Premium
HYBRID ZONE DYNAMICS ARE INFLUENCED BY GENOTYPE‐SPECIFIC VARIATION IN LIFE‐HISTORY TRAITS: EXPERIMENTAL EVIDENCE FROM HYBRIDIZING GAMBUSIA SPECIES
Author(s) -
Scribner Kim T.
Publication year - 1993
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1993.tb02117.x
Subject(s) - gambusia , biology , fecundity , ecology , population , poeciliidae , zoology , demography , fishery , sociology , fish <actinopterygii>
Results from two experiments are presented that contrast differences in life‐history traits and population dynamics between two species of live bearing fishes ( Gambusia affinis and G. holbrooki ) that hybridize across portions of the southeastern United States. Progeny from parental holbrooki and holbrooki‐affinis F 1 crosses exhibited larger lengths at birth, at 15 days, and matured earlier, and at larger size than did progeny from parental affinis and affinis‐holbrooki F 1 crosses. Comparisons of experimental populations of affinis, holbrooki , and mixed ( affinis + holbrooki ) species composition followed over two years revealed that affinis populations consistently exhibited smaller population size, lower carrying capacity, lower recruitment, and larger over‐winter mortality than did holbrooki or mixed populations. Evidence for density‐dependent reductions in fecundity and concomitant increases in juvenile mortality rates were observed in all populations, but were most pronounced for affinis populations. Genotype‐specific differences in life‐history traits appear to confer differential advantage to offspring of parental holbrooki origin and F, progeny of holbrooki maternal parentage given the resource availability and the age structure and densities experienced during these experiments. Results have direct implications regarding the rate and direction of evolution within hybrid zones formed by these two species.