Abstract
Lasthenia burkei (Compositae) is a narrowly restricted California endemic closely related to L. conjugens and L. fremontii . These three species differ from each other by pappus and phyllary characters and in geographical distribution. All are freely intercrossable, but L. fremontii forms rather sterile artificial hybrids with its two relatives which, in turn, form fairly fertile artificial hybrids with each other. Lasthenia burkei and L. conjugens have homologous chromosomes, four of which are homologous with four of those of L. fremontii . The remaining two chromosomes probably have reciprocal translocations which lead to multivalent formation during meiosis in interspecific hybrids. Pollen viability is restored in most F 2 generations, suggesting a close genetic relationship among the three species. The evolutionary relationship among these species may be a linear one with L. burkei occupying an intermediate position between L. fremontii and L. conjugens , although the direction of this linear phylogeny is not certain, or it may be one in which L. burkei has been derived from hybridization between its two relatives. Support for the latter hypothesis comes from the appearance of some individuals in F 1 progenies of L. conjugens × L. fremontii that are morphologically indistinguishable from L. burkei (although fairly sterile). The apparently rather simple genetic basis for the morphological characteristics of each of the species in this trio suggests that the morphologically heterogeneous genus Lasthenia may be considerably more homogeneous genetically than might be suspected. Because of the diverse kinds of relationships among these three Lasthenias, possible alternative taxonomies for the group are dependent upon those relationships that a taxonomist wishes to communicate. Nevertheless, the patterns of diversification in this group have led to reaffirmation of an earlier decision that three species should be recognized.
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Claims 11
Claim · model-written summary
Lasthenia burkei is a narrowly restricted California endemic related to two congeners.
- Taxon
- Lasthenia burkei
Lasthenia burkeie0 - Outcome
- narrowly restricted California endemic closely related to L. conjugens and L. fremontiie0
- Setting
- Californiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lasthenia burkei (Compositae) is a narrowly restricted California endemic closely related to L. conjugens and L. fremontii”
Claim · model-written summary
The three species differ in pappus, phyllary, and geographic distribution.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- differ from each other by pappus and phyllary characters and in geographical distributione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These three species differ from each other by pappus and phyllary characters and in geographical distribution.”
t0“LASTHENIA BURKEI”
Claim · model-written summary
All three Lasthenia species can be intercrossed.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- freely intercrossablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All are freely intercrossable”
t0“LASTHENIA BURKEI”
Claim · model-written summary
L. fremontii produced rather sterile hybrids with each relative.
- Taxon
- L. fremontii
Lasthenia fremontiie0 - Outcome
- rather sterile artificial hybridse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“L. fremontii forms rather sterile artificial hybrids with its two relatives”
Claim · model-written summary
L. burkei and L. conjugens produced fairly fertile hybrids with each other.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- fairly fertile artificial hybridse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which, in turn, form fairly fertile artificial hybrids with each other”
t0“LASTHENIA BURKEI”
Claim · model-written summary
L. burkei and L. conjugens have homologous chromosomes.
- Taxon
- Lasthenia burkeiLasthenia burkeie0
- Outcome
- homologous chromosomese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lasthenia burkei and L. conjugens have homologous chromosomes”
Claim · model-written summary
Four chromosomes of L. burkei and L. conjugens are homologous to four of L. fremontii.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- homologous with four of those of L. fremontiie0
- Value
- foure0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“four of which are homologous with four of those of L. fremontii”
t0“LASTHENIA BURKEI”
Claim · model-written summary
The remaining two chromosomes probably have reciprocal translocations causing meiotic multivalents.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- reciprocal translocations which lead to multivalent formation during meiosise0
- Value
- two chromosomese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The remaining two chromosomes probably have reciprocal translocations which lead to multivalent formation during meiosis in interspecific hybrids.”
t0“LASTHENIA BURKEI”
Claim · model-written summary
Pollen viability was restored in most F 2 generations.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Organ / stage
- F 2 generationse0
- Outcome
- Pollen viabilitye0
- Direction
- restorede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pollen viability is restored in most F 2 generations”
t0“LASTHENIA BURKEI”
Claim · model-written summary
Some L. conjugens × L. fremontii F 1 offspring resembled L. burkei morphologically but were fairly sterile.
- Taxon
- L. conjugens
Lasthenia conjugense0 - Outcome
- morphologically indistinguishable from L. burkei (although fairly sterile)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some individuals in F 1 progenies of L. conjugens × L. fremontii that are morphologically indistinguishable from L. burkei (although fairly sterile)”
Claim · model-written summary
The authors reaffirmed recognition of three species.
- Taxon
- Lasthenia burkeiLasthenia burkeit0
- Outcome
- three species should be recognizede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“patterns of diversification in this group have led to reaffirmation of an earlier decision that three species should be recognized”
t0“LASTHENIA BURKEI”