Pii: S0020-7519(00)00093-x
نویسندگان
چکیده
Larval helminths that share the same intermediate host may or may not also share the same de®nitive hosts. If one or more of these helminth species can manipulate the phenotype of the intermediate host, there can be great advantages or severe costs for other helminths resulting from co-occurring with a manipulator, depending on whether they have the same de®nitive host or not. Among 2372 specimens of the amphipod Echinogammarus stammeri collected from the river Brenta, northern Italy, there was a positive association between two acanthocephalan species with the same ®sh de®nitive hosts, the relatively common Pomphorhynchus laevis and the much less prevalent Acanthocephalus clavula.The number of cystacanths of P. laevis per infected amphipod, which ranged from one to ®ve, did not in ̄uence the likelihood that the amphipod would also host A. clavula. A third acanthocephalan species, Polymorphus minutus,which matures in birds, showed no association with either of the two other species. These results show that associations among helminth species in intermediate hosts are not random, and are instead the product of selection favouring certain pathways of transmission. q 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.
منابع مشابه
Covering a set of points by two axis-parallel boxes
In this paper we consider the following covering problem. Given a set S of n points in d-dimensional space, d 2, nd two axis-parallel boxes that together cover the set S such that the measure of the largest box is minimized, where the measure is a monotone function of the box. We present a simple algorithm for nding boxes in O(n log n + n d?1) time and O(n) space.
متن کاملPii: S0020-7519(00)00132-6
Trichinellosis, is normally not included among those regarded as emerging zoonoses because it has been a public health threat for more than 150 years. However, its dramatic re-emergence in many areas around the world over the past 10±20 years, inspite of a century of veterinary public health efforts to control and eradicate it, justi®es it being included in this group. The reasons for this re-e...
متن کاملPii: S0020-7519(01)00357-5
DNA sequence divergence at internal transcribed spacer regions (ITS-1 and ITS-2) was compared with divergence at mitochondrial cox1 or nad4 loci in pairs of congeneric nematode species. Mitochondrial sequences accumulate substitutions much more quickly than internal transcribed spacer, the difference being most striking in the most closely related species pairs. Thus, mitochondrial DNA may be t...
متن کاملA Lower Bound for Randomized On-Line Multiprocessor Scheduling
We signiicantly improve the previous lower bounds on the performance of randomized algorithms for on-line scheduling jobs on m identical machines. We also show that a natural idea for constructing an algorithm with matching performance does not work.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2000