Systematic Botany 

About: Systematic Botany is an academic journal published by American Society of Plant Taxonomists. The journal publishes majorly in the area(s): Monophyly & Genus. It has an ISSN identifier of 0363-6445. Over the lifetime, 3169 publications have been published receiving 84734 citations.

Gene trees and species trees: Molecular systematics as one-character taxonomy

Abstract: Reconstruction of phylogenies from molecular data has become an important and increasingly common approach in systematics. The product of such studies is a gene tree, hypoth- esizing relationships among genes or genomes. This gene tree may be fundamentally incongruent with the true species phylogeny, due to various biological phenomena such as introgression, lineage sorting, or mistaken orthology. In such circumstances all of the gene tree characters defining the relationships of molecular taxa (haplotypes) may be necessarily correlated, and the gene or genome may behave as a single species tree character. In these circumstances robustness of the gene hypoth- esis is meaningless as a measure of confidence in the species phylogenetic hypothesis. Incongruence between a phylogenetic hypothesis based on numerous, presumably independent, non-molecular characters and a single gene tree should not be assumed to be due to noise in non-molecular data. As with other characters, a character phylogeny, in this case a gene tree, can be tested best by a parsimony analysis in which other characters are included. If independence of molecular characters is assumed, then each is an equivalent phylogenetic hypothesis, as is each non-molecular character, leading to the suggestion that direct combination is appropriate. Swamping becomes an issue when a large molecular data set may be behaving as a single character. To alleviate this problem, a gene tree may be treated as a single multistate character, either ordered or unordered, and included with non-molecular data to obtain a globally parsimonious result. An example is given using published molecular and non-molecular data from the Asteraceae.

Isozymes in plant biology

Abstract: This survey emphasizes the possibilities of isozymes as marker genes in solving a variety of problems important to population geneticists, evolutionists, systematists, and plant breeders.

MatK DNA Sequences and Phylogenetic Reconstruction in Saxifragaceae s. str

Abstract: Comparative DNA sequencing of matK, a maturase coding gene located within the intron of the chloroplast gene trnK, was evaluated for phylogenetic utility using genera of Saxi- fragaceae s. str. The entire matK gene was sequenced for two members of the family, Sullivantia sullivantii and Saxifraga integrifolia. Comparison of base substitution rates between these two species indicated that matK evolves approximately three-fold faster than rbcL. Comparative sequencing of 754 base pairs within matK was subsequently conducted using 25 genera in Saxifragaceae s. str. and two outgroup taxa. Summed over the 31 taxa sequenced for this 754 base pair region, 40% of the base positions were variable and 15.6% were potentially informative. Five insertion/deletion events of three or six base pairs were also detected. Skewness and randomization tests both suggest that significant non-random structure is present in the matK data set. Parsimony analyses provided 72 most parsimonious trees of 223 steps (excluding autapomorphies) with a consistency index of 0.565. Several well-supported groups of genera are highly concordant with relationships suggested by two other chloroplast DNA data sets: chloroplast DNA restriction sites and rbcL sequences.