Influence of substrate types and morphological traits on movement behavior in a toad and newt species

Background Inter-patch movements may lead to genetic mixing, decreasing both inbreeding and population extinction risks, and is hence a crucial aspect of amphibian meta-population dynamics. Traveling through heterogeneous landscapes might be particularly risky for amphibians. Understanding how these species perceive their environment and how they move in heterogeneous habitats is an essential step in explaining metapopulation dynamics and can be important for predicting species’ responses to climate change and for conservation policy and management. Methods Using an experimental approach, the present study focused on the movement behavior (crossing speed and number of stops) on different substrates mimicking landscape components (human-made and natural substrates) in two amphibian species contrasting in locomotion mode: the common toad (Bufo bufo), a hopping and burrowing anuran and the marbled newt (Triturus marmoratus), a walking salamander. We tested the hypothesis that species reaction to substrate is dependent on specific ecological requirements or locomotion modes because of morphological and behavioral differences. Results In both species, substrate type influenced individual crossing speed, with individuals moving faster on soil than on concrete substrate. We also demonstrated that long-legged individuals moved faster than individuals with short legs. In both species, the number of stops was higher in females than in males. In common toads, the number of stops did not vary between substrates tested, whereas in marbled newts the number of stops was higher on concrete than on soil substrate. Discussion We highlighted that concrete substrate (mimicking roads) negatively affect the crossing speed of both studied species, with an effect potentially higher in marbled newts. Our findings corroborate negative effects of such heterogeneous landscapes on movement behavior of two amphibian species, which may have implications for the dynamics of metapopulations

The inner craniodental anatomy of the Papio specimen U.W. 88-886 from the Early Pleistocene site of Malapa, Gauteng, South Africa

Cercopithecoids represent an essential component of the Plio-Pleistocene faunal assemblage. However, despite the abundance of the cercopithecoid fossil remains in African Plio-Pleistocene deposits, the chronological and geographic contexts from which the modern baboons (i.e. Papio hamadryas ssp.) emerged are still debated. The recently discovered Papio (hamadryas) angusticeps specimen (U.W. 88-886) from the Australopithecus sediba-bearing site of Malapa, Gauteng, South Africa, may represent the first modern baboon occurrence in the fossil record. Given the implication of U.W. 88-886 for the understanding of the papionin evolutionary history and the potential of internal craniodental structures for exploring evolutionary trends in fossil monkey taxa, we use X-ray microtomography to investigate the inner craniodental anatomy of this critical specimen. Our goal is to provide additional evidence to examine the origins of modern baboons. In particular, we explore (i) the tissue proportions and the dentine topographic distribution in dental roots and (ii) the endocranial organization. Consistent with the previous description and metrical analyses of its external cranial morphology, U.W. 88-886 shares internal craniodental anatomy similarities with Plio-Pleistocene and modern Papio, supporting its attribution to Papio (hamadryas) angusticeps. Interestingly, average dentine thickness and distribution in U.W. 88-886 fit more closely to the extinct Papio condition, while the sulcal pattern and relative dentine thickness are more like the extant Papio states. Besides providing additional evidence for characterizing South African fossil papionins, our study sheds new light on the polarity of inner craniodental features in the papionin lineage.https://www.wits.ac.za/esi/palaeontologia-africanapm2020Anatom

Marking techniques in the Marbled Newt (Triturus marmoratus): PIT-Tag and tracking device implant protocols

Individual marking has become essential for studying population dynamics and ecological requirements. However, marking small-bodied species such as amphibians is becoming a challenge in the last decades. Amphibian surveys may require to mark manually individuals, using toe clipping, polymers and pigments, or passive integrated transponders (PIT-tags). Even if ethics committees have recently recommend avoiding toe clipping in amphibians, the use of PIT-tags led to controversial results because low tag retention reported in some studies. Here, we describe a protocol of potentially life-long PIT-tag marking in a protected species, the marbled newt Triturus marmoratus. In addition, we also detailed a second procedure of surgery for the implantation of transmitters needed in radio-tracking surveys. During both procedures, we found that the newt phase (either aquatic or terrestrial) strongly affected the anesthesia duration. Indeed, newts in aquatic phase were more quickly anesthetized than newts under terrestrial phase. We then recommend to pay attention of this physiological particularity when performing this kind of procedure. Improving our knowledge on ecological requirements and population dynamics of this species is crucial for management and conservation plans, and could be extended to other large newts

Marking techniques in the Marbled Newt (<em>Triturus marmoratus</em>): PIT-Tag and tracking device implant protocols

Individual marking has become essential for studying population dynamics and ecological requirements. However, marking small-bodied species such as amphibians is becoming a challenge in the last decades. Amphibian surveys may require to mark manually individuals, using toe clipping, polymers and pigments, or passive integrated transponders (PIT-tags). Even if ethics committees have recently recommend avoiding toe clipping in amphibians, the use of PIT-tags led to controversial results because low tag retention reported in some studies. Here, we describe a protocol of potentially life-long PIT-tag marking in a protected species, the marbled newt Triturus marmoratus. In addition, we also detailed a second procedure of surgery for the implantation of transmitters needed in radio-tracking surveys. During both procedures, we found that the newt phase (either aquatic or terrestrial) strongly affected the anesthesia duration. Indeed, newts in aquatic phase were more quickly anesthetized than newts under terrestrial phase. We then recommend to pay attention of this physiological particularity when performing this kind of procedure. Improving our knowledge on ecological requirements and population dynamics of this species is crucial for management and conservation plans, and could be extended to other large newts

The inner craniodental anatomy of the Papio specimen U.W. 88-886 from the Early Pleistocene site of Malapa, Gauteng, South Africa

Cercopithecoids represent an essential component of the Plio-Pleistocene faunal assemblage. However, despite the abundance of the cercopithecoid fossil remains in African Plio-Pleistocene deposits, the chronological and geographic contexts from which the modern baboons (i.e. Papio hamadryas ssp.) emerged are still debated. The recently discovered Papio (hamadryas) angusticeps specimen (U.W. 88-886) from the Australopithecus sediba-bearing site of Malapa, Gauteng, South Africa, may represent the first modern baboon occurrence in the fossil record. Given the implication of U.W. 88-886 for the understanding of the papionin evolutionary history and the potential of internal craniodental structures for exploring evolutionary trends in fossil monkey taxa, we use X-ray microtomography to investigate the inner craniodental anatomy of this critical specimen. Our goal is to provide additional evidence to examine the origins of modern baboons. In particular, we explore (i) the tissue proportions and the dentine topographic distribution in dental roots and (ii) the endocranial organization. Consistent with the previous description and metrical analyses of its external cranial morphology, U.W. 88-886 shares internal craniodental anatomy similarities with Plio-Pleistocene and modern Papio, supporting its attribution to Papio (hamadryas) angusticeps. Interestingly, average dentine thickness and distribution in U.W. 88-886 fit more closely to the extinct Papio condition, while the sulcal pattern and relative dentine thickness are more like the extant Papio states. Besides providing additional evidence for characterizing South African fossil papionins, our study sheds new light on the polarity of inner craniodental features in the papionin lineage.https://www.wits.ac.za/esi/palaeontologia-africanapm2020Anatom

The inner craniodental anatomy of the Papio specimen U.W. 88-886 from the Early Pleistocene site of Malapa, Gauteng, South Africa

Cercopithecoids represent an essential component of the Plio-Pleistocene faunal assemblage. However, despite the abundance of the cercopithecoid fossil remains in African Plio-Pleistocene deposits, the chronological and geographic contexts from which the modern baboons (i.e. Papio hamadryas ssp.) emerged are still debated. The recently discovered Papio (hamadryas) angusticeps specimen (U.W. 88-886) from the Australopithecus sediba-bearing site of Malapa, Gauteng, South Africa, may represent the first modern baboon occurrence in the fossil record. Given the implication of U.W. 88-886 for the understanding of the papionin evolutionary history and the potential of internal craniodental structures for exploring evolutionary trends in fossil monkey taxa, we use X-ray microtomography to investigate the inner craniodental anatomy of this critical specimen. Our goal is to provide additional evidence to examine the origins of modern baboons. In particular, we explore (i) the tissue proportions and the dentine topographic distribution in dental roots and (ii) the endocranial organization. Consistent with the previous description and metrical analyses of its external cranial morphology, U.W. 88-886 shares internal craniodental anatomy similarities with Plio-Pleistocene and modern Papio, supporting its attribution to Papio (hamadryas) angusticeps. Interestingly, average dentine thickness and distribution in U.W. 88-886 fit more closely to the extinct Papio condition, while the sulcal pattern and relative dentine thickness are more like the extant Papio states. Besides providing additional evidence for characterizing South African fossil papionins, our study sheds new light on the polarity of inner craniodental features in the papionin lineage.https://www.wits.ac.za/esi/palaeontologia-africanapm2020Anatom

Comment on “Forest microclimate dynamics drive plant responses to warming”

International audienceZellweger et al . (Reports, 15 May 2020, p. 772) claimed that forest plant communities’ response to global warming is primarily controlled by microclimate dynamics. We show that community thermophilization is poorly explained by the underlying components of microclimate, and that global warming primarily controls the climatic lag of plant communities. Deconstructing the underlying components of microclimate provides insights for managers

Effects of habitat and fragmented-landscape parameters on amphibian distribution at a large spatial scale

International audienceAmphibians generally have low dispersal abilities and are often habitat specialised, which makes them particularly sensitive to landscape changes, such as habitat destruction and fragmentation. Because they depend on wetlands for breeding, many conservation studies focus on aquatic habitat degradation and destruction. Additionally, few studies showed that changes in terrestrial habitats could be another threat that may cause the decline of amphibian populations. However, little is known about the terrestrial habitat preferences of most species. Although the proximity of forests and wetlands was expected to be positively related to amphibian presence, while human-modified habitats were expected to be avoided by these species, we still have little information on how these responses are species-specific. Based on an ecological niche factor analysis completed by partial least squares path modelling, we tested whether or not relationships between terrestrial and aquatic habitat parameters and occurrences are congruent across a metacommunity of seven amphibian species co-occurring at the regional spatial scale. We highlight that habitat type could strongly affect amphibian presence at large spatial scales, but in different ways. Agricultural landscapes, semi-natural areas and fragmented-landscape parameters showed expected negative correlations with the presence of some species. However, these habitats were also positively associated to the presence of other species. Indeed, because they could offer some benefits, some species could show a preference for these landscapes. Our results should have implications in conservation programmes, and could help predict future distribution and responses of these species to global change, which could be different among species

Data from: Intra-specific variability of hindlimb length in the palmate newt: an indicator of population isolation induced by habitat fragmentation?

Habitat fragmentation is one of the main drivers of global amphibian decline. Anthropogenic landscape elements can act as barriers, hindering the dispersal that is essential for maintaining gene flow between populations. Dispersal ability can be influenced by locomotor performance, which in turn can depend on morphological traits, such as hindlimb length (HLL) in amphibians. Here, we tested relationships between HLL and environmental variables—road types, forests and agricultural lands—among 35 sub-populations of palmate newts (Lissotriton helveticus) in southwestern France. We expected roads to select for short-legged newts due to a higher mortality of more mobile individuals (long-legged newts) when crossing roads. Accordingly, short-legged newts were found in the vicinity of roads, whereas long-legged newts were found closer to forests and in ponds close geographically to another water body. HLL in newts was hence influenced by habitat types in a heterogeneous landscape, and could therefore be used as an indicator of population isolation in a meta-population system

Spatial genetic structure of Lissotriton helveticus L. following the restoration of a forest ponds network

International audiencePreserving amphibian genetic diversity through ecological restoration and conservation actions is a major challenge since their populations are declining worldwide. We studied the genetic diversity and spatial genetic structure of the palmate newt (Lissotriton helveticus) 2 years after the restoration of a pond network in northwestern France with the aim of reconstructing fine-scale genetic structure and patterns of colonization. We sampled newts from 29 forest ponds including both restored and non-degraded reference ponds, and genotyped 391 individuals at 12 microsatellite loci. We used two Bayesian clustering methods to spatially delineate genetic clusters, and we also detected potential recent migrants within the network. All ponds showed low levels of observed heterozygosity (Ho = 0.534) and a mean F IS of 0.251, possibly indicating a Wahlund or bottleneck effect. Pairwise F ST suggested limited evidence of genetic differentiation among ponds. Within the pond network, we identified 3 to 4 genetic clusters. Combined with the detection of migrants, the results suggest an increase in gene flow within the restored pond network and that a high number of migrants came from the reference ponds. Our findings indicate an unexpected high dispersal ability for this small-bodied species. Overall, the absence of population structure represents a positive beginning for the restoration project. It also emphasizes the importance of spatial design in restoring a pond network and that such genetic data and methods should be used to monitor amphibians in restored habitats