190
J. HESLOP-HARRISON
observed in the ecotypes studied, they estimate that about 100 or more
loci may be concerned. “Considered in terms of the complex array of
observed recombinations that can be accounted for in the F, and F,
combinations”, they comment, “this number seems to be remarkably
small. Thus with a rather limited number of basic genetic building
blocks, the diploid species Potentilla glandulosa apparently has been
able to evolve an extensive array of ecological races fitted to diverse
environments. ”
TABLE I1
Estimate of Minimum Number of Genes Governing the Inheritance of 19 Characters in Two Inter-ecotypic Hybrids of Potentilla
glandulosa. [From Clausen and Hiesey 1958a.l
Estimated
no. of
gene pairs
Character, and action of genes
1. Orientation of petals : 2 erecting, 1 reflexing
2. Petal notch: 1 producing notch, 2 inhibiting
3. Petal colour : 2 whitening, 2 producing yellow, 1 bleaching
3
3
5
6
ca. 4
(plus possible inhibitors)
4. Petal width: 4 widening, 1 complementary, 1 narrowing
5. Petal length : 4 multiples
6. Sepal length: 3 or 4 multiples for lengthening, 1 for shortening, 1
7. Akene weigh&: 5 multiples for increasing, 1 for decreasing
9. Branching, angle of
complementary
m. 5
ca. 6
4
ca. 2
(also genes for strict to flexuous branching)
ca. 1
(plus modifiers)
ca. 3
(also genes for presence or absence of rhizomes and for
thickness of rhizomes, to which crown height is related)
8. Akene colour : 4 multiples of equal effect
10. Inflorescence, density of
1 1. Crown height
12. Anthocyanin: 4 multiples (1 expressed only a t Timberline), 1
complementary
5
13. Glanduhr pubescence : 5 multiples, in series of decreasing strength
5
14. Leaf length : transgressive segregation; many patterns of expression
in contrasting environments; possibly different sets of multiples
activated
ca. 10-20
ca. 1 ’
‘(plus modifiers)
15. Leaflet nurnber in bracts
16. Stem length: transgressive segregation, 5 to 6 multiples plus inhibitory and complementary genes; many patterns of expression in
contrasting environments
ca. 10-20
ca. 4
many
17. Winter dormancy: 3 multiples of equal effect
3
18. Frost susceptibility : slight transgression toward resistance
19. Earliness of flowering : strongly transgressive ; many patterns of
altitudinal expression; possibly different sets of genes activated
J. HESLOP-HARRISON
observed in the ecotypes studied, they estimate that about 100 or more
loci may be concerned. “Considered in terms of the complex array of
observed recombinations that can be accounted for in the F, and F,
combinations”, they comment, “this number seems to be remarkably
small. Thus with a rather limited number of basic genetic building
blocks, the diploid species Potentilla glandulosa apparently has been
able to evolve an extensive array of ecological races fitted to diverse
environments. ”
TABLE I1
Estimate of Minimum Number of Genes Governing the Inheritance of 19 Characters in Two Inter-ecotypic Hybrids of Potentilla
glandulosa. [From Clausen and Hiesey 1958a.l
Estimated
no. of
gene pairs
Character, and action of genes
1. Orientation of petals : 2 erecting, 1 reflexing
2. Petal notch: 1 producing notch, 2 inhibiting
3. Petal colour : 2 whitening, 2 producing yellow, 1 bleaching
3
3
5
6
ca. 4
(plus possible inhibitors)
4. Petal width: 4 widening, 1 complementary, 1 narrowing
5. Petal length : 4 multiples
6. Sepal length: 3 or 4 multiples for lengthening, 1 for shortening, 1
7. Akene weigh&: 5 multiples for increasing, 1 for decreasing
9. Branching, angle of
complementary
m. 5
ca. 6
4
ca. 2
(also genes for strict to flexuous branching)
ca. 1
(plus modifiers)
ca. 3
(also genes for presence or absence of rhizomes and for
thickness of rhizomes, to which crown height is related)
8. Akene colour : 4 multiples of equal effect
10. Inflorescence, density of
1 1. Crown height
12. Anthocyanin: 4 multiples (1 expressed only a t Timberline), 1
complementary
5
13. Glanduhr pubescence : 5 multiples, in series of decreasing strength
5
14. Leaf length : transgressive segregation; many patterns of expression
in contrasting environments; possibly different sets of multiples
activated
ca. 10-20
ca. 1 ’
‘(plus modifiers)
15. Leaflet nurnber in bracts
16. Stem length: transgressive segregation, 5 to 6 multiples plus inhibitory and complementary genes; many patterns of expression in
contrasting environments
ca. 10-20
ca. 4
many
17. Winter dormancy: 3 multiples of equal effect
3
18. Frost susceptibility : slight transgression toward resistance
19. Earliness of flowering : strongly transgressive ; many patterns of
altitudinal expression; possibly different sets of genes activated