TY - JOUR
T1 - An analysis of species boundaries and biogeographic patterns in a cryptic species complex
T2 - The rotifer-Brachionus plicatilis
AU - Suatoni, Elizabeth
AU - Vicario, Saverio
AU - Rice, Sean
AU - Snell, Terry
AU - Caccone, Adalgisa
N1 - Funding Information:
We thank A. Gómez, A. Derry, and J. Garey for providing critical advice and data for successful DNA sequencing. We thank M. Serra and A. Hagiwara for generously sharing clones from their rotifer collections and W. Wurtsbaugh, F. Boreo, J. Moravec, R. Shiel, S. Halse, J. Cocking, L. Buss, M. Garcia, and R. Rosengarten, for collecting rotifer samples. And, we are indebted to G. Wikfors and M. Dixon at the National Marine Fisheries Service in Milford, CT for supplying algae throughout the study. The thoughtful comments of the editor and David Mark–Welch improved the manuscript enormously. This study was supported by a dissertation improvement grant from the National Science Foundation (DEB-0408014), a grant from Sea Grant of Connecticut (PSA 3259), and seed money from the Yale Institute of Biospheric Studies’ Molecular Systematics and Conservation Genetics laboratory.
PY - 2006/10
Y1 - 2006/10
N2 - Since the advent of molecular phylogenetics, there is increasing evidence that many small aquatic and marine invertebrates-once believed to be single, cosmopolitan species-are in fact cryptic species complexes. Although the application of the biological species concept is central to the identification of species boundaries in these cryptic complexes, tests of reproductive isolation do not frequently accompany phylogenetic studies. Because different species concepts generally identify different boundaries in cryptic complexes, studies that apply multiple species concepts are needed to gain a more detailed understanding of patterns of diversification in these taxa. Here we explore different methods of empirically delimiting species boundaries in the salt water rotifer Brachionus plicatilis by comparing reproductive data (i.e., the traditional biological species concept) to phylogenetic data (the genealogical species concept). Based on a high degree of molecular sequence divergence and largely concordant genetic patterns in COI and ITS1, the genealogical species hypothesis indicates the existence of at least 14 species-the highest estimate for the group thus far. A test of the genealogical species concept with biological crosses shows a fairly high level of concordance, depending on the degree of reproductive success used to draw boundaries. The convergence of species concepts in this group suggests that many of the species within the group may be old. Although the diversity of the group is higher than previously understood, geographic distributions remain broad. Efficient passive dispersal has resulted in global distributions for many species with some evidence of isolation by distance over large geographic scales. These patterns concur with expectations that micro-meiofauna (0.1-1 mm) have biogeographies intermediate to microbial organisms and large vertebrates. Sympatry of genetically distant strains is common.
AB - Since the advent of molecular phylogenetics, there is increasing evidence that many small aquatic and marine invertebrates-once believed to be single, cosmopolitan species-are in fact cryptic species complexes. Although the application of the biological species concept is central to the identification of species boundaries in these cryptic complexes, tests of reproductive isolation do not frequently accompany phylogenetic studies. Because different species concepts generally identify different boundaries in cryptic complexes, studies that apply multiple species concepts are needed to gain a more detailed understanding of patterns of diversification in these taxa. Here we explore different methods of empirically delimiting species boundaries in the salt water rotifer Brachionus plicatilis by comparing reproductive data (i.e., the traditional biological species concept) to phylogenetic data (the genealogical species concept). Based on a high degree of molecular sequence divergence and largely concordant genetic patterns in COI and ITS1, the genealogical species hypothesis indicates the existence of at least 14 species-the highest estimate for the group thus far. A test of the genealogical species concept with biological crosses shows a fairly high level of concordance, depending on the degree of reproductive success used to draw boundaries. The convergence of species concepts in this group suggests that many of the species within the group may be old. Although the diversity of the group is higher than previously understood, geographic distributions remain broad. Efficient passive dispersal has resulted in global distributions for many species with some evidence of isolation by distance over large geographic scales. These patterns concur with expectations that micro-meiofauna (0.1-1 mm) have biogeographies intermediate to microbial organisms and large vertebrates. Sympatry of genetically distant strains is common.
KW - Brachionus
KW - COI
KW - Cryptic species
KW - ITS1
KW - Reproductive isolation
KW - Rotifera
KW - Zooplankton
UR - http://www.scopus.com/inward/record.url?scp=33748130321&partnerID=8YFLogxK
U2 - 10.1016/j.ympev.2006.04.025
DO - 10.1016/j.ympev.2006.04.025
M3 - Article
C2 - 16815046
AN - SCOPUS:33748130321
SN - 1055-7903
VL - 41
SP - 86
EP - 98
JO - Molecular Phylogenetics and Evolution
JF - Molecular Phylogenetics and Evolution
IS - 1
ER -