Benoni H. Seghers

Sexual Conflict as a Consequence of Ecology: Evidence from Guppy, Poecilia reticulata, Populations in Trinidad

An investigation of the behaviour of guppies, Poecilia reticulata, in the wild reveals that sexual conflict varies markedly in different habitats. Males from high-predation sites in Trinidad (where the pike cichlid Crenicichla alta occurs) engage in less antipredator behaviour than females, have lower foraging rates than males from low-risk sites and are able to devote a greater proportion of their time to pursuing females and attempting sneaky matings. As a result, females in such locations receive approximately one sneaky mating attempt per minute. Female behaviour in high-predation sites is thus constrained not only by their own predator avoidance but also by sexual harassment which is itself an indirect consequence of risk. Sexual harassment is likely to compromise female choice and may have significant evolutionary consequences.

A Cost of Sexual Harassment in the Guppy, Poecilia reticulata

Male guppies in wild Trinidadian populations devote a large proportion of their time to pursuing females, and females, as a result, are frequent targets of sneaky mating attempts. In this paper we demonstrate a cost, in terms of lost feeding opportunities, to these female recipients of sexual harassment. An experiment in pools of a Trinidadian stream manipulated sex ratio and fish density within the ranges naturally occurring in the system. We found that sexual harassment (from males) led to a 25% decrease in foraging beyond that which occurred as a result of female competition. Because the fecundity of female fish is a product of their feeding success, reductions in food intake have potentially serious fitness consequences.

Variation in Schooling and Aggression Amongst Guppy (Poecilia Reticulata) Populations in Trinidad

Schooling behaviour is an effective defence against predation but, since it depends on coordinated behaviour, it may restrict individual competition for limited resources. We tested the hypothesis that levels of individual aggression will be reduced in fish with a high schooling tendency by comparing the behaviour of guppies, Poecilia reticulata, from eight Trinidad populations. Schooling tendency was assayed in the wild. Fish were then transferred to the laboratory where aggression was measured when groups of eight males foraged on a small, but profitable, food patch. An inverse relationship between schooling tendency and intensity of aggression emerged. Guppies from populations without fish predators displayed a wide range of aggressive behaviours including active patch defence by the most dominant individual. Conversely, populations experiencing high predation, and with well-developed schooling behaviour, showed little aggression. Female guppies (three population tested) also varied in level of aggression and aggression was present in laboratory-bred as well as wild-caught fish. Individual aggression increased with group size but was independent of tank size. These results point towards a trade-off between antipredator behaviour and resource defence and confirm that schooling has associated costs as well as benefits.

Behavioural Consequences of an Artificial Introduction of Guppies (Poecilia reticulata) in N. Trinidad: Evidence for the Evolution of Anti-Predator Behaviour in the Wild

Experimental transplants are a particularly effective way of assessing the significance of natural selection in the wild and have been successfully employed in the past to determine how the colour patterns and life histories of guppies, Poecilia reticulata, in Trinidad, evolve in response to predation. In this paper we investigate an existing inter-drainage transplant of guppies, undertaken by C. P. Haskins in 1957, to ascertain whether a change in predation pressure also leads to changes in behaviour. We show that inherited behaviour patterns, specifically schooling and predator inspection, are modified by selection. In addition, we document inter-drainage differences in behaviour that cannot readily be attributed to variation in predation regime.

Risk sensitive courtship in the guppy (Poecilia reticulata)

This study investigated population differences in the courtship behaviour of male guppies, Poecilia reticulata, in the presence and absence of predators. Two Trinidad populations were compared: the Lower Aripo where guppies occur sympatrically with a range of piscivores and the Upper Aripo where levels of fish predation are low. Upper Aripo males displayed risk-reckless courtship behaviour and did not reduce their sigmoid display rate or otherwise modify their courtship behaviour when threatened by two Astyanax bimaculatus. The courtship behaviour of the Lower Aripo males was, by contrast, risk sensitive. These fish performed a lower proportion of sigmoid displays and increased their level of sneaky mating attempts in the presence of predators. Although males from the two populations used both sneaky and conventional courtship behaviours there were individual differences in the use of the reproductive tactics.

Population differences in predator recognition and attack cone avoidance in the guppy Poecilia reticulata

Abstract The level of predatory threat encountered by fish may vary from population to population. In Trinidad, for example, guppies in the Lower Aripo River encounter a range of fish predators. Guppies from the Paria River, by contrast, encounter few fish predators but probably experience a high degree of predation from freshwater prawns, Macrobrachium spp. Predation risk from all types of aquatic predators is low for guppies from the Upper Aripo River. Inspection behaviour allows prey fish to recognize and assess potential predators. The risk associated with this behaviour can be minimized if the attack cone around the predators jaws is avoided. This experiment investigated attack-cone avoidance behaviour during inspection of either a fish predator, Rivulus hartii or a macrobrachium, M. crenulatum , by wildcaught guppies. Inspecting Lower Aripo guppies kept a large distance between themselves and the rivulus. They also selectively avoided the dangerous mouth region. These Lower Aripo guppies did not, however, display attack-cone avoidance in the presence of the macrobrachium. Guppies from the Paria population were most wary when inspecting the macrobrachium. Upper Aripo guppies showed no attack-cone avoidance and displayed poor recognition of both predators. The results demonstrate that fish skilled at dealing with one type of predator gain no automatic advantage when faced with a novel predator. They also show that fish exposed to high levels of predation in the wild will not necessarily be more cautious in circumstances where the level of danger is unknown.

PREDATOR INSPECTION BEHAVIOUR COVARIES WITH SCHOOLING TENDENCY AMONGST WILD GUPPY, POECILIA RETICULATA, POPULATIONS IN TRINIDAD

When fish inspect a predator they incur risk. One way of reducing the cost of inspection is to approach predators in groups large enough to benefit from the safety in numbers advantages of schooling. In a survey of nine populations of guppies, Poecilia reticulata, in their native streams in Trinidad, we observed marked variation in schooling behaviour. Guppies from sites also inhabited by a major predator, the pike cichlid, Crenicichla alta, devoted more time to schooling than those from less dangerous locations where the cyprinodont Rivulus hartii was present. We found a strong correlation between schooling tendency and the group sizes adopted by guppies inspecting a realistic model predator. Since guppies in dangerous localities approached a potential predator in large groups it seems unlikely that many of these fish were caught in a Prisoners Dilemma. Inspections by singleton fish were rare in high-risk locations but predominated in those populations where risk from fish predators was reduced.

Evolution of adaptive variation in antipredator behaviour

Evolution of adaptive variation in antipredator behaviour Anne E. Magurran , Benoni H. Seghers , Gary R. Carvalho & Paul W. Shaw To cite this article: Anne E. Magurran , Benoni H. Seghers , Gary R. Carvalho & Paul W. Shaw (1993) Evolution of adaptive variation in antipredator behaviour, Marine & Freshwater Behaviour & Phy, 23:1-4, 29-44, DOI: 10.1080/10236249309378855 To link to this article: https://doi.org/10.1080/10236249309378855

Genetic Consequences of an Artificial Introduction of Guppies (Poecilia reticulata) in N. Trinidad

The population genetic consequences of intraspecific introductions are not well understood. In the present study we verify the success of a 34-year-old transplantation of guppies, Poecilia reticulata, in Trinidad, and document the spread of the introduced fish. Gene frequencies in the introduced population are in accord with the stochastic effects of a founder event. Gene frequencies downstream of the transplant site suggest that the introduced fish have replaced the native guppy population throughout a substantial stretch of the river. There is strong evidence that the enzyme loci studied here are selectively neutral in the face of selection pressures known to have modified behaviour since the introduction.

Genetic divergence, female choice and male mating success in trinidadian guppies

Guppy, Poecilia reticulata, populations from two major Trinidadian drainages, the Caroni and Oropuche, are characterised by high levels of genetic divergence. Our aim in this paper was to determine whether this divergence is linked to behaviourally-based reproductive isolation. We compared two populations of guppies, one from the Tacarigua River in the Caroni drainage, the other from the Oropuche River in the Oropuche drainage. Guppies in both sites are subject to predation from the pike cichlid, Crenicichla alta, and other predators. In visual choice tests, virgin females from both the Oropuche and Tacarigua populations showed no preference for either type of male. This result was confirmed when females had free access to males. However, a population asymmetry in male mating behaviour resulted in Tacarigua males gaining virtually all copulations. We argue that predation risk has constrained female choice and discuss the evolutionary significance of population differences in male behaviour.