Willis (1999) argues that unmarried parents should have less favorable characteristics and be less (positively) assortatively
matched than married parents.
The results extend earlier work showing that limnetics and benthics in Paxton and Enos Lakes, and other sympatric forms of sticklebacks, mate assortatively
(Hagen 1967; Moodie 1972; Hay and McPhail 1975; Ridgway and McPhail 1984; Borland 1986; Blouw and Hagen 1990; Hatfield 1995; Hatfield and Schluter 1996; reviewed by McPhail 1994).
3) Populations assortatively
mate due to host plant preference.
The likelihood for genetic polymorphisms in herbivores is increased when herbivores select and reproduce on the host plant species on which survival is highest, and mate assortatively
(Levene 1953, Maynard Smith 1966, 1970, Dickinson and Antonovics 1973, Felsenstein 1981, Bush and Diehl 1982).
In this study, we showed that movements from rewarding yellow flowers were assortative in all experiments, and there was a greater tendency to move assortatively
when blue and purple flowers were rewarding.
A recent survey of phenotype compositions of mated pairs (n = 119) in northern New York indicates that the two species pair assortatively
with only low levels (3%) of primary hybridization (Confer unpubl.
Song type is heritable among males, and females display a preference for a given song type, although daughters do not appear to pair assortatively
with regard to paternal song type.
These stickleback species mate assortatively
(Nagel 1994), and prior behavioral and morphological analysis of hybrids (McPhail 1992; Schluter 1993; Hatfield 1995) suggest that attractiveness of hybrids should fall within the range delimited by attractiveness of the parental species.
Wilson and Dugatkin (in press) have examined a model of a normal trait x in which groups of size N are formed, either by kin relationships or assortatively
, and fitness depends on individual phenotype x and average group phenotype y according to equation (23).
Second, sockeye mate assortatively
by size (Hanson and Smith 1967; Foote 1988) and by pleiotropy this promotes positive assortative mating of anadromous versus nonanadromous life-history types given concomitant differences in size at maturity (Foote and Larkin 1988; this study).
Females mated assortatively
with males from their own population.
Flies from each of the two host species mate assortatively
in the presence of host plants but randomly when host plants are removed; females show strong oviposition preference for the host species of origin (Craig et al.
Alternatively, the two morphs may mate assortatively
because of their nonrandom microdistribution.
affinis parental types were assumed to mate assortatively
with probabilities a = 0.
This experiment tested whether flies from different host plants would assortatively
mate in the absence of host plants.