Correlation/causation in ecology: towards mechanistic explanations for the Species-Area Relationship

Mapping Intimacies ◽

10.1101/044081 ◽

2016 ◽

Author(s):

Andersonn Prestes

Keyword(s):

Species Richness ◽

Positive Relationship ◽

Abiotic Factors ◽

Causal Explanations ◽

Biotic And Abiotic Factors ◽

Mechanistic Explanations ◽

Species Area ◽

Species Area Relationship ◽

Per Se ◽

Recurrent Patterns

There is a common intuition in biology that strict laws are very difficult to be found. Still, there are recurrent patterns in nature, suggesting broad generalizations and understanding of phenomena. The problem is that many generalizations in biology, especially in the form of correlations, might be decoupled from causality, weakening their power of explanation. Here, I bring an example on the Species-Area Relationship (SAR). The SAR is a well-known generalization in biology. The recurrent pattern states a positive relationship between area size and species richness. Understanding the mechanisms why there is a correlation between area and diversity remains a major challenge. I suggest an explicitly focus on mechanistic explanations for the SAR. I propose to use the integration, comparison and interpretation of other (associated or secondary) natural patterns in the searching for causal explanations. Area per se might not account for causality in species diversification or absolute species richness in larger regions. Biotic and abiotic factors of a given area might be studied in order to discover the causal underpinnings of the SAR.

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Hot-Spot Facts and Artifacts-Questioning Israel's Great Biodiversity

Israel Journal of Ecology and Evolution ◽

10.1560/ijee.55.3.263 ◽

2009 ◽

Vol 55 (3) ◽

pp. 263-279 ◽

Cited By ~ 10

Author(s):

Uri Roll ◽

Lewi Stone ◽

Shai Meiri

Keyword(s):

Species Richness ◽

Biological Diversity ◽

Hot Spot ◽

Flowering Plants ◽

Prediction Intervals ◽

Predicting Factors ◽

Mediterranean Countries ◽

Species Area ◽

Expected Values ◽

Species Area Relationship

Israel's biological diversity has been praised as being particularly rich in relation to its size; however this assumption was never tested when taking into account the empirical form of the species-area relationship. Here we compared the species richness of different countries to see if the Israeli diversity is exceptionally rich when area is accurately accounted for. We compared richness of amphibians, birds, mammals, reptiles, flowering plants, conifers and cycads, and ferns in all the world's countries. We further tested the effects of mean latitude, altitude span, and insularity on species richness both for all world countries and just for Mediterranean countries. For all taxa and in all tests, Israel lies within the prediction intervals of the models. Out of 42 tests, Israel's residuals lie in the upper decile of positive residuals once: for reptiles, when compared to all world countries, taking all predicting factors into account. Using only countries larger than 1000 km2, Israel was placed as top residual when compared to other Mediterranean countries for mammals and reptiles. We therefore conclude that Israel's species richness does not significantly exceed the expected values for a country its size. This is true when comparing it to either world or just Mediterranean countries. Adding more predicting factors does not change this fact.

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Organisation de la richesse et de la composition floristiques d'îles de la Méditerranée occidentale (sud-est de la France)

Canadian Journal of Botany ◽

10.1139/b97-135 ◽

1998 ◽

Vol 76 (2) ◽

pp. 321-331 ◽

Cited By ~ 3

Author(s):

Frédéric Médail ◽

Éric Vidal

Keyword(s):

Species Richness ◽

Species Composition ◽

Plant Species ◽

Habitat Diversity ◽

Mediterranean Islands ◽

Plant Dispersal ◽

Number Of Species ◽

Continental Islands ◽

Species Area ◽

Species Area Relationship

The effects of physiographic variables (area, isolation, elevation, and substrate) and habitat diversity on plant species richness and composition have been investigated on some Mediterranean islands (southeastern France). The number of species - area relationship is significant but there are more diverse vegetation patterns on smallest islands (area smaller than 3.5 ha and, ultimately, 0.2 ha). Although the species composition is positively correlated to the distance from the continent, the effect of isolation is not so obvious because of the small distance of these continental islands from the continent. Some islands nearest to shore show very different plant species composition, suggesting a nonselective plant dispersal through some narrow stretches of sea. Habitat diversity represents one of the major explanatory factors of the species richness; nevertheless, it is not possible to settle between the two hypotheses effect of habitat diversity versus effect of area per se because of the correlation between the two factors. Key words: Mediterranean islands, insular biogeography, number of species - area relationship, isolation, habitat diversity, islets.

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

Entomologica Fennica ◽

10.33338/ef.70076 ◽

2018 ◽

Vol 29 (1) ◽

pp. 21-29 ◽

Cited By ~ 1

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.

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The Similar Usage of a Common Key Resource Does Not Determine Similar Responses by Species in A Community of Oil-collecting Bees

Sociobiology ◽

10.13102/sociobiology.v64i1.1210 ◽

2017 ◽

Vol 64 (1) ◽

pp. 69

Author(s):

Cândida Maria Lima Aguiar ◽

Shantala Lua ◽

Maise Silva ◽

Paulo Enrique Cardoso Peixoto ◽

Heiddy M Alvarez ◽

...

Keyword(s):

Species Richness ◽

Abiotic Factors ◽

Ecological Factor ◽

Total Abundance ◽

Neotropical Savanna ◽

Biotic And Abiotic Factors ◽

Number Of Species ◽

The Common ◽

Species Richness And Abundance ◽

Floral Oil

Variations in abundance and species richness among communities are often determined by interactions between biotic and abiotic factors. However, for communities composed of species that share a common specialization (such as similar foraging adaptations) it may be a key ecological factor involved in the common specialization that affects community variations. To evaluate this possibility, we characterized the guild of oil-collecting bees of a Neotropical savanna in Brazil and tested whether differences in Byrsonima abundance and availability of floral oil explain differences in species richness and abundance of oil-collecting bees of different tribes. Both the number of species and total abundance of Centridini species increased with the abundance of Byrsonima. One plausible explanation for the stronger adjustment between the abundance of Centridini and Byrsonima is that the abundance of these plants affects not only the availability of floral oil, but also of pollen. These findings indicate that the existence of a common specialization among different species does not homogenize their response to variations in a common explored resource.

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The species-area relationship: new challenges for an old pattern

Progress in Physical Geography Earth and Environment ◽

10.1177/030913330102500101 ◽

2001 ◽

Vol 25 (1) ◽

pp. 1-21 ◽

Cited By ~ 9

Author(s):

Mark V. Lomolino

Keyword(s):

Secondary Phase ◽

Species Number ◽

General Tendency ◽

Small Islands ◽

Stochastic Variation ◽

Causal Explanations ◽

Island Area ◽

Species Area ◽

Species Area Relationship ◽

The Relationship

The species-area relationship (i.e., the relationship between area and the number of species found in that area) is one of longest and most frequently studied patterns in nature. Yet there remain some important and interesting questions on the nature of this relationship, its causality, quantification and application for both ecologists and conservation biologists. Traditionally, the species-area relationship describes the very general tendency for species number to increase with island area; a relationship whose slope declines (but remains positive) as area increases. The true relationship, however, may be much more complicated than this, and may in many cases approximate a sigmoidal relationship. On small islands, species number may vary independently of island area. Species richness then increases as we consider larger islands, but the curve eventually slows and asymptotes or levels off when richness equals that of the the source or mainland pool. The relationship may also include a secondary phase of increase in richness if island area becomes large enough to allow in situ speciation. Causal explanations for this relationship may, therefore, need to be multifactorial and include a range of processes from disturbance and stochastic variation in habitat quality on the very small islands, to ecological interactions, immigration, extinction and, finally, evolution on the larger islands.

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Species and Generic Gamma-Scale Diversity in Shallow-Water Marine Amphipoda with Particular Reference to the Mediterranean

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531540002912x ◽

1996 ◽

Vol 76 (1) ◽

pp. 195-202 ◽

Cited By ~ 12

Author(s):

A.A. Myers

Keyword(s):

Species Richness ◽

Mediterranean Sea ◽

Late Miocene ◽

Evolutionary History ◽

Amphipod Species ◽

Species Area ◽

Species Area Relationship ◽

The Mediterranean ◽

Shallow Seas

Major hotspots of amphipod species richness and of species and generic endemicity can be recognized in shallow seas. Recognition of ‘hotspots’ for amphipods must take account of the species-area relationship but not of latitude. The richness and endemicity of amphipods in the Mediterranean Sea is shown to be high when compared with other shallow seas This indicates a long in situ evolutionary history and is therefore not compatible with the hypothesis that the Mediterranean fauna was extirpated in the late Miocene.

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Species Richness of Stream Stones: An Investigation of the Mechanisms Generating the Species-Area Relationship

Oikos ◽

10.2307/3545851 ◽

1994 ◽

Vol 69 (3) ◽

pp. 387 ◽

Cited By ~ 84

Author(s):

M. Douglas ◽

P. S. Lake

Keyword(s):

Species Richness ◽

Species Area ◽

Species Area Relationship

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Beetle Species–Area Relationships and Extinction Rates in Protected Areas

Insects ◽

10.3390/insects11090646 ◽

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.

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