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Heterospecific sociability could enhance invasion success in social species since social non‐natives usually belong to small founding populations during the early stages of invasion. The twospot livebearer (Pseudoxiphophorus bimaculatus) is native to Central America and southern Mexico and is recently recognised as invasive in the Mexican Central Plateau, where it poses a threat to native species. Here, we evaluated twospot livebearer sociability towards either a conspecific pair or a shoal of four fish with one of four possible compositions, all conspecifics or two conspecifics combined with either two guppies, two porthole livebearers or two twoline skiffias. In a second experiment, foraging time, latency to feed, first fish to begin foraging and aggressive interactions were recorded under the same social conditions used in the sociability experiment, with body size included as a covariate in both experiments. All focal twospot livebearers spent significantly more time with the given shoals rather than with the available space in the aquarium. They showed a higher tendency to associate with small shoals of conspecifics than with pairs. Larger twospot livebearers associated more, regardless of the social condition. Twospot livebearer fed more with porthole livebearers, less with guppies and similarly with twoline skiffias. Latency to forage did not vary significantly between social conditions. Twospot livebearers were involved in more aggressive interactions when with guppies or porthole livebearers than when with native twoline skiffias or conspecifics. Twospot livebearers could gain benefits from associating with natives and conspecifics, but not with other invasive poeciliids. Heterospecific shoaling behaviour with natives may enhance invasion success during early stages when conspecifics are scarce while associating with other invasive poeciliids could lead to increased competition. Further research is needed on heterospecific interactions of non‐natives to better understand their behavioural role in invasion likelihood. [ABSTRACT FROM AUTHOR]

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Poeciliids are widely recognized as successful invaders, possessing traits associated with invasion success. Native to Central America and south‐eastern Mexico, the twospot livebearer (Pseudoxiphophorus bimaculatus) is a species recently recognized as invasive in both Central and northern Mexico. Despite its invasive status, limited research exists on its invasion process and the potential threats it poses to native species. In this study, we conducted a comprehensive review of the current knowledge on the twospot livebearer and mapped its current and potential distribution worldwide. The twospot livebearer shares similar traits with other successful invaders within the same family. Notably, it exhibits high fecundity throughout the year and demonstrates resilience to highly polluted and oxygen‐deprived water conditions. This fish serves as a host for several parasites, including generalists, and has been extensively translocated for commercial purposes. Recently, it has also been used for biocontrol within its native range. Apart from existing outside its native range, the twospot livebearer, under current climate conditions and if transported there, could readily colonize biodiversity hotspots in tropical zones worldwide, including the Caribbean Islands, the Horn of Africa, North of Madagascar Island, south‐eastern Brazil, and others located in southern and eastern Asia. Given that this fish is highly plastic and our Species Distribution Model, we consider that all areas with a habitat suitability >0.2 should prevent its arrival and establishment. Our findings underscore the urgent need to recognize this species as a threat to freshwater native topminnows and prevent its introduction and spread. [ABSTRACT FROM AUTHOR]

Human disturbance might be perceived as a threat by animals and interfere in their vital activities. Urbanisation generates changes in habitat structure that allows only a low number of species to adapt, which results in a decrease of species richness and an increase of the abundance of a few dominant species. To survive in urbanised areas, animals need to be highly tolerant to human approximation. One key characteristic of successful invasive species is their high behavioural plasticity. This plasticity could translate to higher chances of surviving in urbanised areas and becoming tough competitors for native species. The Eurasian collared-dove is a successful invader in Europe, it arrived to México during the nineties and has been spreading in the country since. We compared its tolerance to human approximation to that of the already well-established feral pigeon and other native species in agricultural and urban sites. We found the Eurasian collared-dove is less tolerant to humans than the feral pigeon, but more tolerant than native species. Also, we observed that birds showed higher tolerance to humans in urban areas than in agricultural sites, regardless of the species. Interestingly, feral pigeons restrained their distribution to human settlements, and acting as a counterpart, common ground doves were only found in rural sites. However, the Eurasian collared-dove was present also in agricultural areas, which could suggest the Eurasian collared-dove represents a higher threat than the feral pigeon for native species in our study area. We highlight the importance to further understand the behavioural traits that could promote the Eurasian collared-dove invasion to better design management plans for dove diversity in urban areas. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The use of exotic species for pest biocontrol has been a common pathway for introduction and dispersal of invasive species that may have undesired outcomes. Biocontrol agents are believed to be a less damaging alternative than pesticides, but some species may also prey on or parasitize native species or outcompete them for resources. The harlequin ladybird (Harmonia axyridis) is a well-known biocontrol agent originally from Asia that has established invasive populations in 59 countries around the globe. Harlequin ladybirds are generalist predators that in addition to pests prey on an array of different species including other coccinelids’ eggs and larvae. In Mexico, native ladybirds that share ecological requirements with harlequin ladybirds are at risk of being outcompeted and predated upon. The aim of our study was to compare the foraging efficiency of harlequin ladybirds against three species of native coccinelids when preying on aphids. We investigated the foraging behaviour of ladybirds alone and in pairs with a conspecific, a native heterospecific or an exotic heterospecific. We found that the native Cycloneda sanguinea was the species that consumed the most aphids, while Hippodamia convergens was the fastest to find and consume each aphid. Harlequin ladybirds and H. convergens consumed the same number of aphids while P. vittigera consumed less. Conspecific competition was stronger than heterospecific competition. We discuss the suitability of using the exotic invasive harlequin ladybird for aphid biocontrol in comparison with native coccinelids. [ABSTRACT FROM AUTHOR]

Individuals join a group when the benefits of doing so outweigh the disadvantages. Typically, groups are composed by individuals of the same species, as sharing the benefits with relatives dilutes the disadvantages of being part of a group. However, mixed species shoals do occur in the wild. The Mexican Goodeidae are a clade of viviparous topminnows endemic to Central Mexico. Survival of most species is under threat, with some already extinct in nature. Causes of decline include the introduction of exotic species. These include viviparous topminnows of the Family Poeciliidae, such as the Trinidadian guppy (Poecilia reticulata Peters, 1859), as well as the twospot- (Pseudoxiphophorus bimaculatus Heckel, 1848) and porthole livebearer (Poeciliopsis gracilis Heckel, 1848), both native to the Mexican costal slopes but frequently translocated to the central Highlands. Guppies and goodeids readily associate with each other, and guppies entering such associations improve their foraging efficiency. This has been hailed as evidence of a social skill that favours the establishment of viable guppy populations across the globe. It is as yet unknown whether this improvement in guppy foraging efficiency comes at a cost for the interacting goodeids. Here, we investigated how sharing resources with poeciliid invaders affects the foraging efficiency of the goodeid twoline skiffia (Skiffia bilineata Bean, 1887). We measured the time it took them to locate food and the total time spent eating when part of a mixed species shoal that included either a species of exotic poeciliids (guppies, twospot- or porthole livebearers), or another goodeid (Goodea atripinnis). We also measured foraging efficiency of twoline Skiffia in single-species (conspecific) shoals as a control. We found that the total foraging time of twoline skiffias is reduced when shoaling with guppies and twospot livebearers compared to when associating with conspecifics. We provide evidence to support the idea that native species' fitness is reduced when invaders with similar ecological requirements occupy their habitats. [ABSTRACT FROM AUTHOR]

Sociability in animals provides benefits such as reduced predation risk and increased foraging efficiency. During the early stages of invasion, individuals are often vulnerable as part of a small population (Allee effects); associations with native heterospecifics could mitigate some of the disadvantages of small population size and thereby increase the chances of establishment success. Here we explored two potential benefits of heterospecific association to guppies, Poecilia reticulata , a very successful invasive species. We first investigated whether guppies can exploit visual cues from morphologically similar heterospecific individuals as effectively as those from conspecifics. We next tested whether willingness to explore an unfamiliar environment depends on whether guppies are accompanied by conspecifics or heterospecifics. Our results show that guppies can acquire information on food availability from another species, as well as from conspecifics. We also found that guppies engaged in exploratory behaviour more quickly if the habitat had plants in it, and were more likely to associate if it was unstructured; there was, however, no difference in the frequency with which the focal fish was accompanied by a conspecific or a heterospecific individual. These results show that guppies respond to these heterospecifics as they do with conspecifics. Our study reveals some of the traits that could make an invader successful and potentially help to identify species with a higher potential to become established outside their native range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anthropogenic disturbance (built area) increased in the study site over the years. • Species richness and the proportion of exotic species increased with disturbance. • The most diverse families of ruderal flora were Asteraceae, Fabaceae, and Poaceae. • The 16 species that disappeared after 2008 were native. • Thirteen of the exotic species found in the study site are invasive in Mexico. Urbanization creates environmental conditions that hinder the growth of natural vegetation. We surveyed the ruderal vegetation from a periurban university campus in west-central Mexico during the rainy seasons of 2008 and 2016–2018, time during which the campus underwent intensive construction. The built area grew from 4 ha in 2009 to 12.6 ha in 2017. We identified 234 different Angiosperms belonging to 165 genera and 43 families and the community composition changed over time. For example, Asteraceae was replaced by Poaceae as the richest family in 2018. Also, 16 native species found in 2008 disappeared from the study site, 9 of which have been related with low disturbance. In contrast, 98 new species were observed in the latter years, including some that are commonly found in cities. Overall, species richness increased with time, including that of exotic species that increased from 16 % of the total species in 2008 to 24 % in 2018. Thirteen of such exotic species are invasive in Mexico, including Digitaria velutina , Asphodelus fistulosus , Mercurialis annua , and Senecio inaequidens , for which this was their first record in the city of Morelia (population 849,053), where the campus is located. These results suggest that environmental conditions imposed by disturbance can favor the proliferation of various species, especially grasses and several exotic species of different families. [ABSTRACT FROM AUTHOR]

Biological invasions are considered the second major cause of plant, amphibian, reptile, and mammal loss worldwide. Like islands, freshwater ecosystems are especially susceptible to the negative impacts of invasions. The porthole livebearer (Poeciliopsis gracilis), recently identified as invasive in the Mexican Central Plateau, is increasing its populations and could impact freshwater ecosystems like its cousin species the guppy (Poecilia reticulata). Risk-taking behaviours, such as emergence latency, are recognised as key characteristics to invasion success and Poeciliid females can establish a viable population by themselves (due to their multiple paternity broods). We investigated the emergence latency and latency to locate food in simple and complex environments of porthole livebearers, including the effect of their size and sex. For both sexes, bigger fish emerge less times and take longer to do so, but females are faster to exit the refuge than males. We found no differences in porthole livebearer's behaviour in complex or simple habitats, and no significant differences between sex, size or treatment in the time to locate food after exiting the refuge. Our results suggest that the benefit of faster emergence from the refuge in porthole livebearers in novel environments could be higher for females. We consider that porthole livebearer females being bolder could contribute to the invasion success of the species. Our study points at females and smaller fish as being the more likely to explore novel environments, which could contribute to understanding how the invasions by the porthole livebearer are driven., Competing Interests: The authors have declared that no competing interests exist.