ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

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The genetic control and consequences of kin recognition by the larvae of a colonial marine invertebrate (1986)

Grosberg, Richard K. ; Quinn, James F.

[s.l.] : Nature Publishing Group

Nature 322 (1986), S. 456-459

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Botryllus schlosseri colonies are founded after a sexually produced planktonic tadpole larva attaches to a firm substratum and metamorphoses. Repeated cycles of asexual multiplication produce a colony of morphologically and genetically identical zooids, connected by a blood vascular system. As in ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/322456a0

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2

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Prospects for Preservation and Restoration of Riparian Forests in the Sacramento Valley, California, USA (1999)

Hunter, John C. ; B. Willett, Karen ; McCoy, Michael C. ; [et al.]

Springer

Environmental management 24 (1999), S. 65-75

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ISSN: 1432-1009

Keywords: KEY WORDS: Central Valley; Conservation; Floodplains; Geographic information systems; Riparian vegetation

Source: Springer Online Journal Archives 1860-2000

Topics: Energy, Environment Protection, Nuclear Power Engineering

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002679900215

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3

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The influence of colonization in nested species subsets (1995)

Cook, Rosamonde R. ; Quinn, James F.

Springer

Oecologia 102 (1995), S. 413-424

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ISSN: 1432-1939

Keywords: Species composition ; Islands ; Nested subsets ; Conservation ; Colonization

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Biotic communities inhabiting collections of insular habitat patches often exhibit compositional patterns described as “nested subsets”. In nested biotas, the assemblages of species in relatively depauperate sites comprise successive subsets of species in relatively richer sites. In theory, nestedness may result from selective extinction, selective colonization, or other mechanisms, such as nested habitats. Allopatric speciation is expected to reduce nestedness. Previous studies, based largely on comparisons between land-bridge and oceanic archipelagos, have emphasized the role of selective extinction. However, colonization could also be important in generating strong patterns of nestedness. We apply a recently published index of nestedness to more than 50 island biogeographic data sets, and examine the roles of colonization, extinction, endemism, and, to a limited extent, habitat variability on the degree on nestedness. Most data sets exhibit a significant degree of nestedness, although there is no general tendency for land-bridge biotas to appear more nested than oceanic ones. Endemic species are shown to generally reduce nestedness. Comparisons between groups of non-endemic species differing in overwater or inter-patch dispersal ability indicate that superior dispersers generally exhibit a greater degree of nestedness than poorer dispersers, a result opposite that expected if colonization were a less predictable process than extinction. These results suggest that frequent colonization is likely to enhance nestedness, thereby increasing the compositional overlap among insular biotas. The prevalence of selective extinction in natural communities remains in question. The importance of colonization in generating and maintaining nested subsets suggests that (1) minimum critical areas will be difficult to determine from patterns of species distributions on islands; (2) multiple conservation sites are likely to be required to preserve communities in subdivided landscapes; and (3) management of dispersal processes may be as important to preserving species and communities as is minimizing extinctions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00341353

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4

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An evaluation of randomization models for nested species subsets analysis (1998)

Cook, Rosamonde R. ; Quinn, James F.

Springer

Oecologia 113 (1998), S. 584-592

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ISSN: 1432-1939

Keywords: Key words Nested subsets ; Randomization models ; Island biogeography ; Species assemblages ; Patch dynamics

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Randomization models, often termed “null” models, have been widely used since the 1970s in studies of species community and biogeographic patterns. More recently they have been used to test for nested species subset patterns (or nestedness) among assemblages of species occupying spatially subdivided habitats, such as island archipelagoes and terrestrial habitat patches. Nestedness occurs when the species occupying small or species-poor sites have a strong tendency to form proper subsets of richer species assemblages. In this paper, we examine the ability of several published simulation models to detect, in an unbiased way, nested subset patterns from a simple matrix of site-by-species presence-absence data. Each approach attempts to build in biological realism by following the assumption that the ecological processes that generated the patterns observed in nature would, if they could be repeated many times over using the same species and landscape configuration, produce islands with the same number of species and species present on the same number of islands as observed. In mathematical terms, the mean marginal totals (column and row sums) of many simulated matrices would match those of the observed matrix. Results of model simulations suggest that the true probability of a species occupying any given site cannot be estimated unambiguously. Nearly all of the models tested were shown to bias simulation matrices toward low levels of nestedness, increasing the probability of a Type I statistical error. Further, desired marginal totals could be obtained only through ad-hoc manipulation of the calculated probabilities. Paradoxically, when such results are achieved, the model is shown to have little statistical power to detect nestedness. This is because nestedness is determined largely by the marginal totals of the matrix themselves, as suggested earlier by Wright and Reeves. We conclude that at the present time, the best null model for nested subset patterns may be one based on equal probabilities of occurrence for all species. Examples of such models are readily available in the literature.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050412

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5

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Effects of habitat fragmentation and isolation on species richness: evidence from biogeographic patterns (1988)

Quinn, James F. ; Harrison, Susan P.

Springer

Oecologia 75 (1988), S. 132-140

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ISSN: 1432-1939

Keywords: Island biogeography ; Diversity ; Fragmentation ; Nature reserves

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Habitat subdivision by geography or human activity may be an important determinant of regional species richness. Cumulative species-area relationships for vertebrates, land plants, and insects on island archipelagoes show that collections of small islands generally harbor more species than comparable areas composed of one or a few large islands. The effect of the degree of habitat subdivision in increasing species richness appears to increase with the distance from potential sources of colonists. Mountaintop biotas show no clear differences between species richness on large alpine areas and collections of smaller peaks. National park faunas generally have more species in collections of small parks than in the larger parks. In all cases where a consistent effect of subdivision is observed, the more subdivided collection of islands or isolates contains more species. To the degree that these data provide guidance for establishing nature reserves, they suggest that increasing the numbers of reserves may be an important component of conservation strategies.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00378826

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6

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Extinction, turnover and species diversity in an experimentally fragmented California annual grassland (1988)

Robinson, George R. ; Quinn, James F.

Springer

Oecologia 76 (1988), S. 71-82

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ISSN: 1432-1939

Keywords: Extinction ; Species diversity ; Turnover ; Fragmentation ; Grassland

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Many natural populations are subdivided among partially isolated habitat patches, but the influence of habitat patchiness per se on species immigration, extinction, and the resulting patterns of species diversity, has received virtually no experimental study. In an experiment designed to test the effects of habitat subdivision on local community structure, we compare the diversity and annual turnover of flowering plant species in 3 treatments of the same total area, but subdivided to different degrees. We experimentally fragmented a California winter annual grassland into isolated plots, two of 32 m2, eight of 8 m2, and 32 of 2 m2, each treatment representing a combined area of 64 m2. Insularization of the experimental habitat fragments is provided by grazing sheep. The effects of plot area on species diversity, extinction, and turnover are consistent with the MacArthur-Wilson model. Species richness increases with the degree of habitat subdivision. Extinction, immigration, and turnover, however, are relatively independent of the degree of subdivision. These experimental results contrast with predictions that habitat subdivision necessarily results in greater rates of extinction accompanied by reduced species diversity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00379603

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7

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The effect of wave action on growth in three species of intertidal gastropods (1988)

Brown, Kenneth M. ; Quinn, James F.

Springer

Oecologia 75 (1988), S. 420-425

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ISSN: 1432-1939

Keywords: Wave action ; Intertidal snails ; Population differentiation ; Growth rates

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Populations of the limpets Collisella digitalis and C. scabra, as well as the thaidid whelk Nucella (Thais) emarginata, had greater mean shell lengths at a protected site (Tomales Bay) than at an exposed site (Mussel Point) on the California coast near the Bodega Marine Laboratory. To determine the relative importance of wave action as well as genetic differentiation among populations in explaining this pattern, tagged snails of all three species were reciprocally transferred between the two sites. For C. digitalis, total wet mass (tissue plus shell) increased by 34.4% at the protected site, but decreased by 2% at the exposed site over a two and one-half month period. For C. scabra, growth was 43.1% at the protected, and 2.7% at the exposed site, and for Nucella, 9.5% and 1%, respectively. Although some evidence of population differentiation was found, particularly for the direct-developing whelk, source differences in growth were not as large as the site effect. At least for the whelk, absolute differences in barnacle prey abundances did not occur between sites. However, all three gastropods had higher abundances at the exposed site. While factors such as genetic differentiation and competition may partially explain why gastropods are on the average smaller at exposed sites, we suggest that wave action may also play a role, possibly by limiting time available for feeding, and therefore energy available for growth. Although wave action, acting via size-specific mortality, has been suggested to limit the size that consumers can reach on exposed shores, it may also indirectly affect intertidal gastropod populations by altering foraging behavior, growth and life histories.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00376946

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8

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Competitive hierarchies in marine benthic communities (1982)

Quinn, James F.

Springer

Oecologia 54 (1982), S. 129-135

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Patterns of competitive displacement by over-growth were examined in communities of sessile organisms in the low intertidal zone at three sites in Washington state and Alaska. Cruotose invertebrates and algae can be arranged into a hierarchy such that species of lower competitive rank rarely overgrow any higher ranking species. Erect and solitary species show a wide range of competitive abilities, but whether they fall into a strict hierarchy is unknown. Few of the solitary or erect species occupy substantial amounts of space in the communities examined. An approximate competitive hierarchy is well established in middle to high intertidal areas dominated by mussels, fleshy algae, and barncles, and has been an important concept in developing both an intuitive understanding and specific mathematical models of the dynamics of benthic marine communities. In particular, lower ranking species in such communities are thought to depend upon predation or chronic disturbance to the dominants to avoid competitive displacement. An alternative viewpoint, proposed on the basis of “nonstransitive” competitive relationships observed in cryptic encrusting communities on the undersides of coral plates, is that specific competitive “loops” or “networks” allow the coexistence of a number of competitors. Although the growth forms and higher taxa represented in the low intertidal bear some similarity to those in the cryptic coral reef community, there is little evidence of ecologically important competitive loops in the intertidal. A reanalysis of data from cryptic reef communities suggests that they also do not depart substantially from a competitive hierarchy, although there appear to be many more cases of local reversals in the outcome of competition. It is suggested that the ecological importance of departures from a strict hierarchy depends upon the competitive rankings of the participants, with departures involving competitively dominant species likely to contribute much more to community structure than those involving opportunistic species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00541119

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