Research

25 pages, 11307 KiB

Open AccessArticle

Evolutionary Insights into the Relationship of Frogs, Salamanders, and Caecilians and Their Adaptive Traits, with an Emphasis on Salamander Regeneration and Longevity

by Bin Lu

Animals 2023, 13(22), 3449; https://doi.org/10.3390/ani13223449 - 08 Nov 2023

Cited by 1 | Viewed by 1609

Abstract

The extant amphibians have developed uncanny abilities to adapt to their environment. I compared the genes of amphibians to those of other vertebrates to investigate the genetic changes underlying their unique traits, especially salamanders’ regeneration and longevity. Using the well-supported Batrachia tree, I [...] Read more.

The extant amphibians have developed uncanny abilities to adapt to their environment. I compared the genes of amphibians to those of other vertebrates to investigate the genetic changes underlying their unique traits, especially salamanders’ regeneration and longevity. Using the well-supported Batrachia tree, I found that salamander genomes have undergone accelerated adaptive evolution, especially for development-related genes. The group-based comparison showed that several genes are under positive selection, rapid evolution, and unexpected parallel evolution with traits shared by distantly related species, such as the tail-regenerative lizard and the longer-lived naked mole rat. The genes, such as EEF1E1, PAFAH1B1, and OGFR, may be involved in salamander regeneration, as they are involved in the apoptotic process, blastema formation, and cell proliferation, respectively. The genes PCNA and SIRT1 may be involved in extending lifespan, as they are involved in DNA repair and histone modification, respectively. Some genes, such as PCNA and OGFR, have dual roles in regeneration and aging, which suggests that these two processes are interconnected. My experiment validated the time course differential expression pattern of SERPINI1 and OGFR, two genes that have evolved in parallel in salamanders and lizards during the regeneration process of salamander limbs. In addition, I found several candidate genes responsible for frogs’ frequent vocalization and caecilians’ degenerative vision. This study provides much-needed insights into the processes of regeneration and aging, and the discovery of the critical genes paves the way for further functional analysis, which could open up new avenues for exploiting the genetic potential of humans and improving human well-being. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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10 pages, 7011 KiB

Open AccessArticle

Disentangling Exploitative and Interference Competition on Forest Dwelling Salamanders

by Giacomo Rosa, Sebastiano Salvidio and Andrea Costa

Animals 2023, 13(12), 2003; https://doi.org/10.3390/ani13122003 - 15 Jun 2023

Cited by 2 | Viewed by 977

Abstract

Exploitative competition and interference competition differ in the way access to resources is modulated by a competitor. Exploitative competition implies resource depletion and usually produces spatial segregation, while interference competition is independent from resource availability and can result in temporal niche partitioning. Our [...] Read more.

Exploitative competition and interference competition differ in the way access to resources is modulated by a competitor. Exploitative competition implies resource depletion and usually produces spatial segregation, while interference competition is independent from resource availability and can result in temporal niche partitioning. Our aim is to infer the presence of spatial or temporal niche partitioning on a two-species system of terrestrial salamanders in Northern Italy: Speleomantes strinatii and Salamandrina perspicillata. We conducted 3 repeated surveys on 26 plots in spring 2018, on a sampling site where both species are present. We modelled count data with N-mixture models accounting for directional interactions on both abundance and detection process. In this way we were able to disentangle the effect of competitive interaction on the spatial scale, i.e., local abundance, and from the temporal scale, i.e., surface activity. We found strong evidence supporting the presence of temporal niche partitioning, consistent with interference competition. At the same time, no evidence of spatial segregation has been observed. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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24 pages, 11743 KiB

Open AccessArticle

An Isolated and Deeply Divergent Hynobius Species from Fujian, China

by Zhenqi Wang, Siti N. Othman, Zhixin Qiu, Yiqiu Lu, Vishal Kumar Prasad, Yuran Dong, Chang-Hu Lu and Amaël Borzée

Animals 2023, 13(10), 1661; https://doi.org/10.3390/ani13101661 - 17 May 2023

Cited by 1 | Viewed by 9854

Abstract

It is important to describe lineages before they go extinct, as we can only protect what we know. This is especially important in the case of microendemic species likely to be relict populations, such as Hynobius salamanders in southern China. Here, we unexpectedly [...] Read more.

It is important to describe lineages before they go extinct, as we can only protect what we know. This is especially important in the case of microendemic species likely to be relict populations, such as Hynobius salamanders in southern China. Here, we unexpectedly sampled Hynobius individuals in Fujian province, China, and then worked on determining their taxonomic status. We describe Hynobius bambusicolus sp. nov. based on molecular and morphological data. The lineage is deeply divergent and clusters with the other southern Chinese Hynobius species based on the concatenated mtDNA gene fragments (>1500 bp), being the sister group to H. amjiensis based on the COI gene fragment, despite their geographic distance. In terms of morphology, the species can be identified through discrete characters enabling identification in the field by eye, an unusual convenience in Hynobius species. In addition, we noted some interesting life history traits in the species, such as vocalization and cannibalism. The species is likely to be incredibly rare, over a massively restricted distribution, fitting the definition of Critically Endangered following several lines of criteria and categories of the IUCN Red List of Threatened Species. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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19 pages, 2551 KiB

Open AccessArticle

Survived the Glaciations, Will They Survive the Fish? Allochthonous Ichthyofauna and Alpine Endemic Newts: A Road Map for a Conservation Strategy

by Ilaria Bernabò, Mattia Iannella, Viviana Cittadino, Anna Corapi, Antonio Romano, Franco Andreone, Maurizio Biondi, Marcellino Gallo Splendore and Sandro Tripepi

Animals 2023, 13(5), 871; https://doi.org/10.3390/ani13050871 - 27 Feb 2023

Cited by 2 | Viewed by 1582

Abstract

The Calabrian Alpine newt (Ichthyosaura alpestris inexpectata) is a glacial relict with small and extremely localised populations in the Catena Costiera (Calabria, Southern Italy) and is considered to be “Endangered” by the Italian IUCN assessment. Climate-induced habitat loss and recent fish [...] Read more.

The Calabrian Alpine newt (Ichthyosaura alpestris inexpectata) is a glacial relict with small and extremely localised populations in the Catena Costiera (Calabria, Southern Italy) and is considered to be “Endangered” by the Italian IUCN assessment. Climate-induced habitat loss and recent fish introductions in three lakes of the Special Area of Conservation (SAC) Laghi di Fagnano threaten the subspecies’ survival in the core of its restricted range. Considering these challenges, understanding the distribution and abundance of this newt is crucial. We surveyed the spatially clustered wetlands in the SAC and neighbouring areas. First, we provide the updated distribution of this subspecies, highlighting fish-invaded and fishless sites historically known to host Calabrian Alpine newt populations and two new breeding sites that have been recently colonised. Then, we provide a rough estimate of the abundance, body size and body condition of breeding adults and habitat characteristics in fish-invaded and fishless ponds. We did not detect Calabrian Alpine newts at two historically known sites now invaded by fish. Our results indicate a reduction in occupied sites and small-size populations. These observations highlight the need for future strategies, such as fish removal, the creation of alternative breeding habitats and captive breeding, to preserve this endemic taxon. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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9 pages, 1000 KiB

Open AccessArticle

Monitoring of the Endangered Cave Salamander Speleomantes sarrabusensis

by Roberto Cogoni, Milos Di Gregorio, Fabio Cianferoni and Enrico Lunghi

Animals 2023, 13(3), 391; https://doi.org/10.3390/ani13030391 - 24 Jan 2023

Viewed by 1485

Abstract

In this study, we performed the first monitoring activities on one of the most endangered amphibians in Europe, the Sette Fratelli cave salamander Speleomantes sarrabusensis. The data presented here are derived from two monitoring activities aiming to assess the status and abundance [...] Read more.

In this study, we performed the first monitoring activities on one of the most endangered amphibians in Europe, the Sette Fratelli cave salamander Speleomantes sarrabusensis. The data presented here are derived from two monitoring activities aiming to assess the status and abundance of four populations of S. sarrabusensis. With the first monitoring, we surveyed the well-known population occurring within artificial springs during the period 2015–2018, providing monthly data on the number of active individuals. With the second monitoring performed during spring to early summer of 2022, we surveyed four populations at three time points (the one from artificial springs and three from forested areas) and we provided the first estimation of the populations’ abundance. Furthermore, we analyzed for the first time the stomach contents from a population of S. sarrabusensis only occurring in forested environments. With our study, we provided the first information on the abundance of different populations of S. sarrabusensis, representing the starting point for future status assessments for this endangered species. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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10 pages, 479 KiB

Open AccessArticle

Different Traits, Different Evolutionary Pathways: Insights from Salamandrina (Amphibia, Caudata)

by Claudio Angelini, Francesca Antonucci, Jacopo Aguzzi and Corrado Costa

Animals 2022, 12(23), 3326; https://doi.org/10.3390/ani12233326 - 28 Nov 2022

Viewed by 1007

Abstract

Species delimitation is often based on a single or very few genetic or phenetic traits, something which leads to misinterpretations and often does not provide information about evolutionary processes. Here, we investigated the diversity pattern of multiple phenetic traits of the two extant [...] Read more.

Species delimitation is often based on a single or very few genetic or phenetic traits, something which leads to misinterpretations and often does not provide information about evolutionary processes. Here, we investigated the diversity pattern of multiple phenetic traits of the two extant species of Salamandrina, a genus split only after molecular traits had been studied but the two species of which are phenetically very similar. The phenetic traits we studied are size, external body shape and head colour pattern, in a model comparison framework using non-linear mixed models and unsupervised and supervised clustering. Overall, we found high levels of intra-specific variability for body size and shape, depending on population belonging and habitat, while differences between species were generally lower. The habitat the salamanders dwell in also seems important for colour pattern. Basing on our findings, from the methodological point of view, we suggest (i) to take into account the variability at population level when testing for higher level variability, and (ii) a semi-supervised learning approach to high dimensional data. We also showed that different phenotypic traits of the same organism could result from different evolutionary routes. Local adaptation is likely responsible for body size and shape variability, with selective pressures more similar across species than within them. Head colour pattern also depends on habitat, differently from ventral colour pattern (not studied in this paper) which likely evolved under genetic drift. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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11 pages, 634 KiB

Open AccessArticle

The Trophic Niche of Two Sympatric Species of Salamanders (Plethodontidae and Salamandridae) from Italy

by Enrico Lunghi, Claudia Corti, Marta Biaggini, Yahui Zhao and Fabio Cianferoni

Animals 2022, 12(17), 2221; https://doi.org/10.3390/ani12172221 - 29 Aug 2022

Cited by 6 | Viewed by 1789

Abstract

The trophic niche of a species is one of the fundamental traits of species biology. The ideal trophic niche of a species is realized in the absence of interspecific competition, targeting the most profitable and easy-to-handle food resources. However, when a competitor is [...] Read more.

The trophic niche of a species is one of the fundamental traits of species biology. The ideal trophic niche of a species is realized in the absence of interspecific competition, targeting the most profitable and easy-to-handle food resources. However, when a competitor is present, species adopt different strategies to reduce competition and promote coexistence. In this study, we assessed the potential mechanisms that allow the coexistence of two generalist salamanders: the Italian cave salamander (Speleomantes italicus) and the fire salamander (Salamandra salamandra). We surveyed, in April 2021, a forested area of Emilia-Romagna (Italy) during rainy nights. Analyzing the stomach contents of the captured individuals, we obtained information on the trophic niche of these two sympatric populations. Comparing our results with those of previous studies, we found that the two species did not modify their trophic niche, but that alternative mechanisms allowed their coexistence. Specifically, different prey preferences and predator metabolisms were likely the major factors allowing reduced competition between these two generalist predators. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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11 pages, 30143 KiB

Open AccessArticle

A New Disease Caused by an Unidentified Etiological Agent Affects European Salamanders

by Raoul Manenti, Silvia Mercurio, Andrea Melotto, Benedetta Barzaghi, Sara Epis, Marco Tecilla, Roberta Pennati, Giorgio Ulisse Scarì and Gentile Francesco Ficetola

Animals 2022, 12(6), 696; https://doi.org/10.3390/ani12060696 - 10 Mar 2022

Cited by 1 | Viewed by 4670

Abstract

New pathologies are causing dramatic declines and extinctions of multiple amphibian species. In 2013, in one fire salamander population of Northern Italy, we found individuals with undescribed cysts at the throat level, a malady whose existence has not previously been reported in amphibians. [...] Read more.

New pathologies are causing dramatic declines and extinctions of multiple amphibian species. In 2013, in one fire salamander population of Northern Italy, we found individuals with undescribed cysts at the throat level, a malady whose existence has not previously been reported in amphibians. With the aim of describing this novel disease, we performed repeated field surveys to assess the frequency of affected salamanders from 2014 to 2020, and integrated morphological, histological, and molecular analyses to identify the pathogen. The novel disease affected up to 22% of salamanders of the study population and started spreading to nearby populations. Cysts are formed by mucus surrounding protist-like cells about 30 µm long, characterized by numerous cilia/undulipodia. Morphological and genetic analyses did not yield a clear match with described organisms. The existence of this pathogen calls for the implementation of biosecurity protocols and more studies on the dynamics of transmission and the impact on wild populations. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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11 pages, 896 KiB

Open AccessArticle

Temperature and Diet Acclimation Modify the Acute Thermal Performance of the Largest Extant Amphibian

by Chun-Lin Zhao, Tian Zhao, Jian-Yi Feng, Li-Ming Chang, Pu-Yang Zheng, Shi-Jian Fu, Xiu-Ming Li, Bi-Song Yue, Jian-Ping Jiang and Wei Zhu

Animals 2022, 12(4), 531; https://doi.org/10.3390/ani12040531 - 21 Feb 2022

Cited by 4 | Viewed by 2625

Abstract

The Chinese giant salamander (Andrias davidianus), one of the largest extant amphibian species, has dramatically declined in the wild. As an ectotherm, it may be further threatened by climate change. Therefore, understanding the thermal physiology of this species should be the [...] Read more.

The Chinese giant salamander (Andrias davidianus), one of the largest extant amphibian species, has dramatically declined in the wild. As an ectotherm, it may be further threatened by climate change. Therefore, understanding the thermal physiology of this species should be the priority to formulate related conservation strategies. In this study, the plasticity in metabolic rate and thermal tolerance limits of A. davidianus larvae were studied. Specifically, the larvae were acclimated to three temperature levels (7 °C, cold stress; 15 °C, optimum; and 25 °C, heat stress) and two diet items (red worm or fish fray) for 20 days. Our results indicated that cold-acclimated larvae showed increased metabolic capacity, while warm-acclimated larvae showed a decrease in metabolic capacity. These results suggested the existence of thermal compensation. Moreover, the thermal tolerance windows of cold-acclimated and warm-acclimated larvae shifted to cooler and hotter ranges, respectively. Metabolic capacity is not affected by diet but fish-fed larvae showed superiority in both cold and heat tolerance, potentially due to the input of greater nutrient loads. Overall, our results suggested a plastic thermal tolerance of A. davidianus in response to temperature and diet variations. These results are meaningful in guiding the conservation of this species. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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13 pages, 971 KiB

Open AccessArticle

The Reproductive Success of Triturus ivanbureschi × T. macedonicus F₁ Hybrid Females (Amphibia: Salamandridae)

by Tijana Vučić, Ana Ivanović, Maja Ajduković, Nikola Bajler and Milena Cvijanović

Animals 2022, 12(4), 443; https://doi.org/10.3390/ani12040443 - 12 Feb 2022

Cited by 3 | Viewed by 1808

Abstract

Two large-bodied newt species, Triturus ivanbureschi and T. macedonicus, hybridize in nature across the Balkan Peninsula. Consequences of hybridization upon secondary contact of two species include species displacement and asymmetrical introgression of T. ivanbureschi mtDNA. We set an experimental reciprocal cross of [...] Read more.

Two large-bodied newt species, Triturus ivanbureschi and T. macedonicus, hybridize in nature across the Balkan Peninsula. Consequences of hybridization upon secondary contact of two species include species displacement and asymmetrical introgression of T. ivanbureschi mtDNA. We set an experimental reciprocal cross of parental species and obtained two genotypes of F₁ hybrids (with T. ivanbureschi or T. macedonicus mtDNA). When hybrids attained sexual maturity, they were engaged in mutual crossings and backcrossing with parental species. We followed reproductive traits over two successive years. Our main aim was to explore the reproductive success of F₁ females carrying different parental mtDNA. Additionally, we tested for differences in reproductive success within female genotypes depending on the crossing with various male genotypes (hybrids or parental species). Both female genotypes had similar oviposition periods, number of laid eggs and hatched larvae but different body and egg sizes. Overall reproductive success (percentage of egg-laying females and viability of embryos) was similar for both genotypes. The type of crossing led to some differences in reproductive success within female genotypes. The obtained results suggest that processes that led to exclusion of T. macedonicus mtDNA in natural populations may be related to the survival at postembryonic stages of F₂ generation or reproductive barriers that emerged in subsequent hybrid generations. Full article

(This article belongs to the Special Issue Salamanders: Distribution, Diversity, and Conservation)

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