User:Philcha/Sandbox/Portia africana

Sources

• Cross & Jackson 2009 - How cross-modality effects during intraspecific interactions of jumping spiders differ depending on whether a female-choice or mutual-choice mating system is adopted - Fiona R. Cross, Robert R. Jackson - Behavioural Processes - Volume 80, Issue 2 - February 2009 - Pages 162-168 - doi:10.1016/j.beproc.2008.11.001 - Elsevier B.V.
  • In Portia fimbriata, Portia africana and Jacksonoides queenslandicus, more conventional salticids in which female mate-choice and male–male competition appear to be dominant - there is strong competition between males for access to females - the odour of conspecific females primes escalation of vision-based male–male conflict. In Evarcha culicivora, a species in which mutual mate-choice is pronounced, additional evidence shows that conspecific males priming the escalation of female–female conflict.
• (Copyright) Jackson male specimen
• (Copyright) Proszynski Original drawings by J. Proszynski
• Reliance on trial and error signal derivation by Portia africana, an araneophagic jumping spider from East Africa - Robert R. Jackson, Ximena J. Nelson - 8 January 2011 - Japan Ethological Society and Springer 2011 - 29:301–307
  • P. africana derives signals by trial and error ... , ... P. fimbriata, P. labiata and P. schultzi
  • Salticids have eyesight unparalleled in animals of comparable size (Land and Nilsson 2002), and, as might be expected for predators with exceptional eyesight, most of the 5,000 described species in this family (Platnick 2010) appear to be cursorial hunters that, without making use of webs, prey primarily on insects (Richman and Jackson 1992; Jackson and Pollard 1996)
  • The most striking exceptions are African, Asian and Australasian salticids from the genus Portia. Although the salticids from this genus feed on insects, their preferred prey are other spiders that they capture by invading webs (Harland and Jackson 2004). Instead of simply stalking or chasing down the resident spider in an invaded web, Portia uses its legs and palps to make signals (Tarsitano et al. 2000), and, with these signals, gains dynamic fine control over the resident spider’s behavior (Nelson and Jackson 2011).
  • To understand Portias strategy, it is important to appreciate that the eyes of non-salticid web-building spiders support only rudimentary spatial acuity (Homann 1971; Land and Nilsson 2002). As these spiders rely primarily on the interpretation of web signals (i.e., tension and movement patters in web silk), it is appropriate to envisage the web as an integral part of the web-building spider’s sensory apparatus (Witt 1975; Foelix 1996; Barth 2002). This in turn implies that, when practising aggressive mimicry, Portia has intimate contact with its prey’s sensor.
  • An important step toward evaluating this hypothesis is to investigate a wider range of Portia species. Here, we investigate P. africana from a habitat in western Kenya. Prey diversity in this habitat, as in the Los Ban˜os habitat, appears to be considerably higher than in Sagada. We carried out experiments comparable to those used with P. labiata and we predicted that findings for P. africana would be more like those for the Los Baños ther than the Sagada, P. labiata.
  • All individuals of P. africana used as test spiders were adult females (unmated; matured 2–3 weeks prior to being used) taken from a laboratory culture (3rd and 4th generation).
  • P. africana, when deriving signals, relies strongly on a trial and error algorithm.
  • At least short-term memory is implied these findings, as Portia must have remembered the last signal made and the consequence of making it. This, in turn, implies that trial and error signal generation is at least a rudimentary example of learning (see Staddon 1983; Jakob et al. 2011), or more specifically operant onditioning (Skinner 1938). However, many questions related to learning remain. In particular, Portias ability to associate particular signals with particular prey remains to be investigated. How long memory traces persist is also currently unknown. The answers to these questions notwithstanding, Portias signal-making strategy appears to be an example of exceptional flexibility in the context of problem solving.
  • Theoretical accounts of why especially flexible problem-solving ability may have evolved in Portia have emphasized the intimate contact this predator has with its prey’s sensory system, the high level of risk entailed in attempting to gain dynamic fine control over the behavior of another predator, and the potential for coevolution (Jackson 1992; Nelson and Jackson 2011).
  • A precise understanding of the severity of small-size constraints on arthropod cognitive capacity remains elusive (Chittka and Niven 2009; Srinivasan 2010).
  • Geographic variation in the cognitive capacities of single species has been demonstrated in a wide variety of vertebrates (Huntingford and Wright 1992; Huntingford et al. 1994; Nelson et al. 1996; Thompson 1990, 1999). In smaller animals such as spiders, where adaptive tradeoffs may be especially severe, cognitive capacities may be even more likely to diverge geographically within single species or between closely related species (e.g., Heiling and Herberstein 2004). Comparison across ecotypes or species of small animals might, in turn, be especially likely to reveal the particular selection pressures that drive the evolution of the cognitive attributes.
  • The diversity of web-building spiders on which P. labiata preys in a lowland rain forest (Los Ban˜os) appears to be much greater than that in a high-elevation pine forest (Sagada) and, as predicted, more pronounced reliance on trial and error was revealed when the test spiders were from the Los Ban˜os instead of the Sagada population of P. labiata.
  • Our findings for P. africana were remarkably similar to the findings for the Los Ban˜os P. labiata (Jackson and Carter 2001). When we compare data from P. africana with data from P. labiata, considering specifically the numbers of individuals that repeated the focal signal when reinforced, there was no significant difference between P. africana and the Los Ban˜os P. labiata (v2 = 0.146, P = 0.703), but P. africana was significantly different from the Sagada P. labiata (v2 = 5.679, P = 0.017; Fig. 3)
  • At least short-term memory is implied these findings, as Portia must have remembered the last signal made and the consequence of making it. This, in turn, implies that trial and error signal generation is at least a rudimentary example of learning.
  • Scaling factors may also be important, as smaller animals tend to have fewer, not smaller, neurons (Bullock and Horridge 1965), which means fewer components are available for sense organs and brains. It may be indisputable that small brain size constrains how complex and flexible an arthropod can become, relative to much larger animals such as parrots and chimpanzees, but a precise understanding of the severity of small-size constraints on arthropod cognitive capacity remains elusive.
  • ... level to which this species relies on trial and error for signal derivation. The diversity of web-building spiders on which P. labiata preys in a lowland rain forest (Los Ban˜os) appears to be much greater than that in a high-elevation pine forest (Sagada) and, as predicted, more pronounced reliance on trial and error was revealed when the test spiders were from the Los Ban˜os instead of the Sagada population of P. labiata.
  • Our findings for P. africana, like the earlier findings for P. labiata (Jackson and Carter 2001), suggest that level of reliance on trial and error signal derivation is an innate characteristic subject to local adaptation. Having used 3rd and 4th generation individuals of Portia from laboratory rearing under standardized conditions in this study, as in the earlier study (Jackson and Carter 2001), prior experience (see Roff 1998), maternal effects (Wade 1998) and other indirect genetic effects (Moore et al. 1998) are unlikely alternative explanations for the inter-population differences in Portia use of trial and error.
  • ? we should also consider how the presence of especially dangerous prey may have influenced the evolution of inter-population differences in the level of reliance on trial and error during signal derivation by Portia. When entering a web, Portia enters the arena in which the resident spider normally captures its own prey and, in these encounters, Portia’s success at gaining fine control over the resident spider’s behavior may sometimes determine which of the two spiders lives or dies.
  • Theoretical accounts of why especially flexible problem-solving ability may have evolved in Portia have emphasized the intimate contact this predator has with its prey’s sensory system, the high level of risk entailed in attempting to gain dynamic fine control over the behavior of another predator, and the potential for coevolution (Jackson 1992; Nelson and Jackson 2011).
  • Scaling factors may also be important, as smaller animals tend to have fewer, not smaller, neurons (Bullock and Horridge 1965), which means fewer components are available for sense organs and brains. It may be indisputable that small brain size constrains how complex and flexible an arthropod can become, relative to much larger animals such as parrots and chimpanzees, but a precise understanding of the severity of small-size constraints on arthropod cognitive capacity remains elusive.
• (paywall) Entomology - R R Jackson, and S D Pollard - Volume 41 - 1996 - Jackson - pp. 287-308 - Vol. 41: 287-308 - January 1996 - DOI: 10.1146/annurev.en.41.010196.001443
• smokescreens: spider trickster uses background noise to mask stalking movements - R. Stimson Wilcox, Robert R. Jackson & Kristen Gentile - The Association for the Study of Animal Behaviour - 1996 - 0003–3472 - 51, 313–326