Summary1. Some of the most damaging invasive plants are dispersed by frugivores and this is an area of emerging importance in weed management. It highlights the need for practical information on how frugivores affect weed population dynamics and spread, how frugivore populations are affected by weeds and what management recommendations are available. 2. Fruit traits influence frugivore choice. Fruit size, the presence of an inedible peel, defensive chemistry, crop size and phenology may all be useful traits for consideration in screening and eradication programmes. By considering the effect of these traits on the probability, quality and quantity of seed dispersal, it may be possible to rank invasive species by their desirability to frugivores. Fruit traits can also be manipulated with biocontrol agents. 3. Functional groups of frugivores can be assembled according to broad species groupings, and further refined according to size, gape size, pre-and post-ingestion processing techniques and movement patterns, to predict dispersal and establishment patterns for plant introductions. 4. Landscape fragmentation can increase frugivore dispersal of invasives, as many invasive plants and dispersers readily use disturbed matrix environments and fragment edges. Dispersal to particular landscape features, such as perches and edges, can be manipulated to function as seed sinks if control measures are concentrated in these areas. 5. Where invasive plants comprise part of the diet of native frugivores, there may be a conservation conflict between control of the invasive and maintaining populations of the native frugivore, especially where other threats such as habitat destruction have reduced populations of native fruit species. 6. Synthesis and applications . Development of functional groups of frugivore-dispersed invasive plants and dispersers will enable us to develop predictions for novel dispersal interactions at both population and community scales. Increasingly sophisticated mechanistic seed dispersal models combined with spatially explicit simulations show much promise for providing weed managers with the information they need to develop strategies for surveying, eradicating and managing plant invasions. Possible conservation conflicts mean that understanding the nature of the invasive plant-frugivore interaction is essential for determining appropriate management.
SUMMARYNon-random mating may be involved in the maintenance of colour polymorphism in Adalia bipunctata. Mating choice experiments have been carried out on a stock of A. bipunctata from Keele. Specific frequencies of the melanic quadrimaculata form and the non-melanic typica form were placed in population cages or mating chambers and allowed to mate. The frequencies of the forms amongst mating pairs were scored. The results gave a good fit to a model of mixed sexual selection and assortative mating showing a strongly frequency dependent, non-assorting preference for quadrimaculata males in the matings.Data from the wild Keele population showed a similar preference for quadrimaculata males, and an excess of males of a second melanic phenotype, sexpustulata. Observation of courting pairs indicated that female choice determined frequency of mating. Field data from Keele also gave evidence of assortative mating between typica and another non-melanic form, annulata.
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