SFB-​TRR 212

Ge­netic and phe­no­typic char­ac­ter­i­sa­tion of im­muno­log­i­cal niche con­for­mance in cave­fish

Host-​parasite in­ter­ac­tions are a major dri­ver of evo­lu­tion. Co­evo­lu­tion­ary dy­nam­ics be­tween hosts and par­a­sites shape the evo­lu­tion­ary tra­jec­tory of com­plex host im­mune sys­tems, such as the in­nate and adap­tive im­mune sys­tems of ver­te­brates. These dy­nam­ics es­tab­lish the ge­netic basis for an in­di­vid­ual host to con­form to dif­fer­ent par­a­sito­log­i­cal niches, i.e. con­form to fluc­tu­a­tions in par­a­site abun­dance and di­ver­sity. There is, how­ever, in­creas­ing ev­i­dence sug­gest­ing that host-​parasite co­evo­lu­tion also led to a de­pen­dency be­tween host and its par­a­sites to de­velop a func­tional im­mune phe­no­type. This ‘Old-​Friends’ hy­poth­e­sis is based on the ob­ser­va­tion that the de­creas­ing par­a­site di­ver­sity in the en­vi­ron­ment of many human so­ci­eties is ac­com­pa­nied by an in­crease of im­munopatho­log­i­cal phe­no­types. This raises the ques­tion how does local adap­tion to en­vi­ron­ments that dif­fer in par­a­site abun­dance and di­ver­sity af­fect the abil­ity of the host to con­form to dif­fer­ent par­a­sito­log­i­cal niches?

To an­swer these ques­tions, we will in­ves­ti­gate how local adap­ta­tion of the Mex­i­can cave­fish, Astyanax mex­i­canus, to dif­fer­ent par­a­sito­log­i­cal niches af­fects the niche con­for­mance.

We will take a two-​step ap­proach:

1. We will analyse par­a­sito­log­i­cal niches in var­i­ous en­vi­ron­ments of dif­fer­ent cave­fish and sur­face fish pop­u­la­tion. We hy­poth­e­sise that par­a­site abun­dance and di­ver­sity af­fect the in­di­vid­ual im­mune phe­no­type of wild pop­u­la­tions of A. mex­i­canus.
2. We will then pur­sue the ques­tion whether local adap­ta­tions to en­vi­ron­ments with low par­a­site abun­dance and di­ver­sity af­fect the abil­ity of the host to ad­just its im­mune phe­no­type upon changes in the par­a­sito­log­i­cal niche (e.g. in­crease in par­a­site di­ver­sity). We hy­poth­e­sise that the in­di­vid­ual im­mune phe­no­type, more specif­i­cally the im­mune in­vest­ment strat­egy, af­fects the de­gree and ex­pres­sion of niche con­for­mance.

In Sum­mary, we will in­ves­ti­gate whether and how these im­muno­log­i­cal dif­fer­ences af­fect the abil­ity of sev­eral A. mex­i­canus pop­u­la­tions to con­form to dif­fer­ent par­a­sito­log­i­cal niches.