Boreal ground-beetle (Coleoptera: Carabidae) assemblages of the mainland and islands in Lac la Ronge, Saskatchewan, Canada

2017 ◽  
Vol 149 (4) ◽  
pp. 491-503 ◽  
Author(s):  
Aaron J. Bell ◽  
Iain D. Phillips ◽  
Scott E. Nielsen ◽  
John R. Spence
Keyword(s):  
Species Richness ◽  
Island Biogeography ◽  
Passive Sampling ◽  
Unit Area ◽  
Ground Beetle ◽  
Small Islands ◽  
Island Size ◽  
Extinction Rates ◽  
Theory Of Island Biogeography ◽  
Species Area

AbstractWe tested the applicability of the “passive sampling” hypothesis and theory of island biogeography (TIB) for explaining the diversity of forest-dwelling carabid assemblages (Carabidae: Coleoptera) on 30 forested islands (0.2–980.7 ha) in Lac la Ronge and the adjacent mainland in Saskatchewan, Canada. Species richness per unit area increased with distance to mainland with diversity being highest on the most isolated islands. We detected neither a positive species-area relationship, nor significant differences in species richness among island size classes, or between islands and the mainland. Nonetheless, carabid assemblages distinctly differed on islands <1 ha in area and gradually approached the structure of mainland assemblages as island area increased. Small islands were characterised by abundant populations of small-bodied, winged species and few if any large-bodied, flightless species like Carabus taedatus Fabricius. Our findings suggest that neither the “passive sampling” hypothesis nor the theory of island biogeography adequately explain carabid beetle diversity patterns observed among islands in Lac la Ronge. Instead, we hypothesise that population processes such as higher extinction rates of large-bodied, flightless species and the associated release of smaller-bodied, flying species from intra-guild predation on small islands contribute to observed differences in the structure of carabid assemblages between islands.

scholarly journals Maintenance of biodiversity on islands

2016 ◽  
Vol 283 (1829) ◽  
pp. 20160102 ◽  
Author(s):  
Ryan A. Chisholm ◽  
Tak Fung ◽  
Deepthi Chimalakonda ◽  
James P. O'Dwyer
Keyword(s):  
Species Richness ◽  
Island Biogeography ◽  
Mechanistic Model ◽  
Neutral Theory ◽  
Small Island ◽  
Small Islands ◽  
Island Area ◽  
Island Species ◽  
Theory Of Island Biogeography ◽  
Species Area

MacArthur and Wilson's theory of island biogeography predicts that island species richness should increase with island area. This prediction generally holds among large islands, but among small islands species richness often varies independently of island area, producing the so-called ‘small-island effect’ and an overall biphasic species–area relationship (SAR). Here, we develop a unified theory that explains the biphasic island SAR. Our theory's key postulate is that as island area increases, the total number of immigrants increases faster than niche diversity. A parsimonious mechanistic model approximating these processes reproduces a biphasic SAR and provides excellent fits to 100 archipelago datasets. In the light of our theory, the biphasic island SAR can be interpreted as arising from a transition from a niche-structured regime on small islands to a colonization–extinction balance regime on large islands. The first regime is characteristic of classic deterministic niche theories; the second regime is characteristic of stochastic theories including the theory of island biogeography and neutral theory. The data furthermore confirm our theory's key prediction that the transition between the two SAR regimes should occur at smaller areas, where immigration is stronger (i.e. for taxa that are better dispersers and for archipelagos that are less isolated).

scholarly journals Altitudinal diversity gradients and the theory of island biogeography - an explanation

2002 ◽  
Vol 8 (3) ◽  
pp. 213
Author(s):  
John Ogden
Keyword(s):  
Species Richness ◽  
New Zealand ◽  
Environmental Variables ◽  
Island Biogeography ◽  
Environmental Heterogeneity ◽  
Causal Agent ◽  
Forest Diversity ◽  
Island Biogeography Theory ◽  
Diversity Gradients ◽  
Theory Of Island Biogeography

As part of a wider discussion of forest diversity in New Zealand, Ogden (1995) pointed out that the area available between any pair of contours on a conical mountain decreased with altitude in parallel with the decrease in species richness. This correlation is confounded with other environmental variables, such as temperature, which have been widely considered to be causal in the diversity decline. However, generalization has been elusive, and the supposed causal mechanisms are often couched in vague terms such as "harshness". Ogden chose to emphasize area, and invoked the theory of island biogeography of MacArthur and Wilson (1967) by drawing parallels between islands and successively superimposed areas on mountains. Kingston (this issue) objected, mainly on the grounds that the theory of island biogeography refers to "isolated" areas and deals with the equilibrium between immigration and extinction, on which Ogden presented no evidence. In the light of these criticisms the data presented in Ogden (1995) is re-assessed here. I conclude that the "area hypothesis" is at least as good as any other for "explaining" (correlating with) elevational diversity trends. Area is itself correlated with environmental heterogeneity, which is presumably more important as a causal agent. However, Kingston's insistence on the need for evidence on immigration and extinction to support the application of island biogeography theory is acknowledged.

scholarly journals Wood ant assemblages of Formica rufa group on lake islands and in mainland woodland in Central Finland

2018 ◽  
Vol 29 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Jouni Sorvari
Keyword(s):  
Species Richness ◽  
Occurrence Probability ◽  
Island Size ◽  
Formica Rufa ◽  
Wood Ants ◽  
Formica Rufa Group ◽  
Species Area ◽  
Island Community ◽  
Species Area Relationship ◽  
Formica Lugubris

Associations of island size and isolation on the occurrence and species richness of five wood ant species of the Formica rufa group (F. rufa, F. aquilonia, F. lugubris, F. polyctena and F. pratensis) was tested in the Lake Konnevesi archipelago in Central Finland. In addition, the species composition was compared to that of mainland forests of the same region. Island isolation had no associations with the wood ant occurrence in this archipelago, but for most species, increasing island size was positively associated with the occurrence probability. According to the findings among the five species, Formica lugubris is the best adapted for insular living. There was a positive species–area relationship as the species richness of wood ants increased with an increasing island size. The island community of wood ants was dominated by colonies of the monogynous (single queen) species whereas the mainland community was dominated by those of polygynous (multiple queen) species.

scholarly journals Can altitudinal diversity gradients be explained by a reduction in area with altitude?

2002 ◽  
Vol 8 (3) ◽  
pp. 211
Author(s):  
Cath Kingston
Keyword(s):  
Species Richness ◽  
Surface Area ◽  
Environmental Conditions ◽  
Island Biogeography ◽  
Equilibrium Theory ◽  
Diversity Gradients ◽  
Theory Of Island Biogeography ◽  
Reduction In Area

Species richness at higher altitudes of a region typically decreases with altitude, the usual explanation being that environmental conditions become harsher as altitude increases. On conical or ridge shaped mountains the surface area available within equally spaced altitude bands declines as altitude increases. It has been suggested (Ogden 1995) that this may be responsible for the decrease in species richness. The phenomenon of decreasing species richness with altitude has been further interpreted by Ogden as lending support to the equilibrium theory of island biogeography (MacArthur and Wilson 1967) which predicts that larger areas will contain more species. The hypothesis that a decrease in area is responsible for the decline in diversity with altitude is here considered critically, and the evidence presented in support of it is found to be lacking.

scholarly journals Marine subsidies mediate patterns in avian island biogeography

2020 ◽  
Vol 287 (1922) ◽  
pp. 20200108
Author(s):  
Debora S. Obrist ◽  
Patrick J. Hanly ◽  
Jeremiah C. Kennedy ◽  
Owen T. Fitzpatrick ◽  
Sara B. Wickham ◽  
...  
Keyword(s):  
Species Richness ◽  
Population Density ◽  
Island Biogeography ◽  
Forest Edge ◽  
Bird Communities ◽  
Negative Interaction ◽  
Breeding Bird ◽  
Island Area ◽  
Marine Subsidies ◽  
Theory Of Island Biogeography

The classical theory of island biogeography , which predicts species richness using island area and isolation, has been expanded to include contributions from marine subsidies, i.e. subsidized island biogeography (SIB) theory . We tested the effects of marine subsidies on species diversity and population density on productive temperate islands, evaluating SIB predictions previously untested at comparable scales and subsidy levels. We found that the diversity of terrestrial breeding bird communities on 91 small islands (approx. 0.0001–3 km 2 ) along the Central Coast of British Columbia, Canada were correlated most strongly with island area, but also with marine subsidies. Species richness increased and population density decreased with island area, but isolation had no measurable influence. Species richness was negatively correlated with marine subsidy, measured as forest-edge soil δ 15 N. Density, however, was higher on islands with higher marine subsidy, and a negative interaction between area and subsidy indicates that this effect is stronger on smaller islands, offering some support for SIB. Our study emphasizes how subsidies from the sea can shape diversity patterns on islands and can even exceed the importance of isolation in determining species richness and densities of terrestrial biota.

scholarly journals Effects of time and isolation on plant diversity: testing island biogeography theory with an eco-evolutionary model

2017 ◽  
Author(s):  
Juliano Sarmento Cabral ◽  
Robert J. Whittaker ◽  
Kerstin Wiegand ◽  
Holger Kreft
Keyword(s):  
Species Richness ◽  
Endemic Species ◽  
Island Biogeography ◽  
Temporal Trends ◽  
Evolutionary Model ◽  
Simulation Models ◽  
Population Level ◽  
Species Number ◽  
Dispersal Ability ◽  
Extinction Rates

abstractAimsThe General Dynamic Model of oceanic island biogeography (GDM) predicts how biogeographical rates, species richness, and endemism vary depending on island age, area, and isolation, based on the interplay of colonization, extinction, and speciation. Here, we used a simulation model to test whether GDM predictions may arise from individual- and population-level processes.LocationHypothetical hotspot islands.MethodsOur model (i) considers an idealized island ontogeny, (ii) metabolic constraints, and (iii) stochastic, spatially-explicit, and niche-based processes at the level of individuals and populations (plant demography, dispersal, competition, mutation, and speciation). Isolation scenarios involved varying dispersal ability and distances to mainland.ResultsHumped temporal trends were obtained for species richness, endemic richness, proportion of cladogenetic endemic species, number of radiating lineages, number of species per radiating lineage, and biogeographical rates. The proportion of anagenetic endemics and of all endemics steadily increased over time. Extinction rates of endemic species peaked later than for non-endemic species. Species richness and the number of anagenetic endemics decreased with isolation as did rates of colonization, anagenesis, and extinction. The proportion of all endemics and of cladogenetic endemics, the number of cladogenetic endemics, of radiating lineages, and of species per radiating lineage, and the cladogenesis rate all increased with isolation.Main conclusionsThe results confirm most GDM predictions related to island ontogeny and isolation, but predict an increasing proportion of endemics throughout the experiment: a difference attributable to diverging assumptions on late island ontogeny. New insights regarding the extinction trends of endemics further demonstrate how simulation models focusing on low ecological levels provide tools to test biogeographical-scale predictions and to develop more detailed predictions for further empirical tests.

scholarly journals What Do Ecological Paradigms Offer to Conservation?

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Som B. Ale ◽  
Henry F. Howe
Keyword(s):  
Species Richness ◽  
Biodiversity Conservation ◽  
Community Composition ◽  
Carrying Capacity ◽  
Island Biogeography ◽  
Ecological Theory ◽  
Theory And Practice ◽  
Logistic Growth ◽  
Theory Of Island Biogeography ◽  
Conservation Plans

Ecological theory provides applications to biodiversity management—but often falls short of expectations. One possibility is that heuristic theories of a young science are too immature. Logistic growth predicts a carrying capacity, but fisheries managed with the Lotka-Volterra paradigm continue to collapse. A second issue is that general predictions may not be useful. The theory of island biogeography predicts species richness but does not predict community composition. A third possibility is that the theory itself may not have much to do with nature, or that empirical parameterization is too difficult to know. The metapopulation paradigm is relevant to conservation, but metapopulations might not be common in nature. For instance, empirical parameterization within the metapopulation paradigm is usually infeasible. A challenge is to determine why ecology fails to match needs of managers sometimes but helps at other. Managers may expect too much of paradigmatic blueprints, while ecologists believe them too much. Those who implement biodiversity conservation plans need simple, pragmatic guidelines based on science. Is this possible? What is possible? An eclectic review of theory and practice demonstrate the power and weaknesses of the ideas that guide conservation and attempt to identify reasons for prevailing disappointment.

scholarly journals Beetle Species–Area Relationships and Extinction Rates in Protected Areas

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 646
Author(s):  
Simone Fattorini
Keyword(s):  
Species Richness ◽  
Feeding Habits ◽  
Negative Influence ◽  
Extinction Rates ◽  
Ecological Patterns ◽  
Species Area ◽  
Local Extinctions ◽  
Species Area Relationship ◽  
Aquatic Predators ◽  
Using Data

The species–area relationship (SAR, i.e., the increase in species richness with area) is one of the most general ecological patterns. SARs can be used to calculate expected extinction rates following area (habitat) loss. Here, using data from Italian reserves, extinction rates were calculated for beetle groups with different feeding habits: Carabidae (terrestrial predators), Hydradephaga (aquatic predators), coprophagous Scarabaeoidea (dung feeders), phytophagous Scarabaeoidea (herbivores), and Tenebrionidae (detritivores). The importance of other factors besides area (namely latitude and elevation) was investigated. Reserve area was recovered as an important predictor of species richness in all cases. For Carabidae, Hydradephaga, and Tenebrionidae, elevation exerted a negative influence, whereas latitude had a negative influence on coprophagous Scarabaeoidea and Tenebrionidae, as a consequence of current and historical biogeographical factors. Extinction rates were higher for dung beetles, due to their dependence on large grazing areas, and Tenebrionidae, due to their low dispersal capabilities. The lower extinction rates predicted for Carabidae, phytophagous Scarabaeoidea, and Hydradephaga can be explained by their higher dispersal power. If other variables besides area are considered, extinction rates became more similar among groups. Extinction rates by area loss are always relatively low. Thus, in reserves with few species, many local extinctions might be unnoticed.

The distribution of ants on the Wessel and English Company Islands, in the seasonal tropics of Australia’s Northern Territory

1998 ◽  
Vol 46 (6) ◽  
pp. 557 ◽  
Author(s):  
J. C. Z. Woinarski ◽  
Hanna Reichel ◽  
A. N. Andersen
Keyword(s):  
Species Richness ◽  
Functional Group ◽  
Group Composition ◽  
Northern Territory ◽  
Similar Species ◽  
Small Islands ◽  
Island Size ◽  
Generalist Species ◽  
The North ◽  
Continental Islands

A total of 74 ant species (from 23 genera) was recorded from 195 quadrats (50 × 50 m) from 39 continental islands off Arnhem Land, Northern Territory. In general, the ant fauna comprised generalist species widespread on the north Australian mainland. The functional group composition was also comparable to that of similar environments on the north Australian mainland. The ant fauna was not tightly structured. There were few habitat specialists, no species showed a clear preference for smaller islands, and only a few species showed unequivocal preferences for larger islands. There were no clear cases of congeneric, or otherwise ecologically similar, species replacing each other on different islands. In contrast to the north Australian mainland, there were no significant differences between habitats in ant species richness. However, the functional group composition varied significantly between the eight main habitats sampled across the islands, in a manner consistent with that reported for the mainland. The number of ant species recorded per island was most closely related to island size (80% of the deviance explained), but there was only slight or no relationship between island size and the number of species at the quadrat scale. Functional group composition varied between islands, with small islands supporting a relatively high proportion of Generalised Myrmicinae species. Low-lying (and presumably intermittently inundated) islands supported a higher proportion of Dominant Dolichoderinae and few Specialist Predators and Tropical Climate Specialist species. Very small islands supported a relatively high proportion of Dominant Dolichoderinae species. These differences are largely attributable to inter-island differences in habitat availability and disturbance regimes, and to differences between functional groups in dispersability, competitive ability and ecological flexibility. Species richness was little influenced by the extent of island isolation. Patterning in the ant fauna of these islands parallels that reported for islands elsewhere.

Questioning Israel's Great Biodiversity—Relative to Whom? A Comment on Roll et al., 2009

2011 ◽  
Vol 57 (3) ◽  
pp. 183-192 ◽  
Author(s):  
Yoni Gavish
Keyword(s):  
Species Richness ◽  
Linear Regression ◽  
Unit Area ◽  
Biodiversity Hotspot ◽  
Biodiversity Hotspots ◽  
Species Area ◽  
C Value ◽  
Species Area Relationship ◽  
Z Value ◽  
Global Biodiversity

Each evolutionary-independent province has its own mainland species area relationship (SPAR). When using the power law SPAR (S = cAz), separate mainland SPARs are parallel in a log-log space (similar z value), yet they differ in species density per unit area (c value). This implies that there are two main SPAR-based strategies to identify biodiversity hotspots. The first treats all mainland SPARs of all provinces as if they form one global SPAR. This is the strategy employed by Roll et al. (2009) when questioning Israel's high biodiversity. They concluded that Israel is not a global biodiversity hotspot. Their results may arise from the fact that Israel's province, the Palaearctic, is relatively poor. Therefore, countries from richer provinces, whose mainland SPAR lies above the Palaearctic SPAR, are identified as global hotspots. The second strategy is to construct different mainland SPARs for each province and identify the provincial hotspots. In this manuscript I ask whether Israel's biodiversity is high relative to other countries within its province. For six different taxa, I analyzed data for Palaearctic countries. For each taxon, I conducted a linear regression of species richness against the country's area, both log transformed. The studentized residuals were used to explore Israel's rank relative to all other Palaearctic countries. I found that Israel lies above the 95th percentile for reptiles and mammals and above the 90th percentile for birds. Therefore, within the Palaearctic province, Israel is indeed a biodiversity hotspot.

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