Selection on mitochondrial variants occurs between and within individuals in an expanding invasion

Mitochondria are critical for life, yet their underlying evolutionary biology is poorly understood. In particular, little is known about interaction between two levels of evolution: between individuals and within individuals (competition between cells, mitochondria or mitochondrial DNA molecules). Rapid evolution is suspected to occur frequently in mitochondrial DNA, whose maternal inheritance predisposes advantageous mutations to sweep rapidly though populations. Rapid evolution is also predicted in response to changed selection regimes after species invasion or removal of pathogens or competitors. Here, using empirical and simulated data from a model invasive bird species, we provide the first demonstration of rapid selection on the mitochondrial genome within individuals in the wild. Further, we show differences in mitochondrial DNA copy number associated with competing genetic variants, which may provide a mechanism for selection. We provide evidence for three rarely documented phenomena: selection associated with mitochondrial DNA abundance, selection on the mitochondrial control region, and contemporary selection during invasion.

ID scanners and überveillance in the night-time economy: crime prevention or invasion of privacy?

ID scanners are promoted as an effective solution to the problems of anti-social behavior and violence in many urban nighttime economies. However, the acceptance of this and other forms of computerized surveillance to prevent crime and anti-social behavior is based on several unproven assumptions. After outlining what ID scanners are and how they are becoming a normalized precondition of entry into one Australian nighttime economy, this chapter demonstrates how technology is commonly viewed as the key to preventing crime despite recognition of various problems associated with its adoption. The implications of technological determinism amongst policy makers, police, and crime prevention theories are then critically assessed in light of several issues that key informants talking about the value of ID scanners fail to mention when applauding their success. Notably, the broad, ill-defined, and confused notion of "privacy" is analyzed as a questionable legal remedy for the growing problems of überveillance.

Restricting access to invasion hubs enables sustained control of an invasive vertebrate

Biological invasions often occur through expansion of satellite populations that become established at 'invasion hubs'. Invasion hubs can result from random dispersal events, but frequently arise when invading individuals actively choose habitats using cues that signify high-quality environments where the fitness consequences are positive. Theoretical studies suggest that targeted control at invasion hubs can effectively suppress the populations and impacts of invaders. In arid Australia, small dams that provide water for livestock function as invasion hubs by providing an invasive vertebrate, the cane toad Rhinella marina, with refuge from extreme aridity during the annual dry season. Toads are attracted to dams and use them as stepping stone habitats from which they disperse during rainy periods. Here, we ask whether sustained control of this invasive vertebrate can be achieved by converting invasion hubs into ecological traps. We did this by manipulating invasion hub habitats to induce a mismatch between toads' habitat preference and the fitness consequences of their habitat choice to cause high mortality. We constructed fences to exclude toads from dams and maintained these fences for 1 year. This period encompassed periods of dry and wet seasonal climatic conditions. Our manipulation did not alter the attractive cues for invading toads which died en masse while attempting to settle at fenced dams that prevented toads from reaching water. Toad populations at the fenced dams were suppressed by 1-2 orders of magnitude compared to unfenced controls and procedural controls. Toad populations remained suppressed for a year after exclusion. By excluding toads from dams, we converted invasion hubs into ecological traps and effectively thwarted the reinvasion of cane toads. Our research suggests that water exclusion devices could be used to prevent toad invasion or to control cane toad populations in arid landscapes colonized by toads. Synthesis and applications. Our study demonstrates that sustained control of invader populations can be achieved by restricting their access to invasion hubs. Control of invasive species via elimination of invasion hubs could be conducted reactively, to control established populations of invaders, or conducted strategically, by rendering invasion hubs unsuitable for colonization ahead of the invasion front to prevent further population spread.

Genetic analysis along an invasion pathway reveals endemic cryptic taxa, but a single species with little population structure in the introduced range

The invasion pathways of pest arthropods can be traced using genetic tools to develop an understanding of the processes that have shaped successful invasions and to inform both pest management and conservation strategies in their non-native and native ranges, respectively. The redlegged earth mite, Halotydeus destructor, is a major economic pest in Australia, successfully establishing and spreading after arrival from South Africa more than 100 years ago. Halotydeus destructor has recently expanded its range and evolved resistance to numerous pesticides in Australia, raising questions around its origin and spread. Location: South Africa and Australia. Methods: We sampled H. destructor populations in South Africa and Australia and developed a microsatellite marker library. We then examined genetic variation using mtDNA and microsatellite markers across both native and invasive ranges to determine endemic genetic diversity within South Africa, identify the likely origin of invasive populations and test genetic divergence across Australia. Results: The data show that H. destructor comprises a cryptic species complex in South Africa, with putative climatic/host plant associations that may correspond to regional variation. A lineage similar to that found near Cape Town has spread throughout Western and eastern Australia, where populations remain genetically similar. Main conclusions: Tracing the invasion pathway of this economically important pest revealed cryptic lineages in South Africa which points to the need for a taxonomic revision. The absence of significant genetic structure across the wide invasive range of H. destructor within Australia has implications for the development (and spread) of pesticide resistance and also points to recent local adaptation in physiological traits.