skip to main content


Title: A COMBINED MORPHOLOGICAL AND MOLECULAR PHYLOGENETIC ANALYSIS OF FOSSIL AND EXTANT MARINE CLAWED LOBSTERS AND FRESHWATER CRAYFISH
The infraorder Astacidea, comprising marine clawed lobsters and freshwater crayfish, include some of the most recognizable decapod crustaceans, many being harvested commercially for human consumption and aquaculture. While molecular analyses have elucidated relationships among extant lineages, the composition and placement of several fossil groups within Astacidea remain poorly resolved, with several conflicting phylogenetic hypotheses and taxonomic classifications being proposed in previous works. Among these controversial groups, Erymoidea have variably been placed in Astacidea or Glypheidea, a largely extinct infraorder of predominantly pseudochelate marine lobsters. Cladistic relationships of Stenochiroidea have also been problematic, having been regarded as ancestral to freshwater crayfish (Astacida) or extant marine lobsters (Nephropidae). Failure to reach a consensus regarding these groups can be at least partially attributed to the prevalence of morphological convergence and limited taxon sampling. To clarify evolutionary relationships among fossil and extant taxa, a Bayesian phylogenetic analysis of morphological and molecular data (mitochondrial genes: 12S, 16S and COI; nuclear genes: 18S, 28S and H3) was performed that included extensive taxon sampling of all currently recognized families of Astacidea as well as representatives of several potential sister groups. To overcome error introduced by homoplasy, relationships among extant taxa, as revealed by previous molecular analyses, were used to identify morphological characters with potentially robust phylogenetic signal. The resulting phylogeny places erymids within Glypheidea and supports a sister relationship between Astacidea and Glaessnericarididae. Stenochiroidea was found to be polyphyletic, with most genera forming a clade sister to Nephropidae; Pseudastacus is moved to Protastacidae, which resolves as the sister taxon to freshwater crayfish. The relationships among living and fossil taxa presented here provide new insight into the origins and evolutionary histories of the major lineages of marine clawed lobsters and freshwater crayfish.  more » « less
Award ID(s):
1943082
PAR ID:
10503734
Author(s) / Creator(s):
;
Corporate Creator(s):
Publisher / Repository:
Geological Society of America Abstracts with Progams
Date Published:
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Osteoglossid bonytongues (arapaimas, arowanas, and relatives) are extant tropical freshwater fishes with a relatively abundant and diverse fossil record. Most osteoglossid fossils come from a 25-million-year interval in the early Palaeogene, when these fishes were distributed worldwide in both freshwater and marine environments. Despite their biogeographic and palaeoecological relevance, and a relative abundance of well-preserved material, the evolutionary relationships between these Palaeogene forms and extant bonytongues remain unclear. Here we describe a new genus of bonytongue from early Eocene marine deposits of Morocco, represented by an articulated, three-dimensionally preserved skull with associated pectoral girdle. This taxon is characterized by an elongated snout, contrasting with the short jaws usually found in marine representatives of the clade. A revision of morphological characters in bonytongues allows us to place this new genus, together with other marine and freshwater Eocene taxa, within crown osteoglossids and closely related to extant arapaimines. The discovery of the new Moroccan taxon hints at a previously underestimated eco-morphological diversity of marine bonytongues, highlighting the diverse trophic niches that these fishes occupied in early Palaeogene seas.

     
    more » « less
  2. Teeling, Emma (Ed.)
    Deciphering the evolutionary relationships of Chelicerata (arachnids, horseshoe crabs, and allied taxa) has proven notoriously difficult, due to their ancient rapid radiation and the incidence of elevated evolutionary rates in several lineages. Although conflicting hypotheses prevail in morphological and molecular data sets alike, the monophyly of Arachnida is nearly universally accepted, despite historical lack of support in molecular data sets. Some phylotranscriptomic analyses have recovered arachnid monophyly, but these did not sample all living orders, whereas analyses including all orders have failed to recover Arachnida. To understand this conflict, we assembled a data set of 506 high-quality genomes and transcriptomes, sampling all living orders of Chelicerata with high occupancy and rigorous approaches to orthology inference. Our analyses consistently recovered the nested placement of horseshoe crabs within a paraphyletic Arachnida. This result was insensitive to variation in evolutionary rates of genes, complexity of the substitution models, and alternative algorithmic approaches to species tree inference. Investigation of sources of systematic bias showed that genes and sites that recover arachnid monophyly are enriched in noise and exhibit low information content. To test the impact of morphological data, we generated a 514-taxon morphological data matrix of extant and fossil Chelicerata, analyzed in tandem with the molecular matrix. Combined analyses recovered the clade Merostomata (the marine orders Xiphosura, Eurypterida, and Chasmataspidida), but merostomates appeared nested within Arachnida. Our results suggest that morphological convergence resulting from adaptations to life in terrestrial habitats has driven the historical perception of arachnid monophyly, paralleling the history of numerous other invertebrate terrestrial groups. 
    more » « less
  3. Ware, Jessica (Ed.)
    Abstract Recent molecular analyses of transcriptome data from 94 species across 92 genera of North American Plecoptera identified the genus Kathroperla Banks, 1920 as sister group to Chloroperlidae + Perlodidae. Given that the genus Kathroperla has historically been included as a member of the family Chloroperlidae, this discovery indicated further investigation of the genus and the subfamily Paraperlinae was needed. Both transcriptome and genome sequencing datasets were generated from 32 species of the infraorder Systellognatha, including all described species of the Paraperlinae, to test the phylogenetic placement of these taxa. From these datasets, a large phylogenomic data matrix of 800 orthologous genes was produced, and multiple analyses were conducted, including both concatenated and coalescent analyses. Morphological comparisons were made among all Paraperlinae using light microscopy. All molecular results support a monophyletic Kathroperla, which is supported as sister taxon to the remaining Perloidea by five of six molecular analyses. Postocular head length is determined to be a distinct morphological character of this genus. Combined molecular and morphological evidence support the designation of Kathroperlidae, fam. n., as the seventeenth family of extant Plecoptera. 
    more » « less
  4. The almost simultaneous emergence of major animal phyla during the early Cambrian shaped modern animal biodiversity. Reconstructing evolutionary relationships among such closely spaced branches in the animal tree of life has proven to be a major challenge, hindering understanding of early animal evolution and the fossil record. This is particularly true in the species-rich and highly varied Mollusca where dramatic inconsistency among paleontological, morphological, and molecular evidence has led to a long-standing debate about the group’s phylogeny and the nature of dozens of enigmatic fossil taxa. A critical step needed to overcome this issue is to supplement available genomic data, which is plentiful for well-studied lineages, with genomes from rare but key lineages, such as Scaphopoda. Here, by presenting chromosome-level genomes from both extant scaphopod orders and leveraging complete genomes spanning Mollusca, we provide strong support for Scaphopoda as the sister taxon of Bivalvia, revitalizing the morphology-based Diasoma hypothesis originally proposed 50 years ago. Our molecular clock analysis confidently dates the split between Bivalvia and Scaphopoda at ~520 Ma, prompting a reinterpretation of controversial laterally compressed Early Cambrian fossils, includingAnabarella,Watsonella,andMellopegma,as stem diasomes. Moreover, we show that incongruence in the phylogenetic placement of Scaphopoda in previous phylogenomic studies was due to ancient incomplete lineage sorting (ILS) that occurred during the rapid radiation of Conchifera. Our findings highlight the need to consider ILS as a potential source of error in deep phylogeny reconstruction, especially in the context of the unique nature of the Cambrian Explosion.

     
    more » « less
  5. Abstract

    Relationships among the major lineages of Mollusca have long been debated. Morphological studies have considered the rarely collected Monoplacophora (Tryblidia) to have several plesiomorphic molluscan traits. The phylogenetic position of this group is contentious as morphologists have generally placed this clade as the sister taxon of the rest of Conchifera whereas earlier molecular studies supported a clade of Monoplacophora + Polyplacophora (Serialia) and phylogenomic studies have generally recovered a clade of Monoplacophora + Cephalopoda. Phylogenomic studies have also strongly supported a clade including Gastropoda, Bivalvia, and Scaphopoda, but relationships among these taxa have been inconsistent. In order to resolve conchiferan relationships and improve understanding of early molluscan evolution, we carefully curated a high-quality data matrix and conducted phylogenomic analyses with broad taxon sampling including newly sequenced genomic data from the monoplacophoranLaevipilina antarctica. Whereas a partitioned maximum likelihood (ML) analysis using site-homogeneous models recovered Monoplacophora sister to Cephalopoda with moderate support, both ML and Bayesian inference (BI) analyses using mixture models recovered Monoplacophora sister to all other conchiferans with strong support. A supertree approach also recovered Monoplacophora as the sister taxon of a clade composed of the rest of Conchifera. Gastropoda was recovered as the sister taxon of Scaphopoda in most analyses, which was strongly supported when mixture models were used. A molecular clock based on our BI topology dates diversification of Mollusca to ~546 MYA (+/− 6 MYA) and Conchifera to ~540 MYA (+/− 9 MYA), generally consistent with previous work employing nuclear housekeeping genes. These results provide important resolution of conchiferan mollusc phylogeny and offer new insights into ancestral character states of major mollusc clades.

     
    more » « less