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Brownstein CD, Near T. Colonization of the ocean floor by jawless vertebrates across three mass extinctions. BMC Ecol Evol 2024; 24:79. [PMID: 38867201 PMCID: PMC11170801 DOI: 10.1186/s12862-024-02253-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/07/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND The deep (> 200 m) ocean floor is often considered to be a refugium of biodiversity; many benthic marine animals appear to share ancient common ancestry with nearshore and terrestrial relatives. Whether this pattern holds for vertebrates is obscured by a poor understanding of the evolutionary history of the oldest marine vertebrate clades. Hagfishes are jawless vertebrates that are either the living sister to all vertebrates or form a clade with lampreys, the only other surviving jawless fishes. RESULTS We use the hagfish fossil record and molecular data for all recognized genera to construct a novel hypothesis for hagfish relationships and diversification. We find that crown hagfishes persisted through three mass extinctions after appearing in the Permian ~ 275 Ma, making them one of the oldest living vertebrate lineages. In contrast to most other deep marine vertebrates, we consistently infer a deep origin of continental slope occupation by hagfishes that dates to the Paleozoic. Yet, we show that hagfishes have experienced marked body size diversification over the last hundred million years, contrasting with a view of this clade as morphologically stagnant. CONCLUSION Our results establish hagfishes as ancient members of demersal continental slope faunas and suggest a prolonged accumulation of deep sea jawless vertebrate biodiversity.
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Affiliation(s)
- Chase Doran Brownstein
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA.
| | - Thomas Near
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
- Yale Peabody Museum, Yale University, New Haven, CT, 06511, USA
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Martin RP, Smith WL. First evidence of sexual dimorphism in olfactory organs of deep-sea lanternfishes (Myctophidae). PeerJ 2024; 12:e17075. [PMID: 38495764 PMCID: PMC10941764 DOI: 10.7717/peerj.17075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/18/2024] [Indexed: 03/19/2024] Open
Abstract
Finding a mate is of the utmost importance for organisms, and the traits associated with successfully finding one can be under strong selective pressures. In habitats where biomass and population density is often low, like the enormous open spaces of the deep sea, animals have evolved many adaptations for finding mates. One convergent adaptation seen in many deep-sea fishes is sexual dimorphism in olfactory organs, where, relative to body size, males have evolved greatly enlarged olfactory organs compared to females. Females are known to give off chemical cues such as pheromones, and these chemical stimuli can traverse long distances in the stable, stratified water of the deep sea and be picked up by the olfactory organs of males. This adaptation is believed to help males in multiple lineages of fishes find mates in deep-sea habitats. In this study, we describe the first morphological evidence of sexual dimorphism in the olfactory organs of lanternfishes (Myctophidae) in the genus Loweina. Lanternfishes are one of the most abundant vertebrates in the deep sea and are hypothesized to use visual signals from bioluminescence for mate recognition or mate detection. Bioluminescent cues that are readily visible at distances as far as 10 m in the aphotic deep sea are likely important for high population density lanternfish species that have high mate encounter rates. In contrast, myctophids found in lower density environments where species encounter rates are lower, like those in Loweina, likely benefit from longer-range chemical or olfactory cues for finding and identifying mates.
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Affiliation(s)
- Rene P. Martin
- Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States
- Division of Ichthyology, American Museum of Natural History, New York, New York, United States
| | - W. Leo Smith
- Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States
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Alternating regimes of shallow and deep-sea diversification explain a species-richness paradox in marine fishes. Proc Natl Acad Sci U S A 2022; 119:e2123544119. [PMID: 36252009 PMCID: PMC9618140 DOI: 10.1073/pnas.2123544119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The deep sea contains a surprising diversity of life, including iconic fish groups such as anglerfishes and lanternfishes. Still, >65% of marine teleost fish species are restricted to the photic zone <200 m, which comprises less than 10% of the ocean's total volume. From a macroevolutionary perspective, this paradox may be explained by three hypotheses: 1) shallow water lineages have had more time to diversify than deep-sea lineages, 2) shallow water lineages have faster rates of speciation than deep-sea lineages, or 3) shallow-to-deep sea transition rates limit deep-sea richness. Here we use phylogenetic comparative methods to test among these three non-mutually exclusive hypotheses. While we found support for all hypotheses, the disparity in species richness is better described as the uneven outcome of alternating phases that favored shallow or deep diversification over the past 200 million y. Shallow marine teleosts became incredibly diverse 100 million y ago during a period of warm temperatures and high sea level, suggesting the importance of reefs and epicontinental settings. Conversely, deep-sea colonization and speciation was favored during brief episodes when cooling temperatures increased the efficiency of the ocean's carbon pump. Finally, time-variable ecological filters limited shallow-to-deep colonization for much of teleost history, which helped maintain higher shallow richness. A pelagic lifestyle and large jaws were associated with early deep-sea colonists, while a demersal lifestyle and a tapered body plan were typical of later colonists. Therefore, we also suggest that some hallmark characteristics of deep-sea fishes evolved prior to colonizing the deep sea.
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Zhang S, Peng X, Yang S, Li X, Huang M, Wei S, Liu J, He G, Zheng H, Yang L, Li H, Fan Q. The regulation, function, and role of lipophagy, a form of selective autophagy, in metabolic disorders. Cell Death Dis 2022; 13:132. [PMID: 35136038 PMCID: PMC8825858 DOI: 10.1038/s41419-022-04593-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 01/07/2022] [Accepted: 01/27/2022] [Indexed: 12/15/2022]
Abstract
Autophagy is a conserved method of quality control in which cytoplasmic contents are degraded via lysosomes. Lipophagy, a form of selective autophagy and a novel type of lipid metabolism, has recently received much attention. Lipophagy is defined as the autophagic degradation of intracellular lipid droplets (LDs). Although much remains unknown, lipophagy appears to play a significant role in many organisms, cell types, metabolic states, and diseases. It participates in the regulation of intracellular lipid storage, intracellular free lipid levels (e.g., fatty acids), and energy balance. However, it remains unclear how intracellular lipids regulate autophagy. Impaired lipophagy can cause cells to become sensitive to death stimuli and may be responsible for the onset of a variety of diseases, including nonalcoholic fatty liver disease and metabolic syndrome. Like autophagy, the role of lipophagy in cancer is poorly understood, although analysis of specific autophagy receptors has helped to expand the diversity of chemotherapeutic targets. These studies have stimulated increasing interest in the role of lipophagy in the pathogenesis and treatment of cancer and other human diseases.
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Affiliation(s)
- Sheng Zhang
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Xueqiang Peng
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Shuo Yang
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Xinyu Li
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Mingyao Huang
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Shibo Wei
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Jiaxing Liu
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Guangpeng He
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Hongyu Zheng
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Liang Yang
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Hangyu Li
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China
| | - Qing Fan
- Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, 110032, China.
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Martin RP, Davis MP. The evolution of specialized dentition in the deep-sea lanternfishes (Myctophiformes). J Morphol 2020; 281:536-555. [PMID: 32239773 DOI: 10.1002/jmor.21120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 02/12/2020] [Accepted: 03/13/2020] [Indexed: 01/29/2023]
Abstract
The evolution of heterodonty, the possession of varied tooth morphologies on the jaws of animals, has been relatively unexplored in ray-finned fishes compared to terrestrial vertebrates, and to an even lesser degree in deep-sea fish lineages. Lanternfishes (Myctophiformes) are an abundant and species-rich group endemic to deep-sea pelagic habitats. In this study, we document the presence of heterodonty on the oral jaws of lanternfishes, identifying differing anatomical and positional variations of dentition. We survey the anatomical variation in tooth morphology on the oral jaws of 114 lanternfish species across 37 genera and integrate our findings with a hypothesis of evolutionary relationships of lanternfishes to infer the number of times heterodonty evolved in this lineage. Our results indicate that heterodonty evolved at least six separate times on the oral jaws of lanternfishes, occurring as variable tooth morphologies in combination with villiform teeth. These combinations of tooth types include villiform plus hooked teeth, villiform plus hooked and recurved teeth, villiform plus spade, tricuspid, and hooked teeth, and villiform plus caniniform teeth. The reoccurring evolution of hooked teeth on the premaxilla and dentary in lanternfishes suggests heterodonty may serve an important functional role in their pelagic deep-sea environment. Hooked teeth could aid in securing and retaining prey in the oral cavity and allow for species to specialize on differing food resources, vital attributes for organisms living in open-ocean habitats.
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Affiliation(s)
- Rene P Martin
- Department of Biological Sciences, St. Cloud State University, St. Cloud, Minnesota, USA.,Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas, USA
| | - Matthew P Davis
- Department of Biological Sciences, St. Cloud State University, St. Cloud, Minnesota, USA
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Christiansen H, Dettai A, Heindler FM, Collins MA, Duhamel G, Hautecoeur M, Steinke D, Volckaert FAM, Van de Putte AP. Diversity of Mesopelagic Fishes in the Southern Ocean - A Phylogeographic Perspective Using DNA Barcoding. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00120] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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