Invasion genetics of the mummichog (Fundulus heteroclitus): recent anthropogenic introduction in Iberia

Abstract

Human activities such as trade and transport have increased considerably in the last decades, greatly facilitating the introduction and spread of non-native species at a global level. In the Iberian Peninsula, Fundulus heteroclitus, a small euryhaline coastal fish with short dispersal, was found for the first time in the mid-1970s. Since then, F. heteroclitus has undergone range expansions, colonizing the southern region of Portugal, southwestern coast of Spain and the Ebro Delta in the Mediterranean Sea. Cytochrome b sequences were used to elucidate the species invasion pathway in Iberia. Three Iberian locations (Faro, Cádiz and Ebro Delta) and 13 other locations along the native range of F. heteroclitus in North America were sampled. Results revealed a single haplotype, common to all invasive populations, which can be traced to the northern region of the species’ native range. We posit that the origin of the founder individuals is between New York and Nova Scotia. Additionally, the lack of genetic structure within Iberia is consistent with a recent invasion scenario and a strong founder effect. We suggest the most probable introduction vector is associated with the aquarium trade. We further discuss the hypothesis of a second human-mediated introduction responsible for the establishment of individuals in the Ebro Delta supported by the absence of adequate muddy habitats linking Cádiz and the Ebro Delta. Although the species has a high tolerance to salinity and temperature, ecological niche modelling indicates that benthic habitat constraints prevent along-shore colonisation suggesting that such expansions would need to be aided by human release.

Adaptive introgression enables evolutionary rescue from extreme environmental pollution

“…A recent discrete hybridization event occurred in the Houston Ship Channel, introducing highly advantageous adaptive haplotypes from F. heteroclitus and leaving behind evidence of F. heteroclitus ancestry scattered across the genome. Because F. heteroclitus have small home ranges (16) and the nearest populations are in Florida, >2500 km away, humanmediated transport is the likely mechanism of introduction (17), possibly through ballast water transfer (18) or baitfish transport (19).…”

The occurrence, distribution and biology of invasive fish species in fresh and brackish water bodies of NE Morocco

“…It was found in Iberia for the first time between 1970 and 1973 (Bernardi et al, 1995). Since then, F. heteroclitus has been found in many parts of Spain and Portugal (Morim et al, 2019). We found it for the first time in Morocco and Northern Africa at the Moulouya River mouth This study aimed to evaluate the presence of A. fasciatus or any native Aphanius species in NE Morocco, in parallel with the two invasive species G. holbrooki and F. heteroclitus.…”

Spread beyond the border: Small Scale genetic structure of the introduced Banggai cardinalfish (Pterapogon kauderni) population in the Bali Strait

“…Although further analysis using Tajima's D, and Fu's Fs tests could not confirm the results since these tests were not significant. The founder effect occurs when a new population is formed by individuals from a larger population; this can result in changes to allele frequencies relative to the source population, due to the significant reduction in population size (Johnson et al, 2016;Morim et al, 2019). P. kauderni has been spread outside of its native range, mediated by the living marine aquarium trade (Militz et al, 2016;Rhyne et al, 2012).…”