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THE EVOLUTIONARY SIGNIFICANCE OF NATURAL FRAGARIA CHILOENSIS × F. VESCA HYBRIDS RESULTING FROM UNREDUCED GAMETES
Author(s) -
Bringhurst R. S.,
Senanayake Y. D. A.
Publication year - 1966
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1966.tb06865.x
Subject(s) - biology , hybrid , ploidy , backcrossing , gamete , botany , genetics , gene , sperm
A natural nonaploid hybrid (2 n = 63) from fusion of a reduced F. vesca male gamete with an unreduced F. chiloensis gamete, and a partially fertile natural hexaploid hybrid (2 n = 42) from fusion of an unreduced F. vesca (2 n = 14) male gamete with a reduced F. chiloensis (2 n = 56) gamete were discovered in separate mixed colonies along with over 20 additional pentaploid hybrids (2 n = 35). Plants of all hybrids aggressively compete with F. chiloensis. This relatively high percentage of hybrids from unreduced gametes may mean that they have higher survival value than pentaploids, since some evidence indicates that unreduced gametes may not function that often in successful F. chiloensis × F. vesca hybridization. The partial fertility of the hexaploid shows that intermediate fertile levels of ploidy need not be derived exclusively from lower ploidy species, and unreduced gametes from such hybrids should produce a high percentage of decaploid offspring in natural backcrossing to F. chiloensis. The successful functioning of unreduced vesca and chiloensis gametes in natural hybridization justifies the postulation that other euploid levels also may occur naturally, including triploids, tetraploids, decaploids, 12 ploids, and 16 ploids. Of these, the even multiples—tetraploids, decaploids, 12 ploids, and 16 ploids—should be at least partially fertile.