Polyploid plants have faster rates of multivariate niche differentiation than their diploid relatives

Polyploid speciation entails substantial and rapid postzygotic reproductive isolation of nascent species that are initially sympatric with one or both parents. Despite strong postzygotic isolation, ecological niche differentiation has long been thought to be important for polyploid success. Using biogeographic data from across vascular plants, we tested whether the climatic niches of polyploid species are more differentiated than their diploid relatives and if the climatic niches of polyploid species differentiated faster than those of related diploids. We found that polyploids are often more climatically differentiated from their diploid parents than the diploids are from each other. Consistent with this pattern, we estimated that polyploid species generally have higher rates of multivariate niche differentiation than their diploid relatives. In contrast to recent analyses, our results confirm that ecological niche differentiation is an important component of polyploid speciation and that niche differentiation is often significantly faster in polyploids.Polyploid speciation entails substantial and rapid postzygotic reproductive isolation of nascent species that are initially sympatric with one or both parents. Despite strong postzygotic isolation, ecological niche differentiation has long been thought to be important for polyploid success. Using biogeographic data from across vascular plants, we tested whether the climatic niches of polyploid species are more differentiated than their diploid relatives and if the climatic niches of polyploid species differentiated faster than those of related diploids.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/1/ele13402-sup-0001-TableS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/2/ele13402_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/3/ele13402-sup-0007-TableS7.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/4/ele13402-sup-0003-TableS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/5/ele13402-sup-0005-TableS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/6/ele13402.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/7/ele13402-sup-0006-TableS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/8/ele13402-sup-0002-TableS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/9/ele13402-sup-0004-TableS4.pd

Amixicile reduces severity of cryptosporidiosis but does not have in vitro activity against Cryptosporidium

Cryptosporidium species cause significant morbidity in malnourished children. Nitazoxanide (NTZ) is the only approved treatment for cryptosporidiosis, but NTZ has diminished effectiveness during malnutrition. Here, we show that amixicile, a highly selective water-soluble derivative of NTZ diminishes Cryptosporidium infection severity in a malnourished mouse model despite a lack of direct anticryptosporidial activity. We suggest that amixicile, by tamping down anaerobes associated with intestinal inflammation, reverses weight loss and indirectly mitigates infection-associated pathology

The origin of polyploids via 2n gametes in Vaccinium section Cyanococcus

The production of 2n pollen (pollen with the sporophytic chromosome number) was evaluated in 4x and 6x taxa of Vaccinium section Cyanococcus . Mean frequencies of 2n pollen producers were 17.1% and 8.3% in natural 4x and 6x populations, respectively. The frequency of 2n pollen producers in the 4x species ranged from 8.6% ( V. angustifolium ) to 23.8% ( V. pallidum ). Level of 2n pollen production was genotypically variable (1% to 37.4%). The widespread occurrence of 2n pollen in 2x, 4x and 6x taxa suggests that sexual polyploidization was widespread and responsible for the origin of the polyploid species found in this genus. The frequency of 2n pollen producers was not significantly different between the 4x species and their putative 2x ancestors. These results support the origin of 4x and 6x taxa as a consequence of sexual polyploidization. Polyploids derived from sexual polyploidization would be expected to have increased fitness and flexibility due to the mode of 2n pollen formation. In blueberry species the predominant mode of 2n pollen formation is genetically equivalent to a first division restitution mechanism (FDR). FDR 2n pollen transmits a high percentage of the heterozygosity and a large fraction of the epistasis from the 2x parent to the 4x offspring.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42736/1/10681_2004_Article_BF00039664.pd

Phenotypic, cytogenetic and spike fertility characterization of a population of male-sterile triticale

Triticale (X Triticosecale Wittmack) is a good cereal for production of flour and feed. A segregating population of triticale was developed from a male-sterile (MS) plant. To determine whether this new source of male sterility in triticale is appropriate for use in breeding programs the expression of the male sterility phenotype was characterized through spike fertility, meiotic behavior, and pollen. Controlled crosses between male-sterile plants and control varieties male-fertile (MF) of triticale were also conducted, and cytological analyses were performed in the F2 and backcross plants. Plants with male-sterile phenotypes displayed reduced spike fertility when compared to plants with male-fertile phenotypes. Compared to male-fertile plants, male-sterile plants exhibited a lower percentage of normal meiotic cells, a reduced meiotic index and reduced pollen viability. The F2 plants had improved pollen fertility when compared to the male-sterile population; however there were no corresponding improvements in the percentage of normal meiotic cells or in the meiotic index. A single generation of backcrosses resulted in an improved meiotic index and increased pollen viability. However, no changes in the percentage of normal meiotic cells were observed. Meiotic instability, which was shown to be inheritable, was the likely cause of male sterility. Therefore, the use of this population in triticale breeding was considered to be inappropriate because it could promote or contribute to the maintenance of meiotic instability, which is commonly observed in this species