Seasonal timing of non‐zero stage transition rates are indicated in continuous bars. savignyi inhabits coral reef zones, is found under rocks and can occur in high densities in different sponges (Boffi 1972).O. 2005a,b), predicting eventual loss of one sex or the other from the patch. McLetchie, unpublished data) but were not produced by our simulations. Can’t identify parents – 1 individual becomes 2 "daughter" individuals, fully developed. 2(a). For spores, the model also considers a weighted sum of two exponential functions to depict leptokurtic distributions with ‘fat tails’ often observed in dispersal data (Higgins & Cain 2002; Levin et al. In none of the simulations at the metapopulation level did males persist without females. Ecol. Pechenik, J.A. The file will be sent to your Kindle account. When males have a greater asexual production of propagules (as in the default scenario), the metapopulation dynamics lead to permanent coexistence. They inhabit virtually all … (2002) for within‐patch details. These models address how this population structure retains genes under frequency‐dependent selection (McCauley & Taylor 1997) and the effect of the colonization on the genetic variation for sex determination (Couvert et al. The biology of asexual reproduction in the fissiparous brittle star Ophiocomella ophiactoides (H.L. Modified from McLetchie et al. For spores, establishment is limited to the maximum r and is prevented all together unless at least some minimal fraction of the patch area is unoccupied. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm). Note that for large dispersal there is no effect of spore limitation on establishment as a reduced number of spores stay on the originating patch [f(0) in Fig. Ecological aspects of ophiuroids from the phytal of S.W. As such, the metapopulation perspective obviously opens many new avenues for addressing competition, coexistence and spatially distributed reproduction. Brusca R.C., and Brusca, G.J. Clark, S.M. Finally, we conducted a sensitivity analysis that evaluated changes in individual parameter magnitudes relative to default values, based on the linear array and single isolated immortal patches. 4.2. Does the silver moss Bryum argenteum exhibit sex-specific patterns in vegetative growth rate, asexual fitness or prezygotic reproductive investment?. Germinating spores – sporelings – give rise to non‐reproductive males (stage 2) or females (stage 5) with equal frequency. Recently split specimens with only three arms and half of a disc were present in winter and summer suggesting that asexual reproduction occurs throughout the year. Our results suggest, however, that spatial heterogeneity, although a likely contributor to coexistence of the sexes, is unlikely to be a requirement for coexistence in nature. On the reproductive biology of Ptilium crista-castrensis (Pylaisiaceae, Bryophyta), British Ecological Society, 42 Wharf Road, London, N1 7GS, https://doi.org/10.1111/j.1365-2745.2007.01264.x, Initial conditions (male/female spores in unit per patch), Stage transition rates from 2 to 4 and 5 to 7, Stage transition rates 3–2, 4–2, 6–5, 7–5, Stage transition rates from 2 to 3 and 5 to 6, Asexual reproduction rates by stages 3 and 6, Sexual reproduction rate per sex by stage 1, First proportion for spore dispersal functions, Uncovered threshold for spore germination, Probability of a patch disturbance in a month, Probability of a patch extinction during a month. Initiation of fission appeared to be internally controlled. In these species, Williams (1975) pointed out that the asexually produced offspring will develop near the parent, but the sexually produced propagules will disperse more widely. 2002). Population sex ratios, sex‐specific clonal traits and tradeoffs among these traits in the liverwort, Bryophyte dispersal inferred from colonization of an introduced substratum on Whiteface Mountain, New York, The Evolution of Asexual Reproduction in Plants, Spatial patterns of seed dispersal, their determinants and consequences for recruitment, The evolutionary significance of asexual reproduction in mosses, The maintenance of gynodioecy and androdioecy in a metapopulation, A hypothesis for the evolution of androdioecy: the joint influence of reproductive assurance and local mate competition in a metapopulation, Evolution of aquatic angiosperm reproductive systems, Sexual dimorphism in biomass allocation and clonal growth of, Life‐cycle graphs and matrix modeling of bryophyte populations, VI. An upper limit on the rate of sporeling establishment (i.e. 5b). Light bars represent male and dark bars female stage. 1995. 2005. Next we describe our metapopulation model – an array of patches, each linked to the others by spore dispersal, subjected to extinction and following single‐patch dynamics as in McLetchie et al. A key feature of metapopulation structure and dynamics in the field may be resource heterogeneity. 1998). Increased transition rates from non‐reproductive stages to sexual stages (T42 and T75) favoured males (Table 3). Atlantic Ocean warm waters. was studied during June, July, August and December, 1981 and July, 1982. We did not detect any evidence of sexual production of broods. Appendix S1 Estimating the default parameters values of P:804-805,812. In the model, males were often eliminated by competition from individual patches, but both sexes almost always persisted in the metapopulation (as in nature), with females typically predominating. Fission occurred before the new arms were fully regenerated. At initial stages of patch colonization, Marchantia males are expected to do as well or better than females as a result of higher levels of asexual reproduction (Voth & Hamner 1940; McLetchie & Puterbaugh 2000). In fact, for species having genetically fixed sex and the sexes in separate individuals (dioecy), situations in which at least one sex is at risk of local extinction are common, including those characterized by small population sizes, high disturbance frequencies, or intense competition or predation that may fall more heavily on one of the sexes. 1(a) taken to be linearly determined by the donor‐stage (Table 1). 2002). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors.

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