The evolutionary origins of Syngnathidae: pipefishes and seahorses

Abstract

Despite their importance as evolutionary and ecological model systems, the phylogenetic relationships among gasterosteiforms remain poorly understood, complicating efforts to understand the evolutionary origins of the exceptional morphological and behavioural diversity of this group. The present review summarizes current knowledge on the origin and evolution of syngnathids, a gasterosteiform family with a highly developed form of male parental care, combining inferences based on morphological and molecular data with paleontological evidence documenting the evolutionary history of the group. Molecular methods have provided new tools for the study of syngnathid relationships and have played an important role in recent conservation efforts. Despite recent insights into syngnathid evolution, however, a survey of the literature reveals a strong taxonomic bias towards studies on the species-rich genera Hippocampus and Syngnathus, with a lack of data for many morphologically unique members of the family. The study of the evolutionary pressures responsible for generating the high diversity of syngnathids would benefit from a wider perspective, providing a comparative framework in which to investigate the evolution of the genetic, morphological and behavioural traits of the group as a whole.

Absence of major histocompatibility complex class II mediated immunity in pipefish, Syngnathus typhle : evidence from deep transcriptome sequencing

“…Nevertheless, among the Syngnathidae, seahorses (Hippocampus abdominalis) are reported to possess a single functional MHC class IIb-gene locus [23] which is, however, divergent in terms of nucleotide sequences from all other Acanthopterygii, in particular in the second exon that codes for the peptide binding region (see the electronic supplementary materials, table S2). Because the Syngnathus genus diverged from the general Syngnathidae lineage 34 Ma [24], we postulate that the major immune system modification occurred during the cladogenesis of genus Syngnathus.…”

Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae)

“…The classification we propose is derived from tail-brooding and trunk-brooding species distributed across the entire phylogenetic tree (cp. [2]), and is based on species representing a variety of morphologically distinct adult forms, including species with different degrees of brooding-structure complexity [6]. As such, we believe that the classification is likely applicable to the majority of species of this family.…”

“…To date approximately 300 extant species are known [2], most of which live in near-shore marine habitats, although some species live in the open sea or in brackish or fresh-water [1]. Increased interest in the biology of these fish in recent years has led to the development of syngnathids as model organisms for studies in evolution, ecology, and conservation biology [3], with particular attention being directed towards their extraordinary reproductive biology.…”

Candidatus Syngnamydia Venezia, a Novel Member of the Phylum Chlamydiae from the Broad Nosed Pipefish, Syngnathus typhle

“…Pipefish and seahorses of the Syngnathidae are the focus of evolutionary studies at both the genetic and behavioural levels in many parts of the world [27], [28], [29]. This research often involves the collection of fish from free-living populations, requiring basic data on their population genetic structure.…”