01867nas a2200181   4500008004100000245014500041210006900186260001200255300001400267490000700281520121700288100001101505700001301516700001101529700001101540700001701551856011701568       2004                        eng d00aChromosome behavior during meiosis and development of spore mother cells in the Chinese quillwort Isoetes sinensis T. C. Palmer (Isoetaceae)0 aChromosome behavior during meiosis and development of spore moth  c2004///  a183 - 1950 v943 aChromosome behavior during meiosis of the tetraploid Isoetes sinensis was observed to be similar to that of basic diploid Isoetes species. This observation was consistent with the previous report that polyploid species of Isoetes are allopolyploids. Meiosis was generally similar in both megaspore and microspore mother cells, but differences were observed. Due to the smaller size of the microspore mother cells, during prophase I, chromosomes are not as dispersed as those in megaspore mother cells. Cytomixis was observed in all stages of meiosis in microspore mother cells, but it was not seen at any stage of meiosis in megaspore mother cells. Cytomixis, lagging chromosomes, chromosome bridges, chromosome fragments, and micronuclei, observed during meiosis in I. sinensis, can affect sexual reproduction, but it does not appear to be a major cause of population decline in this species. The major cause of decline is habitat degradation from human disturbance. The few remaining populations of the Chinese quillwort are fragmented and the numbers of individuals contained in these populations dwindle as a result of habitat degradation. Conservation efforts are needed to save I. sinensis from extinction.1 aHe, Z.1 aWang, H.1 aLi, J.1 aYe, Q.1 aTaylor, W.C.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-11444270683&partnerID=40&md5=e3b19a6dd117ccd20573e526dceb63bf01961nas a2200193   4500008004100000245017900041210007100220260001200291300001400303490000700317520123100324100001701555700001901572700001501591700001201606700001701618700001501635856011701650       2004                        eng d00aPhylogenetic relationships of Isoëtes (Isoëtaceae) in China as revealed by nucleotide sequences of the nuclear ribosomal ITS region and the second intron of a LEAFY homolog0 aPhylogenetic relationships of Isoëtes Isoëtaceae in China as rev  c2004///  a196 - 2050 v943 aIsoëtes is an ancient lycopod lineage with a highly conserved morphology that provides few morphological characters to resolve the phylogeny of its species. Species appear to have evolved by divergence and allopolyploidy. The basic diploids I. hypsophila, I. taiwanensis, and I. yunguiensis and the tetraploid I. sinensis occur in China. Analysis of ITS sequences indicates that the Chinese Isoëtes species are part of an Australasian clade including I. brevicula from Western Australia and I. kirkii from New Zealand. Two distinct cloned sequences of the second intron of a LEAFY homolog were recovered from I. sinensis supporting the hypothesis that I. sinensis is an allotetraploid. One of the I. sinensis cloned sequences was similar to the I. taiwanensis sequence and the other cloned sequence was similar to the I. yunguiensis sequence identifying I. taiwanensis and I. yunguiensis as the likely parents of I. sinensis. Other cloned sequences recovered from I. sinensis were recombined parts of the two distinct sequences. Morphological evidence supporting an allotetraploid origin of I. sinensis is found in its larger microspore size and intermediate megaspore texture compared to I. taiwanensis, and I. yunguiensis.1 aTaylor, W.C.1 aLekschas, A.R.1 aQing, F.W.1 aLiu, X.1 aNapier, N.S.1 aHoot, S.B.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-11444262662&partnerID=40&md5=7b7a2b568e139bee1b60bd62836ff6ef02291nas a2200205   4500008004100000245010500041210007100146260001200217300001400229490000700243520160200250653001901852653001901871653001201890653001701902100001501919700001701934700001701951856011701968       2004                        eng d00aRevealing unknown or extinct lineages within Isoëtes (Isoëtaceae) using DNA sequences from hybrids0 aRevealing unknown or extinct lineages within Isoëtes Isoëtaceae   c2004///  a899 - 9040 v913 aIsoëtes, a heterosporous lycopod with a fossil record dating back to the Paleozoic, has numerous putative allopolyploids (resulting from hybridization events coupled with doubling of chromosome number). By using the highly variable nucleotide sequences from the second intron of a LFY homologue in Isoëtes, species could be delimited and hybrid origins determined. The data suggest that reticulate evolution is both common and complex within a more derived species complex of Isoëtes. Sequences of identifiable parentage and sequences that are unlike any diploid species known were recovered, leading to the conclusion that one or both of the putative parents have not yet been discovered or are extinct. A range of observations concerning allopolyploid speciation were categorized as follows: (1) verification of previous hypotheses regarding parentage (e.g., I. riparia, I. appalachiana), (2) determination that two morphologically distinct allotetraploid species can share the same parentage (I. azorica and I. acadiensis), (3) recognition of a cryptic allotetraploid species, indicated by the presence of different parental genomes (I. "appalachiana" from Florida), and (4) identification of allotetraploid species with one or two unknown parents (e.g., I. tuckermanii, I. acadiensis, I. azorica, and I. hyemalis). Some sequences from diploid species are remarkably uniform among populations (e.g., I. echinospora from various locations in North America, Iceland, and Wales), while others are variable at the subspecies level (e.g., northern and southern populations within I. engelmannii).10aAllopolyploidy10aHybrid origins10aIsoetes10aLEAFY intron1 aHoot, S.B.1 aNapier, N.S.1 aTaylor, W.C.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-11444256350&partnerID=40&md5=420a4ad06820ce82f60d7a70e7db9dec