Life History Patterns and Biogeography: An Interpretation of Diadromy in Fishes¹

Abstract

Diadromy, broadly defined here as the regular movement between freshwater and marine habitats at some time during their lives, characterizes numerous fish and invertebrate taxa. Explanations for the evolution of diadromy have focused on ecological requirements of individual taxa, rarely reflecting a comparative, phylogenetic component. When incorporated into phylogenetic studies, center of origin hypotheses have been used to infer dispersal routes. The occurrence and distribution of diadromy throughout fish (aquatic non-tetrapod vertebrate) phylogeny are used here to interpret the evolution of this life history pattern and demonstrate the relationship between life history and ecology in cladistic biogeography. Cladistic biogeography has been mischaracterized as rejecting ecology. On the contrary, cladistic biogeography has been explicit in interpreting ecology or life history patterns within the broader framework of phylogenetic patterns. Today, in inferred ancient life history patterns, such as diadromy, we see remnants of previously broader distribution patterns, such as antitropicality or bipolarity, that spanned both marine and freshwater habitats. Biogeographic regions that span ocean basins and incorporate ocean margins better explain the relationship among diadromy, its evolution, and its distribution than do biogeographic regions centered on continents.

Why be amphidromous: expatrial dispersal and the place of source and sink population dynamics?

“…These are important questions for future research on the life histories especially of tropical gobioids, but at present I know of no rigorous claims for an entirely freshwater, nonmigratory life cycle in any of the sicydiine gobies. Amphidromy is often assumed (Keith et al 1999Lim et al 1997Lim et al , 2002Marquet et al 2003;Keith and Marquet 2007;Parenti 2008).…”

The evolutionary origins of diadromy inferred from a time-calibrated phylogeny for Clupeiformes (herring and allies)

“…An expected outcome in both the productivity and safe-site hypotheses is that diadromy is a precursor to permanent transitions between marine and freshwater biomes in fish lineages (although see [20,21,61,62]). This concept is intuitively appealing: a species that migrates between marine and freshwater environments could become isolated in one habitat and successfully establish a permanent population.…”

“…The evolutionary origins of diadromy are the subject of considerable theoretical discussion [1,14,[18][19][20][21][22][23]. In an important contribution, Gross [22] and Gross et al [23] proposed that differences in ecological productivity between marine and freshwater biomes determine the origins of the different modes of diadromy (herein referred to as the 'productivity hypothesis').…”

The shape of biogeography: Endemism, maps, and classification of fish distributions in the western Pacific

“…The oldest fossils of Anguilla are from 50 to 55 Ma (Patterson, ). Today anguillids live in pantropical and temperate habitats and exhibit remnants of antitropical distributions (Parenti, : fig. 6).…”

“…An area may be unique to a clade, but it may also reflect general, congruent distributions, such as Pantropical, Holarctic, Trans-Pacific or Trans-Atlantic, or just remnants of those distributional patterns (Humphries & Parenti, 1999;Parenti, 2008). The broad, general distributional patterns shared across taxa in a biota form the basis of a biogeographical classification (e.g., Ebach & Michaux, 2017;Ebach, Morrone, Parenti, & Viloria, 2008) (Figure 1).…”