The state of chondrichthyan taxonomy and systematics

Csiro, Australia

doi:10.1071/mf07003

Cited by 20 publications

(19 citation statements)

References 2 publications

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“…Despite being home to ~50% of all known chondrichthyan species (Kyne and Simpfendorfer, 2007), the study of deep-water elasmobranchs is very much in its infancy; indeed, many genera need further investigation on the most fundamental genetic and taxonomic level (Last, 2007;Naylor et al, 2012;. Estimates of species productivity and intrinsic rebound potential only exist for 2.2% of deep-ocean chondrichthyans (Kyne and Simpfendorfer, 2010), and those that have been assessed have among the lowest values documented for any species of fish to date (Simpfendorfer and Kyne, 2009).…”

Section: Introductionmentioning

confidence: 99%

First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas

Brooks

Williams

et al. 2015

Deep Sea Research Part II: Topical Studies in Oceanography

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Section: Introductionmentioning

confidence: 99%

First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas

Brooks

Williams

et al. 2015

Deep Sea Research Part II: Topical Studies in Oceanography

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“…For example, a recent review of the species Centrophorus granulosus using both morphological characters and molecular tools suggests that this species is, in fact, a senior synonym of C. niaukang and C. acus (the latter is known only from the north-western Pacific) (White et al 2013). Indeed, management policies will not be effective unless species are unambiguously and correctly identified, either by morphological traits or molecular approaches (Last 2007). The use of molecular tools is particularly relevant when only parts of the fishes are landed, such as trunks, fins or livers, or when species need to be unequivocally identified in the market trade (e.g.…”

Section: Introductionmentioning

confidence: 99%

Barcoding deep-water chondrichthyans from mainland Portugal

Moura

Silva

Figueiredo

2015

Mar. Freshwater Res.

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Most deep-water chondrichthyans occurring off mainland Portugal are distributed worldwide. There are many closely related species with similar morphology, and the lack of diagnostic characters that unambiguously allow species discrimination has led to extensive identification problems. Here, DNA barcodes were used to evaluate the suitability of cytochrome c oxidase I (COI) to identify deep-water chondrichthyans and to further contribute to the worldwide molecular databases currently in use. The sample was composed of 40 individuals from the families Chimaeridae, Centrophoridae, Somniosidae, Etmopteridae, Oxynotidae, Dalatiidae, Scyliorhinidae, Mitsukurinidae, Chlamydoselachidae and Hexanchidae. COI proved to be adequate for species identification, with almost all putative species recovered as well supported monophyletic clades, with low intraspecific variation. Sequence matches against the BOLD database provided evidence for the existence of identification problems particularly within the genera Hydrolagus, Galeus and Centrophorus. Present results suggest that three different Centrophorus species occur off the Portuguese mainland, C. squamosus, C. granulosus and C. uyato. The sample also included an albino Deania calcea and a C. squamosus specimen without dermal denticles. This study updates the current knowledge on diversity and distribution of deep-water chondrichthyans occurring along the Portuguese coast, and provides an essential tool for species identification and consistency of taxonomic designations worldwide.

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“…Chondrichthyans, comprising more than 1100 extant sharks, skates, rays and chimaeras (Last 2007), offer an ideal taxon in which to study the potential links between reproduction and the brain size and morphology. Chondrichthyans have the most diverse array of reproductive strategies of any vertebrate taxa, ranging from single oviparity to placental viviparity, with many intermediate forms of matrotrophy (i.e.…”

Section: Introductionmentioning

confidence: 99%

Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans

Mull

Yopak

Dulvy

2011

Mar. Freshwater Res.

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Abstract. Chondrichthyans have the most diverse array of reproductive strategies of any vertebrate group, ranging from egg-laying to live-bearing with placental matrotrophy. Matrotrophy is defined as additional maternal provisioning beyond the yolk to the developing neonate; in chondrichthyans, this occurs through a range of mechanisms including uterine milk, oophagy, uterine cannibalism and placentotrophy. Chondrichthyans also exhibit a wide range of relative brain sizes and highly diverse patterns of brain organisation. Brains are energetically expensive to produce and maintain, and represent a major energetic constraint during early life in vertebrates. In mammals, more direct maternal-fetal placental connections have been associated with larger brains (steeper brain-body allometric scaling relationships). We test for a relationship between reproductive mode and relative brain size across 85 species from six major orders of chondrichthyans by using several phylogenetic comparative analyses. Ordinary least-squares (OLS) and reduced major axis (RMA) regression of body mass versus brain mass suggest that increased maternal investment results in a larger relative brain size. Our findings were supported by phylogenetic generalised least-squares models (pGLS), which also highlighted that these results vary with evolutionary tempo, as described by different branch-length assumptions. Across all analyses, maximum body size had a significant influence on the relative brain size, with large-bodied species (body mass .100 kg) having relatively smaller brains. The present study suggests that there may be a link between reproductive investment and relative brain size in chondrichthyans; however, a more definitive test requires a better-resolved phylogeny and a more nuanced categorisation of the level of maternal investment in chondrichthyans.

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The state of chondrichthyan taxonomy and systematics

Cited by 20 publications

References 2 publications

First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas

First description of deep-water elasmobranch assemblages in the Exuma Sound, The Bahamas

Barcoding deep-water chondrichthyans from mainland Portugal

Does more maternal investment mean a larger brain? Evolutionary relationships between reproductive mode and brain size in chondrichthyans

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