ORIGINS AND GENETIC DIVERSITY OF INTRODUCED POPULATIONS OF THE PUERTO RICAN RED-EYED COQUÍ, ELEUTHERODACTYLUS ANTILLENSIS, IN SAINT CROIX (U.S. VIRGIN ISLANDS) AND PANAMÁ

Abstract

The Red-eyed Coquí, Eleutherodactylus antillensis, is a terrestrial frog endemic to the Puerto Rican Bank (Puerto Rico and numerous islands and cays off its eastern coast), in the eastern Caribbean Sea. The species was likely introduced in Saint Croix, an island c. 100 km southeast of Puerto Rico, in the late 1930s, and in Panamá City, Panamá, in the late 1950s or early 1960s, but the source(s) of these introductions are unknown. We analyzed sequence data from one mtDNA locus and four nuDNA introns to infer the origin(s) of the Saint Croix and Panamá City populations and quantify their genetic diversity. Saint Croix and Panamanian populations do not share any haplotypes, and they cluster with different native populations, suggesting that they are derived from separate sources in the Puerto Rican Bank. Patterns of population structure trace the probable sources of E. antillensis in Saint Croix to islands off Puerto Rico's eastern coast, which include Vieques, Culebra, Saint Thomas, Saint John, Tortola, and Virgin Gorda, and possibly to eastern Puerto Rico as well. In contrast, Panamá City E. antillensis probably originated from either western or eastern Puerto Rico. Genetic diversity in the introduced populations is similar to or lower than in populations in the species' native range, indicating that genetic diversity has not increased in the alien frogs. Our findings may facilitate the development of preventive measures to minimize introductions of non-native amphibians in the Caribbean and Central America.

Keywords: Caribbean Sea; Puerto Rican Bank; West Indies; human-mediated introduction; introduced species; population genetics.

Fig. 1

Maps of (A) the Puerto Rican Bank, in the eastern Caribbean Sea, (A, B) Panamá City, Panamá, (C) Puerto Rico, (D) the Eastern Islands (specifically Vieques, Culebra, Saint Thomas, Saint John, Jost van Dyke, Tortola, Guana, Great Camanoe, Beef, Virgin Gorda), and (E) Saint Croix. Circles indicate the approximate geographic locations of the sampling localities of Eleutherodactylus antillensis [note that localities 57 and 58 were depicted as a single locality in Fig. 1 of Barker et al. (2012)]. The lines within (B) Panamá City depict the borders of districts. The dotted line in Puerto Rico (C) delineates a phylogeographic break in E. antillensis (Barker et al., 2012) that we used to define two groups for genetic analyses (western Puerto Rico; eastern Puerto Rico).

Fig. 2

Maximum parsimony network representing the relationships among haplotypes of the mtDNA control region of 323 Eleutherodactylus antillensis from their native ranges in the Puerto Rican Bank (western Puerto Rico [green], eastern Puerto Rico [red], Eastern Islands [light blue]), and their introduced ranges in Saint Croix (yellow) and Panamá City, Panamá (violet). Indels were included in this analysis. Haplotypes detected in the introduced ranges are indicated with a thick, black line. Circles represent unique haplotypes; hatch marks depict single mutations; empty squares indicate missing (i.e., unsampled or extinct) haplotypes. Circle size is proportional to haplotype frequency. (Modified from Barker et al., 2012.)

Fig. 3

Principal coordinates analysis based on haplotypes of one mtDNA locus (CR) and four nuDNA loci (CRYBA, MYH, RH1, RPL9int4) from 202 Eleutherodactylus antillensis from their native ranges in the Puerto Rican Bank (western Puerto Rico [green, n = 84], eastern Puerto Rico [red, n = 39], Eastern Islands [light blue, n = 41]) and their introduced ranges in Saint Croix (yellow, n = 28) and Panamá City, Panamá (violet, n = 10). Ovals are 95% confidence ellipses representing regional groups. Individuals from the Puerto Rican Bank are depicted by circles, whereas individuals from Saint Croix and Panamá City are represented by empty squares.