Effects of competition on sexual and clonal reproduction of a tunicate: the importance of competitor identity

Dias, Gustavo Muniz; Delboni, Cynthia Grazielle Martins; Duarte, Luiz Francisco Lembo

doi:10.3354/meps07447

Cited by 22 publications

(21 citation statements)

References 36 publications

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“…Sebens 1982, Buss 1990, Stocker & Underwood 1991, Dias et al 2008. As expected, individuals at lower densities with access to more space (and hence to more energy and nutrient sources like sunlight, suspended food particles or dissolved chemical compounds; Sebens 1982) often grow faster, larger and more fecund than crowded individuals.…”

Section: Introductionmentioning

confidence: 61%

Responses to conspecific density in an arborescent bryozoan

Gooley

Marshall

Monro

2010

Mar. Ecol. Prog. Ser.

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Sessile colonial invertebrates that must tolerate environmental variation without the luxury of mobility may be expected to cope with such variation through phenotypic plasticity. While plastic responses to a range of biotic factors (e.g. predation) are increasingly documented, the details of responses to competition (mediated by the densities of conspecifics or heterospecifics vying for the same resources) remain unclear, despite a rich literature for terrestrial plants on which to draw. We examined phenotypic responses to conspecific density in a colonial invertebrate (the arborescent bryozoan, Bugula neritina) under field conditions. We found that colonies at higher densities were generally less fecund, lower in biomass and more elongate than those growing virtually alone. We also found such responses to vary only subtly with the life history stage of neighbours, with colonies exposed to higher densities of contemporary recruits achieving elongation via increased budding between bifurcation points and the elongation of individual zooids, while colonies exposed to established adults achieved elongation via increased budding only. These responses are broadly consistent with those of terrestrial plants competing for light and are probably due to the combined effects of resource limitation and altered flow in high density stands. Future studies are needed to disentangle these effects and the extent to which such responses to density in branching colonial invertebrates are a passive result of food limitation, or reflect active (and potentially adaptive) plasticity to other aspects of the local density environment.KEY WORDS: Branching · Colony form · Density · Foraging behaviour · Intraspecific competition plasticity · Bryozoa Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 415: [83][84][85][86][87][88][89][90] 2010 the same fixed resource -is widely believed to determine the structure of many benthic communities (Jackson 1977, Vermeij & Sandin 2008.To date, research on phenotypic responses to density in such systems has emphasised changes in overall growth and reproductive output, especially in encrusting bryozoans and ascidians (e.g. Sebens 1982, Buss 1990, Stocker & Underwood 1991, Dias et al. 2008. As expected, individuals at lower densities with access to more space (and hence to more energy and nutrient sources like sunlight, suspended food particles or dissolved chemical compounds; Sebens 1982) often grow faster, larger and more fecund than crowded individuals. In other cases, however, this expectation is not met (Stocker & Underwood 1991, Abdo et al. 2008, possibly because adverse effects of competition on performance are ameliorated by responses in other (e.g. morphological) traits. For example, barnacles at high conspecific densities may express a tall 'hummocked' morphology that improves access to suspended food particles (Bertness et al. 1998). Similarly, encrusting bryozoans that are encroached upon may start to produce stolons that slow the ...

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Section: Introductionmentioning

confidence: 61%

Responses to conspecific density in an arborescent bryozoan

Gooley

Marshall

Monro

2010

Mar. Ecol. Prog. Ser.

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“…Indeed, this species has been described as globally distributed in tropical ports and other artificial substrates (Monniot and Monniot 1997). Only recently, the ecology of this species has attracted attention and the effects of competition on sexual and clonal reproduction of D. perlucidum were studied in São Paulo (Dias et al 2008).…”

Section: Introductionmentioning

confidence: 99%

An experimental test of colonization ability in the potentially invasive Didemnum perlucidum (Tunicata, Ascidiacea)

2009

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Exotic species invasions are one of the greatest threats to marine systems and ascidians have many characteristics that favor transport, colonization and establishment into new regions. Didemnum perlucidum is a widespread species that has been introduced into tropical ports around the world. Here we examine the colonizing ability of D. perlucidum by experimental use of artificial plates in a shellfish culture. The experiment comprised paired plates for colonization (bare and occupied) in 16 monthly replicates. Recruitment and space occupation were compared between bare and occupied plates and an estimation of reproductive effort was based on the number of larvae produced in each of ten colonies collected on the culture structures. D. perlucidum reproduced continuously but greatest reproduction occurred between December 2006 and May 2007. While recruitment was somewhat greater (number of new colonies) on bare plates, this species can colonize already occupied substrates and, surprisingly, colony area was always similar between treatments. Thus, while fewer colonies formed on occupied plates, once formed, colonies grew at rates similar to those on clean plates. Thus, D. perlucidum colonizes substrates very efficiently, especially when unoccupied space is available.

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“…Therefore, environmental niche models may be sufficient to predict the distribution of this exotic species in fouling communities. This finding does not reject strong interference effects of particular species (see Dias et al 2008), it only suggests that these strong interactions were not naturally common enough to make a large impact on population growth. This Results of summer (a) and winter (b) growth model selection.…”

Section: Discussionmentioning

confidence: 56%

“…violaceus has colonized many marine fouling communities, which are assemblages of sessile marine invertebrates that occupy hard substrata. Space competition, seasonal recruitment and predation are all common features of fouling communities (Mook 1976;Sutherland and Karlson 1977;Stachowicz et al 1999;Nydam and Stachowicz 2007;Dias et al 2008).…”

Section: Study Systemmentioning

confidence: 99%

Relative effects of environment and direct species interactions on the population growth rate of an exotic ascidian

Grey

2011

Oecologia

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The success of exotic species can be influenced by both the abiotic environment and species interactions. Many studies have demonstrated significant effects of either type of factor on aspects of exotic success, but few have considered their relative effects on population growth rate, a more holistic measure of success. To quantify the relative effects of environment and direct competition on an exotic ascidian, Botrylloides violaceus, I manipulated direct contact interactions at four sites with different abiotic environments and tracked individual colonies over 3 years. I tested site and contact treatment effects on survival, growth and fecundity, and then conducted a life table response experiment on a periodic, size-structured population matrix model to test their effects on population growth rate. Both site and contact interaction were important to explaining variation in survival and growth. Contact interactions decreased the survival and growth of larger colonies but unexpectedly increased the survival of small colonies at some sites, which led to relatively weaker and spatially variable effects on overall population growth rates. Site effects on population growth rates were an order of magnitude larger than contact effects, and site variation in winter vital rates made the largest contributions to changes in population growth rate. The results of this study suggest that the abiotic environment plays a larger role in the success of B. violaceus. Thus, environmental variables, such as temperature and salinity, could be used to predict this exotic species' success under different environmental scenarios, including global climate change.

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Effects of competition on sexual and clonal reproduction of a tunicate: the importance of competitor identity

Cited by 22 publications

References 36 publications

Responses to conspecific density in an arborescent bryozoan

Responses to conspecific density in an arborescent bryozoan

An experimental test of colonization ability in the potentially invasive Didemnum perlucidum (Tunicata, Ascidiacea)

Relative effects of environment and direct species interactions on the population growth rate of an exotic ascidian

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