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281.
Plant Ecology - The family Melastomataceae shows two major modes of dispersal for its small seeds: wind for capsular fruits, and birds for berry-type fruits. Distribution patterns of these two... 相似文献
282.
The interplay between coevolutionary and population or community dynamics is currently the focus of much empirical and theoretical
consideration. Here, we develop a simulation model to study the coevolutionary and population dynamics of a hypothetical host–parasitoid
interaction. In the model, host resistance and parasitoid virulence are allowed to coevolve. We investigate how trade-offs
associated with these traits modify the system's coevolutionary and population dynamics. The most important influence on these
dynamics comes from the incorporation of density-dependent costs of resistance ability. We find three main outcomes. First,
if the costs of resistance are high, then one or both of the players go extinct. Second, when the costs of resistance are
intermediate to low, cycling population and coevolutionary dynamics are found, with slower evolutionary changes observed when
the costs of virulence are also low. Third, when the costs associated with resistance and virulence are both high, the hosts
trade-off resistance against fecundity and invest little in resistance. However, the parasitoids continue to invest in virulence,
leading to stable host and parasitoid population sizes. These results support the hypothesis that costs associated with resistance
and virulence will maintain the heritable variation in these traits found in natural populations and that the nature of these
trade-offs will greatly influence the population dynamics of the interacting species.
Received: December 20, 1999 / Accepted: July 17, 2000 相似文献
283.
Plant Ecology - In this paper we address two questions concerning the interaction between fleshy-fruited plants and their seed dispersers: (1) What determines optimal disperser coterie size... 相似文献
284.
285.
Sociobiology of slave-making ants 总被引:4,自引:0,他引:4
Social parasitism is the coexistence in the same nest of two species of social insects, one of which is parasitically dependent
on the other. Though parasitism in general is known to be of crucial importance in the evolution of host species, social parasites,
though intriguing, are often considered as a phenomenon of marginal interest and are typically not taken into account in reviews
on parasitism. Nevertheless, social parasites are rather common in social bees, wasps, and ants and therefore may offer unique
model systems to study a number of fundamental problems in evolutionary biology. Here we review several aspects of the peculiar
life history of slave-making ants, which is characterized by socially parasitic founding of colonies and the pillage of broods
from neighboring host colonies during slave raids. In particular we focus on the evolution of slave-making habits (dulosis),
communication mechanisms between slave makers and their hosts, sex-allocation ratios and reproductive conflict, and the effect
of slave makers on host populations.
Received: 2 February 2000 / Received in revised form: 21 December 2000 / Accepted: 8 January 2001 相似文献