Unraveling genetic load dynamics during biological invasion: insights from two invasive insect species
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (Arcadia Science)
Abstract
Many invasive species undergo a significant reduction in genetic diversity, i.e. a genetic bottleneck, in the early stages of invasion. However, this reduction does not necessarily prevent them from achieving considerable ecological success and becoming highly efficient colonizers. Here we investigated the purge hypothesis, which suggests that demographic bottlenecks may facilitate conditions (e.g., increased homozygosity and inbreeding) under which natural selection can purge deleterious mutations, thereby reducing genetic load. We used a transcriptome-based exome capture protocol to identify thousands of SNPs in coding regions of native and invasive populations of two highly successful invasive insect species, the western corn rootworm (Chrysomelidae: Diabrotica virgifera virgifera) and the harlequin ladybird (Coccinelidae: Harmonia axyridis). We categorized and polarized SNPs to investigate changes in genetic load between invasive populations and their sources. Our results differed between species. In D. virgifera virgifera, although there was a general reduction in genetic diversity in invasive populations, including that associated with genetic load, we found no clear evidence for purging of genetic load, except marginally for highly deleterious mutations in one European population. Conversely, in H. axyridis, the reduction in genetic diversity was minimal, and we detected signs of genetic load fixation in invasive populations. These findings provide new insights into the evolution of genetic load during invasions, but do not offer a definitive answer to the purge hypothesis. Future research should include larger genomic datasets and a broader range of invasive species to further elucidate these dynamics.
Article activity feed
-
Adult HA were sampled at four sites: two in the native area (Russia [Siberia] and China)
The results certainly seem to suggest these native populations might be bottlenecked too. Is there any indication on how central these sampling locations are to the species native range? Is it possible that the range edge was sampled?
-
In all populations studied and for each species, derived alleles were mostly rare (with frequencies below 0.1)
Site-frequency spectrum plots per population+mutation would quantitatively demonstrate these patterns without the need to arbitrarily bin allele frequency.
-
and a negative correlation between t
This correlation is based on two autocorrelated measures (as theta pi synonymous is measured in both the X and Y axis), so it should be interpreted with caution.
-
crop pest (DVV)
I wonder how much the fact that DVV is a crop pest might influence the results for this species. It would be easy for me to imagine that most DVV populations (native and invasive) have experienced agriculture related bottlenecks and/or population expansions. Pests like corn rootworm have repeatedly adapted to the use of pesticides/GM crops a process which often involved a bottleneck (followed by expansion) and may cause similar effects on the evolution of load in native/invasive populations. Data on the population ecology or local agricultural practices (and history of pest load) may be helpful in figuring if the selective landscape of these populations could have such effects
-
-