# Faster Weight Growth in Invasive Mosquitofish Gambusia holbrooki and Gambusia affinis (Poeciliidae) Under Climate Change

## TL;DR

Mosquitofish may grow faster in weight under climate change, especially in certain regions, increasing their threat to native aquatic species.

## Contribution

Identifies climate sensitivity in mosquitofish weight growth and its implications for invasiveness.

## Key findings

- G. affinis populations are more sensitive to climate variation in weight-length allometry than G. holbrooki.
- Climate change is expected to increase weight growth in G. affinis, particularly in East Asia and Eastern Europe.
- Faster weight growth may enhance the invasiveness of mosquitofish, threatening native aquatic ecosystems.

## Abstract

Mosquitofish
Gambusia holbrooki
and
Gambusia affinis
(Poeciliidae) threaten native aquatic diversity globally. Climate change likely increases the body weight and alters the body condition of mosquitofish, resulting in higher invasive ability. The growth of mosquitofish follows the allometric relationship between length (L) and weight (W), which can be estimated as W = aL

b
. The values of the scaling exponent b among global mosquitofish populations range from 2.68 to 3.76, where b > 3 indicates faster growth in weight than in length. The populations with higher values of the scaling exponent b demonstrate stronger body conditions, reproductive ability, and invasiveness. Currently, there is little understanding of how the length‐weight allometries of global mosquitofish populations vary by climate conditions. In this study, we compiled the values of the scaling exponent b of 79 mosquitofish populations from six continents and built generalized least squares and random forest regression models on the scaling exponent b with year of sample, elevation, and 11 bioclimatic variables. We find that the populations of
G. affinis
are more sensitive to climatic variation than
G. holbrooki
in terms of length‐weight allometries. Under climate change, the populations of
G. affinis
, especially those in East Asia and Eastern Europe, are expected to grow faster in weight than in length, posing greater threats to native aquatic diversity. This finding informs the need for early identification and eradication of mosquitofish in newly invaded aquatic ecosystems under climate change.

Global populations of western mosquitofish
G. affinis
are more sensitive to climatic variation than eastern mosquitofish
G. holbrooki
in terms of length‐weight allometries. Under climate change, the populations of
G. affinis
, especially those in East Asia and Eastern Europe, are expected to grow faster in weight, posing greater threats to native aquatic diversity.