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Simple Summary: The chukar partridge (Alectoris chukar) is an important bird species with significant economic and ecological value. Every year, thousands of partridges raised in Ministry of Agriculture and Forestry breeding farms are released into nature for hunting purposes. Our investigation of the gene pools of different A. chukar populations using mitochondrial and microsatellite markers from across Türkiye revealed that the Eastern, Western, and Thracian genetic structures have been shaped by Türkiye's geography and topography, past climatic fluctuations, and human-mediated artificial hybridizations. There were no signs of congeneric genetic contamination in native chukar populations, but there were contaminations with the China clade-B, which were detected as reported in the previous studies. Türkiye is considered an important evolutionary area for Chukar partridge (Alectoris chukar), since it is both a potential ancestral area and a diversification center for the species. Using 2 mitochondrial (Cty-b and D-loop) and 13 polymorphic microsatellite markers, we investigated the geographic genetic structure of A. chukar populations to determine how past climatic fluctuations and human activities have shaped the gene pool of this species in Türkiye. Our results indicate, firstly, that only A. chukar of the genus Alectoris is present in Türkiye (Anatolia and Thrace), with no natural or artificial gene flow from congenerics. Secondly, the geographic genetic structure of the species in Türkiye has been shaped by topographic heterogeneity, Pleistocene climatic fluctuations, and artificial transport by humans. Third, there appears to be three genetic clusters: Thracian, Eastern, and Western. Fourth, the post-LGM demographic expansion of the Eastern and Western populations has formed a hybrid zone in Central Anatolia (~8 kyBP). Fifth, the rate of China clade-B contamination in Türkiye is about 8% in mtDNA and about 12% in nuDNA, with the Southeastern Anatolian population having the highest contamination. Sixth, the Thracian population was the most genetically distinct, with the lowest genetic diversity and highest level of inbreeding and no China clad-B contamination. These results can contribute to the conservation regarding A. chukar populations, especially the Thracian population. [ABSTRACT FROM AUTHOR]

The Ombrone palaeovalley was incised during the last glacial sea-level fall and was infilled during the subsequent Late-glacial to Holocene transgression. A detailed sedimentological and stratigraphic study of two cores along the palaeovalley axis led to reconstruction of the post-Last Glacial Maximum valley-fill history. Stratigraphic correlations show remarkable similarity in the Late-glacial to early-Holocene succession, but discrepancy in the Holocene portion of the valley fill. Above the palaeovalley floor, about 60 m below sea-level, Late-glacial sedimentation is recorded by an unusually thick alluvial succession dated back to ca 18 cal kyr bp. The Holocene onset was followed by the retrogradational shift from alluvial to coastal facies. In seaward core OM1, the transition from inner to outer estuarine environments marks the maximum deepening of the system. By comparison, in landward core OM2, the emplacement of estuarine conditions was interrupted by renewed continental sedimentation. Swamp to lacustrine facies, stratigraphically equivalent to the fully estuarine facies of core OM1, represent the proximal expression of the maximum flooding zone. This succession reflects location in a confined segment of the valley, just landward of the confluence with a tributary valley. It is likely that sudden sediment input from the tributary produced a topographic threshold, damming the main valley course and isolating its landward segment from the sea. The seaward portion of the Ombrone palaeovalley presents the typical estuarine backfilling succession of allogenically controlled incised valleys. In contrast, in the landward portion of the system, local dynamics completely overwhelmed the sea-level signal, following marine ingression. This study highlights the complexity of palaeovalley systems, where local morphologies, changes in catchment areas, drainage systems and tributary valleys may produce facies patterns significantly different from the general stratigraphic organization depicted by traditional sequence-stratigraphic models. [ABSTRACT FROM AUTHOR]

Abstract: Small river systems contribute a significant component of sediment delivered to oceans, but the temporal evolution of fluvially eroded landscapes is needed. A sequence of postglacial terraces in the unglaciated Waipaoa River catchment provides the opportunity to document fluvial incision and sediment flux on an ~2000-year timescale since the Last Glacial Maximum (LGM), which has previously only been undertaken for the entire post-LGM period. This study also calculates sediment mass, where previously sediment volume was calculated. Using a 15-m DEM, field mapping and surveying, and tephrochronology, we calculate rates of fluvial incision and sediment volumes excavated during successive age-constrained, postglacial, incision events and correlate these with a framework of inferred climatic events established for New Zealand. We identify seven periods of terrace formation each succeeded by a period of fluvial incision, six in total. Although the magnitude of the response during each incision event and thus the sediment volumes generated varied through time and across subcatchments draining two contrasting lithological terrains, we conclude that incision events were essentially synchronous, at least within the timeframe constrained by the ca. 2000year interval between successive eruptive airfall events. Slope relaxation processes were simultaneous with incision thereby indicating that both processes were likely climate driven. We identify a period of accelerated fluvial incision ~7mmy−1 commencing before ca. 14.0cal. ka BP (during the early postglacial period) and ceasing ca. 7.9cal. ka BP toward the end of the Early Holocene Warming period. The magnitude of this incision response was significantly higher in subcatchments draining highly erodible lithologies in the higher uplifting parts of the catchment when river bedload was at over capacity. In contrast, within the remainder of subcatchments draining the more resistant lithologies and in areas of lower uplift (and in parts subsiding), incision and sediment generation was moderated by the presence of knickpoints. Overall, since abandonment of the LGM to present day, fluvial incision in the Waipaoa and the adjacent Waimata catchments generated ~16.7km3 of sediment of which ~10km3 (~90% of the estimated 35Mt of glacial–postglacial slope and shelf sediment mass) was potentially available for transport offshore. Of this, 14.08km3 (7.4km3 derived from ‘upper’ and 6.7km3 from ‘remainder’ of subcatchments) was excavated from Waipaoa catchment at an average of ~0.6km3 ka−1 of which ~80% was generated by ca. 7.9cal. ka BP. This potentially validates previous accounts of high rates of offshore sediment flux before 8000 14C YBP (ca. 8877cal. YBP). Thereafter, for the period mid-Holocene cooling and variability (MHCV) (ca. 6.5cal. ka BP) until the present day, the rate of incision across all subcatchments slowed to ~2mmy−1 and generated just ~20% of the total sediment volume. In part, this reflected a depletion of available sediment as rivers in the upper subcatchments returned to a steady state and, coincidental with an increase in accommodation space in the rapidly growing coastal floodplain, sediment flux to the marine depocentres was thereby limited. [Copyright &y& Elsevier]

The geomorphological study by means of remote sensing imagery of the Rio Pastaza Megafan (Ecuador and northern Peru) reveals the traces of numerous avulsions. One hundred and eight avulsion sites have been defined. The location of these sites, the available radiocarbon ages as well as historical maps of the seventeenth century, enable us to propose an evolution history of the migration and avulsions of the Rio Pastaza since the Last Glacial Maximum. The first avulsions of the Río Pastaza occurred after the LGM in a zone close to and roughly parallel to the sudandean front, where the developed avulsion gave a distributive pattern to the ancient stream of the Río Pastaza in an area located between the modern Río Morona and Pastaza, where they caused the Rio Pastaza to develop a fan-like distributary pattern. This is interpreted as a response to thrust-related forelimb tilt, progressively shifting eastward the Rio Pastaza and the apex of the megafan. This sequence of events ended with the Great Diversion of the Rio Pastaza towards the modern Rios Corrientes and Tigre. Avulsions occurred in the Tigre-Corrientes Area between 9200 and 8,500 years Cal BP. Afterwards, the Río Pastaza was diverted to its present-day north-south course. This last significant avulsion occurred before AD 1691. In the area located between the modern Río Morona and Pastaza, avulsion frequency-probably overestimated-ranges between 100 and 200 years. In the Ríos Tigre and Corrientes area, avulsion frequency-probably underestimated-ranges from 300 to 400 years. Regional tectonics is likely to have triggered most of the avulsions in the Morona Pastaza area but its influence is restricted to this area. The factors controlling the avulsions in the Tigre-Corrientes area are less clear because the frequently described 'hydrologic'-driven avulsion as observed in areas characterized by contrasted hydrologic cycles are inconsistent with the characteristics of the hydrologic cycles of the Rio Pastaza. [ABSTRACT FROM AUTHOR]