Biology subjects

Saglam, I. K.

Publications and source records attributed to Saglam, I. K..

3 recordsLinked to original sources

bioRxiv2025

The effects of thermal deterioration on the life history traits of Daphnia magna

Global warming often pushes species toward their physiological limits, yet the pace of change may be as important as the absolute temperature reached. Most experiments rely on abrupt shifts, leaving the demographic and evolutionary consequences of gradual warming poorly understood. We conducted a 30-generation experiment with clonal populations of Daphnia magna maintained either under constant temperature (26 {degrees}C) or gradual warming (+1 {degrees}C every 4-6 generations, up to 32 {degrees}C). We measured fecundity, growth rate, age at maturation, body size, and lifespan across generations, and used a reciprocal transplant assay to disentangle genetic and plastic responses. Warming populations matured earlier, grew faster, and initially reproduced more than controls, but suffered shorter lifespans and lost their reproductive advantage near 30 {degrees}C, a sub-lethal ceiling that coincided with extinction events. This rate-dependent trajectory contrasts with one-step warming studies that typically report uniformly reduced reproduction. Reciprocal transplants revealed a persistent reduction in adult body size of warming-line offspring, regardless of rearing environment, consistent with heritable or trans-generational change, while growth rate remained largely plastic. Together, these results show that gradual warming can simultaneously elicit plastic and heritable trait shifts, and that reproductive ceilings well below lethal limits act as tipping points for population persistence.

evolutionary biology↗

bioRxiv2023

Human-brown bear conflicts in Turkey are driven by increased human presence around protected areas

Human-wildlife conflict is increasing steadily worldwide and is rapidly becoming an important challenge for the success of conservation programs. Brown bears, which suffer from reduced habitat suitability and quality globally, frequently conflict with humans. These animals need large home ranges to fulfill their habitat requirements. When space and food are restricted, brown bears frequently shift towards human-dominated landscapes that offer reliable food sources. As a country where most of the landscape and habitats are human-dominated, human-brown bear conflict events (HBCs) are frequent in Turkiye. However, there has been no formal analysis of the nature and scope of these conflicts at the country level. Here, using HBC data from 2017 to 2022, we determined the spatial and temporal dynamics of HBC events and generated a risk probability map based on anthropogenic predictors and geographic profiling, to determine the factors driving HBC across Turkiye. HBC events did not show any annual or seasonal trends but varied considerably across biogeographic regions, with most conflicts occurring along the Black Sea coast and Eastern Anatolia. Sixty percent of all conflicts were due to bear foraging behavior in human settlements while twelve percent were the result of human activity in forests, with 57% of all conflict events resulting in direct injury to either humans or bears. We found that distance to villages, distance to protected areas, distance to farmland and human footprint to be the most important factors contributing to conflict risk. Consequently, 21% of the country was found to be under human-bear conflict risk, with 43% of the risks occurring within a 10 km radius from the centers of protected areas. Our analyses indicate that the high occurrence of HBCs is mainly the result of limited natural areas and resources available to brown bears and the increasing human encroachment in and around core bear habitats.

ecology↗

bioRxiv2019

Phylo-comparative analyses reveal the dual role of drift and selection in reproductive character displacement.

When incipient species meet in secondary contact, natural selection can rapidly reduce costly reproductive interactions by directly targeting reproductive traits. This process, called reproductive character displacement (RCD), leaves a characteristic pattern of geographic variation where divergence of traits between species is greater in sympatry than allopatry. However, because other forces can also cause similar patterns, care must be given in separating pattern from process. Here we show how the phylo-comparative method together with genomic data can be used to evaluate evolutionary processes at the population level in closely related species. Using this framework, we test the role of RCD in speciation of two cricket species endemic to Anatolian mountains by quantifying patterns of character displacement, rates of evolution and adaptive divergence. Our results show differing patterns of character displacement between species for reproductive vs. non-reproductive characters and strong patterns of asymmetric divergence. We demonstrate diversification results from rapid divergence of reproductive traits towards multiple optima under the dual influence of strong drift and selection. These results present the first solid evidence for RCD in Anatolian mountains, quantify the amount of drift and selection necessary for RCD to lead to speciation, and demonstrate the utility of phylo-comparative methods for quantifying evolutionary parameters at the population level.

evolutionary biology↗