Why are there so few evolutionary transitions between aquatic and terrestrial ecosystems?

Abstract

Insects and flowering plants have rarely invaded the sea. Explanations for this have traditionally centered on the unique shortcomings of these groups in the marine environment. We show, however, that transitions among terrestrial, freshwater, and marine environments are infrequent in all major plant and animal clades except tetrapod vertebrates. In general, well-adapted incumbents are at a competitive advantage over would-be invaders from a physically different habitat. Data on the times and places of transition are consistent with our contention that evolutionary transitions among physically different environments are most likely when incumbents in the recipient environment exist in a regime of low-intensity competition and predation, as in terrestrial communities of the middle Paleozoic or the land biotas of oceanic islands. Freshwater environments, in which inferred intensities of predation are lower than in most marine and terrestrial environments, offer less biotic resistance to invaders than do communities in the sea or on land. Most invaders respond to novel physical circumstances by shutting down their metabolic machinery, and therefore add to their subordinate status as competitors with active incumbents. Only active tetrapods, particularly those with high and endothermically driven rates of metabolism, have successfully overcome this limitation.

Phylogenetic relationships and evolution of pulmonate gastropods (Mollusca): New insights from increased taxon sampling

“…Addressing macro-evolutionary transitions between aquatic and terrestrial habitats requires a full range of data (Vermeij and Dudley, 2000): a phylogenetic pattern of relationships; the study of physiological and morphological constraints and adaptations to new habitats; the biological context in which transitions occurred (e.g., temporal and geographical dimensions, and competitions between invaders and incumbents).…”

Global diversity of gastropods (Gastropoda; Mollusca) in freshwater

“…Published estimates, although not comparable as classifications have changed and fossil lineages have been variably included or excluded, range from 6 to 7 (Hutchinson, 1967), or 10 (Taylor in Gray, 1988, to as many as 15 Recent freshwater gastropod colonizations (Vermeij & Dudley, 2000). Based on the current classification (Bouchet & Rocroi, 2005) and our present understanding of gastropod phylogenetic relationships, we estimate that there are a minimum of 33-38 independent freshwater lineages represented among Recent gastropods: in the Rissooidea, there are at least 2 each in Assimineidae and Cochliopidae, 1-2 in Pomatiopsidae, at least 1 each in Stenothyridae, Lithoglyphidae, Moitessieriidae, 1 in Bithyniidae, possibly 1 in Helicostoidae, possibly 6-8 in the Hydrobiidae; 5-6 in the Neritimorpha (Holthuis, 1995); 2-3 in the Cerithioidea (Lydeard et al, 2002); probably 2 each in the "Architaenioglossa" (e.g., Simone, 2004) and the Acochlidiida; and 1 in each of the Litttorinidae, Buccinidae, Marginellidae, Glacidorbidae, Valvatidae and Hygrophila (see Table 1).…”

Mechanical challenges to freshwater residency in sharks and rays

“…For major transitions, such as those between aquatic and terrestrial or marine and fresh water environments, successful invasions are relatively infrequent in most plant and animal taxa, except for tetrapods (Vermeij and Dudley, 2000). However, transitions from saltwater to freshwater habitats can facilitate radiation and speciation events, which in some systems manifest as rapid and repeated invasions worldwide (Lee and Bell, 1999).…”