Climatic and geographic variation as a driver of phenotypic divergence in reproductive characters and body sizes of invasive Gambusia holbrooki

Abstract

Understanding the invasion success of alien species includes developing knowledge on how the biological traits of their populations respond to spatial differences in environmental conditions. For invasive fishes, while the influence of latitudinal and climatic gradients on their biological traits over large spatial scales are well established, there is less certainty in how these vary over smaller scales. Here, we tested the influence of a climatic and geographic gradient on the reproductive traits and body sizes of the invasive mosquito fish Gambusia holbrooki across five climatic regions in Turkey. The results revealed that the environmental conditions across eight sites provided two gradients: a latitudinal gradient (where northern sites were cooler with less rainfall) and a coastal-inland gradient (where changes were apparent from coastal areas and into inland areas). These gradients had marked effects on the traits of both sexes, in sites in coastal and southern areas, male had significantly larger gonopodia and females had higher egg numbers than in inland and warmer areas, and with both sexes having body sizes that were smaller. The spatial differences in the male traits were suggested as being driven by differences in selection pressures at the sites that related to differences in their population abundances. The results revealed that environmental conditions across a relatively small spatial scale had some strong influences on the expression of specific biological traits of these mosquito fish populations, but with further work needed to test how these influences affect their invasion success.

Contemporary perspectives on the ecological impacts of invasive freshwater fishes

“…However, empirical evidence supporting this assumption is weak due to most abundance-impact studies only testing invader absence versus high invader density (e.g., Britton et al, 2010a). Yet the population abundances of an invasive fish can vary considerably across their range due to being affected by a wide range of abiotic and biotic characteristics (e.g., Kurtul et al, 2022). Testing of invader abundance versus ecological impact often indicates these relationships are nonlinear (Elgersma & Ehrenfeld, 2011;Kornis et al, 2014), with Yokomizo et al (2009) suggesting four relationships potentially exist: linear, S-shaped, low-threshold and high-threshold.…”

Decadal‐scale regional variability in monitoring efforts significantly influences fish diversity trends in the Euphrates and Tigris catchments, Türkiye

“…Similarly, the Asian stinging catfish ( H. fossilis ) was introduced to the Tigris catchment for the first time within the second half of the 1950s in southern Iraq (Zakaria, 1964) and recorded for the first time in Türkiye in 2011 (Ünlü et al, 2011). Considering that the Eastern mosquitofish ( G. holbrooki ) was also identified in the Euphrates catchment, it is likely that it will or already has spread substantially (Kurtul et al, 2022). The Eastern mosquitofish is recognized for its harmful effects on indigenous fish populations (Pyke, 2008; Kurtul et al, 2024), which introduces a critical spatial and temporal aspect to the significance of including non‐native species in biodiversity evaluations, particularly in biodiversity‐rich regions such as Mesopotamia.…”

Predicting the potential implications of perch (Perca fluviatilis) introductions to a biodiversity-rich lake using stable isotope analysis

“…This could be attributed to a combination of factors, including differences in habitat preferences, feeding behavior, and size 47 , 48 . Some species, such as Gambusia holbrooki , Capoeta tinca , and Salaria fluviatilis , occupy different ecological niches or exhibit specific adaptations that reduce their vulnerability to predation by perch 49 – 52 . It is important to note that gobiid species like Proterorhinus semilunaris , are highly unlikely to occur in reservoirs located in remote areas established for irrigation purposes due to their incompatible habitat requirements 53 .…”