Fitness components analysis in a natural population of Drosophila buzzatii from Argentina

HASSON, E.R.; VILARDI, J.; H. NAVEIRA; FANARA, J.; RODRIGUEZ, C.; REIG, O.A.; FONTDEVILA

JOURNAL OF EVOLUTIONARY BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 1991 vol. 4 p. 209 - 225

1010-061X

The  adaptive  significance  of  the  chromosomal  polymorphism  of  Drosophila buzzati  has been  studied  by  means of  fitness component  analysis  in  an  original population  from  Argentina.  The  results show evidence  of  selection acting  through pupal  viability,  longevity  (adult  viability)  and  fecundity  on  the second chromosome polymorphism,  and  through  pupal  viability  and virility  on  the  fourth  chromosome polymorphism. Changes  in  chromosomal  inversion  frequencies  throughout  the  life-cycle suggested an endocyclic  pattern  of  directional  selection, which  at  first  seems  to  be the only  detectable mechanism responsible  for  the maintenance  of  the  polymorphism. However,  slow, long-term  frequency  changes cannot  be ruled  out.  The way  in which endocyclic  selection  acts on  this  population  is different  from  that  in  a  colonized population  previously  studied;  that  is, different  fitness components  are  involved  in the  maintenance  of  chromosomal  polymorphism.  The  possible  factors  that  may explain  these differences are discussed.