İç Anadolu’da Marnlı Bir Bozkır Habitatında Yetişen Dar Yayılışlı ve Yaygın Bitkilerin Polinatör Böcek Çeşitliliği Örüntüleri

Abstract

Pollination is the transfer of pollen from the anthers to the stigma of plants. Insects play a key role in pollination, and floral visitors contribute to process at varying levels. In ecology, understanding the factors shaping species distribution patterns is a central focus. Pollen limitation, defined by inadequate or poor-quality pollen receipt, can occur when pollinators are insufficient or ineffective, influencing plant distribution. Specialized and generalist behaviors relate to resource use capacity of taxa. Limited niche breadth indicates specialization, while broader niche breadth in generalists allows tolerance to diverse conditions. Differences in these behaviorsbetween plants and pollinators may also affect plant distribution, and most insights into these interactions are achievable only through an interaction network approach. While pollinator effects on plant distribution have been examined from various angles, diversity patterns of pollinators across plant distribution groups remain understudied. This thesis investigates whether plant distribution patterns are associated with the taxon richness, diversity, visitation frequency, and taxonomic composition of insect pollinators. Fieldwork was conducted in marl steppe habitats in Sivrihisar, Eskişehir, on three species each from narrowly distributed endemic, widespread endemic, and widespread non-endemic plant groups. For each species, pollinator observations were carried out on five individuals, and additional general samples were taken. Flower samples were collected for eDNA metabarcoding. Observational samples were categorized into pollinator insects and other floral visitors, with analyses conducted separately for pollinators and all-inclusive visitor groups. Taxon richness and visitation frequency were analyzed using generalized linear models based on Poisson distribution. Taxon diversity was assessed using the Shannon index, general linear models, and one-way ANOVA. For taxon composition, non-metric multidimensional scaling and non-parametric multivariate analysis of variance were performed, and Jaccard similarity index was used for taxon similarity. Interaction network analyses were also conducted. Results showed differences in the communities formed by pollinators and all visitors across plant distribution groups. Narrowly distributed plants had significantly lower taxon richness, diversity, and visitation frequency for both pollinators and all visitors, whereas widespread non-endemic plants had the highest values. This suggests that pollen limitation may be occurring in narrowly distributed plants due to reduced pollinator visitation. However, no distinct differences were found in community composition between groups. This may be explained by the distributional variability of pollinator taxa among plants and broad variation within the data. While eDNA metabarcoding enabled the detection of some hard-to-observe floral visitors, it failed to yield data specific to pollinator insects. This study identifies the pollinator insects present in Central Anatolia's marl steppe ecosystem and their interactions with plant species exhibiting different distribution patterns. Its findings provide valuable insights for improving conservation strategies, especially for narrowly distributed and endemic species, by incorporating species interactions into planning.