F 1 [HoHe

If F is primarily determined by mating behavior, it can be equated with an inbreeding coefficient (Wright, 1969). If Ho is not significantly different than He, then F is not significantly greater than zero and the population is assumed to be in Hardy-Weinberg equilibrium and, thus, randomly mating. IfHo is significantly greater than He, then F will be significantly less than zero (i.e., there is an excess of heterozygotes) and the population is assumed to be primarily outcrossing. If Ho is significantly less than He, then F will be significantly greater than zero (i.e., there is a deficiency of heterozygotes) and the population is assumed to be primarily inbreeding. Complete intragametophytic selfing would result in a value of F of 1.0.

Most sexually reproducing, diploid populations of homosporous ferns and lycophytes that have been surveyed allozymically exhibit F values that are either not significantly different than zero or are significantly less than zero, and, therefore, are either randomly mating or primarily outcrossing (Table 4.2). Mean F across the 24 species reported in Table 4.2 is 0.106 (range -0.077 to 0.962). Across populations within species, mating systems of sexual diploids are usually dominated by random mating or outcrossing, with a minority of taxa being primarily inbreeding or mixed-mating. See reviews and summaries of Haufler (1987,1992, 2002) and Soltis and Soltis (1987b) for detailed examples and citations.

Table 4.2 Mating systems, fixation index (F), differentiation (F$ t), genetic identity (I), and gene flow (Nm) estimates of populations of diploid, homosporous ferns available directly from the cited literature or calculated from data provided; blanks indicate that estimates or data were not available for a particular parameter

Table 4.2 Mating systems, fixation index (F), differentiation (F$ t), genetic identity (I), and gene flow (Nm) estimates of populations of diploid, homosporous ferns available directly from the cited literature or calculated from data provided; blanks indicate that estimates or data were not available for a particular parameter

Was this article helpful?

0 0
10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment