Pub Date : 2025-08-19DOI: 10.1016/j.zool.2025.126293
Marangaby Mahamat , Luis F. De León , Mery L. Martínez
An organism's ability to produce viable offspring, or reproductive fitness, often depends on several environmental and ecological factors such as temperature, food availability and predation. Changes in these factors can act as stressors, forcing organisms to optimize energy allocation, resulting in trade-offs. In this study, we investigate the reproductive biology of the South American electric fish Brachyhypopomus occidentalis, examining whether perceived predation risk can influence reproductive output. We sampled four populations during the reproductive season at two pairs of sites with differing levels of predation risk across independent river drainages. We assessed several traits including sexual dimorphism and reproductive traits such as gonad mass, fecundity, and gamete morphology parameters. Our findings reveal physical sexual dimorphism, with males being larger and heavier than females. Individuals from low predation risk sites were significantly larger, had heavier gonads, and exhibited higher gonadosomatic indices. Females from low predation risk sites invested more in gonad development, showing increased relative and absolute fecundities and higher oocyte counts at each maturity stage. Collectively, our results strongly suggest that predation risk plays a significant role in shaping reproductive strategies in electric fishes and also underscore how ecological pressures can drive variation in reproductive investment across fish populations.
{"title":"Reproductive investment in the knifefish Brachyhypopomus occidentalis","authors":"Marangaby Mahamat , Luis F. De León , Mery L. Martínez","doi":"10.1016/j.zool.2025.126293","DOIUrl":"10.1016/j.zool.2025.126293","url":null,"abstract":"<div><div>An organism's ability to produce viable offspring, or reproductive fitness, often depends on several environmental and ecological factors such as temperature, food availability and predation. Changes in these factors can act as stressors, forcing organisms to optimize energy allocation, resulting in trade-offs. In this study, we investigate the reproductive biology of the South American electric fish <em>Brachyhypopomus occidentalis</em>, examining whether perceived predation risk can influence reproductive output. We sampled four populations during the reproductive season at two pairs of sites with differing levels of predation risk across independent river drainages. We assessed several traits including sexual dimorphism and reproductive traits such as gonad mass, fecundity, and gamete morphology parameters. Our findings reveal physical sexual dimorphism, with males being larger and heavier than females. Individuals from low predation risk sites were significantly larger, had heavier gonads, and exhibited higher gonadosomatic indices. Females from low predation risk sites invested more in gonad development, showing increased relative and absolute fecundities and higher oocyte counts at each maturity stage. Collectively, our results strongly suggest that predation risk plays a significant role in shaping reproductive strategies in electric fishes and also underscore how ecological pressures can drive variation in reproductive investment across fish populations.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"172 ","pages":"Article 126293"},"PeriodicalIF":1.6,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-14DOI: 10.1016/j.zool.2025.126283
Mariana B.J. Picasso , María Clelia Mosto , Alejandro M. Tudisca , Laura M. Biondi
The jaw muscle architecture is crucial for understanding how muscle morphology influences diet and feeding behavior in birds, yet ontogenetic scaling patterns and their characteristics in herbivorous species remain understudied. This study examines the physiological cross-sectional area (PCSA) and fiber length of the jaw muscles in Rhea americana, an herbivorous bird whose chicks are insectivorous during early stages. The main jaw muscles of 19 Rhea americana specimens across four ontogenetic stages were analyzed, including the depressor mandibulae (a jaw depressor) and the adductor mandibulae externus, pseudotemporalis, and pterygoideus lateralis (primarily jaw adductors). Both architectural parameters showed a negative allometric scaling and only significant differences in PCSA were found between immature ages and between these and adulthood in certain adductor muscles. These variations suggest increasing force demands in adductor muscles as chicks transition from an insectivorous to an herbivorous diet. The lower PCSA in early-staged chicks reflects the reduced force required for insectivory, while the increasing PCSA with age enables force generation needed for detaching plants in adults. In comparison to other avian diets, the herbivory of greater rhea seems to be linked to a lower force-generating capacity in the adductor muscle group. This study contributes to expanding the knowledge on avian jaw musculature by exploring postnatal ontogenetic changes and their potential relationship with dietary shifts while providing morphological data that can serve as a comparative basis for understanding the link between diet and morphology in birds.
{"title":"Jaw muscle architecture in the greater rhea (Rhea americana): Morphological patterns and postnatal ontogeny in an herbivorous bird","authors":"Mariana B.J. Picasso , María Clelia Mosto , Alejandro M. Tudisca , Laura M. Biondi","doi":"10.1016/j.zool.2025.126283","DOIUrl":"10.1016/j.zool.2025.126283","url":null,"abstract":"<div><div>The jaw muscle architecture is crucial for understanding how muscle morphology influences diet and feeding behavior in birds, yet ontogenetic scaling patterns and their characteristics in herbivorous species remain understudied. This study examines the physiological cross-sectional area (PCSA) and fiber length of the jaw muscles in <em>Rhea americana</em>, an herbivorous bird whose chicks are insectivorous during early stages. The main jaw muscles of 19 <em>Rhea americana</em> specimens across four ontogenetic stages were analyzed, including the depressor mandibulae (a jaw depressor) and the adductor mandibulae externus, pseudotemporalis, and pterygoideus lateralis (primarily jaw adductors). Both architectural parameters showed a negative allometric scaling and only significant differences in PCSA were found between immature ages and between these and adulthood in certain adductor muscles. These variations suggest increasing force demands in adductor muscles as chicks transition from an insectivorous to an herbivorous diet. The lower PCSA in early-staged chicks reflects the reduced force required for insectivory, while the increasing PCSA with age enables force generation needed for detaching plants in adults. In comparison to other avian diets, the herbivory of greater rhea seems to be linked to a lower force-generating capacity in the adductor muscle group. This study contributes to expanding the knowledge on avian jaw musculature by exploring postnatal ontogenetic changes and their potential relationship with dietary shifts while providing morphological data that can serve as a comparative basis for understanding the link between diet and morphology in birds.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126283"},"PeriodicalIF":1.6,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-09DOI: 10.1016/j.zool.2025.126282
Joscha A. Alt, Reinhard Lakes-Harlan
Mechanosensation is a universal sensory modality and respective receptors in insects are located in all body parts. For perception of substrate vibrations, highly specialized sensory organs have evolved. In insects, the legs contain specialized vibration sensors, but insects also touch the substrate with other body parts, like their abdomen. Here, we used extracellular recordings from abdominal nerves to test for vibrational sensitivity in two evolutionarily distant insect species. Vibrational stimuli of defined frequencies (30 Hz – 10 kHz) and accelerations (0.01 – 10 m/s2) were applied to the caudal region of the abdomen while recording from nerves associated with mechanosensitive chordotonal organs. In the grasshopper Schistocerca gregaria (Forsskal), abdominal nerves are almost as sensitive to substrate vibrations as the leg nerves. In the cicada Okanagana rimosa (Say), the sensitivity of abdominal sense organs is even higher than that of the leg associated sense organs. In both species, their abdominal tympanate ears are also sensitive to substrate vibrations. The results show that chordotonal organs in the abdomen can significantly contribute to vibration perception in insects.
{"title":"Abdominal sensing of substrate vibrations in insects","authors":"Joscha A. Alt, Reinhard Lakes-Harlan","doi":"10.1016/j.zool.2025.126282","DOIUrl":"10.1016/j.zool.2025.126282","url":null,"abstract":"<div><div>Mechanosensation is a universal sensory modality and respective receptors in insects are located in all body parts. For perception of substrate vibrations, highly specialized sensory organs have evolved. In insects, the legs contain specialized vibration sensors, but insects also touch the substrate with other body parts, like their abdomen. Here, we used extracellular recordings from abdominal nerves to test for vibrational sensitivity in two evolutionarily distant insect species. Vibrational stimuli of defined frequencies (30 Hz – 10 kHz) and accelerations (0.01 – 10 m/s<sup>2</sup>) were applied to the caudal region of the abdomen while recording from nerves associated with mechanosensitive chordotonal organs. In the grasshopper <em>Schistocerca gregaria</em> (Forsskal), abdominal nerves are almost as sensitive to substrate vibrations as the leg nerves. In the cicada <em>Okanagana rimosa</em> (Say), the sensitivity of abdominal sense organs is even higher than that of the leg associated sense organs. In both species, their abdominal tympanate ears are also sensitive to substrate vibrations. The results show that chordotonal organs in the abdomen can significantly contribute to vibration perception in insects.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126282"},"PeriodicalIF":1.6,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144240619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Symbiotic associations with prokaryotes are common among marine filter-feeding invertebrates. In the almost exclusively colonial phylum Bryozoa, however, such associations have only been recorded in some species of the order Cheilostomata (class Gymnolaemata). Here we describe for the first time symbiotic bacteria in the colonies, larvae and developing ancestrulae of the bryozoan Patinella verrucaria from the order Cyclostomata (class Stenolaemata) using transmission electron and fluorescent microscopy. Ultrastructural and molecular data suggest the existence of two distinct bacterial species, both from the family Rhodobacteraceae. The presence of bacteria in all three stages of the bryozoan life cycle indicates a vertical transfer of symbionts. Both intracellular and free bacteria were recorded in the colonies, being presumably transported by amoebocytes from autozooids to the colonial incubation chamber. The bacteria are accumulated in the placental analogue and in associated cells surrounding developing embryos and larvae, and are presumably transmitted to the mature ciliated larvae during rupture of the placenta facilitated by the movements of their cilia before and/or during larval release. Thus, the nourishing function of the placenta is complemented by the symbiont transfer, which can be regarded as an example of extension of functions. This is the first example of a placenta providing bacterial infection to the progeny in invertebrates.
{"title":"Vertical transfer of bacterial symbionts via a placental analogue in the cyclostome bryozoan Patinella verrucaria (Stenolaemata): Ultrastructural and molecular evidence","authors":"M.A. Demidova , A.E. Vishnyakov , N.P. Karagodina , O.N. Kotenko , U.A. Nekliudova , E.A. Bogdanov , A.N. Ostrovsky","doi":"10.1016/j.zool.2025.126281","DOIUrl":"10.1016/j.zool.2025.126281","url":null,"abstract":"<div><div>Symbiotic associations with prokaryotes are common among marine filter-feeding invertebrates. In the almost exclusively colonial phylum Bryozoa, however, such associations have only been recorded in some species of the order Cheilostomata (class Gymnolaemata). Here we describe for the first time symbiotic bacteria in the colonies, larvae and developing ancestrulae of the bryozoan <em>Patinella verrucaria</em> from the order Cyclostomata (class Stenolaemata) using transmission electron and fluorescent microscopy. Ultrastructural and molecular data suggest the existence of two distinct bacterial species, both from the family Rhodobacteraceae. The presence of bacteria in all three stages of the bryozoan life cycle indicates a vertical transfer of symbionts. Both intracellular and free bacteria were recorded in the colonies, being presumably transported by amoebocytes from autozooids to the colonial incubation chamber. The bacteria are accumulated in the placental analogue and in associated cells surrounding developing embryos and larvae, and are presumably transmitted to the mature ciliated larvae during rupture of the placenta facilitated by the movements of their cilia before and/or during larval release. Thus, the nourishing function of the placenta is complemented by the symbiont transfer, which can be regarded as an example of extension of functions. This is the first example of a placenta providing bacterial infection to the progeny in invertebrates.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126281"},"PeriodicalIF":1.6,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-08DOI: 10.1016/j.zool.2025.126280
Summer E. Duba, David C. Collar
Body elongation is a major feature of ray-finned fish evolution. Elongate body shapes have arisen repeatedly across lineages and led to a phylogenetically diverse array of eel-like fishes. Despite apparent convergence in overall shape, independent elongation events have occurred through a diversity of skeletal anatomical changes, suggesting variability in underlying developmental, functional, and ecological shifts. It is less clear, however, whether such diversity characterizes evolution in lineages following elongation. In this study, we show that, even within a predominantly elongate radiation of teleost fishes, the Zoarcoidei (eelpouts, pricklebacks, and others), a variety of anatomical shifts have occurred, and they exhibit a complex relationship with body shape. We measured dimensions of the cranial and axial skeleton as well as overall body shape from 71 species representing 12 of 14 recognized zoarcoid families, and we fit multi-optimum adaptive evolutionary (Ornstein-Uhlenbeck) models to these data. We estimated a moderately elongate ancestral optimum for Zoarcoidei that was retained in most lineages. Still, we identified three peak shifts to highly elongate body shapes, which differed in associated anatomical changes. In addition, we detected multiple cryptic anatomical peak shifts in which transitions in cranial and axial skeletal anatomy occurred in lineages that retained the ancestral body shape optimum. Altogether, our results reveal a hidden level of morphological evolution in elongate fishes, suggesting that similarity in body shape belies diverse ecological demands and varied functional capacities.
{"title":"Cryptic anatomical adaptive peak shifts and transitions along the body elongation continuum in zoarcoid fishes","authors":"Summer E. Duba, David C. Collar","doi":"10.1016/j.zool.2025.126280","DOIUrl":"10.1016/j.zool.2025.126280","url":null,"abstract":"<div><div>Body elongation is a major feature of ray-finned fish evolution. Elongate body shapes have arisen repeatedly across lineages and led to a phylogenetically diverse array of eel-like fishes. Despite apparent convergence in overall shape, independent elongation events have occurred through a diversity of skeletal anatomical changes, suggesting variability in underlying developmental, functional, and ecological shifts. It is less clear, however, whether such diversity characterizes evolution in lineages following elongation. In this study, we show that, even within a predominantly elongate radiation of teleost fishes, the Zoarcoidei (eelpouts, pricklebacks, and others), a variety of anatomical shifts have occurred, and they exhibit a complex relationship with body shape. We measured dimensions of the cranial and axial skeleton as well as overall body shape from 71 species representing 12 of 14 recognized zoarcoid families, and we fit multi-optimum adaptive evolutionary (Ornstein-Uhlenbeck) models to these data. We estimated a moderately elongate ancestral optimum for Zoarcoidei that was retained in most lineages. Still, we identified three peak shifts to highly elongate body shapes, which differed in associated anatomical changes. In addition, we detected multiple cryptic anatomical peak shifts in which transitions in cranial and axial skeletal anatomy occurred in lineages that retained the ancestral body shape optimum. Altogether, our results reveal a hidden level of morphological evolution in elongate fishes, suggesting that similarity in body shape belies diverse ecological demands and varied functional capacities.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126280"},"PeriodicalIF":1.6,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-07DOI: 10.1016/j.zool.2025.126279
Wan-Ruo Ma, Jia-Li Bai, Bao-Zhen Hua
The larvae of Bittacidae normally bear a pair of compound eyes on the lateral sides of the head. The compound eyes each are reported to consist of seven ommatidia. However, whether the eyes have variations in number among species and individuals remain unclear to date. Here, ommatidial variations of compound eyes were investigated in four species of Bittacidae larvae using light microscopy. The results show that the number of ommatidia remains constant for a larval eye across instars of the same larva, but numerical variations of ommatidia were found for different individuals and different species of Bittacidae. The compound eyes of larvae each consist of six to ten ommatidia in the most widely distributed Bittacus cirratus Tjeder, but are composed of seven to nine ommatidia in B. planus Cheng and B. lii Zhou, and seven to eight ommatidia in Terrobittacus longisetus Tan & Hua. Seven ommatidia are the most common number, likely representing the ground plan of larval compound eyes in Bittacidae. The distribution patterns of ommatidia can be categorized into five types. The significance of larval ommatidial variation of Bittacidae is briefly discussed with behavior of larvae and evolution of visual organs of holometabolous larvae.
{"title":"Variations of larval ommatidia in four species of Bittacidae (Insecta: Mecoptera)","authors":"Wan-Ruo Ma, Jia-Li Bai, Bao-Zhen Hua","doi":"10.1016/j.zool.2025.126279","DOIUrl":"10.1016/j.zool.2025.126279","url":null,"abstract":"<div><div>The larvae of Bittacidae normally bear a pair of compound eyes on the lateral sides of the head. The compound eyes each are reported to consist of seven ommatidia. However, whether the eyes have variations in number among species and individuals remain unclear to date. Here, ommatidial variations of compound eyes were investigated in four species of Bittacidae larvae using light microscopy. The results show that the number of ommatidia remains constant for a larval eye across instars of the same larva, but numerical variations of ommatidia were found for different individuals and different species of Bittacidae. The compound eyes of larvae each consist of six to ten ommatidia in the most widely distributed <em>Bittacus cirratus</em> Tjeder, but are composed of seven to nine ommatidia in <em>B. planus</em> Cheng and <em>B. lii</em> Zhou, and seven to eight ommatidia in <em>Terrobittacus longisetus</em> Tan & Hua. Seven ommatidia are the most common number, likely representing the ground plan of larval compound eyes in Bittacidae. The distribution patterns of ommatidia can be categorized into five types. The significance of larval ommatidial variation of Bittacidae is briefly discussed with behavior of larvae and evolution of visual organs of holometabolous larvae.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126279"},"PeriodicalIF":1.6,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-08DOI: 10.1016/j.zool.2025.126272
Varvara I. Krolenko , Glafira D. Kolbasova , Alexander B. Tzetlin
Caobangia billeti is an aberrant shell-burrowing annelid with a phoronid-like body plan and U-shaped digestive tract, an anterior anus on the dorsal side near the head, and reduced metamerism. The segmental dissepiments in C. billeti are absent, but the circulatory system is complex and consists of numerous lacunae and vessels. We asked the question how this modified circulatory system compares to that of other Sabellida. To that end, we collected C. billeti from the type locality and for the first time provide a detailed morphological investigation of these worms using both electron (TEM) and light microscopy. Our data show that, despite the significant modification of the body plan, the circulatory system is generally similar to that of other Sabellida representatives. The central circulatory system includes dorsal and ventral vessels, circular segmental vessels, and the peri-intestinal sinus, while the peripheral system includes the vessels of the branchial crown, collar vessels and esophageal plexuses, and transseptal vessels. However, compared to other representatives of the order Sabellida this species possesses four paired lateroventral vessels instead of two, and extravasal rather than intravasal hematopoietic tissue. The abdomen of C. billeti has lost all internal metameric structures, except segmental vessels, the number of which coincides with the number of uncinial tori. The direction of blood flow was reconstructed using vital and morphological observations. There are no specialized propulsatory organs, but all vessels pulsate, except for the branchial vessels, which are passively filled with blood. In the circulatory system, the direction of blood flow can be reversed (from the head to the back of the body inside the dorsal vessel and vice versa ventrally), which has not previously been described for other Sabellida.
{"title":"Morphology of the circulatory system in Caobangia billeti Giard, 1893 (Annelida, Sabellidae)","authors":"Varvara I. Krolenko , Glafira D. Kolbasova , Alexander B. Tzetlin","doi":"10.1016/j.zool.2025.126272","DOIUrl":"10.1016/j.zool.2025.126272","url":null,"abstract":"<div><div><em>Caobangia billeti</em> is an aberrant shell-burrowing annelid with a phoronid-like body plan and U-shaped digestive tract, an anterior anus on the dorsal side near the head, and reduced metamerism. The segmental dissepiments in <em>C. billeti</em> are absent, but the circulatory system is complex and consists of numerous lacunae and vessels. We asked the question how this modified circulatory system compares to that of other Sabellida. To that end, we collected <em>C. billeti</em> from the type locality and for the first time provide a detailed morphological investigation of these worms using both electron (TEM) and light microscopy. Our data show that, despite the significant modification of the body plan, the circulatory system is generally similar to that of other Sabellida representatives. The central circulatory system includes dorsal and ventral vessels, circular segmental vessels, and the peri-intestinal sinus, while the peripheral system includes the vessels of the branchial crown, collar vessels and esophageal plexuses, and transseptal vessels. However, compared to other representatives of the order Sabellida this species possesses four paired lateroventral vessels instead of two, and extravasal rather than intravasal hematopoietic tissue. The abdomen of <em>C. billeti</em> has lost all internal metameric structures, except segmental vessels, the number of which coincides with the number of uncinial tori. The direction of blood flow was reconstructed using vital and morphological observations. There are no specialized propulsatory organs, but all vessels pulsate, except for the branchial vessels, which are passively filled with blood. In the circulatory system, the direction of blood flow can be reversed (from the head to the back of the body inside the dorsal vessel and vice versa ventrally), which has not previously been described for other Sabellida.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"171 ","pages":"Article 126272"},"PeriodicalIF":1.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-01DOI: 10.1016/j.zool.2025.126271
Jorge Ayala-Berdon , Kevin I. Medina-Bello , Jorge D. Carballo-Morales , Romeo A. Saldaña-Vázquez , Federico Villalobos
Thermal energetics define the way animals spend energy for thermoregulation. In this regard, numerous studies have determined that body mass (Mb) is the most influential morphological trait affecting the thermal traits in different species of birds and mammals. However, most of the studies have been focused on the basal metabolic rate (BMR), while other thermal traits have been less studied. We addressed this gap by examining thermal variables on bats of the family Vespertilionidae. Using open-flow respirometry, we measured BMR, absolute thermal conductance (C’), lower and upper critical temperatures (TLC and TUC), and breadth of the thermoneutral zone (TNZb) of 16 bat species ranging in Mb from ∼ 4.0–21.0 g from central Mexico. We: 1) combined our empirical data with information gathered from the literature and conducted phylogenetic analyses to investigate the relationship between Mb and thermal traits, 2) tested the relationship between mass independent C’ and mass independent BMR with TLC and TUC of bats, and the relationship between critical temperatures and TNZb, and 3) mapped the thermal energetic traits along the phylogeny to explore their evolutionary trends. We found a positive relationship between Mb and BMR and absolute C’ but not to TLC, TUC and TNZb of bats. Mass independent BMR and mass independent C’ were positively related to TLC and TUC. Finally, TLC showed a negative relationship with TNZb while TUC exhibited a positive relationship with this thermal trait. The phylogenetic approach indicates that over the evolutionary history, BMR and C´ have decreased while TLC, TUC and TNZb have increased. Our results suggest that: 1) differences in the limits of the TNZ and C’ may have helped bats to avoid the constraints on heat dissipation imposed by ambient temperatures, and 2) adaptive changes in Mb and thermal traits may have influenced the geographical distribution and energy-saving strategies of bats. These findings contribute to an understanding of how small endotherms cope with thermal challenges, shedding light on the physiological and evolutionary mechanisms that shape species’ ecological niches and biogeographic patterns across diverse environments.
{"title":"Thermal energetics of bats of the family Vespertilionidae: An evolutionary approach","authors":"Jorge Ayala-Berdon , Kevin I. Medina-Bello , Jorge D. Carballo-Morales , Romeo A. Saldaña-Vázquez , Federico Villalobos","doi":"10.1016/j.zool.2025.126271","DOIUrl":"10.1016/j.zool.2025.126271","url":null,"abstract":"<div><div>Thermal energetics define the way animals spend energy for thermoregulation. In this regard, numerous studies have determined that body mass (<em>M</em><sub><em>b</em></sub>) is the most influential morphological trait affecting the thermal traits in different species of birds and mammals. However, most of the studies have been focused on the basal metabolic rate (<em>BMR</em>), while other thermal traits have been less studied. We addressed this gap by examining thermal variables on bats of the family Vespertilionidae. Using open-flow respirometry, we measured <em>BMR</em>, absolute thermal conductance (<em>C</em>’), lower and upper critical temperatures (<em>T</em><sub><em>LC</em></sub> and <em>T</em><sub><em>UC</em></sub>), and breadth of the thermoneutral zone (<em>TNZ</em><sub><em>b</em></sub>) of 16 bat species ranging in <em>M</em><sub><em>b</em></sub> from ∼ 4.0–21.0 g from central Mexico. We: 1) combined our empirical data with information gathered from the literature and conducted phylogenetic analyses to investigate the relationship between <em>M</em><sub><em>b</em></sub> and thermal traits, 2) tested the relationship between mass independent <em>C</em>’ and mass independent <em>BMR</em> with <em>T</em><sub><em>LC</em></sub> and <em>T</em><sub><em>UC</em></sub> of bats, and the relationship between critical temperatures and <em>TNZ</em><sub><em>b</em></sub>, and 3) mapped the thermal energetic traits along the phylogeny to explore their evolutionary trends. We found a positive relationship between <em>M</em><sub><em>b</em></sub> and <em>BMR</em> and absolute <em>C’</em> but not to <em>T</em><sub><em>LC</em></sub>, <em>T</em><sub><em>UC</em></sub> and <em>TNZ</em><sub><em>b</em></sub> of bats. Mass independent <em>BMR</em> and mass independent <em>C</em>’ were positively related to <em>T</em><sub><em>LC</em></sub> and <em>T</em><sub><em>UC</em></sub>. Finally, <em>T</em><sub><em>LC</em></sub> showed a negative relationship with <em>TNZ</em><sub><em>b</em></sub> while <em>T</em><sub><em>UC</em></sub> exhibited a positive relationship with this thermal trait. The phylogenetic approach indicates that over the evolutionary history, <em>BMR</em> and <em>C´</em> have decreased while <em>T</em><sub><em>LC</em></sub>, <em>T</em><sub><em>UC</em></sub> and <em>TNZ</em><sub><em>b</em></sub> have increased. Our results suggest that: 1) differences in the limits of the <em>TNZ</em> and <em>C’</em> may have helped bats to avoid the constraints on heat dissipation imposed by ambient temperatures, and 2) adaptive changes in <em>M</em><sub><em>b</em></sub> and thermal traits may have influenced the geographical distribution and energy-saving strategies of bats. These findings contribute to an understanding of how small endotherms cope with thermal challenges, shedding light on the physiological and evolutionary mechanisms that shape species’ ecological niches and biogeographic patterns across diverse environments.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"170 ","pages":"Article 126271"},"PeriodicalIF":1.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143935840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-01DOI: 10.1016/j.zool.2025.126270
Guang Gao , Bingxin Guan , Guangbin Shao , Jiawei Zhang , Zhizhong Xiao , Kun Wang
Cartilaginous fishes (sharks, skates and chimaeras) exhibit diverse behavioral patterns and unique endoskeleton, which provide insights into their ecological adaptations and evolution. However, research on the development of cartilaginous fish is still limited. To evaluate the relationship between embryonic behavior and cartilage development in cartilaginous fishes, the developing Okamejei kenojei was analyzed through behavioral, anatomical, and histological approaches, with an atlas of embryonic behavior and skeletal morphology. The result shows that the behavior of skate embryos evolves from early rhythmic movements to vigilance behavior to external stimuli. Data from Alcian blue and Alizarin red staining and histology sections showed that the vertebrae are the earliest regions to mineralize, with the mineralization process starting at the neural arch area and expanding along the body axis. In the anterior area, mineralized structures spread along the synarcual and neurocranium towards the pectoral fins and fin rays. Interestingly, a novel branching pattern of fin rays was observed in the pectoral fins of embryonic O. kenojei, characterized by the inward growth of the perichondrium into the cartilage element, potentially linked to the morphogenesis of the skate's pectoral fins. Additionally, this study provides a set of open-source morphological data for O. kenojei, which will serve as a valuable reference for marine animal conservation and evolutionary developmental biology.
{"title":"Embryonic behavior and skeletogenesis in developing skate Okamejei kenojei","authors":"Guang Gao , Bingxin Guan , Guangbin Shao , Jiawei Zhang , Zhizhong Xiao , Kun Wang","doi":"10.1016/j.zool.2025.126270","DOIUrl":"10.1016/j.zool.2025.126270","url":null,"abstract":"<div><div>Cartilaginous fishes (sharks, skates and chimaeras) exhibit diverse behavioral patterns and unique endoskeleton, which provide insights into their ecological adaptations and evolution. However, research on the development of cartilaginous fish is still limited. To evaluate the relationship between embryonic behavior and cartilage development in cartilaginous fishes, the developing <em>Okamejei kenojei</em> was analyzed through behavioral, anatomical, and histological approaches, with an atlas of embryonic behavior and skeletal morphology. The result shows that the behavior of skate embryos evolves from early rhythmic movements to vigilance behavior to external stimuli. Data from Alcian blue and Alizarin red staining and histology sections showed that the vertebrae are the earliest regions to mineralize, with the mineralization process starting at the neural arch area and expanding along the body axis. In the anterior area, mineralized structures spread along the synarcual and neurocranium towards the pectoral fins and fin rays. Interestingly, a novel branching pattern of fin rays was observed in the pectoral fins of embryonic <em>O. kenojei</em>, characterized by the inward growth of the perichondrium into the cartilage element, potentially linked to the morphogenesis of the skate's pectoral fins. Additionally, this study provides a set of open-source morphological data for <em>O. kenojei</em>, which will serve as a valuable reference for marine animal conservation and evolutionary developmental biology.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"170 ","pages":"Article 126270"},"PeriodicalIF":1.6,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143948390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-16DOI: 10.1016/j.zool.2025.126269
Mariana Bessa Sanches , Lucas Henrique Bonfim Souza , Bruno Cansanção Silva , Conrado Mario da Rosa , Antonio Domingos Brescovit , Luciana Bolsoni Lourenço , Douglas Araujo
Spiders represent a fascinating group for studying chromosomal evolution due to their dynamic karyotypes, which reveal significant differences even between closely related taxa. Lycosidae, one of the most species-rich families of spiders, has its major relationships well stablished, though minor interspecific relationships remain poorly understood. Here, we analyzed chromosomal data from four species belonging to Aglaoctenus and Diapontia, two genera within the subfamily Sosippinae, to discuss the evolution of chromosomal traits within this lineage. For karyological analysis, we employed Giemsa staining, C-banding, Ag-NOR staining, and 28S rDNA FISH to identify key chromosomal characteristics and the distribution of repetitive elements. Both A. oblongus and D. uruguayensis exhibited 2n♂=28, X1X2, with acro/telocentric morphology, hypothesized to represent the ancestral condition for Lycosoidea. However, regarding the 28S rDNA chromosome mapping, these species revealed an unusually high number of loci with eight chromosome clusters in A. oblongus and a polymorphic condition in D. uruguayensis (10–14 signals), underscoring the utility of additional techniques for detecting specific chromosomal regions. Interestingly, A. castaneus and A. lagotis displayed a more derived karyotype, characterized by 2 n♂= 14, X1X2 and acro/telocentric morphology, with the sex chromosomes (X1 and X2) smaller than the autosomes. Taken together, these data suggest that, following the diversification of Aglaoctenus, a significant reduction in diploid number occurred, affecting only the autosomes. These findings encourage further cytogenetic research within Sosippinae and support the use of these data in future phylogenetic studies.
{"title":"Cytogenetic insights into Sosippinae (Araneae, Lycosidae) reveal pronounced diploid number reduction in Aglaoctenus and elevated number of rDNA loci in two unrelated species","authors":"Mariana Bessa Sanches , Lucas Henrique Bonfim Souza , Bruno Cansanção Silva , Conrado Mario da Rosa , Antonio Domingos Brescovit , Luciana Bolsoni Lourenço , Douglas Araujo","doi":"10.1016/j.zool.2025.126269","DOIUrl":"10.1016/j.zool.2025.126269","url":null,"abstract":"<div><div>Spiders represent a fascinating group for studying chromosomal evolution due to their dynamic karyotypes, which reveal significant differences even between closely related taxa. Lycosidae, one of the most species-rich families of spiders, has its major relationships well stablished, though minor interspecific relationships remain poorly understood. Here, we analyzed chromosomal data from four species belonging to <em>Aglaoctenus</em> and <em>Diapontia</em>, two genera within the subfamily Sosippinae, to discuss the evolution of chromosomal traits within this lineage. For karyological analysis, we employed Giemsa staining, C-banding, Ag-NOR staining, and 28S rDNA FISH to identify key chromosomal characteristics and the distribution of repetitive elements. Both <em>A. oblongus</em> and <em>D. uruguayensis</em> exhibited 2n♂=28, X<sub>1</sub>X<sub>2</sub>, with acro/telocentric morphology, hypothesized to represent the ancestral condition for Lycosoidea. However, regarding the 28S rDNA chromosome mapping, these species revealed an unusually high number of loci with eight chromosome clusters in <em>A. oblongus</em> and a polymorphic condition in <em>D. uruguayensis</em> (10–14 signals), underscoring the utility of additional techniques for detecting specific chromosomal regions. Interestingly, <em>A. castaneus</em> and <em>A. lagotis</em> displayed a more derived karyotype, characterized by 2 n♂= 14, X<sub>1</sub>X<sub>2</sub> and acro/telocentric morphology, with the sex chromosomes (X<sub>1</sub> and X<sub>2</sub>) smaller than the autosomes. Taken together, these data suggest that, following the diversification of <em>Aglaoctenus</em>, a significant reduction in diploid number occurred, affecting only the autosomes. These findings encourage further cytogenetic research within Sosippinae and support the use of these data in future phylogenetic studies.</div></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"170 ","pages":"Article 126269"},"PeriodicalIF":1.6,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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