CRESSEY ET AL.: COPEPODS AND SCOMBRID FISHES 



Katsuwomis 



Euthynnus 

 Auxis 



Katsuwonidae 



Neothuuiius 

 Parathumuis 

 Thtmnus 



Thunnidas 



I 

 PLECOSTEI 



GyrnuosardH 

 Sarda\ / Cybium 



Ac;uithocybiuni 



Cybiidae 



Iliistrelli^er 



Scomber 



Scombridae 



Other Acautbopt^iygian families of 

 the TELEOSTEI 



Figure 14.— Diagram showing classification of scombrid fishes 

 adopted by Kishinouye (1923). 



isolated parasite populations may remain the same, 

 speciate, or one or both may become extinct. Mor- 

 phological data from hosts or parasites may be used 

 to reconstruct or estimate phylogenetic relation- 

 ships. If questions regarding revolutionary events 

 are asked, however, information concerning the phy- 

 logeny of both hosts and parasites is necessary. 

 Brooks (1979) discussed types of host-parasite rela- 

 tionships and outlined parasitic distributions on 

 hosts and the revolutionary implications of such 

 distributions. Brooks (1981) provided a method for 

 testing coevolutionary hypotheses. 



Cladistic analysis of hosts and parasites, using mor- 

 phological characters, will provide information con- 

 cerning the phylogeny of both hosts and parasites. If 

 host and parasite phylogenies are concordant, the 

 distribution of parasites on hosts can be explained by 

 cospeciation events. If, on the other hand, host-para- 

 site relationships are convergent, they indicate host 

 transfer or broadening coaccommodation (Brooks 

 1981). Using the additive binary coding method pre- 

 sented by Brooks to generate character state trees 

 for host or parasite phyletic relationships, it is pos- 

 sible through character analysis to generate host 

 trees based on parasite phyletic relationships and 

 parasite trees based on host phyletic relationships. 

 By direct comparison of these trees with each other it 

 is possible to test hypotheses of coevolution. 



In an attempt to utilize parasite data and to objec- 

 tively resolve the problem of phyletic relationships 

 among the genera of Scombridae, the first author 

 coded our copepod infestation data and the third 

 author subjected the data to a cladistic analysis, us- 

 ing a computer program (WAGNER 78) written by J. 



FIGURE 15. — Diagram of relationships of scombrid 

 fishes from Fraser-Brunner (1950). 



253 



