanımlanan akarsu taraça basamaklanması, akarsuların gelişim süreci üzerindeki iklim, kaide seviyesi ve genç tektonik etkinin analitik olarak belirlenmesi için önemli kayıtlar sunmaktadır. Bu çalışmanın odağında bulunan Yeşilırmak Nehri’nin Çekerek Irmağı ile birleştiği Geldingen Ovası’nın (Amasya) güney kesiminde, her iki akarsuyun kenarlarında bulunan depolanmalı taraça sistemi çalışılmıştır. Bu taraça sistemi, güncel nehir taşkın ovasından +70 metre üst kotlara kadar ulaşan üç basamaktan oluşmaktadır. Bu basamakların gelişim süreci, farklı seviyelerinden elde edilen toplam 12 adet örneğin lüminesans yöntemi kullanılarak tarihlendirilmesi ile araştırılmıştır. Elde edilen sonuçlar, taraça seviyelerinin Son Buzul Çağı içerisinde güncel taşkın ovasından T3 (+70), T2 (+35) ve T1(+15) metre göreceli konumlarda, sırasıyla MIS5a, MIS3 ve LGM sonu dönemleri içerisinde depolandığını ortaya koymaktadır. Elde edilen depolanmalı/aşınmalı dönemlerin, Türkiye ve yakın çevresinde gerçekleştirilen iklim değişikliği kayıtları ve Karadeniz seviye değişimleri ile karşılaştırılması, inceleme alanında taraça oluşumunun, son buzul dönemi içerisinde Doğu Akdeniz için tanımlanan yağışlı/kurak dönemlerle uyumlu olduğunu göstermektedir. Her üç taraçanın terkedilme zamanı ve konumu oranlandığında, Kuzey Anadolu Fayı Zonu’nun içbükey sıkışmalı bir büklüm yaptığı orta kesiminde ortalama 0.94±0.26 mm/yıl yükselme hızı hesaplanmaktadır.
