Summary1. Ants show complex interactions with plants, both facultative and mutualistic, ranging from grazers through seed predators and dispersers to herders of some herbivores and guards against others. But ants are rarely pollinators, and their visits to flowers may be detrimental to plant fitness. 2. Plants therefore have various strategies to control ant distributions, and restrict them to foliage rather than flowers. These 'filters' may involve physical barriers on or around flowers, or 'decoys and bribes' sited on the foliage (usually extrafloral nectaries -EFNs). Alternatively, volatile organic compounds (VOCs) are used as signals to control ant behaviour, attracting ants to leaves and ⁄ or deterring them from functional flowers. Some of the past evidence that flowers repel ants by VOCs has been equivocal and we describe the shortcomings of some experimental approaches, which involve behavioural tests in artificial conditions. 3. We review our previous study of myrmecophytic acacias, which used in situ experiments to show that volatiles derived from pollen can specifically and transiently deter ants during dehiscence, the effects being stronger in ant-guarded species and more effective on resident ants, both in African and Neotropical species. In these plants, repellence involves at least some volatiles that are known components of ant alarm pheromones, but are not repellent to beneficial bee visitors. 4. We also present new evidence of ant repellence by VOCs in temperate flowers, which is usually pollen-based and active on common European ants. We use these data to indicate that across a wide range of plants there is an apparent trade-off in ant-controlling filter strategies between the use of defensive floral volatiles and the alternatives of decoying EFNs or physical barriers.
Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.
A common problem affecting many animal species is the soaring demand for their body parts for use in medicinal products. In Benin, in spite of intense commercial exploitation of wildlife for medicinal purposes, no official statistics on the use of animals for medicinal and magic/religious purposes are available and consequently, there is little consideration of the issue in laws, decision-making processes, and conservation strategies. The aim of this study was to list the mammal species sold on the medicinal market and the conservation implications of the use of mammal species in traditional folk medicines. Among the 87 mammal species traded on the traditional medicine market in Benin, 46 were sold by at least half of those traders surveyed; the conservation status of these animals included rare, vulnerable, and threatened species. Moreover, it was noticed that the source of animals is not limited to Benin since some species available at markets are not listed in the Benin's fauna. This study also found that rarer species were more costly and this constitutes an economic motivation for sellers to develop strategies for the availability of threatened species on their displays. Urgent conservation actions are needed to reduce the pressure that this activity sector might contribute to biodiversity loss.
Flowers act as "sensory billboards" with multiple signals (color, morphology, odor) attracting and manipulating potential pollinators. Many use changing signals as indicators that visitation and/or pollination have occurred). Floral color change is commonly used to transmit this information (often correlated with reduced nectar reward) and can be specifically triggered by pollination or visitation. By retaining color-changed flowers, plants benefit from larger floral displays but also indicate at close range which flowers are still rewarding (and still unpollinated), so that visitors forage more efficiently. However, the legume Desmodium setigerum shows a unique ability, if inadequately pollinated, to reverse its flowers' color and shape changes. Single visits by bees mechanically depress the keel and expose stigma and anthers (termed "tripping"); visits also initiate a rapid color change from lilac to white and turquoise and a slower morphological change, the upper petal folding downwards over the reproductive parts. But flowers receiving insufficient pollen can partially reopen, re-exposing the stigma, with a further color change to deeper turquoise and/or lilac. Thus, most flowers achieve pollination from one bee visit, but those with inadequate pollen receipt can reverse their signals, earning a "second chance" by eliciting attention from other potential pollinators.
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