title: Phylogenetic niche conservatism and the evolutionary basis of ecological speciation.
abstract: Phylogenetic niche conservatism (PNC) typically refers to the tendency of closely related species to be more similar to each other in terms of niche than they are to more distant relatives. This has been implicated as a potential driving force in speciation and other species-richness patterns, such as latitudinal gradients. However, PNC has not been very well defined in most previous studies. Is it a pattern or a process? What are the underlying endogenous (e.g. genetic) and exogenous (e.g. ecological) factors that cause niches to be conserved? What degree of similarity is necessary to qualify as PNC? Is it possible for the evolutionary processes causing niches to be conserved to also result in niche divergence in different habitats? Here, we revisit these questions, codifying a theoretical and operational definition of PNC as a mechanistic evolutionary process resulting from several factors. We frame this both from a macroevolutionary and population-genetic perspective. We discuss how different axes of physical (e.g. geographic) and environmental (e.g. climatic) heterogeneity interact with the fundamental process of PNC to produce different outcomes of ecological speciation. We also review tests for PNC, and suggest ways that these could be improved or better utilized in future studies. Ultimately, PNC as a process has a well-defined mechanistic basis in organisms, and future studies investigating ecological speciation would be well served to consider this, and frame hypothesis testing in terms of the processes and expected patterns described herein. The process of PNC may lead to patterns where niches are conserved (more similar than expected), constrained (divergent within a limited subset of available niches), or divergent (less similar than expected), based on degree of phylogenetic relatedness between species.
authors.affiliation: Department of Biological Sciences, The George Washington University, 2023 G Street NW, Washington, DC 20052, U.S.A.
authors.forename: R Alexander
authors.initials: RA
authors.lastname: Pyron
authors.affiliation: Departamento de Ecologia, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Campus Universitário Lagoa Nova, Natal, 59072-970, Rio Grande do Norte, Brazil.
authors.forename: Gabriel C
authors.initials: GC
authors.lastname: Costa
authors.affiliation: Oklahoma Biological Survey, University of Oklahoma, 111 E. Chesapeake Street, Norman, OK 73019, U.S.A.|Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, U.S.A.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Patten
authors.affiliation: Department of Biology, The Graduate School and University Center, The City University of New York, 365 5th Avenue, New York, NY 10016, U.S.A.|Department of Biology, The College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, NY 10314, U.S.A.
authors.forename: Frank T
authors.initials: FT
authors.lastname: Burbrink
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D049810:Genetic Speciation; D010802:Phylogeny
keywords: allopatry; canalization; ecological speciation; evolutionary constraint; niche divergence; phylogenetic niche conservatism