PAPER 1: MACROECOLOGY: THE DIVISION OF FOOD AND SPACE AMONG SPECIES ON CONTINENTS – J. H. BROWN AND B. A. MAURER (1989)

J. H. Brown – Commentary author/Author  

Dr. Brown is a well-known American biologist and academic interested in (1) theoretical research in biological scaling, biocomplexity, biogeography and macroecology as well as (2) experimental research in desert ecology. He is internationally known for the elaboration of the Metabolic Theory which gave him the Robert H. MacArthur Award in 2005. He is also the father of Macroecology (with this paper and a previous one in 1987) and the main author of the Foundations of Macroecology.

He has a total of 649 publications and a 67534 citations based on Google Scholar.

Brian A. Maurer – Commentary author/Author

Dr. Maurer is an Associate Professor in the Department of Fisheries & Wildlife at Michigan State University. His research interests are on macroecology, biogeography and quantitative ecology. More specifically, he is interested in population modeling and community dynamics to better understand biological processes at a geographical scale. His lab uses GIS and other tools to analyze and model spatial processes. He has published about 100 papers since 1981.

Cliff Notes of the paper:

[632 citations – Google Scholar]

James Brown and Brian Maurer were interested on synthesizing the findings of many studies to find a general pattern that would explain some regularities found in nature. The main goal in this paper was to understand the ecological processes that affect how species divide space and resources (energy) among the continent. 

They compiled large datasets for mammals and birds in North America using ecologically relevant data: body mass, population density and area/shape geographic range. They analyzed the same variables among species to capture de variance among assemblages taxonomically different (birds and mammals).

Brown and Maurer found some generalities in body mass among species in different taxon [Fig. 1] that vary with special scale (we already talk about that in paper 18 of this book). The general pattern goes from a right-skewed modal distribution at a continental scale to almost flat distribution among body sizes at a local scale. They hypothesized three mechanisms that explain the distribution of body size in spatial scale:

1.  Interspecific competition caused a flat distribution in local habitats [Fig.1E, 1F]. Competitive exclusion prevents local similar sized species to coexist.
2. Large species have a low frequency in the continental scale due to a higher probability of extinction when the population size is small [Fig. 2].
3. Specialization smaller species due to energetic constrains. Modal-sized species turnover from one habitat to the other [Fig. 4]

The authors also talk about the area and shape of species geographic range. They found that species with small ranges are distributed along the range north-south because are mainly limited by topographic features that run in that direction. On the other hand, species with large ranges are distributed along the range east-west where are limited by climatic zones ruining in that direction [Fig. 6A]. They predicted that other taxonomic groups (birds) would have a similar distribution [Fig. 6B]. They also predicted that in other areas like Europe, the distribution would change accordingly with the different direction of the topographic features and climatic zones [Fig. 6C].

At the end of this paper, the authors point out the importance of this study in applied disciplines like conservation biology to predict and manage the protection of endangered species and their habitats at a global scale.

Question: Would all this hypothesis related to body size and geographic range distributions be applicable to marine habitats?