A typing error in Tokeshi's test of bimodality

Barreto, Sandhi Maria; Borges, Paulo A. V.; Guo, Qinfeng

doi:10.1046/j.1466-822x.2003.00018.x

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…Species incidences within an island were measured as the number of plots where a species was recorded (maximum ten). To test for bimodality, we computed the Tokeshi statistical test for bimodality (Tokeshi 1992, Barreto et al 2003.…”

Section: Data Analysesmentioning

confidence: 99%

Community structure of woody plants on islands along a bioclimatic gradient

Borges¹,

Cardoso²,

Fattorini³

et al. 2018

Frontiers of Biogeography

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Understanding patterns of community structure and the causes for their variation can be furthered by comparative biogeographic analyses of island biotas. We used woody plant data at the local scale to investigate variations in species rarity, alpha, beta, and gamma diversity within and between three islands from the oceanic archipelagoes of Azores, Canaries and Mascarene. We used standardized protocols to sample ten 50 m × 50 m forest plots in each of the three islands with contrasting climate and regional species pools: Terceira (Azores), Tenerife (Canaries), and Reunion (Mascarene Islands). Occupancy frequency distributions and species abundance distributions were used to investigate rarity. The partitioning of beta diversity in a distance-decay framework was used to test for spatial patterns of community composition. Rarity was much more pronounced in the highly diverse islands of Tenerife and Reunion than in the regionally poorer island of Terceira. The number of species rose faster with increasing sample area in both Tenerife and Reunion. The slope of the species rank abundance curve was steeper in Terceira whereas the richer island assemblages approached a lognormal model. Compositional changes according to spatial distance were mostly due to replacement of species in Terceira and Reunion. Our results point to important differences in the community structure of Terceira, which is the less diverse and temperate region in comparison to Tenerife and Reunion which are highly diverse.

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Section: Data Analysesmentioning

confidence: 99%

Community structure of woody plants on islands along a bioclimatic gradient

Borges¹,

Cardoso²,

Fattorini³

et al. 2018

Frontiers of Biogeography

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show abstract

“…(2000). They show that an increase in the extent of their study area (to an area similar to ours) changed the occupancy frequency distribution of forest birds from a bimodal to a unimodal pattern – despite the shortcomings of technical caveats of van Rensburg et al 's (2000) analyses addressed by Barreto et al. (2003).…”

Section: Discussionmentioning

confidence: 54%

Forest patch size and isolation as drivers of bird species richness in Maputaland, Mozambique

Guldemond

Aarde²

2010

Journal of Biogeography

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Aim To examine the response of forest-dependent and generalist bird assemblages and feeding guilds to patch characteristics of forest fragments in the context of island biogeography and metapopulation theories in an area that supports high levels of species diversity and endemism.Location Dune, riverine, sand and swamp forest fragments in southern Mozambique's Maputaland.Methods We recorded 20 forest-dependent and 69 generalist bird species at 220 survey points in 30 forest fragments that ranged in size from 5 to 7432 ha and that were 100 to 5100 m apart. We used linear regressions to relate the number of species to forest fragment size, isolation, perimeter, fractal dimension, shape and core area for frugivores, insectivores, granivores, nectarivores, carnivores and omnivores separately for forest-dependent and generalist bird assemblages. We tested for modality in occupancy frequency distributions of species in forest fragments and used the binary matrix temperature calculator to determine whether the assemblages had a nested structure separately for forest-dependent and generalist bird species. ResultsThe number of forest-dependent and generalist bird species categorized into the feeding guilds varied independently from forest patch parameter values. Occupancy models showed a random distribution for forest-dependent birds, and generalists had a unimodal distribution. Both the forest-dependent and generalist bird assemblages had a non-nested structure. The presence of eight rare forestdependent and four endemic bird species in 22 of the 30 fragments contributed to the non-nested structure of these bird assemblages.Main conclusions Fragmented forests did not induce the expected responses of the forest bird assemblages in that the number of species was not explained by patch characteristics, nor could we find evidence for metapopulation dynamics. Non-nestedness may be caused by the few rare and endemic species occupying forest fragments with a wide range of patch characteristics. Knowledge of the response of species to forest fragmentation can benefit conservation planning catering for rare and endemic species. Our study suggests that all forest fragments in the region may have to be included in a conservation network to complement existing landscape-based plans to protect the region.

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The contribution of common and rare species to species abundance patterns in alpine meadows: The effect of elevation gradients

Liu

et al. 2023

Ecological Informatics

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A typing error in Tokeshi's test of bimodality

Cited by 4 publications

References 13 publications

Community structure of woody plants on islands along a bioclimatic gradient

Community structure of woody plants on islands along a bioclimatic gradient

Forest patch size and isolation as drivers of bird species richness in Maputaland, Mozambique

The contribution of common and rare species to species abundance patterns in alpine meadows: The effect of elevation gradients

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