mtDNA variation of humpback whales in their wintering grounds of Guerrero, southern Mexican Pacific

Here, we describe variation in mtDNA haplotypes among 22 individual humpback whales off the Guerrero coast in southern Mexico and compare this to other wintering regions in the eastern North Pacific Ocean using published data. After correcting for different sample sizes, Guerrero humpback whales fit the cline in the eastern North Pacific in which A types are more abundant northwards, while E and F types are more abundant southwards. Whales observed around Guerrero in early winter exhibited a greater frequency of F types that are also observed earlier in winter at Bahía de Banderas in the mainland region, suggesting a seasonal passage of whales from Mexico to Central America. Four diversity indices were higher in different wintering regions between Nayarit and Guerrero. Departures from neutrality were observed in the bordering wintering grounds of the region. Four measures of differentiation by distance indicated boundaries between Nayarit and Southern Jalisco, and between Guerrero and Oaxaca, suggesting a transitional region between wintering regions of Mexico and Central America from 17.5° to 19.5°N.