منابع مشابه
Evolution and biogeography of gymnosperms.
Living gymnosperms comprise only a little more than 1000 species, but represent four of the five main lineages of seed plants, including cycads, ginkgos, gnetophytes and conifers. This group has huge ecological and economic value, and has drawn great interest from the scientific community. Here we review recent advances in our understanding of gymnosperm evolution and biogeography, including ph...
متن کاملMale Gametophyte Development and Evolution in Extant Gymnosperms
The male gametophytes of gymnosperms are characterized by the diversities in pollen morphology, cellular composition and pattern of cell division, pollen tube morphology, sperm delivery, growth pattern through the ovule and nucellus, and pollen tube wall composition both within and among the four living orders, i.e., Cycadales, Ginkgoales, Coniferales, and Gnetales. At dehiscence, gymnosperm po...
متن کاملGene Family: Structure, Organization and Evolution
Gene families are considered as groups of homologous genes which they share very similar sequences and they may have identical functions. Members of gene families may be found in tandem repeats or interspersed through the genome. These sequences are copies of the ancestral genes which have underwent changes. The multiple copies of each gene in a family were constructed based on gene duplicati...
متن کاملContrasting Rates of Molecular Evolution and Patterns of Selection among Gymnosperms and Flowering Plants
The majority of variation in rates of molecular evolution among seed plants remains both unexplored and unexplained. Although some attention has been given to flowering plants, reports of molecular evolutionary rates for their sister plant clade (gymnosperms) are scarce, and to our knowledge differences in molecular evolution among seed plant clades have never been tested in a phylogenetic fram...
متن کاملMolecular phylogeny of extant gymnosperms and seed plant evolution: analysis of nuclear 18S rRNA sequences.
To study the evolutionary relationships among the four living gymnosperm orders and the interfamilial relationships in each order, a set of 65 nuclear 18S rRNA sequences from ferns, gymnosperms, and angiosperms was analyzed using the neighbor-joining and maximum-parsimony methods. With Selaginella as the outgroup, the analysis strongly indicates that the seed plants form a monophyletic group wi...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: American Midland Naturalist
سال: 1935
ISSN: 0003-0031
DOI: 10.2307/2420041