It has been a century since the species-area relationship (SAR) was first proposed as a power law to explain how species richness scales with area. There have been many attempts to explain the origin of this predominant form. Apart from the power law, numerous empirical studies also report a semi-log form of the SAR, but very few have addressed its incidence. In this work, we test whether these relationships could emerge from the assembly of large random communities. To this end, we reformulate the generalized Lotka-Volterra model replacing the interaction strength parameter by the inverse of area . This framework allows us to track the species richness values resulting from the assembly of large competitive communities over a range of areas. Our analysis demonstrates that the two most widely reported relationship forms can emerge due to differences in immigration rates and skewness towards weak interactions. We support our results regarding immigration rates through two related studies from the literature .
It has been a century since the species-area relationship (SAR) was first proposed as a power law to explain how species richness scales with area. There have been many attempts to explain the origin of this predominant form. Apart from the power law, numerous empirical studies also report a semi-log form of the SAR, but very few have addressed its incidence. In this work, we test whether these relationships could emerge from the assembly of large random communities. To this end, we reformulate the generalized Lotka-Volterra model by introducing an area parameter . This framework allows us to track the species richness values resulting from the assembly of large competitive communities over a range of areas. Our analysis demonstrates that the two most widely reported relationship forms can emerge due to differences in immigration rates and skewness towards weak interactions. We particularly highlight the incidence of the semi-log SAR for low immigration rates from a source pool, which has been alluded to in empirical studies. The two SAR forms might show good fits to data over a large span of areas but the extinction rates could be significantly higher for smaller areas when the semi-log relationship holds. This calls for a critical evaluation of extinction scenarios based on SARs so as to not underestimate the possible effects of habitat loss .
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replacing the interaction strength parameter by the inverse of area
by introducing an area parameter
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support our results regarding immigration rates through two related studies from the literature
particularly highlight the incidence of the semi-log SAR for low immigration rates from a source pool, which has been alluded to in empirical studies. The two SAR forms might show good fits to data over a large span of areas but the extinction rates could be significantly higher for smaller areas when the semi-log relationship holds. This calls for a critical evaluation of extinction scenarios based on SARs so as to not underestimate the possible effects of habitat loss