Home About us Contact
|
Home About us Contact | ||
|
|
||
Host Switching (host + switching)
Selected AbstractsA BAYESIAN FRAMEWORK FOR THE ANALYSIS OF COSPECIATIONEVOLUTION, Issue 2 2000John P. Huelsenbeck Abstract., Information on the history of cospeciation and host switching for a group of host and parasite species is contained in the DNA sequences sampled from each. Here, we develop a Bayesian framework for the analysis of cospeciation. We suggest a simple model of host switching by a parasite on a host phylogeny in which host switching events are assumed to occur at a constant rate over the entire evolutionary history of associated hosts and parasites. The posterior probability density of the parameters of the model of host switching are evaluated numerically using Markov chain Monte Carlo. In particular, the method generates the probability density of the number of host switches and of the host switching rate. Moreover, the method provides information on the probability that an event of host switching is associated with a particular pair of branches. A Bayesian approach has several advantages over other methods for the analysis of cospeciation. In particular, it does not assume that the host or parasite phylogenies are known without error; many alternative phylogenies are sampled in proportion to their probability of being correct. [source] The historical biogeography of co-evolution: emerging infectious diseases are evolutionary accidents waiting to happenJOURNAL OF BIOGEOGRAPHY, Issue 8 2005Daniel R. Brooks Abstract Ecological fitting refers to interspecific associations characterized by ecologically specialized, yet phylogenetically conservative, resource utilization. During periods of biotic expansion, parasites and hosts may disperse from their areas of origin. In conjunction with ecological fitting, this sets the stage for host switching without evolving novel host utilization capabilities. This is the evolutionary basis of emerging infectious diseases (EIDs). Phylogenetic analysis for comparing trees (PACT) is a method developed to delineate both general and unique historically reticulated and non-reticulated relationships among species and geographical areas, or among parasites and their hosts. PACT is based on ,Assumption 0', which states that all species and all hosts in each input phylogeny must be analysed without modification, and the final analysis must be logically consistent with all input data. Assumption 0 will be violated whenever a host or area has a reticulated history with respect to its parasites or species. PACT includes a Duplication Rule, by which hosts or areas are listed for each co-evolutionary or biogeographical event affecting them, which satisfies Assumption 0 even if there are reticulations. PACT maximizes the search for general patterns by using Ockam's Razor , duplicate only enough to satisfy Assumption 0. PACT applied to the host and geographical distributions of members of two groups of parasitic helminths infecting anthropoid primates indicates a long and continuous association with those hosts. Nonetheless, c. 30% of the host associations are due to host switching. Only one of those involves non-primate hosts, suggesting that most were constrained by resource requirements that are phylogenetically conservative among primates (ecological fitting). In addition, most of the host switches were associated with episodes of biotic expansion, also as predicted by the ecological fitting view of EIDs. [source] Speciation in fig pollinators and parasitesMOLECULAR ECOLOGY, Issue 8 2002George D. Weiblen Abstract Here we draw on phylogenies of figs and fig wasps to suggest how modes of speciation may be affected by interspecific interactions. Mutualists appear to have cospeciated with their hosts to a greater extent than parasites, which showed evidence of host shifting. However, we also repeatedly encountered a pattern not explained by either cospeciation or host switching. Sister species of fig parasites often attack the same host in sympatry, and differences in ovipositor length suggest that parasite speciation could result from divergence in the timing of oviposition with respect to fig development. These observations on fig parasites are consistent with a neglected model of sympatric speciation. [source] Escaping the matrix: a new algorithm for phylogenetic comparative studies of co-evolutionCLADISTICS, Issue 4 2004Maggie Wojcicki An algorithm for generating host cladograms from parasite-host cladograms derived from parasite phylogenies, Phylogenetic Analysis for Comparing Trees (PACT), is described. PACT satisfies Assumption 0, that all the information in each parasite-host cladogram must be used in a co-evolutionary analysis, and that the host relationships depicted in the final host cladogram must be logically consistent with the phylogenetic relationships depicted in every part of every parasite-host cladogram used to construct the host cladogram. It accounts for cases of speciation by host switching and expansion of host range, and reticulated host relationships, in addition to co-speciation, sympatric speciation, and extinction in all input parasite-host cladograms, and does so without a priori weighting schemes and without a posteriori manipulation of the data. [source] | ||||||||||