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Cochrane MM, Addis BR, Lowe WH. Stage-Specific Demographic Effects of Hydrologic Variation in a Stream Salamander. Am Nat 2024; 203:E175-E187. [PMID: 38635365 DOI: 10.1086/729466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
AbstractWe lack a strong understanding of how organisms with complex life histories respond to climate variation. Many stream-associated species have multistage life histories that are likely to influence the demographic consequences of floods and droughts. However, tracking stage-specific demographic responses requires high-resolution, long-term data that are rare. We used 8 years of capture-recapture data for the headwater stream salamander Gyrinophilus porphyriticus to quantify the effects of flooding and drying magnitude on stage-specific vital rates and population growth. Drying reduced larval recruitment but increased the probability of metamorphosis (i.e., adult recruitment). Flooding reduced adult recruitment but had no effect on larval recruitment. Larval and adult survival declined with flooding but were unaffected by drying. Annual population growth rates (λ) declined with flooding and drying. Lambda also declined over the study period (2012-2021), although mean λ was 1.0 over this period. Our results indicate that G. porphyriticus populations are resilient to hydrologic variation because of compensatory effects on recruitment of larvae versus adults (i.e., reproduction vs. metamorphosis). Complex life cycles may enable this resilience to climate variation by creating opportunities for compensatory demographic responses across stages. However, more frequent and intense hydrologic variation in the latter half of this study contributed to a decline in λ over time, suggesting that increasing environmental variability poses a threat even when demographic compensation occurs.
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Zheng X, Babst F, Camarero JJ, Li X, Lu X, Gao S, Sigdel SR, Wang Y, Zhu H, Liang E. Density-dependent species interactions modulate alpine treeline shifts. Ecol Lett 2024; 27:e14403. [PMID: 38577961 DOI: 10.1111/ele.14403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 04/06/2024]
Abstract
Species interactions such as facilitation and competition play a crucial role in driving species range shifts. However, density dependence as a key feature of these processes has received little attention in both empirical and modelling studies. Herein, we used a novel, individual-based treeline model informed by rich in situ observations to quantify the contribution of density-dependent species interactions to alpine treeline dynamics, an iconic biome boundary recognized as an indicator of global warming. We found that competition and facilitation dominate in dense versus sparse vegetation scenarios respectively. The optimal balance between these two effects was identified at an intermediate vegetation thickness where the treeline elevation was the highest. Furthermore, treeline shift rates decreased sharply with vegetation thickness and the associated transition from positive to negative species interactions. We thus postulate that vegetation density must be considered when modelling species range dynamics to avoid inadequate predictions of its responses to climate warming.
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Affiliation(s)
- Xiangyu Zheng
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Flurin Babst
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona, USA
| | | | - Xiaoxia Li
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Xiaoming Lu
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Shan Gao
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Shalik Ram Sigdel
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Yafeng Wang
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Haifeng Zhu
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Eryuan Liang
- State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
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Cayuela H, Lackey ACR, Ronget V, Monod-Broca B, Whiteman HH. Polyphenism predicts actuarial senescence and lifespan in tiger salamanders. J Anim Ecol 2024; 93:333-347. [PMID: 38279640 DOI: 10.1111/1365-2656.14048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 12/08/2023] [Indexed: 01/28/2024]
Abstract
Actuarial senescence (called 'senescence' hereafter) often shows broad variation at the intraspecific level. Phenotypic plasticity likely plays a central role in among-individual heterogeneity in senescence rate (i.e. the rate of increase in mortality with age), although our knowledge on this subject is still very fragmentary. Polyphenism-the unique sub-type of phenotypic plasticity where several discrete phenotypes are produced by the same genotype-may provide excellent study systems to investigate if and how plasticity affects the rate of senescence in nature. In this study, we investigated whether facultative paedomorphosis influences the rate of senescence in a salamander, Ambystoma mavortium nebulosum. Facultative paedomorphosis, a unique form of polyphenism found in dozens of urodele species worldwide, leads to the production of two discrete, environmentally induced phenotypes: metamorphic and paedomorphic individuals. We leveraged an extensive set of capture-recapture data (8948 individuals, 24 years of monitoring) that were analysed using multistate capture-recapture models and Bayesian age-dependent survival models. Multistate models revealed that paedomorphosis was the most common developmental pathway used by salamanders in our study system. Bayesian age-dependent survival models then showed that paedomorphs have accelerated senescence in both sexes and shorter adult lifespan (in females only) compared to metamorphs. In paedomorphs, senescence rate and adult lifespan also varied among ponds and individuals. Females with good body condition and high lifetime reproductive success had slower senescence and longer lifespan. Late-breeding females also lived longer but showed a senescence rate similar to that of early-breeding females. Moreover, males with good condition had longer lifespan than males with poor body condition, although they had similar senescence rates. In addition, late-breeding males lived longer but, unexpectedly, had higher senescence than early-breeding males. Overall, our work provides one of the few empirical cases suggesting that environmentally cued polyphenism could affect the senescence of a vertebrate in nature, thus providing insights on the ecological and evolutionary consequences of developmental plasticity on ageing.
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Affiliation(s)
- Hugo Cayuela
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
| | - Alycia C R Lackey
- Department of Biology, University of Louisville, Louisville, Kentucky, USA
- Department of Biological Sciences and Watershed Studies Institute, Murray State University, Murray, Kentucky, USA
| | - Victor Ronget
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
| | - Benjamin Monod-Broca
- Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, Villeurbanne, France
| | - Howard H Whiteman
- Department of Biological Sciences and Watershed Studies Institute, Murray State University, Murray, Kentucky, USA
- Rocky Mountain Biological Laboratory, Gothic, Colorado, USA
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Lyu S, Alexander JM. Compensatory responses of vital rates attenuate impacts of competition on population growth and promote coexistence. Ecol Lett 2023; 26:437-447. [PMID: 36708049 DOI: 10.1111/ele.14167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 01/29/2023]
Abstract
Competition is among the most important factors regulating plant population and community dynamics, but we know little about how different vital rates respond to competition and jointly determine population growth and species coexistence. We conducted a field experiment and parameterised integral projection models to model the population growth of 14 herbaceous plant species in the absence and presence of neighbours across an elevation gradient (284 interspecific pairs). We found that suppressed individual growth and seedling establishment contributed the most to competition-induced declines in population growth, although vital rate contributions varied greatly between species and with elevation. In contrast, size-specific survival and flowering probability and seed production were frequently enhanced under competition. These compensatory vital rate responses were nearly ubiquitous (occurred in 92% of species pairs) and significantly reduced niche overlap and stabilised coexistence. Our study highlights the importance of demographic processes for regulating population and community dynamics, which has often been neglected by classic coexistence theories.
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Affiliation(s)
- Shengman Lyu
- Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Jake M Alexander
- Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
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Landler L, Burgstaller S, Schweiger S. Land-use preferences of the European green toad (Bufotes viridis) in the city of Vienna (Austria): the importance of open land in urban environments. Front Zool 2023; 20:3. [PMID: 36647115 PMCID: PMC9843927 DOI: 10.1186/s12983-022-00480-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 12/04/2022] [Indexed: 01/18/2023] Open
Abstract
Urban areas are increasing worldwide, which poses threats to animal wildlife. However, in certain cases cities can provide refuges for endangered animals. The European green toad (Bufotes viridis) is one of such examples, which is known from cities throughout their distribution. In contrast, considerable areas of their former (primary) habitats have been degraded. The primary habitats of this species include steppes and wild river floodplains, both characterized by dynamic changes and the presence of open areas. We used available green toad observation data (2007-2020) to model the effects of land-use types on occurrence probability in the city of Vienna. Forest and densely populated areas were highly significantly negatively associated with green toad presence, while transformation/construction site areas showed a strong positive effect. Such occurrence pattern might be characteristic for early succession species, which depend on stochastic environmental disturbances (e.g., droughts and floods) in their primary habitats. We argue that urban landscape planning should appreciate the potential ecological value of open land in cities which is either in a transition phase or a permanent 'wasteland'. Ecological managing of such landscape could vastly increase urban biodiversity.
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Affiliation(s)
- Lukas Landler
- Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Gregor-Mendel-Straße 33/I, 1180, Vienna, Austria.
| | - Stephan Burgstaller
- Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Gregor-Mendel-Straße 33/I, 1180, Vienna, Austria
| | - Silke Schweiger
- First Zoological Department, Herpetological Collection, Natural History Museum Vienna, Burgring 7, 1010, Vienna, Austria
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Despite early deaths, toads persist in human-dominated habitats. Proc Natl Acad Sci U S A 2022; 119:e2214266119. [PMID: 36179042 PMCID: PMC9565250 DOI: 10.1073/pnas.2214266119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Where Land and Water Meet: Making Amphibian Breeding Sites Attractive for Amphibians. DIVERSITY 2022. [DOI: 10.3390/d14100834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The protection of wetlands is a cornerstone in the conservation of pond-breeding amphibians. Because protected wetlands are rarely natural areas, but are often man-made, at least in Europe, it is important that they are well managed to fulfill their intended function. Appropriate management requires knowledge of the ecology of the species, particularly habitat requirements. Here, we combine species monitoring data and habitat mapping data in an analysis where our goal was to describe the factors that determine the occupancy of amphibian species in federally protected amphibian breeding sites. As expected, every species had its own habitat requirements, often a combination of both a terrestrial and aquatic habitat (i.e., landscape complementation). In most species, occupancy was strongly positively affected with the amount of aquatic habitat, but predicted occupancy probabilities were low because the amount of aquatic habitat was low in most sites. The area or proportion of ruderal vegetation also had positive effects on multiple species, while other types of terrestrial habitat (e.g., meadows) led to low occupancy probabilities. The total area of the protected breeding sites was never included in a final model and connectivity was important only for one species (Triturus cristatus). The latter finding implies that the quality of the landscape between breeding sizes is more important than distance per se, while the former implies that the area of some specific habitats within breeding sites is crucial for high occupancies. Thus, increasing the amount of aquatic habitats and likewise terrestrial habitats within protected areas would make them more likely to achieve their conservation objectives. Our study is an example of how the joint analysis of monitoring data and habitat data (based on mapping in the field) can lead to evidence-based suggestions on how to improve conservation practice.
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