Courtship Display Persists Despite Early Social Deprivation

The effects of familiarity on escape responses in the Trinidadian guppy (Poecilia reticulata)

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 composed either of familiar or non-familiar individuals. Contrary to the prediction, groups composed of familiar individuals were less responsive than groups of unfamiliar individuals. Reactive distance and magnitude of response were more dependent on individual size rather than on familiarity. Larger individuals reached higher maximum speeds and total distances in their escape response. Our result indicates that familiarity is likely to affect behaviour earlier in a predator-prey interaction, which then affects the behavioural component of the response. Taken together, our study contributes to previous ones by distinguishing which components of an escape response are modulated by familiarity.

Strategic exploitation of fluctuating asymmetry in male Endler's guppy courtship displays is modulated by social environment

Lateral asymmetry in signalling traits enables males to strategically exploit their best side. In many animals, both body colouration and fluctuating asymmetry are signals of male attractiveness. We demonstrated experimentally that even sexually naïve male Poecilia wingei were able to identify their most attractive side (i.e. that with a higher proportion of carotenoid pigmentation) and use it preferentially during courtship. Notably, males retained their strategic signalling in a male-biased social environment, whereas they ceased to signal strategically in a female-biased environment. The degree of asymmetry in colouration did not affect overall courtship activity. Strategic lateralization in courtship displays was strongest and most repeatable in the male-biased social environment where males competed with rivals for matings. Individual asymmetry in colouration changed considerably over a period of 3 months. This suggests that colouration is a dynamic feature during adulthood and that males are capable of tracking and strategically exploiting their lateral asymmetry in accordance with their social environment.

Forced monogamy in a multiply mating species does not impede colonisation success

BACKGROUND

The guppy (Poecilia reticulata) is a successful invasive species. It is also a species that mates multiply; previous studies have demonstrated that this strategy carries fitness benefits. Guppies are routinely introduced to tanks and troughs in regions outside their native range for mosquito-control purposes, and often spread beyond these initial confines into natural water bodies with negative ecological consequences. Here, using a mesocosm set up that resembles the containers into which single guppies are typically introduced for mosquito control, we ask whether singly-mated females are at a disadvantage, relative to multiply-mated females, when it comes to founding a population. Treatments were monitored for one year.

RESULTS

A key finding was that mating history did not predict establishment success, which was 88% in both treatments. Furthermore, analysis of behavioural traits revealed that the descendants of singly-mated females retained antipredator behaviours, and that adult males showed no decrease in courtship vigour. Also, we detected no differences in behavioural variability between treatments.

CONCLUSIONS

These results suggest that even when denied the option of multiple mating, singly-mated female guppies can produce viable populations, at least at the founder stage. This may prove to be a critical advantage in typical introduction scenarios where few individuals are released into enclosed water bodies before finding their way into natural ecosystems.