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Likely multiple origins of a diploid hybrid sunflower species
Author(s) -
Schwarzbach A. E.,
Rieseberg L. H.
Publication year - 2002
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2002.01557.x
Subject(s) - biology , ploidy , microsatellite , chloroplast dna , gene flow , helianthus , hybrid , genetic algorithm , genetics , haplotype , evolutionary biology , genetic variation , genotype , genome , gene , allele , botany , sunflower , agronomy
The recurrent origin of diploid hybrid species is theoretically improbable because of the enormous diversity of hybrid genotypes generated by recombination. Recent greenhouse experiments, however, indicate that the genomic composition of hybrid lineages is shaped in part by deterministic forces, and that recurrent diploid hybrid speciation may be more feasible than previously believed. Here we use patterns of variation from chloroplast DNA (cpDNA), nuclear microsatellite loci, cross‐viability and chromosome structure to assess whether a well‐characterized diploid hybrid sunflower species, Helianthus anomalus , was derived on multiple occasions from its parental species, H. annuus and H. petiolaris . Chloroplast DNA and crossability data were most consistent with a scenario in which H. anomalus arose three times: three different H. anomalus fertility groups were discovered, each with a unique cpDNA haplotype. In contrast, there was no clear signature of multiple, independent origins from the microsatellite loci. Given the age of H. anomalus (> 100 000 years bp), it may be that microsatellite evidence for recurrent speciation has been eroded by mutation and gene flow through pollen.