Scientific REPORTs | 7: 16815 | DOI:10.1038/s41598-017-17070-1
On the proportional abundance
of species: Integrating population
genetics and community ecology
Pablo A. Marquet
, Guillermo Espinoza
, Sebastian R. Abades
, Angela Ganz
The frequency of genes in interconnected populations and of species in interconnected communities
are aected by similar processes, such as birth, death and immigration. The equilibrium distribution of
gene frequencies in structured populations is known since the 1930s, under Wright’s metapopulation
model known as the island model. The equivalent distribution for the species frequency (i.e. the species
proportional abundance distribution (SPAD)), at the metacommunity level, however, is unknown. In
this contribution, we develop a stochastic model to analytically account for this distribution (SPAD). We
show that the same as for genes SPAD follows a beta distribution, which provides a good description of
empirical data and applies across a continuum of scales. This stochastic model, based upon a diusion
approximation, provides an alternative to neutral models for the species abundance distribution
(SAD), which focus on number of individuals instead of proportions, and demonstrate that the relative
frequency of genes in local populations and of species within communities follow the same probability
law. We hope our contribution will help stimulate the mathematical and conceptual integration of
theories in genetics and ecology.
Ever since the evolutionary synthesis, population genetics theory has been integrated, to dierent extents, into
dierent disciplines within biology including systematics and ecology. is later integration took o with the
development of theoretical formulations relating the processes that drive changes in numbers of individuals
within age-structured populations, with changes in the tness of dierent genotypes
. Yet further integration was
achieved with the emergence of the new ecological genetics spoused by Antonovics
, one of whose tenets was that
“Forces maintaining species diversity and genetic diversity are similar. An understanding of community structure
will come from considering how these kind of diversity interact”. More recently, the emergence of community
has reinvigorated the search for connections between population genetics and community ecology,
along with the realization that there is a striking similarity between processes driving changes in the abundance
and diversity of species within communities and genes within populations
e recent development of neutral approaches to the study of ecological systems
have provided a renewed
emphasis upon the value of theory and stochasticity in ecology
and a locus for the further integration of
genetical and ecological theories
. By merging the mathematical and statistical tools developed by population
geneticists with the neutrality approach, neutral theory in ecology allows us to better understand the factors
aecting the abundance and distribution of species
. But there is a major barrier to this integration, while
population geneticists pioneered the use of diusion approximations (i.e. a continuous process) to the under-
standing of processes aecting gene frequencies
, ecologists have favored to work with the distribution of the
number of individuals across species (i.e. a discrete process) or SAD
). It is not surprising then that
Departamento de Ecología, Facultad de Ciencias Biológicas, Ponticia Universidad Católica de Chile, Alameda, 340
C.P., 6513677, Santiago, Chile.
Instituto de Ecología y Biodiversidad (IEB), Las Palmeras, 3425, Santiago, Chile.
Instituto de Sistemas Complejos de Valparaíso (ISCV), Artillería 470, Cerro Artiller, Valpara, Chile.
Internacional en Cambio Global (LINCGlobal) and Centro de Cambio Global (PUCGlobal), Ponticia Universidad
Católica de Chile, Alameda 340 C.P., 6513677, Santiago, Chile.
The Santa Fe Institute, 1399 Hyde Park Road, Santa
Fe, NM, 87501, USA.
GEMA Center for Genomics, Ecology & Environment, Universidad Mayor, Camino La Pirámide,
5750, Huechuraba, Chile.
Centro de Análisis Estocástico y Aplicaciones, Facultad de Ingeniería and Facultad de
Matemáticas, Ponticia Universidad Católica de Chile, Casilla 306, Santiago, 22, Chile.
Centro de Investigación y
Modelamiento de Fenómenos Aleatorios (CIMFAV), Facultad de Ingeniería Universidad de Valparaíso, Valparaíso,
Chile. Correspondence and requests for materials should be addressed to P.A.M. (email: firstname.lastname@example.org)
Received: 24 March 2017
Accepted: 21 November 2017
Published: xx xx xxxx