Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus)

Authors

Margaret E. Hunter, Wetland and Aquatic Research CenterFollow
Nathan A. Johnson, Wetland and Aquatic Research Center
Brian J. Smith, Wetland and Aquatic Research Center
Michelle C. Davis, Wetland and Aquatic Research Center
John S.S. Butterfield, Wetland and Aquatic Research Center
Ray W. Snow, Everglades National Park
Kristen M. Hart, Wetland and Aquatic Research Center,

ORCID IDs

Margaret E. Hunter http://orcid.org/0000-0002-4760-9302

Nathan A. Johnson http://orcid.org/0000-0001-5167-1988

Kristen M. Hart http://orcid.org/0000-0002-5257-7974

Document Type

Article

Date of this Version

8-2-2017

Citation

Hunter ME, Johnson NA, Smith BJ, et al. Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus). Ecol Evol. 2018;00:1–14. https://doi.org/10.1002/ ece3.4423

Comments

U.S. Government Work.

Abstract

The invasive Burmese python (Python bivittatus) has been reproducing in the Florida Everglades since the 1980s. These giant constrictor snakes have caused a precipitous decline in small mammal populations in southern Florida following escapes or releases from the commercial pet trade. To better understand the invasion pathway and genetic composition of the population, two mitochondrial (mtDNA) loci across 1,398 base pairs were sequenced on 426 snakes and 22 microsatellites were assessed on 389 snakes. Concatenated mtDNA sequences produced six haplotypes with an average nucleotide and haplotype diversity of π = 0.002 and h = 0.097, respectively. Samples collected in Florida from morphologically identified P. bivittatus snakes were similar to published cytochrome oxidase 1 and cytochrome b sequences from both P. bivittatus and Python molurus and were highly divergent (genetic distances of 5.4% and 4.3%, respectively). The average number of microsatellite alleles and expected heterozygosity were N_A = 5.50 and H_E = 0.60, respectively. Nuclear Bayesian assignment tests supported two genetically distinct groups and an admixed group, not geographically differentiated. The effective population size (N_E = 315.1) was lower than expected for a population this large, but reflected the low genetic diversity overall. The patterns of genetic diversity between mtDNA and microsatellites were disparate, indicating nuclear introgression of separate mtDNA lineages corresponding to cytonuclear discordance. The introgression likely occurred prior to the invasion, but genetic information on the native range and commercial trade is needed for verification. Our finding that the Florida python population is comprised of distinct lineages suggests greater standing variation for adaptation and the potential for broader areas of suitable habitat in the invaded range.