Genetic and Taxonomic Studies in Gilia. XI. Fertility Relationships of the Diploid Cobwebby Gilias

Grant, Verne; Grant, Alva

doi:10.5642/aliso.19600403.02

Cited by 35 publications

(12 citation statements)

References 3 publications

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“…Selection apParently favors the pollen size with just enough metabolites for pollen tube growth to the embryo sac. This view is supported by the fac t that congeners with different style length s may not be successful when the short style and small pollen pare nt serves as the pollen source (e.g., Polemonium , Ostenfeld, 1929; Cilia, Grant and Grant, 1960;Phlox, Levin, 1966). The rela tion ship between pollen size and s tyle length is distorted by polyploidy, which increases pollen size.…”

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confidence: 68%

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Tn¹,

Levin²

1975

Grana

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.: Pollen morphology of Polemoniaceae in relation to systematics and pollination systems: Scanning electron microscopy. Grana. Vol. 15, pp. 91-112, 1975. Uppsala 1976. ISSN 0017-3 134. Representative pollen grains of each genus and section of the family Polemoniaceae were examined with scanning electron microscopy. Exine pattern diversi ty within the family is di scussed in relation to pollination biology. Pollen data su pport some previously recognized rel ation ships within the fa mily; in other instances the use of polle n morphology suggests the institution of new associa tions. The value of pollen morphology as an index to possible phylogenetic interpretations within th e Polemoniaceae is discussed.

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confidence: 68%

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Tn¹,

Levin²

1975

Grana

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“…What is needed for this extension is the modem recognition that species, especially those of sessile organisms such as plants, are far from homogeneous genetic entities. Thus, partial or complete reproductive isolation is not ruled out among subspecies, varieties, or distinct populations within plant species, and indeed is found commonly in the form of sterility of crosses and/or reduced viability or fertility of F I or F 2 "hybrids" (see Miiller 1883;Kruckeberg 1957;Grant and Grant 1960;Martin 1963;Grant 1971;Vickery 1978;Banyard and James 1979). Furthermore, there is no a priori logical reason to reject the possibility of outbreeding depression on even finer scales.…”

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confidence: 99%

CROSSING‐DISTANCE EFFECTS IN DELPHINIUM NELSONII : OUTBREEDING AND INBREEDING DEPRESSION IN PROGENY FITNESS

1994

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Abstract. -Depending on its genetic causes, outbreeding depression in quantitative characters may occur first in the free-living F, generation produced by a wide cross. In 1981-1985, we generated F, progenies by hand-pollinating larkspurs (Delphinium nelsoniii with pollen from l-m, 3-m, lOrn, or 30-m distances. From the spatial genetic structure indicated by previous electrophoretic and reciprocal transplantation studies, we estimate that these crosses range from being inbred (f "" 0.06) to outbred. We planted 594 seeds from 66 maternal sibships under natural conditions. As of 1992, there was strong evidence for both inbreeding depression and outbreeding depression. Progeny from intermediate crossing distances grew approximately twice as large as more inbred or outbred progeny in the first 5 yr after planting (P = 0.013, repeated measures ANOVA), and survived almost 1 yr longer on average (contrast of 3-m and l Ovm treatments versus I m and 30 m; P = 0.028, ANOVA). Twenty maternal sibships produced flowering individuals; only four and two of these represented l-m and 30-m crossing distances, respectively (P = 0.021, G-test). The cumulative fitness of intermediate distance sibships averaged about twice that of l-rn sibships, and five to eight times that of 30-m sibships (P = 0.017, ANOVA). Thus, even though progeny of I-m crosses were inbred to a degree only about one-eighth that ofselfing, inbreeding depression approximated 50%,and outbreeding depression equaled or exceeded50%for all fitnesscomponents.Key words.-Crossing distance, Delphinium nelsonii, inbreeding depression, larkspur, outbreeding depression, plant population structure, progeny fitness.Received December 29, 1992. Accepted July 30, 1993.Outbreeding depression refers to a reduction in character means following crosses between genetically dissimilar individuals belonging to a single species (Dobzhansky

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“…In some cases, however, a postzygotic barrier on a moderate spatial scale may be reinforced by differential fertilization success of pollen (Paterniani 1969;Crosby 1970;Waser 1993a and references therein;Waser and Price 1993). In all these features outbreeding depression over moderate distances resembles, and indeed may precede, the partial or complete reproductive isolation that characterizes crosses between many (although not all) entities defined as distinct angiosperm species (Grant and Grant 1960;Martin 1963;Vickery 1978;Levin 1979;Levy 1991;Waser 1998). Unfortunately, we know relatively little about the expression of outbreeding depression in angiosperms or how this expression changes with increasing spatial, genetic, and taxonomic distance, ultimately to the level of species and genus.…”

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Outbreeding Depression Varies Among Cohorts of Ipomopsis Aggregata Planted in Nature

2000

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Outbreeding depression in progeny fitness may arise from disruption of local adaptation, disruption of allelic coadaptation, or a combination of these "environmental" and "physiological" mechanisms. Thus the minimum spatial scale over which outbreeding depression arises should depend on the spatial scale of gene dispersal and (with an environmental mechanism) of change in selection regimes. We previously reported substantial outbreeding depression in lifetime fitness of progeny resulting from crosses among parents separated by 100 m in natural populations of the herbaceous plant Ipomopsis aggregata. In this paper we explore the effect of crossing distance on fitness in two additional experiments begun in 1987 and 1990. We planted seed progeny derived from partial diallel crossing designs in randomized blocks in maternal environments and scored emergence of seedlings, survival, and eventual flowering of individuals over the subsequent six to eight years. Nested within each diallel design were crossing distances of 1 m, 10 m, and 100 m. Compared to 1-m and 10-m progeny, 100-m progeny of the 1987 diallel suffered a significant reduction in seedling emergence, and both 1-m and 100-m progeny that survived to flower achieved lower lambda-values on average than 10-m progeny. Total outbreeding depression suffered by 100-m relative to 10-m progeny was approximately 10%, compared to approximately 30% in our earlier study of I. aggregata. Progeny of 10-m crosses also outperformed 1-m and 100-m progeny of the 1990 diallel by approximately 5%, but no difference among crossing distance treatments was significant. Thus, the magnitude of outbreeding depression in 100-m crosses varied among experiments. This is not surprising given likely spatial and temporal variation in gene flow and selection regimes, different population histories, and different parental and progeny environments. Characterizing outbreeding depression on the shortest spatial scales over which it is expressed, as well as its variation and causes, is worthwhile because it promises to shed light on the earliest stages of angiosperm speciation.

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Genetic and Taxonomic Studies in Gilia. XI. Fertility Relationships of the Diploid Cobwebby Gilias

Cited by 35 publications

References 3 publications

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

CROSSING‐DISTANCE EFFECTS IN DELPHINIUM NELSONII : OUTBREEDING AND INBREEDING DEPRESSION IN PROGENY FITNESS

Outbreeding Depression Varies Among Cohorts of Ipomopsis Aggregata Planted in Nature

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