Selfing within random fertilization
Random fertilization compared to cross-fertilization
It is easy to overlook that random fertilization includes self-fertilization. Sewall Wright showed that a proportion 1/N of random fertilizations is actually self fertilization (⨂)
![{\textstyle f_{t}=\Delta f\left[1+f_{t-1}\left(2N-1\right)\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/17a24c2fb8d160fe93430b166097b4cc095d60ad "{\textstyle f_{t}=\Delta f\left[1+f_{t-1}\left(2N-1\right)\right]}")
and (B)
The recognition that selfing may intrinsically be a part of random fertilization leads to some issues about the use of the previous random fertilization 'inbreeding coefficient'. Clearly, then, it is inappropriate for any species incapable of self fertilization, which includes plants with self-incompatibility mechanisms, dioecious plants, and bisexual animals. The equation of Wright was modified later to provide a version of random fertilization that involved only cross fertilization with no self fertilization. The proportion 1/N formerly due to selfing now defined the carry-over gene-drift inbreeding arising from the previous cycle. The new version is:[13]
The graphs to the right depict the differences between standard random fertilization RF, and random fertilization adjusted for "cross fertilization alone" CF. As can be seen, the issue is non-trivial for small gamodeme sample sizes.
It now is necessary to note that not only is "panmixia" not a synonym for "random fertilization", but also that "random fertilization" is not a synonym for "cross fertilization".
