engleski

Competitive pressure from conspecifics underlies the behavioural gradient and population dynamics along the expanding range of an invasive species

Biological invasions are a major component of rapid environmental change, causing dramatic distributional changes of both native and non-native taxa. While numerous studies addressed potential mechanisms that drive range expansions, our understanding of these processes remains limited. Beneficial traits that exhibit natural variation and aid in the invasion process should exhibit a gradient across the expansion range and be more pronounced in individuals at the expansion front. We examined differences in aggression levels – a behavioral trait considered advantageous both in novel environment and for maintaining population dynamics ; body condition and reproductive investment of the signal crayfish (Pacifastacus leniusculus). This species is a successful invader of European freshwaters that is also actively expanding its range in Croatia. Rather than favouring expansion, higher aggression was more pronounced in established populations at the invasion core, suggesting its potential advantages in populations with scarce resources, such as competition in conditions of high population density. Furthermore, individuals from invasion fronts possessed better body condition and exhibited a higher reproductive investment compared to established populations from the invasion core. Reduced competitive pressure from conspecifics at the invasion front likely led to less aggressive interactions and allowed for higher fitness and reproductive investment. These findings highlight the role of competitive pressure from conspecifics in regulation of population dynamics during range expansion of invasive species.

range expansion; dispersal mechanisms; invasive crayfish; freshwater invasion

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