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Invasive Species


we research species that move outside of their native distribution


Our research focuses on the ways biological invasions work and how they alter ecosystems


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Apr, 2023

Most invasions start with the introduction of a few individuals and the majority fail to establish and become invasive populations. A possible explanation for this is that some species are subject to Allee effects—disadvantages of low densities—and fail to perform vital activities due to the low availability of conspecifics. We propose that ‘facilitation’ from native individuals to non-natives through heterospecific sociability could enhance chances of the latter establishing in novel environments by helping them avoid Allee effects and even reducing the minimum number of non-native individuals necessary to achieve the density for a viable population (the Allee effect threshold). There is evidence from experiments carried out with freshwater fish, snails, lizards, mussels and bird that supports the idea of heterospecific sociability between native and non-native species as a process to promote invasion success. We propose that to understand invasion success in social non-native species we need to investigate how they integrate into the recipient community. Furthermore, to manage them, it may be necessary to reduce population density not just below the Allee effect threshold but also to understand how natives could help them shift the conspecific Allee effect threshold to their benefit.

This article is part of the theme issue ‘Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes’.

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Feb, 2023

Invasive species represent a threat to biodiversity and ecosystem services and cost millions of dollars to the global economy. The viviparous Mexican fish known as the tequila splitfin (Zoogoneticus tequila) became extinct in the wild as a consequence of habitat loss and degradation, and interactions with invasive species. Tequila splitfins are native to the Teuchitlan River in Central Mexico; they were kept in captivity and reintroduced into their native distribution in 2016. Approximately 80% of the fish in the Teuchitlan River are exotic species, and over 50% are twospot livebearers (Pseudoxiphophorus bimaculatus). We performed an ex-situ mesocosm experiment to explore whether tequila splitfin populations would establish and increase, and how fish would behave when introduced into sites already colonised by other species. We tested this idea by introducing tequila splitfin individuals into empty mesocosms, mesocosms where individuals of the native Ameca splendens had established, mesocosms with individuals of the native Goodea atripinnis and mesocosms with individuals of exotic invasive twospot livebearers. All heterospecific species have been recorded in tequila splitfin's native range, are viviparous fish and share ecological requirements with them. We found that tequila splitfin abundance (number of individuals that survived and new individuals) was greater when sharing mesocosms with native species. Furthermore, they had reduced activity levels when inhabiting mesocosms with exotic invasive twospot livebearers, in comparison, interactions with natives proved to be beneficial. Our results highlight the need to remove exotic invasive species and protect other native species to increase reintroduction success. Close monitoring is needed during the initial stages of the reintroduction, and several reintroduction events from captive breeding facilities may also be necessary. When planning a reintroduction, it is critical to remove exotic species and make an effort to restore the habitat as close as possible to the original conditions.


Nov, 2022

Climate change and biological invasions are two of the major threats to biodiversity. They could act synergistically to the detriment of natives as non-native species may be more plastic and resilient when facing changing environments. The twoline skiffia (Skiffia bilineata) is an endangered Mexican topminnow that cohabits with invasive guppies (Poecilia reticulata) in some areas in central Mexico. Guppies have been found to take advantage from associating with the twoline skiffia and are considered partially responsible for the decline of its populations. Refuge use and exploratory behaviours are trade-offs between being safe from the unknown and the opportunity to explore novel areas in search for better resources or to disperse. The aim of this study is to investigate how a change in temperature affects the refuge use and exploratory behaviours for both species. We found that temperature affects the refuge use of twoline skiffias, and the swimming activity of both species. Skiffias explored the rock more than guppies regardless of the temperature scenario. Also, smaller fish spent more time performing exploratory behaviours than bigger ones. Our study is the first to test the effect of temperature on the refuge use and exploratory behaviour of a goodeid species, and our results contribute to the idea that some natives could be more affected by climate change than some invaders.


Instituto de Ciencias del Mar y Limnología 
Ciudad Universitaria UNAM, Mexico City

+ 52 555 622 5844

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