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

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.

Alien fish, amphibian and reptile species in Romania and their invasive status: a review with new data

“…Varanus exanthematicus (Bosc, 1792). (Barker and Barker 2008;Hunter et al 2018 -the last paper speaking about "taxonomic uncertainty specimen, most likely a terrarium escape/release, was found and killed by villagers in November 1997, close to Lake Snagov (Ilfov county) (Andrei, M.-D., pers. comm.; "Grigore Antipa" National Museum of Natural History collection).…”

Novel ecological and climatic conditions drive rapid adaptation in invasive Florida Burmese pythons

“…Given the invasive Burmese python population was established from pet‐trade snakes originating from various native‐range regions and populations (Hunter et al., ), we used our inferred sample genotypes at RAD locus variable sites to estimate how many source populations comprise the invasive population with no a priori information about potential source population. We used the lea package v. 1.0 (Frichot, François, & O'Meara, ; Frichot, Mathieu, Trouillon, Bouchard, & François, ) in the r statistical environment (v. 3.3.; R Core Team, ) to estimate the number of ancestral populations, commonly referred to as K , which in this case should correspond to the number of source populations given the relatively recent introduction of pythons to Florida.…”

Burmese pythons in Florida: A synthesis of biology, impacts, and management tools

“…Further, although Burmese and Indian pythons were recently identified as reciprocally monophyletic by Reynolds et al (2014), the DNA-sequence data used in that analysis were obtained from the online repository GenBank, with unsuitable sample groupings for species delimitation (i.e., single terminals for each taxon) from a non-curated database (Reynolds et al 2014). More specifically, because the two taxa were thought to be one species for many years, users may have categorized a Burmese python as P. molurus, which is now identified as the Indian python (see discussion in Hunter et al 2018).…”