Urban environment decreases pollinator availability, fertility, and prolongs anthesis in the field bindweed ( Convolvulus arvensis Linnaeus, 1753)

Abstract

Urbanization alters the natural environment, with broad negative impacts on living organisms. Urbanization can also disrupt plant-pollinator networks by reducing the abundance and diversity of invertebrates. Firstly, I investigated whether the field bindweed ( Convolvulus arvensis ) is an obligatory entomophilous plant because previous reports were ambiguous. Secondly, I investigated how the obligatory entomophilous plant, field bindweed, responds to urbanization by comparing the flowering duration (anthesis) and the reproductive success of field bindweeds in urban and rural populations. Unlike cross-pollinated flowers and controls, flowers experimentally prevented from pollination and self-pollinated flowers did not produce seeds, suggesting that the field bindweed is self-incompatible and obligatory entomophilous. The abundance of urban pollinators was 5–6 times lower than the abundance of rural pollinators, and flies (Diptera), beetles (Coleoptera) and moths (Lepidoptera) were significantly more negatively influenced by the urban environment than hymenopterans (Hymenoptera). Urban plants showed significantly longer anthesis duration and lower reproductive success than rural plants. Illuminance and low pollinator abundance were negatively associated with the duration of the anthesis, but relative humidity did not affect the anthesis. Prolonged duration of the anthesis may be an adaptation to pollinator scarcity because more prolonged flowering increases the likelihood of pollination. Future research should unravel whether the longer anthesis of urban flowers is determined by behavioral plasticity or by the evolutionary selection of plants with a genetically determined longer anthesis.

The City as an Evolutionary Hothouse—The Search for Rapid Evolution in Urban Settings

“…Similarly, despite the growth in interest and claims, some observations attributed to selection in urban settings, though suggestive, lack sufficient evidence of selection pressure, genetic response, or improved fitness [118]. For example, we know that urbanization reduces the availability of many pollinators, and we also know that some plants, such as the field bindweed (Convolvulus arvensis), show reduced reproductive success and changes in reproductive activities consistent with an adaptive response [119]. Yet, the underlying genetic mechanism(s) remain unknown [119], leaving cases such as this suggestive but inconclusive.…”

“…For example, we know that urbanization reduces the availability of many pollinators, and we also know that some plants, such as the field bindweed (Convolvulus arvensis), show reduced reproductive success and changes in reproductive activities consistent with an adaptive response [119]. Yet, the underlying genetic mechanism(s) remain unknown [119], leaving cases such as this suggestive but inconclusive. The study of Badyaev et al (2008) goes a step further [120].…”