The fish gill is a multipurpose organ that, in addition to providing for aquatic gas exchange, plays dominant roles in osmotic and ionic regulation, acid-base regulation, and excretion of nitrogenous wastes Thus, despite the fact that all fish groups have functional kidneys, the gill epithelium is the site of many processes that are mediated by renal epithelia in terrestrial vertebrates Indeed, many of the pathways that mediate these processes in mammalian renal epithelial are expressed in the gill, and many of the extrinsic and intrinsic modulators of these processes are also found in fish endocrine tissues and the gill itself The basic patterns of gill physiology were outlined over a half century ago, but modern immunological and molecular techniques are bringing new insights into this complicated system Nevertheless, substantial questions about the evolution of these mechanisms and control remain

https://people.clas.ufl.edu/devans/files/PRVGill.pdf

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0376892902000097

Threats to the running water ecosystems of the world

Amniote phylogeny and the importance of fossils

The uneven distribution of species richness is a fundamental and unexplained pattern of vertebrate biodiversity. Although species richness in groups like mammals, birds, or teleost fishes is often attributed to accelerated cladogenesis, we lack a quantitative conceptual framework for identifying and comparing the exceptional changes of tempo in vertebrate evolutionary history. We develop MEDUSA, a stepwise approach based upon the Akaike information criterion for detecting multiple shifts in birth and death rates on an incompletely resolved phylogeny. We apply MEDUSA incompletely to a diversity tree summarizing both evolutionary relationships and species richness of 44 major clades of jawed vertebrates. We identify 9 major changes in the tempo of gnathostome diversification; the most significant of these lies at the base of a clade that includes most of the coral-reef associated fishes as well as cichlids and perches. Rate increases also underlie several well recognized tetrapod radiations, including most modern birds, lizards and snakes, ostariophysan fishes, and most eutherian mammals. In addition, we find that large sections of the vertebrate tree exhibit nearly equal rates of origination and extinction, providing some of the first evidence from molecular data for the importance of faunal turnover in shaping biodiversity. Together, these results reveal living vertebrate biodiversity to be the product of volatile turnover punctuated by 6 accelerations responsible for >85% of all species as well as 3 slowdowns that have produced “living fossils.” In addition, by revealing the timing of the exceptional pulses of vertebrate diversification as well as the clades that experience them, our diversity tree provides a framework for evaluating particular causal hypotheses of vertebrate radiations.

/pdf/nine-exceptional-radiations-plus-high-turnover-explain-3csb7graon.pdf

Nine exceptional radiations plus high turnover explain species diversity in jawed vertebrates

Clearly, the possibility that Van Peenen's statements are correct exists, but no molecular geneticist would contend that these assertions have been established, in any but a very few cases, which appear at present to be atypical. The educated lavman, for whom this book is intended, will find the author's leaps from the level of the quoted material into sophisticated physical chemistry and back again disconcerting at least, if not completely confusing. It can be said, however, that the authors have assembled an excellent group of illustrations; lecturers in elementary genetics wishing to locate clear illustrations to use as slides would do well to look in this book first.

Animal Tissue Techniques.

The comparative osteology, phylogenetic relationships, and historical biogeography of all known taxa of fossil and living amiid fishes (Halecomorphi: Amiidae) are investigated in detail. Previously, the detailed osteology of nearly all fossil amiids was unknown. We present the first well-supported comprehensive phylogeny for fossil and living amiid fishes. We synthesize clearly documented phylogenetic data on amiids and other halecomorph fishes with other historical phenomena such as ontogeny, historical biogeography, stratigraphic paleontology, and paleoecology (both “stationary” and “historical”). We also use our study of halecomorph fishes as a platform to explore several fundamental methodological and theoretical concepts important to phylogenetic/evolutionary investigations. These concepts pertain mainly to (1) the use of comparative empirical data to interpret various historical patterns and (2) the practice of integrating fossil and living species together in original (i.e., non-literature...

https://dash.harvard.edu/bitstream/handle/1/14117769/A%20Comprehensive%20Phylogenetic%20Study%20of%20Amiid%20Fishes%20%28Amiidae%29%20Based%20on%20Comparative%20Skeletal%20Anatomy.pdf?sequence=1

A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History

Acipenseriformes occupy a special place in the history of ideas concerning fish evolution, but in many respects, phylogenetic studies of the group remain in their infancy Even such basic questions as the monophyly of Acipenser (the largest genus) are unanswered We define relationships based on comparative osteology, which allows us to incorporate well-preserved fossils into analyses Acipenseriformes has existed at least since the Lower Jurassic (approximately 200 MYBP), and all fossil and recent taxa are from the Holarctic Phylogenetic relationships among Paleozoic and Early Mesozoic actinopterygians are problematic, but most workers agree that Acipenseriformes is monophyletic and derived from some component of ‘paleonisciform’ fishes (‘Paleonisciformes’ is a grade of primitive non-neopterygian actinopterygians, sensu Gardiner 1993) Taxa discussed in comparison here are: †Cheirolepis, Polypterus, †Mimia †Moythomasia, †Birgeria, †Saurichthys, Lepisosteus and Amia We review generic diversity within the four nominal families of fossil and recent Acipenseriformes (†Chondrosteidae, †Peipiaosteidae, Polyodontidae, and Acipenseridae), and provide a cladogram summarizing osteological characters for those four groups Monophyly of the two extant families is well-supported, but there are no comprehensive studies of all of the known species and specimens of †Chondrosteidae and †Peipiaosteidae As a result, sister-group relationships among †Chondrosteidae, †Peipiaosteidae, and Acipenseroidei (= Polyodontidae + Acipenseridae)are unresolved We discuss five features fundamental to the biology of acipenseriforms that benefit from the availability of our new phylogenetic hypothesis: (1) specializations of jaws and operculum relevant to jaw protrusion, feeding, and ram ventilation; (2) anadromy or potamodromy and demersal spawning; (3) paedomorphosis and evolution of the group; (4) the biogeography of Asian and North American polyodontids and scaphirhynchines; and (5) the great abundance of electroreceptive organs in the rostral and opercular regions Finally, we summarize our nomenclatural recommendations

An overview of Acipenseriformes

Part I: Background for the Study of Vertebrate Anatomy. 1. Introduction. 2. Phylogenetic Relationships of Chordates and Craniates. 3. Diversity and Phylogenetic History of Craniates. 4. Early Development and Comparative Embryology. 5. Form and Function. Part II: Protection, Support, and Movement. 6. The Integument. 7. The Cranial Skeleton. 8. The Postcranial Skeleton: The Axial Skeleton. 9. The Postcranial Skeleton: The Appendicular Skeleton. 10. The Muscular System. 11. Functional Anatomy of Support and Locomotion. Part III: Integration. 12. The Sense Organs. 13. The Nervous System I: Organization, Spinal Cord, and Peripheral Nerves. 14. The Nervous System II: The Brain. 15. Endocrine Integration. Part IV: Metabolism and Reproduction. 16. The Digestive System: Oral Cavity and Feeding Mechanisms. 17. The Digestive System: Pharynx, Stomach, and Intestine. 18. The Respiratory System. 19. The Circulatory System. 20. The Excretory System and Osmoregulation. 21. The Reproductive System and Reproduction. Part V: Conclusion. 22. Conclusion/Epilogue.

Functional Anatomy of the Vertebrates: An Evolutionary Perspective

We present an overview of the global distribution of all 27 living species of Acipenseriformes in an attempt to understand their biogeographic history and the range of life history patterns displayed by different species. Our biogeographic analysis (based on the most recent phylogenetic analysis including fossil Acipenseriformes) suggests that Acipenseriformes originated in Europe, and that early diversification took place in Asia. Acipenseriformes do not have a common life history; variation within and between species is the rule rather than exception. The few relatively well-known case studies (e.g., Caspian Sea sturgeons, European Atlantic sturgeons in the Gironde system, and shortnose and North American Atlantic sturgeons in rivers of the east coast of America) greatly influence what we think we know about sturgeon biology. Our present level of phylogenetic understanding does not allow us to determine whether anadromy or potamodromy is the plesiomorphic life history pattern for Acipenseriformes. We propose that rivers in which spawning occurs must be the central unit for biogeographic analysis of living Acipenseriformes. After mapping these rivers, we recognized nine biogeographic provinces for acipenseriforms. Some repeated historical patterns emerge from this analysis, but, again, we are limited by our current understanding of phylogenetic relationships within the genus Acipenser in particular. Distribution and biogeographic data are central to deciding where to make new efforts to update existing status information for acipenseriform species. We single out a widely ranging and highly variable species, Acipenser ruthenus, as particularly intriguing, for it spans three of our nine biogeographic provinces, and apparently has different life history patterns in different river systems. Finally, we note new areas in need of basic research, particularly the need for more detailed descriptions and analyses of life histories of different populations of sturgeons.

Sturgeon rivers: an introduction to acipenseriform biogeography and life history

The comparative osteology and phylogenetic relationships of fossil and living paddlefishes (Polyodontidae) are investigated in detail for the first time. This peculiar, poorly known group is of gre...

William E. Bemis

Papers

A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History

An overview of Acipenseriformes

Functional Anatomy of the Vertebrates: An Evolutionary Perspective

Sturgeon rivers: an introduction to acipenseriform biogeography and life history

Osteology and Phylogenetic Relationships of Fossil and Recent Paddlefishes (Polyodontidae) with Comments on the Interrelationships of Acipenseriformes