skip to main content

This content will become publicly available on May 19, 2024

Title: An island ‘endemic’ born out of hybridization between introduced lineages

Humans have profoundly impacted the distribution of plant and animal species over thousands of years. The most direct example of these effects is human‐mediated movement of individuals, either through translocation of individuals within their range or through the introduction of species to new habitats. While human involvement may be suspected in species with obvious range disjunctions, it can be difficult to detect natural versus human‐mediated dispersal events for populations at the edge of a species' range, and this uncertainty muddles how we understand the evolutionary history of populations and broad biogeographical patterns. Studies combining genetic data with archaeological, linguistic and historical evidence have confirmed prehistoric examples of human‐mediated dispersal; however, it is unclear whether these methods can disentangle recent dispersal events, such as species translocated by European colonizers during the past 500 years. We use genomic DNA from historical museum specimens and historical records to evaluate three hypotheses regarding the timing and origin of Northern Bobwhites (Colinus virginianus) in Cuba, whose status as an endemic or introduced population has long been debated. We discovered that bobwhites from southern Mexico arrived in Cuba between the 12th and 16th centuries, followed by the subsequent introduction of bobwhites from the southeastern USA to Cuba between the 18th and 20th centuries. These dates suggest the introduction of bobwhites to Cuba was human‐mediated and concomitant with Spanish colonial shipping routes between Veracruz, Mexico and Havana, Cuba during this period. Our results identify endemic Cuban bobwhites as a genetically distinct population born of hybridization between divergent, introduced lineages.

more » « less
Award ID(s):
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
Date Published:
Journal Name:
Molecular Ecology
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract Aim

    Introduced species offer insight on whether and how organisms can shift their ecological niches during translocation. The genusAmazonaoffers a clear test case, where sister species Red‐crowned (A. viridigenalis) and Lilac‐crowned Parrots (A. finschi) have established breeding populations in southern California following introduction via the pet trade from Mexico where they do not coexist. After establishment in the 1980s, introduced population sizes have increased, with mixed species flocks found throughout urban Los Angeles. Here, we investigate the differences between the environmental conditions of the native and introduced ranges of these now co‐occurring species.


    Southern California and Mexico.


    Using environmental data on climate and habitat from their native and introduced ranges, we tested whether Red‐crowned and Lilac‐crowned Parrots have divergent realized niches between their native ranges, and whether each species has significantly shifted its realized niche to inhabit urban southern California. We also analysed data from Texas and Florida introductions of Red‐crowned Parrots for comparative analysis.


    There are significant differences in the native‐range niches of both parrot species, but a convergence into a novel, shared environmental niche into urban southern California, characterized by colder temperatures, less tree cover and lower rainfall. Texas and Florida Red‐crowned Parrots also show evidence for niche shifts with varying levels of niche conservatism through the establishment of somewhat different realized niches.

    Main Conclusions

    Despite significant niche shifts, introduced parrots are thriving, suggesting a broad fundamental niche and an ability to exploit urban resources. Unique niche shifts in different U.S. introductions indicate thatAmazonaparrots can adapt to diverse environmental conditions, with cities offering a resource niche and the timing of introduction playing a crucial role. Cities can potentially serve as refugia for threatened parrot species, but the risk of hybridization between species emphasizes the need for ongoing monitoring and genetic investigations.

    more » « less
  2. Abstract

    Seed bank, seed dispersal and historical disturbance are critical factors affecting plant population persistence. However, because of difficulties collecting data on these factors they are often ignored.

    We evaluated the roles of seed bank, seed dispersal and historical disturbance on metapopulation persistence ofHypericum cumulicola, a Florida endemic. We took advantage of long‐term demographic data of multiple populations (22 years; ~11 K individuals; 15 populations) and a wealth of information on burn history (1962–present), and habitat attributes (patch specific location, elevation, area and aggregation) of a system of 92 patches of Florida rosemary scrub. We used previously developed integral projection models to assess the relative ability of simulations with different levels of seed dormancy for recently produced and older seeds and different dispersal kernels (including no dispersal) to predict regional observed occupancy and plant abundance in patches in 2016–2018. We compared a simulation with this model using historical burn history to 500 model simulations with the same average fire regime (using a Weibull distribution to determine the probability of ignition) but with random ignition years.

    The most likely model had limited dispersal (mean = 0.5 m) and the highest dormancy (field estimates × 1.2 %) and its predictions were associated with observed occurrences (67% correct) and densities (20% of variance explained). Historical burn synchrony among neighbouring patches (skewness in the number of patches burned by year = 1.79) probably explains the higher densities predicted by the simulation with the historical fire regime compared with predicted abundances after simulations using random ignition years (skewness = 0.20 +SE= 0.01).

    Synthesis.Our findings demonstrate the pivotal role of seed dormancy, dispersal and fire history on population dynamics, distribution and abundance. Because of the prevalence of metapopulation dynamics, we should be aware of the significance of changes in the availability and configuration of suitable habitat associated with human or non‐human landscape changes. Decisions on prescribed fires (or other disturbances) will benefit from our knowledge of consequences of fire frequency, but also of location of ignition and the probability of fire spread.

    more » « less
  3. Abstract

    Invasive species are a major threat to global biodiversity, yet also represent large‐scale unplanned ecological and evolutionary experiments to address fundamental questions in nature. Here we analyzed both native and invasive populations of predatory northern pike (Esox lucius) to characterize landscape genetic variation, determine the most likely origins of introduced populations, and investigate a presumably postglacial population from Southeast Alaska of unclear provenance. Using a set of 4329 SNPs from 351 individual Alaskan northern pike representing the most widespread geographic sampling to date, our results confirm low levels of genetic diversity in native populations (average 𝝅 of 3.18 × 10−4) and even less in invasive populations (average 𝝅 of 2.68 × 10−4) consistent with bottleneck effects. Our analyses indicate that invasive northern pike likely came from multiple introductions from different native Alaskan populations and subsequently dispersed from original introduction sites. At the broadest scale, invasive populations appear to have been founded from two distinct regions of Alaska, indicative of two independent introduction events. Genetic admixture resulting from introductions from multiple source populations may have mitigated the negative effects associated with genetic bottlenecks in this species with naturally low levels of genetic diversity. Genomic signatures strongly suggest an excess of rare, population‐specific alleles, pointing to a small number of founding individuals in both native and introduced populations consistent with a species' life history of limited dispersal and gene flow. Lastly, the results strongly suggest that a small isolated population of pike, located in Southeast Alaska, is native in origin rather than stemming from a contemporary introduction event. Although theory predicts that lack of genetic variation may limit colonization success of novel environments, we detected no evidence that a lack of standing variation limited the success of this genetically depauperate apex predator.

    more » « less
  4. Abstract Aim

    Refugial isolation during glaciation is an established driver of speciation; however, the opposing role of interglacial population expansion, secondary contact, and gene flow on the diversification process remains less understood. The consequences of glacial cycling on diversity are complex and especially so for archipelago species, which experience dramatic fluctuations in connectivity in response to both lower sea levels during glacial events and increased fragmentation during glacial recession. We test whether extended refugial isolation has led to the divergence of genetically and morphologically distinct species within Holarctic ermine (Mustela erminea), a small cosmopolitan carnivore species that harbours 34 extant subspecies, 14 of which are insular endemics.




    We use genetic sequences (complete mitochondrial genomes, four nuclear genes) from >100 ermine (stoats) and geometric morphometric data for >200 individuals (27 of the 34 extant subspecies) from across their Holarctic range to provide an integrative perspective on diversification and endemism across this complex landscape. Multiple species delimitation methods (iBPP,bPTP) assessed congruence between morphometric and genetic data.


    Our results support the recognition of at least three species within theM. ermineacomplex, coincident with three of four genetic clades, tied to diversification in separate glacial refugia. We found substantial geographic variation within each species, with geometric morphometric results largely consistent with historical infraspecific taxonomy.

    Main conclusions

    Phylogeographic structure mirrors patterns of diversification in other Holarctic species, with a major Nearctic‐Palearctic split, but with greater intraspecific morphological diversity. Recognition of insular endemic speciesM. haidarumis consistent with a deep history of refugial persistence and highlights the urgency of mindful management of island populations along North America's North Pacific Coast. Significant environmental modification (e.g. industrial‐scale logging, mining) has been proposed for a number of these islands, which may elevate the risk of extinction of insular palaeoendemics.

    more » « less
  5. Abstract

    The ecosystem engineer onuphid polychaeteDiopatra biscayensishas a continuous population in the Bay of Biscay from the Cantabria coast in Spain to southern Brittany in France. A group of disjunct populations also are found in the English Channel, separated from the Biscay population by more than 400 coastal kilometers. It remains unclear whetherD. biscayensisis native to the Bay of Biscay; it is also debated whether the disjunct populations in the English Channel are relics of a formerly continuous population, or the product of recent introductions through aquaculture. Here, we use climate hindcasts to explore hypotheses about theD. biscayensishistorical distribution in Europe. IfD. biscayensisis native, its range would have been restricted to southern Iberia and the Mediterranean during the Last Glacial Maximum (21,000BP). However, the species is completely absent from both regions today, further supporting its interpretation as a non‐native species. If it was historically present in Europe, the climate hindcasts are congruent with range contraction in the Last Glacial Maximum (21,000BP), expansion in the Mid‐Holocene Warm Period (6000BP), and contraction again in the past 1000 years (850–1850), prior to the first reports ofD. biscayensison the Spanish and French Atlantic coasts. However, the simulations do not support there being climatic refugia along the English Channel coast that would account for the existence of relic populations. Taken together, the evidence suggests thatD. biscayensishas been introduced to the Bay of Biscay, and that disjunct populations in the English Channel are the result of recent transport through human activities, perhaps aquaculture.

    more » « less