Quantitative genetic approach for assessing invasiveness: geographic and genetic variation in life-history traits

Abstract

Predicting the spread of invasive species is a challenge for modern ecology. Although many invasive species undergo genetic bottlenecks during introduction to new areas resulting in a loss of genetic diversity, successful invaders manage to flourish in novel environments either because of pre-adaptations or because important traits contain adaptive variation enabling rapid adaptation to changing conditions. To predict and understand invasion success, it is crucial to analyse these features. We assessed the potential of a well-known invader, the Colorado potato beetle (Leptinotarsa decemlineata), to expand north of its current range in Europe. A short growing season and harsh overwintering conditions are apparent limiting factors for this species' range. By rearing full-sib families from four geographically distinct populations (Russia, Estonia, Poland, Italy) at two fluctuating temperature regimes, we investigated (a) possible differences in survival, development time, and body size among populations and (b) the amount of adaptive variation within populations in these traits. All populations were able to complete their development in cooler conditions than in their current range. A significant genotype-environment interaction for development time and body size suggests the presence of adaptive genetic variation, indicating potential to adapt to cooler conditions. The northernmost population had the highest survival rates and fastest development times on both temperature regimes, suggesting pre-adaptation to cooler temperatures. Other populations had minor differences in development times. Interestingly, this species lacks the classical trade-off between body size and development time which could have contributed to its invasion potential. This study demonstrates the importance of considering both ecological and evolutionary aspects when assessing invasion risk

Population dependent effects of photoperiod on diapause related physiological traits in an invasive beetle (Leptinotarsa decemlineata)

“…I did not see any significant population dependent differences in burrowing in response to the topical application treatments, even though the populations strongly differed in respect to photoperiodic response (as in Study I). I therefore conclude that even though a slight population dependent difference was found in H17 receptivity concerning egg production, the overall small differences between the populations indicate that latitudinal variation seen in life-history and physiological traits (Danilevski 1965, de Kort 1990, Boman et al 2008, Study I, II, III, V) are probably not driven by local adaptation in the mechanisms directly related to JH reception. Before drawing final conclusions it would however be important to assess JH titers directly (Zera 2007) to see whether populations differ in baseline JH values (which could explain why they differ in receptivity as well).…”

“…Lastly, to assess whether thermal stress is constraining further range expansion as suggested by my thesis (study II) and other studies (Boman et al 2008, Valosaari et al 2008, Lyytinen et al 2009), a comparative cold tolerance physiology experiment is presently underway. Here two chrysomelid beetles (Agelastica alni and Chrysolina polita) found at high latitude have been investigated together with L. decemlineata.…”

“…The difference between the northern and southern populations was only one day, which might seem fairly ecologically insignificant. It is important to note that the beetles were maintained at optimal growing conditions during the experiment (23 °C) (Alyokhin 2009) and a larger difference between northern and southern populations might have been observed at lower ambient temperatures (see Boman et al 2008, Lyytinen et al 2009). Beetles from the northern population had lighter body weight at emergence in both experiments (I and II).…”

Geographic patterns of genetic diversity from the native range of Cactoblastis cactorum (Berg) support the documented history of invasion and multiple introductions for invasive populations

“…Successful invasion concomitant with low genetic diversity has become known as the ''genetic paradox'' (Frankham 2005). Increasingly, there is evidence that reduction in genetic diversity as measured by neutral markers does not necessarily result in a reduction of adaptive potential (Reed and Frankham 2001;Boman et al 2008;Dlugosch and Parker 2008a, b), but there also is growing evidence that multiple introductions often enhance genetic diversity or that large initial introductions capture much of the native diversity through ''gene pool capture'' (Holland 2001;Novak and Mack 2005;Wares et al 2005;Roman and Darling 2007). In addition, novel combinations of genetic diversity due to hybridization among distantly related populations in the non-native range may contribute to rapid evolution and spread (Kolbe et al 2004;Novak 2007;Lavergne and Molofsky 2007).…”

Traits related to biological invasion: A note on the applicability of risk assessment tools across taxa

“…Growth rate Invasive insects have rapid growth rates compared to natives (Labrie et al 2006, Ward andMasters 2007) A, O Preimaginal (pre-adult) development time Invasive insects have shorter preimaginal development time than natives (Cervo et al 2000, Gamboa et al 2004, Boman et al 2008, Delatte et al 2009); Invasive insects have a longer preimaginal development time than natives (Bonato et al 2007) A, E, O…”