Evolution of Microsatellite Loci in the Adaptive Radiation of Hawaiian Honeycreepers

Abstract

Previous studies have examined germ-line mutations to infer the processes that generate and maintain variability in microsatellite loci. Few studies, however, have examined patterns to infer processes that act on microsatellite loci over evolutionary time. Here, we examine changes in 8 dinucleotide loci across the adaptive radiation of Hawaiian honeycreepers. The loci were found to be highly variable across the radiation, and we did not detect ascertainment bias with respect to allelic diversity or allele size ranges. In examining patterns at the sequence level, we found that changes in flanking regions, repeat motifs, or repeat interruptions were often shared between closely related species and may be phylogenetically informative. Genetic distance measures based on microsatellites were strongly correlated with those based on mitochondrial DNA (mtDNA) sequences as well as with divergence time up to 3 My. Phylogenetic inferences based on microsatellite genetic distances consistently recovered 2 of the 4 honeycreeper clades observed in a tree based on mtDNA sequences but differed from the mtDNA tree in the relationships among clades. Our results confirm that microsatellite loci may be conserved over evolutionary time, making them useful in population-level studies of species that diverged from the species in which they were characterized as long as 5 Ma. Despite this, we found that their use in phylogenetic inference was limited to closely related honeycreeper species.

Biogeography and the evolution of flightlessness in a radiation of Hawaiian moths (Xyloryctidae: Thyrocopa)

“…Thyrocopa is now one of a few groups to occur on, and be sampled from, both the main Hawaiian Islands and the NWHI (see also Price, 2004; Cowie & Holland, 2008; Rubinoff, 2008; Eggert et al. , 2009; Shapiro et al.…”

Horizontal gene transfer in plants

“…Microsatellites are considered to be one of the most variable elements in a genome due to the high level of variation in microsatellite sequence motifs, lengths, and repeat numbers. The mutation rate of SSRs range from 10 -2 to 10 -6 events per locus per generation, which is significantly higher than that of any other region of a genome (Sia et al, 2000) due to factors such as allopolyploidization (Tang et al, 2009), stress (Nevo et al, 2005), and radiation (Eggert et al, 2009). Microsatellites comprise a force to drive divergence of species-specific sequences.…”