CHROMATOGRAPHIC EVIDENCE OF HYBRIDIZATION AND EVOLUTION IN PHLOX MACULATA

Representatives of P. maculata ssp. maculata and P. glaberrima ssp. interior and 36 putative hybrids were collected from a population in central Indiana. Chromatographic analysis revealed the presence of nine diagnostic components in P. maculata ssp. maculata and eight such components in P. glaberrima ssp. interior. Putative F₁ hybrids contained all or most of the parental marker components; markers of the non-recurrent parent were absent in the two classes of putative backcross progeny. The characters of P. maculata ssp. pyramidalis are a composite of those present in P. maculata ssp. maculata and P. glaberrima ssp. interior, and the former is virtually identical to certain hybrids from the population in question. The contention that P. maculata ssp. pyramidalis is a stabilized derivative of natural hybridization between these taxa is substantiated by the presence of all of the diagnostic constituents of the putative parents on its chromatograms. It is the author's opinion that the definitive data which chromatography affords will be invaluable in elucidating the complex pathways of evolution in Phlox.     

NATURAL HYBRIDIZATION BETWEEN PHLOX MACULATA AND PHLOX GLABERRIMA AND ITS EVOLUTIONARY SIGNIFICANCE

Levin, 1). A. (U. Illinois, Urbana.) Natural hybridization between Phlox maculata and Phlox glaberrima and its evolutionary significance. Amer. Jour. Bot. 50(7): 714–720. Illus. 1963.—Field and herbarium studies indicate that Phlox maculata ssp. pyramidalis is similar to P. glaberrima ssp. interior in a number of characteristics. A hybrid swarm involving P. maculata ssp. maculata and P. glaberrima ssp. interior was discovered which contained some plants that were almost identical to P. maculata ssp. pyramidalis. Crosses between P. maculata and P. glaberrima indicate that the 2 species cross readily. The chromosome complements of the 2 species are morphologically similar. These data suggest that P. maculata ssp. pyramidalis is a stabilized introgressant type.     

RETICULATE EVOLUTION IN PHLOX AS SEEN THROUGH PROTEIN ELECTROPHORESIS

Seed protein profiles were used to document the genome constitutions of seven Phlox taxa believed to be stabilized derivatives of hybridization between P. pilosa and P. carolina, P. drummondii or P. amoena. These species have very distinctive seed protein profiles. Analyses of profiles from these and other phloxes not involved in the reticulum (P. maculata, P. glaberrima and their hybrid derivative P. maculata subsp. pyramidalis) demonstrated that profile components are inherited as co-dominant units, alteration of ploidal level does not alter the profile, profile components may undergo segregation and recombination, and profile components in hybrids do not re-combine in vivo or in vitro to produce new proteins. The putative derivatives of hybridization between P. pilosa and P. carolin, i.e., P. pilosa subsp. detonsa, P. pilosa subsp. sangamonensis, P. floridana and P. pulcherrima, display protein profiles which are nearly summations of the parental patterns as do the putative derivatives of P. pilosa and P. drummondii. i.e., P. villosissima and P. aspera. The putative derivative of P. pilosa and P. amoena, i.e., P. pilosa subsp. deamii, displays a completely additive profile. Genome constitutions judged from morphological, cytological, and chromatographical data are fully corroborated by the protein profiles.     

Cold tolerance of invasive freshwater snails,Pomacea canaliculata,P. maculata,and their hybrids helps explain their different distributions

相似文献   

VARIATIONS IN POLYMNIA POLLEN

Photomicrographs of normal and aberrant Polymnia (Compositae) pollen were made with the scanning electron microscope and with the light microscope. Anomalous pollen forms from F₁ hybrids of P. maculata Cav. are compared to the parental type and to the closely related P. uvedalia (L.) L. Among the variations discussed are differences in size and form, fused aggregates, and reduction in length of spines. The cause of these variations is unknown, although similar anomalies were later found in a single P. maculata parent, Wells No. 740, which grew under similar standard greenhouse conditions.     

The characterisation and identification of a naturally occurring hybrid in the genusLeucaena (Leguminosae: Mimosoideae)

Phytogeographical, morphological, and molecular evidence for the widespread but sporadic occurrence of sterile hybrids betweenLeucaena leucocephala subsp.glabrata andL. esculenta subsp.esculenta in South-Central Mexico is presented. Most morphological and DNA characters studied in the putative hybrids showed states intermediate between the proposed parental taxa. The occurrence of non-additive nuclear ribosomal DNA phenotypes is discussed and the need to use a suite of nuclear taxon-specific markers to determine hybridity is emphasized. The origin of the hybrid is discussed in relation to the disruption of the distributions of both parental taxa through use by man as minor food plants, providing another example of the important influence of human interference on the evolution ofLeucaena. The successful use of dried leaf material as a source of DNA is highlighted as an efficient way to identify sterile hybrids at the molecular level.     

Geographical variation and systematics of the tetraploid marsh orchid Dactylorhiza majalis subsp. sphagnicola (Orchidaceae) and closely related taxa

Dactylorhiza majalis subsp. sphagnicola is an allotetraploid marsh orchid derived from parents closely similar to present‐day D. incarnata and the western European form of D. maculata subsp. maculata, suggesting that it has a postglacial origin. It extends from northwestern continental Europe into areas formerly covered by the Weichselian ice sheet in mid‐Scandinavia. Here, we studied the variation at both the plastid and nuclear marker systems to describe the geographical variation in subsp. sphagnicola and its evolutionary history. We investigated whether subsp. sphagnicola is affected by secondary hybridization and gene flow from its parental lineages or from other allotetraploid marsh orchids, and we also compared subsp. sphagnicola with other allotetraploids of similar origins. We analysed 492 plants from 50 populations. Thirty‐seven populations were collected as potential Dactylorhiza majalis subsp. sphagnicola, five as subsp. sesquipedalis (D. elata), one as D. elata subsp. brennensis, one as subsp. calcifugiens, one as subsp. occidentalis and the remaining five as populations with some affinity to subsp. lapponica (including D. traunsteineri). All populations were analysed for plastid haplotypes and nuclear internal transcribed spacer (ITS) allele frequencies, and a subset of 43 populations was analysed for five nuclear microsatellite loci. Dactylorhiza majalis subsp. sphagnicola was dominated by a single plastid haplotype that was also dominant in western European D. maculata subsp. maculata, and most of the alternative haplotypes differed by only one mutation from the dominant one. There was more variation in nuclear microsatellites and ITS, and the variation was geographically structured in these markers. Subspecies occidentalis and calcifugiens shared haplotypes with subsp. sphagnicola, whereas subsp. sesquipedalis and brennensis had other haplotypes. Dactylorhiza majalis subsp. sphagnicola may have a postglacial origin within its present continental distribution. It has incorporated genetic material from D. maculata subsp. maculata by secondary hybridization and introgression, and some northern populations have assimilated strongly divergent haplotypes from the northeastern form of D. maculata subsp. maculata. Subspecies sphagnicola has also evolved morphologically divergent local populations in the north that do not differ from the typical populations in genetic markers. It may form mixed populations with other allotetraploid subspecies of D. majalis and, at least at one site, it has become integrated with subsp. lapponica, demonstrating that independently derived allotetraploids may contribute to a common gene pool. Subspecies calcifugiens seems to be derived from subsp. sphagnicola, and further studies based on a larger sample may confirm that it is better recognized as a variety. The so‐called D. elata subsp. brennensis is of hybrid origin and combines markers from subsp. sesquipedalis with markers from the D. majalis core complex, possibly subsp. majalis. The new combination Dactylorhiza majalis subsp. sesquipedalis (Willd.) H.A.Pedersen & Hedrén comb. nov. is provided. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 174–193.     

COMPARATIVE ANATOMY OF SOME PARENTS AND HYBRIDS OF THE HAWAIIAN MADIINAE (ASTERACEAE)

Comparative leaf morphology and anatomy was examined in five species and four hybrids involving three genera of Hawaiian Madiinae (Asteraceae). The comparisons included Argyroxiphium grayanum, Dubautia ciliolata subsp. ciliolata, D. knudsenii subsp. knudsenii, D. scabra subsp. leiophylla, D. scabra subsp. scabra, and Wilkesia gymnoxiphium, and the hybrids A. grayanum × D. scabra subsp. leiophylla, D. ciliolata subsp. ciliolata × D. scabra subsp. scabra, D. knudsenii subsp. knudsenii × D. scabra subsp. leiophylla, and W. gymnoxiphium × D. scabra subsp. leiophylla. Foliar morphology, leaf tissue organization, and various characters of stomata and trichomes were compared, using epidermal peels, cross and paradermal sections, and clearings of leaves. Pronounced anatomical differences among these closely related taxa were characterized, and effects of hybridization on the expression of anatomical features were documented. Most comparisons of parents and hybrids revealed statistically significant differences in leaf size, distribution of adaxial and abaxial stomata, and marginal and surface trichomes. In most instances hybrids demonstrated intermediate status in their foliar characters, indicating that these features are inherited from both parents. However, differences in foliar characters were usually of sufficient magnitude to allow recognition of hybrids as well as parents.     

Silk filaments enhance the settlement of stream insect larvae

The recombination that follows natural hybridization may produce hybrid genotypes with traits that are intermediate or extreme relative to the parental species, and these traits may influence the relative fitness of the hybrids. Here we examined leaf ecophysiological traits that may influence fitness patterns in a natural plant hybrid zone. We compared the biochemical photosynthetic capacity of Ipomopsis aggregata, I. tenuituba, and early generation hybrids, as well as their photosynthetic responses to varying light and temperature, two abiotic factors found to differ among sites along the hybrid zone. In general, ecophysiological traits expressed in these plants were consistent with their natural habitat, even when grown under common greenhouse conditions. I. tenuituba reached higher photosynthetic rates (A) at higher light levels than I. aggregata, and also had a higher optimal temperature for photosynthesis (T _opt). This suite of traits may reflect adaptations to the more exposed, rocky sites where I. tenuituba is found, compared to the more vegetated, mesic I. aggregata site. Hybrids had characters that were largely intermediate or tenuituba-like, but particular individual hybrids were extreme for some traits, including light saturation level, light-saturated A, and T _opt. Many of these traits are consistent with adaptations reported for plants found in warm, dry sites, so they may put certain hybrids at an advantage at the relatively xeric center of the natural hybrid zone.     

Changes in the photosynthetic apparatus of maize in response to simulated natural temperature fluctuations

The response of the photosynthetic apparatus to low temperature periods differed among three hybrids of maize (Zea mays L.) grown in a phytotron. Light-saturated photosynthetic rates, leaf chlorophyll content, and mesophyll cell photosynthetic unit density all declined with increasing duration of low temperature. No single metabolic or physiological parameter appeared to control the response of the three hybrids to low temperature stress. Among all temperature treatments, net photosynthetic rate on a leaf area basis was more closely correlated with leaf chlorophyll content than with any other measured parameter. Final shoot dry weight was most highly correlated with stomatal conductance to CO₂.     

Heteroses in Net Photosynthetic Rate, Leaf Area, Tillering, and Some Physiological Characters of 35 F1 Rice Hybrids

Net photosynthetic rate, leaf area, tillering, shoot weight,and leaf area ratio for 35 F₁ rice (Oryza sativa L.) hybridsduring the vegetative stage were compared with correspondingvalues for parental varieties. Shoot weight and leaf area showedheterosis. However, hybrid vigour was not reflected in net photosyntheticrate. Leaf area was closely correlated with heteroses in shootdry weight and tillering. Thus F₁ rice hybrids grow vigorouslybecause of their high leaf area development, which is causedby high tillering. Key words: F₁ rice hybrid, Net photosynthetic rate, Leaf area     

Natural and experimental hybridization inArmeria (Plumbaginaceae):A. villosa subsp.carratracensis

An experimental crossing program was carried out in order to test the hypothesis thatArmeria villosa subsp.carratracensis, a serpentine endemic from Southern Spain, is of hybrid origin. Fruit-set and mainly pollen stainability data in artificial hybrids demonstrate that internal interspecific barriers are weak. Two generations of backcrossing with the two putative parents —A. colorata andA. villosa subsp.longiaristata— can restore pollen stainability to an average of 83.2 and 68.7, respectively. A morphometric analysis of 148 specimens belonging to parental species, different artificial hybrid generations and wild putative hybrid race shows that (1) morphological characters have a strong genetic basis and thus are good markers in identifying hybrids and introgression inArmeria; (2) artificial backcrossing produces in morphometrical characters a variation which conforms in both trend and magnitude to what is commonly attributed in the wild to introgression; (3) the position of the putative hybrid race is intermediate between the two parental species used in the program. These results are in accordance with the hypothesis of hybrid origin ofA. villosa subsp.carratracensis. Natural and experimental hybridization inArmeria, I     

Experimental evidence on the affinities ofPapaver somniferum (Papaveraceae)

Results obtained from crossing experiments betweenP. somniferum subsp.somniferum (2n = 22) and subsp.setigerum (2n = 44),P. glaucum (2n = 14) andP. gracile (2n = 14) and from the observation of meiotic chromosome pairing in the various hybrids obtained do not provide straightforward evidence for the hypothesis thatP. somniferum originated as a triploid hybrid between taxa similar toP. glaucum andP. gracile (Kadereit 1986a, b).—On the one hand, the pattern of crossability found reflects the closer similarity of subsp.somniferum toP. glaucum and of subsp.setigerum toP. gracile, which was interpreted as segregation of parental characters, and the high frequency of 2n = 28 chromosomes among F₂-progeny from the hybrid subsp.somniferum × subsp.setigerum (2n = 33) might reveal n = 7 as the base number also ofP. somniferum. On the other hand, however, the general difficulty of obtaining hybrids, and the low incidence of bivalent formation in their meiosis, probably indicating a lack of chromosome homology between the different species, do not fit the above hypothesis.—These results are in marked contrast to the morphological similarity between the three species involved.     

Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents,Pinus tabuliformis and Pinus yunnanensis

Genetic analyses indicate that Pinus densata is a natural homoploid hybrid originating from Pinus tabuliformis and Pinus yunnanensis. Needle morphological and anatomical features show relative species stability and can be used to identify coniferous species. Comparative analyses of these needle characteristics and phenotypic differences between the artificial hybrids, P. densata, and parental species can be used to determine the genetic and phenotypic evolutionary consequences of natural hybridization. Twelve artificial hybrid families, the two parental species, and P. densata were seeded in a high‐altitude habitat in Linzhi, Tibet. The needles of artificial hybrids and the three pine species were collected, and 24 needle morphological and anatomical traits were analyzed. Based on these results, variations in 10 needle traits among artificial hybrid families and 22 traits among species and artificial hybrids were predicted and found to be under moderate genetic control. Nineteen needle traits in artificial hybrids were similar to those in P. densata and between the two parental species, P. tabuliformis and P. yunnanensis. The ratio of plants with three needle clusters in artificial hybrids was 22.92%, which was very similar to P. densata. The eight needle traits (needle length, the mean number of stomata in sections 2 mm in length of the convex and flat sides of the needle, mean stomatal density, mesophyll/vascular bundle area ratio, mesophyll/resin canal area ratio, mesophyll/(resin canals and vascular bundles) area ratio, vascular bundle/resin canal area ratio) relative to physiological adaptability were similar to the artificial hybrids and P. densata. The similar needle features between the artificial hybrids and P. densata could be used to verify the homoploid hybrid origin of P. densata and helps to better understand of the hybridization roles in adaptation and speciation in plants.     

The evaluation of photosynthetic parameters in maize inbred lines subjected to water deficiency: Can these parameters be used for the prediction of performance of hybrid progeny?

The response of selected photosynthetic and morphological parameters of plants to drought was examined in 5 inbred lines of maize (Zea mays L.) and their 10 F1 hybrids. The aim of the study was to establish whether the photosynthetic performance of parental genotypes under drought conditions correlates with the performance of their progeny and whether the net photosynthetic rate, the chlorophyll fluorescence parameters or the content of photosynthetic pigments could be used as reliable physiological markers for early breeding generations. The relative importance of the additive and the nonadditive (dominance, maternal) genetic effects in the inheritance of these parameters was also assessed by means of the quantitative genetics analysis. The results showed that the nonadditive genetic effects associated with a particular combination of genotypes or a particular direction of crossing are at least equally and often even more important as the additivity and that these genetic effects almost totally change with the exposure of plants to drought conditions. This was reflected in the inability to predict the response of F1 hybrids to drought on the basis of the photosynthetic performance of their parents, which indicates that the practical usability of such parameters in maize breeding programs is rather limited.     

The interspecific hybrid Petunia parodii × P. inflata and its relevance to somatic hybridization in the genus Petunia

Summary Attempts at the reciprocal cross between Petunia parodii and P. inflata using standard emasculation and pollination techniques failed. Limited pollen tube growth down the style in reciprocal crosses led to reproductive isolation between the self-compatible P. parodii and self-incompatible P. inflata. The interspecific hybrid was successfully produced by bud-pollination of P. parodii with P. inflata as the male parent in 22 percent of attempts, but not in the opposite direction. In vitro pollination of P. parodii ovaries with P. inflata pollen also produced hybrids. The small size of the ovary made it technically impossible to use P. inflata as the female parent for in vitro pollination. The interspecific hybrids were intermediate, as compared to the two parents, for six of the seven plant and flower characters measured. Furthermore, the hybrids had high pollen fertility, set abundant seed upon self-pollination, and readily inter-crossed with the parental species. The results are consistent with a high degree of chromosomal homology in the parental species and with minor genetic divergency leading to reproductive isolation that is pre-zygotic in nature. Overcoming the barriers to cross-incompatibility by practical techniques resulted in fertile interspecific hybrids that segregated for parental characters. The potential value of employing the parental species in somatic hybridization experiments is discussed.Michigan Agricultural Experiment Station Journal Article No. 8404     

Patterns of inheritance of mating signals in interspecific hybrids between sailfin and shortfin mollies (Poeciliidae: Poecilia: Mollienesia)

Differences in male morphology and mating behaviors are thought to confer species sexual isolation between sailfin and shortfin species of mollies. This study used interspecific crosses between the sailfin molly, P. latipinna, and the shortfin molly, P. mexicana, to investigate patterns of inheritance of morphological traits and behavioral rates of three mating behaviors in F1 hybrid males. The two parental species showed clear species differences with respect to the length of the dorsal fin and dorsal fin ray number. First generation hybrid males were intermediate between the two parental species for dorsal fin length and fin ray number, suggesting autosomal control of this trait with little effect of dominance by genes from either parental species. Parental species showed clear species differences in their rates of courtship displays. Unlike the pattern for dorsal fin morphology, F1 hybrid males showed a clear distinction in display rates with respect to the direction of the interspecific cross. Male hybrids whose sires were P. latipinna had courtship display rates that were up to three times higher than the rates of displays performed by hybrid males whose fathers were P. mexicana. The distribution of phenotypes between the parental species and that of hybrid males sired by that parental species was nearly identical. Such a pattern suggests the influence of Y-linked genes on the inheritance of courtship display rates in mollies.     

Effects of Di-n-Butyl Phthalate on Mycorrhizal and Non-Mycorrhizal Cowpea Plants

This study examined the effect of mycorrhizal colonization with Glomus intraradices on physiological parameters and foliar nutrient concentrations in Olea europaea L. subsp. sylvestris and Rhamnus lycioides L. seedlings subjected to well-watered or drought-stressed conditions. Under drought stress, mycorrhizal O. europaea seedlings showed significantly higher photosynthetic and transpiration rates, stomatal conductance and foliar P concentration than its similarly-sized non-mycorrhizal counterpart. The intrinsic water use efficiency (photosynthetic rate to stomatal conductance ratio) was not change in O. europaea and decreased in R. lycioides seedlings due to mycorrhizal colonization under both well-watered and drought-stress conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

A combined barcode and morphological approach to the systematics and biogeography of Laurencia pyramidalis and Laurenciella marilzae (Rhodophyta)

In the present study we undertook an integrative approach, using both morphological and molecular data (COI-5P + rbcL), to assess the presence of Laurencia pyramidalis in Lusitanian Macaronesia. We studied type material of L. pyramidalis from the herbarium of the Naturalis Biodiversity Center, the Netherlands, and designated a lectotype and syntypes. Vegetative and reproductive features of L. pyramidalis were observed and we included a specimen from the type locality in our molecular analyses. We also investigated the geographical distribution of Laurenciella marilzae, a species recently described from the Canary Islands. Barcode sequences (COI-5P and rbcL) were generated for L. pyramidalis from the type locality (Normandy, France), the Azores, Madeira and the Canary Islands, and for L. marilzae from its type locality (Tenerife, Canary Islands), the Azores and Brazil.