Alfredo Ojanguren - Academia.edu (original) (raw)

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Papers by Alfredo Ojanguren

Freshwater Biology, Feb 14, 2023

Invasive species represent a threat to biodiversity and ecosystem services and cost millions of d... more 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.

Behaviour, 2014

Animals gain benefits by forming groups with phenotypically and behaviourally similar individuals... more Animals gain benefits by forming groups with phenotypically and behaviourally similar individuals. The most common groups are homogenous, composed by conspecifics, although in some cases associations of similar organisms of different species have been reported when individuals benefit from it. In this study, we tested the prediction that the Trinidadian guppy, Poecilia reticulata, a fish that has successfully invaded at least 70 countries, will shoal with heterospecifics. We measured shoaling tendency and shoal companion preference in wild-caught female guppies when they encounter two heterospecific species: the native Poecilia picta and the non-native Poecilia sphenops, a poeciliid recently introduced in Trinidad. Our results show that guppies have a higher tendency to shoal with conspecifics; if the alternative is be alone, they readily shoal with both species even when they have had no previous experience with other poeciliids. Individuals in these associations could benefit from...

Marine Ecology Progress Series, 2009

Journal of Thermal Biology, 2001

Journal of Animal Ecology, 2011

Aquaculture International, 1999

Behaviour, 2009

Social behaviour is critical for survival and fitness in many organisms. The aim of this study wa... more Social behaviour is critical for survival and fitness in many organisms. The aim of this study was to examine the effects of developmental state, physiological state and their differences between individuals on the intensities of aggressive and grouping behaviours in red drum (Sciaenops ocellatus) larvae. Body size was used as a proxy for developmental state and body condition (i.e., residual of wet weight from the relationship between body size and wet weight) as a measure of physiological condition. Social interactions between two fish were observed for 30 min in a 9-l tank. We found that the duration of grouping behaviour increased as body size increased, but aggressive behaviour was less frequent as body size and condition increased. The larger fish in a trial tended to be aggressive to the smaller one, and fish of similar sizes tended to show grouping behaviour. Fish that more frequently displayed aggressive behaviours tended to occupy the lower part of the water column. Body s...

Emergence from the gravel nest represents an important ontogenetic niche switch for salmonid fish... more Emergence from the gravel nest represents an important ontogenetic niche switch for salmonid fishes (Elliott, 1989). During this phase, juveniles should compete for territories, which provide profitable feeding positions and protection against predators. Larger body size would be advantageous by increasing the ability for territorial competition, and by reducing the vulnerability to predation. A recent study on Atlantic salmon have demonstrated that selection may favour larger body size and early emergence (Einum & Fleming, 2000). According to Atkinson’s (1994) general rule for ectotherms, increased rearing temperature will increase both developmental and growth rates, but will reduce the size at a given ontogenetic stage. Thus, thermal environment during the embryonic development can be an influential factor affecting the whole life cycle of ectotherms. The aim of this study was to assess the effect of incubation temperature on embryo survival and growth during the endogenous feedi...

Journal of Fish Biology, 2000

ABSTRACT The maximum swimming stamina of hatchery reared juvenile brown trout Salmo trutta, swimm... more ABSTRACT The maximum swimming stamina of hatchery reared juvenile brown trout Salmo trutta, swimming against a fixed-velocity water flow of 36·6 cm s-1 (6·97 L s-1), was achieved at 16·1° C, and a 90% performance level occurred over a breadth of 7·7° C (12·2–19·9° C). The wide range of temperatures at which swimming performance is close to the maximal capacity could be a consequence of the implications for survival of this function.

PeerJ, 2017

Predation is the main cause of mortality during early life stages. The ability to avoid and evade... more Predation is the main cause of mortality during early life stages. The ability to avoid and evade potential threats is, therefore, favoured to evolve during the early stages of life. It is also during these early stages that the process of familiarization occurs. It has long been recognized that associating with familiar individuals confers antipredator benefits. Yet gaps in our knowledge remain about how predator evasion is affected by social experience during early stages. In this study, we test the hypothesis that familiarization acquired during early life stages improves escape responses. Using the guppy Poecilia reticulata, we examine the effect of different recent social conditions in the three main components of predator evasion. Using high-speed motion analysis, we compared the number of individuals in each test group that responded to a visual stimulus, their reactive distance and magnitude of their response (maximum speed, maximum acceleration and distance) in groups compo...