Is bolder better? The influence of personality on competitive success and predation susceptibility in the invasive round goby (Neogobius melanostomus)

Abstract

Invasive species are currently one of the main causes of biodiversity loss across the globe and recent research has shown that the personality of an invader can have significant impacts on the invasion dynamics for that species. Therefore, this study examined the impact of personality on both competitive success and predation susceptibility of the highly invasive round goby (Neogobius melanostomus). Boldness was measured as the time to return to normal behavior after a simulated predation strike. Fish with shorter panic times were categorized as “bold”, fish with longer times were categorized as “shy”, and those who fell in between these two categories were determined to be “intermediate”. Competitive impacts of personality were determined in a laboratory experiment in which intra- (intermediate round goby) and interspecific (juvenile Atlantic cod, Gadus morhua) competitors were exposed to both bold and shy round goby competitors. Predation susceptibility of bold and shy personality-type round gobies was determined in a predator preference experiment. Results from the competition experiment showed that interspecific competitors consumed fewer prey when competing with bolder round gobies than when competing with shy round gobies. Bold and shy treatment gobies consumed similar amounts of prey, and the number of interactions between competitors did not vary depending on the personality of the treatment round goby. Results from the predation experiment indicated a trend of increased susceptibility to predation by adult Atlantic cod for bold round gobies over shy round gobies, but it was not statistically significant. These results show that personality mediates competitive interactions within the round goby, and suggests that the high proportions of bold individuals found along invasion fronts in this species may have stronger-than-population-average impacts on native communities, potentially facilitating the further invasion of the round goby.

Popular Abstract

Boldness makes for a better invader

Invasions of non-native species are currently one of the largest threats to global biodiversity. Introductions of these species result in both severe economic and ecological harm, as invaders outcompete native species and disrupt normal ecosystem processes in the habitats to which they are introduced. Therefore, it is vitally important that ecologists and others working to limit the further spread of invasive species understand the dynamics and processes by which these invasions actually occur.

Research from recent decades has shown that consistent differences between animal individuals for a wide range of personality traits have important consequences for an individual’s life history. Individuals who are more aggressive, or bolder than others may have better access to resources such as food, shelter or mates. However, at the same time, these bold or aggressive behaviors may increase that same individuals likelihood of being consumed by a predator. So, might these kinds of personality differences also impact the invasion dynamics of non-native species?

Originally from the Caspian Sea region, the round goby is a prolific invasive fish now found across much of Europe, the Baltic Sea region, as well as the Great Lakes region in North America. Additionally, invasion fronts of this species are known to contain high proportions of bold individuals. Therefore, in this study I examined the competitive impacts of bold and shy personality round gobies on both intermediate-personality round gobies as well as Atlantic cod. Secondly, I examined personality dependent predation susceptibility by exposing groups of bold and shy round gobies to a predator.

Results from the competition experiment show that Atlantic cod eat less when competing with bold gobies than they do when competing with shy gobies, while no such trend was seen in the intermediate-personality round gobies. Results from the predation experiment show no increased susceptibility to predation for either personality-type.

This study provides strong evidence that the bold-biased invasion fronts seen in the round goby have the capability of exerting stronger-than-population-average impacts on the native competitors and communities that this invader comes into contact with. Such impacts may in turn generate negative fitness consequences for inferior competitors, which would likely positively influence further invasions of the round goby. Additionally, this study provides insights into how round goby populations are regularly recorded at high densities despite the species known aggressive nature. It appears that there are other mechanisms at play that mediate the impact of personality on competition between individual round gobies. This resulting tolerance for members of the same species is likely another aspect of round goby life history that aides this species success as one of Europe’s top 100 worst invasive species.

Master’s Degree Project in Biology 60 credits 2018
Department of Biology, Lund University
Advisors: Anders Nilsson & Anders Persson
Aquatic Ecology Department

• author: Ericsson, Philip
• supervisor: Anders Nilsson; Anders Persson
• organization: Degree Projects in Biology
• course: BIOP01 20172
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Biology and Life Sciences
• language: English
• id: 8952942
• date added to LUP: 2018-06-27 08:22:27
• date last changed: 2018-06-27 08:22:27