skip to main content


This content will become publicly available on December 1, 2024

Title: Global patterns of genomic and phenotypic variation in the invasive harlequin ladybird
Abstract Background

The harlequin ladybirdHarmonia axyridis(Coleoptera: Coccinellidae), native to Asia, has been introduced to other major continents where it has caused serious negative impacts on local biodiversity. Though notable advances to understand its invasion success have been made during the past decade, especially with then newer molecular tools, the conclusions reached remain to be confirmed with more advanced genomic analyses and especially using more samples from larger geographical regions across the native range. Furthermore, althoughH. axyridisis one of the best studied invasive insect species with respect to life history traits (often comparing invasive and native populations), the traits responsible for its colonization success in non-native areas warrant more research.

Results

Our analyses of genome-wide nuclear population structure indicated that an eastern Chinese population could be the source of all non-native populations and revealed several putatively adaptive candidate genomic loci involved in body color variation, visual perception, and hemolymph synthesis. Our estimates of evolutionary history indicate (1) asymmetric migration with varying population sizes across its native and non-native range, (2) a recent admixture between eastern Chinese and American populations in Europe, (3) signatures of a large progressive, historical bottleneck in the common ancestors of both populations and smaller effective sizes of the non-native population, and (4) the southwest origin and subsequent dispersal routes within its native range in China. In addition, we found that while two mitochondrial haplotypes-Hap1 and Hap2 were dominant in the native range, Hap1 was the only dominant haplotype in the non-native range. Our laboratory observations in both China and USA found statistical yet slight differences between Hap1 and Hap2 in some of life history traits.

Conclusions

Our study onH.axyridisprovides new insights into its invasion processes into other major continents from its native Asian range, reconstructs a geographic range evolution across its native region China, and tentatively suggests that its invasiveness may differ between mitochondrial haplotypes.

 
more » « less
Award ID(s):
2147812
NSF-PAR ID:
10502091
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
BMC
Date Published:
Journal Name:
BMC Biology
Volume:
21
Issue:
1
ISSN:
1741-7007
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The genomic variation of an invasive species may be affected by complex demographic histories and evolutionary changes during the invasion. Here, we describe the relative influence of bottlenecks, clonality, and population expansion in determining genomic variability of the widespread red macroalgaAgarophyton vermiculophyllum. Its introduction from mainland Japan to the estuaries of North America and Europe coincided with shifts from predominantly sexual to partially clonal reproduction and rapid adaptive evolution. A survey of 62,285 SNPs for 351 individuals from 35 populations, aligned to 24 chromosome‐length scaffolds indicate that linkage disequilibrium (LD), observed heterozygosity (Ho), Tajima's D, and nucleotide diversity (Pi) were greater among non‐native than native populations. Evolutionary simulations indicate LD and Tajima's D were consistent with a severe population bottleneck. Also, the increased rate of clonal reproduction in the non‐native range could not have produced the observed patterns by itself but may have magnified the bottleneck effect on LD. Elevated marker diversity in the genetic source populations could have contributed to the increasedHoand Pi observed in the non‐native range. We refined the previous invasion source region to a ~50 km section of northeastern Honshu Island. Outlier detection methods failed to reveal any consistently differentiated loci shared among invaded regions, probably because of the complexA. vermiculophyllumdemographic history. Our results reinforce the importance of demographic history, specifically founder effects, in driving genomic variation of invasive populations, even when localized adaptive evolution and reproductive system shifts are observed.

     
    more » « less
  2. Summary

    Biological invasions offer model systems of contemporary evolution. We examined trait differences and evolution across geographic clines among continents of the intertidal grassSpartina alterniflorawithin its invasive and native ranges.

    We sampled vegetative and reproductive traits in the field at 20 sites over 20° latitude in China (invasive range) and 28 sites over 17° in the US (native range). We grew both Chinese and US plants in a glasshouse common garden for 3 yr.

    Chinese plants werec. 15% taller,c. 10% denser, and set up to four times more seed than US plants in both the field and common garden. The common garden experiments showed a striking genetic cline of seven‐fold greater seed set at higher latitudes in the introduced but not the native range. By contrast, there was a slight genetic cline in some vegetative traits in the native but not the introduced range.

    Our results are consistent with others showing that introduced plants can evolve rapidly in the new range.S. alterniflorahas evolved different trait clines in the native and introduced ranges, showing the importance of phenotypic plasticity and genetic control of change during the invasion process.

     
    more » « less
  3. Abstract Aim

    Invasive species are ideal systems for testing geographical differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth,Lymantria dispar disparL. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. The invasion front extends from Minnesota to North Carolina and the ability of this species to adapt to local climate may contribute to its continuing spread. We evaluated the performance of populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.

    Location

    Eastern United States of America

    Taxon

    Lymantria dispar disparL. (Lepidoptera: Erebidae)

    Methods

    Insects from 14 populations across the US invasion front and interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass and larval development time were analysed as a function of source climate (annual mean normal temperature), rearing temperature and their interaction using multiple polynomial regression.

    Results

    With the exception of female development time, there were no significant interactions between source climate and rearing temperature, indicating little divergence in the shape of thermal reaction norms among populations. Source population and rearing temperature were significant predictors of survival and pupal mass. Independent of rearing temperature, populations from warmer climates had lower survival than those from colder climates, but attained larger body size despite similar development times. Larval development time was dependent on rearing temperature, but there were not consistent relationships with source climate.

    Main Conclusions

    Thermal adaptation can be an important factor shaping the spread of invasive species, particularly in the context of climate change. Our results suggest thatL. d. disparis highly plastic, but has undergone climate‐related adaptation in thermal performance and life‐history traits as it spread across North America.

     
    more » « less
  4. Abstract Aim

    Preventing the spread of range‐shifting invasive species is a top priority for mitigating the impacts of climate change. Invasive plants become abundant and cause negative impacts in only a fraction of their introduced ranges, yet projections of invasion risk are almost exclusively derived from models built using all non‐native occurrences and neglect abundance information.

    Location

    Eastern USA.

    Methods

    We compiled abundance records for 144 invasive plant species from five major growth forms. We fit over 600 species distribution models based on occurrences of abundant plant populations, thus projecting which areas in the eastern United States (U.S.) will be most susceptible to invasion under current and +2°C climate change.

    Results

    We identified current invasive plant hotspots in the Great Lakes region, mid‐Atlantic region, and along the northeast coast of Florida and Georgia, each climatically suitable for abundant populations of over 30 invasive plant species. Under a +2°C climate change scenario, hotspots will shift an average of 213 km, predominantly towards the northeast U.S., where some areas are projected to become suitable for up to 21 new invasive plant species. Range shifting species could exacerbate impacts of up to 40 invasive species projected to sustain populations within existing hotspots. On the other hand, within the eastern U.S., 62% of species will experience decreased suitability for abundant populations with climate change. This trend is consistent across five plant growth forms.

    Main Conclusions

    We produced species range maps and state‐specific watch lists from these analyses, which can inform proactive regulation, monitoring, and management of invasive plants most likely to cause future ecological impacts. Additionally, areas we identify as becoming less suitable for abundant populations could be prioritized for restoration of climate‐adapted native species. This research provides a first comprehensive assessment of risk from abundant plant invasions across the eastern U.S.

     
    more » « less
  5. Abstract

    Research conducted during the past two decades has demonstrated that biological invasions are excellent models of rapid evolution. Even so, characteristics of invasive populations such as a short time for recombination to assemble optimal combinations of alleles may occasionally limit adaptation to new environments. Here, we investigated such genetic constraints to adaptation in the invasive brown anole (Anolis sagrei)—a tropical ectotherm that was introduced to the southeastern United States, a region with a much colder climate than in its native Caribbean range. We examined thermal physiology for 30 invasive populations and tested for a climatic cline in cold tolerance. Also, we used genomics to identify mechanisms that may limit adaptation. We found no support for a climatic cline, indicating that thermal tolerance did not shift adaptively. Concomitantly, population genomic results were consistent with the occurrence of recombination cold spots that comprise more than half of the genome and maintain long‐range associations among alleles in invasive populations. These genomic regions overlap with both candidate thermal tolerance loci that we identified using a standard genome‐wide association test. Moreover, we found that recombination cold spots do not have a large contribution to population differentiation in the invasive range, contrary to observations in the native range. We suggest that limited recombination is constraining the contribution of large swaths of the genome to adaptation in invasive brown anoles. Our study provides an example of evolutionary stasis during invasion and highlights the possibility that reduced recombination occasionally slows down adaptation in invasive populations.

     
    more » « less