laredoensis A, it was the parthenogen
's paternal progenitor Cnemidophorus sexlineatus that was the most abundant whiptail lizard at the site (n = 25 + 10 observed); relatively few C.
Therefore, we suggest that the alterations in phenotypic characteristics, ecology, and behavior are more likely in clones of hybrid origin than in non-hybrid parthenogens
. If true, this would suggest that maintenance of sex hypotheses - to which the cost of males is essential - are more relevant for non-hybrids than for interspecific hybrids.
have been found together at several sites in Starr, Hidalgo and Webb counties.
The Cnemidophorus laredoensis complex consists of two, independently derived, diploid parthenogens
that commonly coexist in sandy, disturbed habitats in the Rio Grande Valley of southern Texas and northern Mexico (Walker 1987a; 1987b; Abuhteba 1990).
Our results show that a hybrid unisexual taxon - which persists as a self-sustaining clonal parthenogen
- not only mates with ancestral males but even produces offspring that incorporate or carry the paternal genome.
gularis dominates nondesert habitats (15 visits to nine sites have produced only three LAR-B because of the haphazard approach to urban and suburban development in Mexico, which generates numerous patches and enclaves of disturbed habitat that are favored by parthenogens
However, yearly bouts of short-term evolution of the type documented here might also be quite prevalent, particularly in cyclical parthenogens
that may be exposed to antagonistic forces of selection at different time periods during the clonal phase or in which the disruption of favorable genotypes caused by genetic slippage during recombination may regularly move populations away from a selectively advantageous phenotype.
In all, 42% of the species apparently lack males and are most probably apomictic parthenogens
(Tressler 1959), as genetic studies have now confirmed the reliability of breeding system assignments based on gender determinations (Havel et al.
Under the gene-for-gene hypothesis, a priori expectations for the relative performance of parthenogen
and sexual thrips on outcrossed host progeny were less clear-cut.
Alterations in sex determination could have dire consequences to populations of cyclic parthenogens
such as D.
In some lizards, the remote relationships between species that later hybridized to form parthenogens
are reflected in mitochondrial markers of distant past speciation and differentiation that are carried by the parthenogens
(Moritz et al.
lugubris (all female parthenogens
) often engage in prolonged agonistic encounters while foraging ([ILLUSTRATION FOR FIGURE 12 OMITTED]; Petren et al.