Abstract
An important step in invasive biology is to assess biological variables that could be used to predict invasion success. The study of genetics, evolution, and interactions of invasive and native species in invaded ranges provides a unique opportunity to study processes in population genetics and the capability of a species' range expansion. Here, we used information from microsatellite DNA markers to test if genetic variation relates to propagule pressure in the successful invasion of an apex predator (the Amazonian cichlid Cichla) into Southeastern Brazilian River systems. Invasive populations of Cichla have negatively impacted many freshwater communities in Southeastern Brazil since the 1960s. Reduction of genetic variation was observed in all invasive populations for both Cichla kelberi (CK) and Cichla piquiti(CP). For instance, heterozygosity was lower in the invasive range when compared to native populations from the Amazon basin (CP HE= 0.179/0.44; CK HE= 0.258/0.536 respectively). Therefore, despite the successful invasion of Cichla in southeast Brazil, low genetic diversity was observed in the introduced populations. We suggest that a combination of factors, such as Cichla's reproductive and feeding strategies, the "evolutionary trap" effect and the biotic resistance hypothesis, overcome their depauperete genetic diversity, being key aspects in this apex predator invasion.
Highlights
Invasive species could be treated as natural experiments that provide a unique opportunity to study basic processes in population genetics and the capability of range expansion (Sakai et al, 2001; Sax et al, 2005)
Peacock bass genetic diversity and invisibility to take place (Okada et al, 2009; Suarez & Tsutsui, 2008). This fact leads to the genetic paradox in invasion biology: how invasive species with low genetic variation due to bottlenecks after founder effects are able to persist and adapt to novel conditions and evolutionary challenges (Allendorf & Lundquist, 2003; Kolbe et al, 2004; Sakai et al, 2001)
We show a heterogeneous pattern of genetic diversity in the invasive range of two species of the apex predator genus Cichla (Fig. 1)
Summary
Invasive species could be treated as natural experiments that provide a unique opportunity to study basic processes in population genetics and the capability of range expansion (Sakai et al, 2001; Sax et al, 2005). Genetic data have been useful to provide information on the frequency in which a species is introduced into a specific area, the size of introductions and the subsequent pattern of genetic structure in the new range (Banks et al, 2010; Carvalho et al, 2009b; Dlugosch & Parker, 2008; Henry et al, 2009) It is yet unclear what role genetics may have in the propagule pressure effect (Allendorf & Lundquist, 2003). Assessing how multiple introductions (i.e., intense propagule pressure), hybridization and genetic diversity are related to the invasive genetic paradigm might provide insights into the high invasibility success and adaptability of Cichla into new habitats and assist in management decisions
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