What can DNA tell us about biological invasions?

Abstract

It is often hoped that population genetics can answer questions about the demographic and geographic dynamics of recent biological invasions. Conversely, invasions with well-known histories are sometimes billed as opportunities to test methods of population genetic inference. In both cases, underappreciated limitations constrain the usefulness of genetic methods. The most significant is that humancaused invasions have occurred on historical timescales that are orders of magnitude smaller than the timescales of mutation and genetic drift for most multicellular organisms. Analyses based on the neutral theory of molecular evolution cannot resolve such rapid dynamics. Invasion histories cannot be reconstructed in the same way as biogeographic changes occurring over millenia. Analyses assuming equilibrium between mutation, drift, gene flow, and selection will rarely be applicable, and even methods designed for explicitly non-equilibrium questions often require longer timescales than the few generations of most invasions of current concern. We identified only a few population genetic questions that are tractable over such short timescales. These include comparison of alternative hypotheses for the geographic origin of an invasion, testing for bottlenecks, and hybridization between native and invasive species. When proposing population genetic analysis of a biological invasion, we recommend that biologists ask (i) whether the questions to be addressed will materially affect management practice or policy, and (ii) whether the proposed analyses can really be expected to address important population genetic questions. Despite our own enthusiasm for population genetic research, we conclude that genetic analysis of biological invasions is justified only under exceptional circumstances.

Genetic evaluation of an attempted Rattus rattus eradication on Congo Cay, U.S. Virgin Islands, identifies importance of eradication units

“…Wright's F-statistics), may not be valid as these conditions may require long timescales. Furthermore, if there is gene flow and populations are not sufficiently genetically differentiated, it becomes increasingly difficult to match individuals to their source population (Manel et al 2005;Muirhead et al 2008;Fitzpatrick et al 2012). Thus, in our system, where we appeared to have low but ongoing gene flow between Lovango and Congo and low levels of polymorphism, even if we had pre-eradication samples, it may have been difficult to distinguish between the two hypotheses of a failed eradication versus recolonization.…”

“…However, several papers have cautioned about the potential limitations of genetic analyses (e.g. Manel et al 2005;Chikhi et al 2010;Fitzpatrick et al 2012). For instance, inferences based on genetic methods that assume equilibrium conditions (e.g.…”

Clonal structure and reduced diversity of the invasive alien plant Erigeron annuus in Lithuania

“…The use of a two-marker system is especially important for polyploids such as E. annuus (triploid) because part of the genotype diversity in polyploid species may be masked by the dominant character of particular RAPD, AFLP or ISSR markers [30]. Only a coincidence of results between two or more marker systems can eliminate arguments about the suitability of such markers for invasive plant studies [10,27,35]. In our study, there was a significant correlation (r=0.91, P<0.05) between genetic distances among populations established using RAPD and ISSR data.…”

Potential of genomic approaches in conservation of plant and animal biodiversity in Africa: A review

“…This makes conservation of plant and animal biodiversity very easier, and thus reducing the rate of biodiversity loss and even extinction from the wild (Hongbo et al 2015). Genomics has enabled studies of how climate change has limited biodiversity by looking at DNA of ancient preserved specimens of plants and animals to understand, and how biodiversity has changed with time (Fitzpatrick et al 2012;Johnson and Koepfli, 2014;McMahon et al 2014;). These techniques can further inform sound policy decisions for conservation and management of wildlife biodiversity against climate change effect.…”