Observations on the external morphology and vasculature of a fetal heart of the bowhead whale,Balaena mysticetus

Tarpley, Raymond J.; Hillmann, Daniel J.; Henk, William G.; George, J. C.

doi:10.1002/(sici)1097-0185(199704)247:4<556::aid-ar14>3.0.co;2-o

Cited by 13 publications

(5 citation statements)

References 21 publications

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“…Although the basic structure of the cetacean heart is similar to that of other mammals, based on our findings we hypothesized the importance of ion channels, among other proteins, in adapting to diving. Thus, besides the welldocumented morphological changes in the cetacean heart (Tarpley et al 1997;Latorre et al 2022) mostly attributed to diving adaptations, our results show adaptive changes in genes encoding ion channels, which are fundamental for their physiological divergence.…”

Section: Ion Channels With the Signature Of Positive Selection Are Re...supporting

confidence: 66%

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Uribe

Nery

Zavala

et al. 2023

Preprint

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Cetaceans could be seen as a natural experiment within the tree of life in which a mammalian lineage changed from terrestrial to aquatic habitats. This shift involved extensive phenotypic modifications representing an opportunity to explore the genetic bases of phenotypic diversity. Furthermore, the availability of whole genome sequences in representative species of all main cetacean groups means that we are in a golden age for this type of study. Ion channels are a crucial component of the cellular machinery for the proper physiological functioning of all living species. This study aims to explore the evolution of ion channels during the evolutionary history of cetaceans. To do so, we created a bioinformatic pipeline to annotate the repertoire of ion channels in the genome of the species included in our sampling. Our main results show that cetaceans have fewer ion channels than non-cetacean mammals and that the signal of positive selection was found in ion channels related to heart, locomotion, and hearing phenotypes. Interestingly the NaV1.5 ion channel of most toothed whales (odontocetes) seems to be sensitive to TTX, similar to NaV1.7, given the presence of tyrosine, instead of cysteine, in a specific position of the ion channel. Finally, the gene turnover rate of the cetacean crown group is more than two times faster than non-cetacean mammals.

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Section: Ion Channels With the Signature Of Positive Selection Are Re...supporting

confidence: 66%

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Uribe

Nery

Zavala

et al. 2023

Preprint

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“…The dolphin heart shows specific features that are likely to be diving adaptations, such as anastomoses between the dorsal and the ventral inter ventricular arteries, and hypertrophy of the right ventricle [48]. Examples of positively selected genes related to heart development are ADAM9, NKX2, CAD15, CRFR2, GDF9, CADH3, TAB2 and PLN.…”

Section: Discussionmentioning

confidence: 99%

How to Make a Dolphin: Molecular Signature of Positive Selection in Cetacean Genome

2013

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Cetaceans are unique in being the only mammals completely adapted to an aquatic environment. This adaptation has required complex changes and sometimes a complete restructuring of physiology, behavior and morphology. Identifying genes that have been subjected to selection pressure during cetacean evolution would greatly enhance our knowledge of the ways in which genetic variation in this mammalian order has been shaped by natural selection. Here, we performed a genome-wide scan for positive selection in the dolphin lineage. We employed models of codon substitution that account for variation of selective pressure over branches on the tree and across sites in a sequence. We analyzed 7,859 nuclear-coding ortholog genes and using a series of likelihood ratio tests (LRTs), we identified 376 genes (4.8%) with molecular signatures of positive selection in the dolphin lineage. We used the cow as the sister group and compared estimates of selection in the cetacean genome to this using the same methods. This allowed us to define which genes have been exclusively under positive selection in the dolphin lineage. The enrichment analysis found that the identified positively selected genes are significantly over-represented for three exclusive functional categories only in the dolphin lineage: segment specification, mesoderm development and system development. Of particular interest for cetacean adaptation to an aquatic life are the following GeneOntology targets under positive selection: genes related to kidney, heart, lung, eye, ear and nervous system development.

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“…There is a broad diversity in vaginal fold morphology across cetaceans [13]. In many, but not all species, these vaginal folds are located in the cranial end of the vagina [14] and typically decrease in size cranially-to-caudally ([12; 15]; but see [16]). Similar vaginal structures are present in hippopotamuses (e.g., Hippopotamus amphibius [17]), which are the closest terrestrial relatives to cetaceans and also mate in the water.…”

Section: Introductionmentioning

confidence: 99%

Patterns of cetacean vaginal folds yield insights into functionality

Orbach¹,

Marshall²,

Mesnick³

et al. 2017

PLoS ONE

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Complex foldings of the vaginal wall are unique to some cetaceans and artiodactyls and are of unknown function(s). The patterns of vaginal length and cumulative vaginal fold length were assessed in relation to body length and to each other in a phylogenetic context to derive insights into functionality. The reproductive tracts of 59 female cetaceans (20 species, 6 families) were dissected. Phylogenetically-controlled reduced major axis regressions were used to establish a scaling trend for the female genitalia of cetaceans. An unparalleled level of vaginal diversity within a mammalian order was found. Vaginal folds varied in number and size across species, and vaginal fold length was positively allometric with body length. Vaginal length was not a significant predictor of vaginal fold length. Functional hypotheses regarding the role of vaginal folds and the potential selection pressures that could lead to evolution of these structures are discussed. Vaginal folds may present physical barriers, which obscure the pathway of seawater and/or sperm travelling through the vagina. This study contributes broad insights to the evolution of reproductive morphology and aquatic adaptations and lays the foundation for future functional morphology analyses.

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Observations on the external morphology and vasculature of a fetal heart of the bowhead whale,Balaena mysticetus

Cited by 13 publications

References 21 publications

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

Evolution of ion channels in cetaceans: A natural experiment in the Tree of life

How to Make a Dolphin: Molecular Signature of Positive Selection in Cetacean Genome

Patterns of cetacean vaginal folds yield insights into functionality

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