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Wagener C, du Plessis M, Measey J. Invasive Amphibian Gut Microbiota and Functions Shift Differentially in an Expanding Population but Remain Conserved Across Established Populations. MICROBIAL ECOLOGY 2022; 84:1042-1054. [PMID: 34735604 DOI: 10.1007/s00248-021-01896-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Studies of laboratory animals demonstrate extensive variation of host gut microbiomes and their functional capabilities across populations, but how does anthropogenic change impact the microbiomes of non-model species? The anthropogenic movement of species to novel environments can drastically alter animals' microbiomes; however, factors that shape invasive species gut microbiota during introduction remain relatively unexplored. Through 16S amplicon sequencing on guttural toad (Sclerophrys gutturalis) faecal samples, we determine that residence time does not impact microbiome variation between source and introduced populations. The youngest population (~ 20 years in Cape Town) has the most distinct microbiome and associated functional capabilities, whereas longer residence times (~ 100 years in Réunion and Mauritius) produce less divergent microbial compositional, phylogenetic, and predicted functional diversity and differential abundance from source populations (Durban). Additionally, we show extensive variation of microbial and functional diversity, as well as differential abundance patterns in an expanding introduced population (Cape Town) between core and periphery sites. Contrasting previous studies, we suggest that introduction pathways might be an important factor impacting host microbial divergence. These findings also imply that the microbiome can diverge in accordance with host population dynamics.
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Affiliation(s)
- Carla Wagener
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa.
| | - Morne du Plessis
- Zoological Research, Foundational Research and Services, South African National Biodiversity Institute, Pretoria, South Africa
| | - John Measey
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
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Baxter-Gilbert J, Riley JL, Wagener C, Baider C, Florens FBV, Kowalski P, Campbell M, Measey J. Island Hopping through Urban Filters: Anthropogenic Habitats and Colonized Landscapes Alter Morphological and Performance Traits of an Invasive Amphibian. Animals (Basel) 2022; 12:ani12192549. [PMID: 36230289 PMCID: PMC9559409 DOI: 10.3390/ani12192549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/28/2022] [Accepted: 09/19/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Invasive species are common on islands and, increasingly so, in urban ecosystems. They can pose serious ecological and socioeconomic impacts, making research on how invasions are promoted critically important. We examined different traits of guttural toads (Sclerophrys gutturalis) in their natural and invasive ranges (both natural and urban populations in native and invasive sites) to understand if divergences in habitats in their native range could increase their invasive potential. We found that invasive island populations on Mauritius and Réunion (Indian Ocean) have reduced body sizes, proportionally shorter limbs, slower escape speeds, and reduced endurance capacities compared to the native South African populations. In short, these changes occurred post-invasion. However, increase climbing ability was seen within the urban-native toads, a trait maintained within the two invasions, suggesting that it may have been an advantageous prior adaptation. Becoming climbers may have benefited the toad during colonization, increasing navigation and hunting ability within the urbanized areas where they were introduced, prior to their spread into natural areas. This change in climbing performance is an example of how the urbanization of native taxa may be increasing the ability of certain species to become better invaders should they be introduced outside their native range. Abstract A prominent feature of the modern era is the increasing spread of invasive species, particularly within island and urban ecosystems, and these occurrences provide valuable natural experiments by which evolutionary and invasion hypotheses can be tested. In this study, we used the invasion route of guttural toads (Sclerophrys gutturalis) from natural-native and urban-native populations (Durban, South Africa) to their urban-invasive and natural-invasive populations (Mauritius and Réunion) to determine whether phenotypic changes that arose once the toads became urbanized in their native range have increased their invasive potential before they were transported (i.e., prior adaptation) or whether the observed changes are unique to the invasive populations. This urban/natural by native/invasive gradient allowed us to examine differences in guttural toad morphology (i.e., body size, hindlimb, and hindfoot length) and performance capacity (i.e., escape speed, endurance, and climbing ability) along their invasion route. Our findings indicate that invasive island populations have reduced body sizes, shorter limbs in relation to snout-vent length, decreased escape speeds, and decreased endurance capacities that are distinct from the native mainland populations (i.e., invasion-derived change). Thus, these characteristics did not likely arise directly from a pre-transport anthropogenic “filter” (i.e., urban-derived change). Climbing ability, however, did appear to originate within the urban-native range and was maintained within the invasive populations, thereby suggesting it may have been a prior adaptation that provided this species with an advantage during its establishment in urban areas and spread into natural forests. We discuss how this shift in climbing performance may be ecologically related to the success of urban and invasive guttural toad populations, as well as how it may have impacted other island-derived morphological and performance phenotypes.
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Affiliation(s)
- James Baxter-Gilbert
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7405, South Africa
- Department of Biology, Mount Allison University, Sackville, NB E4L 1E2, Canada
- Correspondence:
| | - Julia L. Riley
- Department of Biology, Mount Allison University, Sackville, NB E4L 1E2, Canada
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7405, South Africa
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Carla Wagener
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7405, South Africa
- Department of Zoology, University of Oxford, Oxford OX1 4BH, UK
| | - Cláudia Baider
- The Mauritius Herbarium, Agricultural Services, Ministry of Agro-Industry and Food Security, Réduit 80835, Mauritius
| | - F. B. Vincent Florens
- Tropical Island Biodiversity, Ecology and Conservation Pole of Research, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius
| | | | - May Campbell
- Grow Learning Support, Ballito 4391, South Africa
| | - John Measey
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7405, South Africa
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Mühlenhaupt M, Baxter-Gilbert J, Makhubo BG, Riley JL, Measey J. Growing up in a new world: trait divergence between rural, urban, and invasive populations of an amphibian urban invader. NEOBIOTA 2021. [DOI: 10.3897/neobiota.69.67995] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cities are focal points of introduction for invasive species. Urban evolution might facilitate the success of invasive species in recipient urban habitats. Here we test this hypothesis by rearing tadpoles of a successful amphibian urban coloniser and invader in a common garden environment. We compared growth rate, morphological traits, swimming performance, and developmental rate of guttural toad tadpoles (Sclerophrys gutturalis) from native rural, native urban, and non-native urban habitats. By measuring these traits across ontogeny, we were also able to compare divergence across different origins as the tadpoles develop. The tadpoles of non-native urban origin showed significantly slower developmental rate (e.g., the proportion of tadpoles reaching Gosner stage 31 or higher was lower at age 40 days) than tadpoles of native urban origin. Yet, tadpoles did not differ in growth rate or any morphological or performance trait examined, and none of these traits showed divergent ontogenetic changes between tadpoles of different origin. These findings suggest that prior adaptation to urban habitats in larval traits likely does not play an important role in facilitating the invasion success of guttural toads into other urban habitats. Instead, we suggest that evolutionary changes in larval traits after colonization (e.g., developmental rate), together with decoupling of other traits and phenotypic plasticity might explain how this species succeeded in colonising extra-limital urban habitats.
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Negative impacts of invasive predators used as biological control agents against the pest snail Lissachatina fulica: the snail Euglandina ‘rosea’ and the flatworm Platydemus manokwari. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02436-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AbstractSince 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flatworms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L. fulica and native snails. Since 1993 there have been unofficial releases of Euglandina within island groups. Only three official P. manokwari releases took place, but new populations are being recorded at an increasing rate, probably because of accidental introduction. Claims that these predators controlled L. fulica cannot be substantiated; in some cases pest snail declines coincided with predator arrival but concomitant declines occurred elsewhere in the absence of the predator and the declines in some cases were only temporary. In the Hawaiian Islands, although there had been some earlier declines of native snails, the Euglandina impacts on native snails are clear with rapid decline of many endemic Hawaiian Achatinellinae following predator arrival. In the Society Islands, Partulidae tree snail populations remained stable until Euglandina introduction, when declines were extremely rapid with an exact correspondence between predator arrival and tree snail decline. Platydemus manokwari invasion coincides with native snail declines on some islands, notably the Ogasawara Islands of Japan, and its invasion of Florida has led to mass mortality of Liguus spp. tree snails. We conclude that Euglandina and P. manokwari are not effective biocontrol agents, but do have major negative effects on native snail faunas. These predatory snails and flatworms are generalist predators and as such are not suitable for biological control.
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Baxter-Gilbert J, Riley JL, Wagener C, Mohanty NP, Measey J. Shrinking before our isles: the rapid expression of insular dwarfism in two invasive populations of guttural toad ( Sclerophrys gutturalis). Biol Lett 2020; 16:20200651. [PMID: 33202183 DOI: 10.1098/rsbl.2020.0651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Island ecosystems have traditionally been hailed as natural laboratories for examining phenotypic change, including dramatic shifts in body size. Similarly, biological invasions can drive rapid localized adaptations within modern timeframes. Here, we compare the morphology of two invasive guttural toad (Sclerophrys gutturalis) populations in Mauritius and Réunion with their source population from South Africa. We found that female toads on both islands were significantly smaller than mainland counterparts (33.9% and 25.9% reduction, respectively), as were males in Mauritius (22.4%). We also discovered a significant reduction in the relative hindlimb length of both sexes, on both islands, compared with mainland toads (ranging from 3.4 to 9.0%). If our findings are a result of natural selection, then this would suggest that the dramatic reshaping of an amphibian's morphology-leading to insular dwarfism-can result in less than 100 years; however, further research is required to elucidate the mechanism driving this change (e.g. heritable adaptation, phenotypic plasticity, or an interaction between them).
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Affiliation(s)
- James Baxter-Gilbert
- Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - Julia L Riley
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa.,Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Carla Wagener
- Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - Nitya P Mohanty
- Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - John Measey
- Centre for Invasion Biology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
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