The role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern African anurans of different habitat specialisation

Temperature and water availability are two of the most important variables affecting all aspects of an anuran’s key physiological processes such as body temperature (T b), evaporative water loss (EWL) and standard metabolic rate (SMR). Since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (VPD), sex and body mass (M b). However, a limited number of studies have tested the generality of these results across a wide range of ecologically relevant ambient temperatures (T a), while taking habitat use into account. Thus, the aim of this study was to investigate the role of T a on T b, whole-animal EWL and whole-animal SMR in three wild caught African anuran species with different ecological specialisations: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis)

Frog eat frog: exploring variables influencing anurophagy

Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested

More time for aliens? Performance shifts lead to increased activity time budgets propelling invasion success

© 2022 The Authors. Published by Springer. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1007/s10530-022-02903-6In the Grinnellian niche concept, the realized niche and potential distribution is characterized as an interplay among the fundamental niche, biotic interactions and geographic accessibility. Climate is one of the main drivers for this concept and is essential to predict a taxon’s distribution. Mechanistic approaches can be useful tools, which use fitness-related aspects like locomotor performance and critical thermal limits to predict the potential distribution of an organism. These mechanistic approaches allow the inclusion key ecological processes like local adaptation and can account for thermal performance traits of different life-history stages. The African Clawed Frog, Xenopus laevis, is a highly invasive species occurring on five continents. The French population is of special interest due to an ongoing expansion for 40 years and a broad base of knowledge. We hypothesize that (1) the French population exhibits increased activity time in the invasive European range that could be devoted to fitness-relevant activity and (2) tadpoles may have less activity time available than adult frogs from the same range. We investigate how thermal performance traits translate into activity time budgets and how local adaptation and differences in the thermal responses of life-history stages may boost the European Xenopus invasion. We use a mechanistic approach based on generalized additive mixed models, where thermal performance curves were used to predict the hours of activity and to compare the potential activity time budgets for two life-history stages of native and invasive populations. Our results show that adult French frogs have more activity time available in Europe compared to South African frogs, which might be an advantage in searching for prey or escaping from predators. However, French tadpoles do not have more activity time in Europe compared to the native South African populations suggesting that tadpoles do not suffer the same strong selective pressure as adult frogs.Open Access funding enabled and organized by Projekt DEAL. This work was supported by the ERANET BiodivERsA grant INVAXEN, with the national funders Agence Nationale de la Recherche (ANR), Deutsche Forschungsgemeinschaft (DFG), Belgian Federal Science Policy Office (BELSPO), and Fundaçao para a Ciencia e a Tecnologia (FCT), as part of the 2013 BiodivERsA call for research proposals. INVAXEN “Invasive biology of Xenopus laevis in Europe: ecology, impact and predictive models”. CW, NK, MM and JM thank the DSI-NRF Centre of Excellence for Invasion Biology (South Africa) and the National Research Foundation of South Africa (NRF Grant No. 87759 to JM). NK would like to acknowledge the Ambassade de France en Afrique du Sud (France). This study was part of the project Life Control Strategies of Alien Invasive Amphibians (CROAA)—LIFE15 NAT/FR/000864 funded by the Life program of the European Commission.Published onlin

Evaluating the effects of changing global climate on amphibian functional groups of southern Africa: an ecophysiology modelling approach

Thesis (PhD)--Stellenbosch University, 2018.ENGLISH ABSTRACT: Global climate change is suggested to be one of the leading threats to anuran diversity by the end of the century. This is largely because, compared to other vertebrates, anurans have characteristically small distribution ranges and limited dispersal abilities, making them particularly vulnerable to climate change. To predict how climatic changes may impact species, biologists have used correlative-based species distribution models (SDMs). However, correlative-based SDMs have been criticised for their simplistic approach of correlating known distributions with climatic variables, and thus not accounting for other process-based variables that determine distributions such as physiology, performance and morphology. Using a multi-disciplinary approach, the aim of this study is to synergise data from multiple lines of evidence and incorporate them into SDMs to aid in accurately predicting the responses of southern African amphibians with different life-history traits to climate change. In chapter two, I used correlative-based SDMs to determine the impact of past (LGM: Last Glacial Maximum, HGM: Holocene Glacial Minimum) and future (2080) climate change on species distribution ranges of 37, narrowly distributed Cape Floristic Region (CFR) anuran fauna. I found that the biotic velocity at which the CFR anuran community is expected to shift North and East far exceeds historical rates. These models further suggest that the CFR anuran community has already lost ≈ 56% of suitable climate space since the LGM and this is expected to accelerate under future emission scenarios. Chapter three assessed the impacts of climate change on the distribution ranges of three widely distributed anuran species with different ecological specialisations: Xenopus laevis, Amietia delalandii and Sclerophrys capensis. Although all three species have lost suitable climate since the LGM, the models further suggest that A. delalandii is expected to gain suitable climate space by 2080, at least under two GCMs namely, CCSM (25%) and MPI-ESM (7%), while S. capensis and X. laevis are expected to lose suitable climate space by 2080. In chapter four, I examined how changes in ambient temperature (Ta) and body mass (Mb) affect body temperature (Tb), standard metabolic rates (SMR) and evaporative water loss (EWL). I found that Tb, whole-animal EWL and whole-animal SMR increased with an increase in temperature. Body temperature increased with an increase in Mb in A. delalandii and S. capensis but not in X. laevis. Wholeanimal SMR increased with an increase in Mb in S. capensis only. Chapter five examined the impact of temperature on i) burst swimming and hopping (velocity and acceleration) and hoppping endurance (distance and time) in the same three frog species. Here, I show that temperature changes affect thermal reaction norms only in terrestrial performance traits. Furthermore, A. delalandii outperformed X. laevis in both speed and acceleration traits in both burst swimming and hopping experiments, despite X. laevis being adapted to an aquatic lifestyle. Lastly, I implemented ecophysiology models using the results of the temperature-trait relationships obtained in chapter four and five by constructing spatially explicit surface models which were used as input layers in Maxent. Following the same methods as in chapter three, I found that ecophysiology modelling techniques accurately predict current distributions of these widely distributed African anurans. Although species have lost suitable climate space in the past, models predict that A. delalandii will gain thermally suitable space by the year 2080 while X. laevis is also expected to gain suitable thermal space only under MPI-ESM GCM. Sclerophrys capensis is expected to lose suitable climate space in the same period under all GCMs. In conclusion, I showed that although correlative-based SDMs are useful, bottom-up trait-based techniques such as ecophysiology models improves our understanding on how large-scale climate variables affect key physiological traits in shaping what we observe at species distribution level. In addition to biological traits and ecological specialisations, the incorporation of climate variation in modelling processes is also a necessary aspect, given that we have no clear understanding of how climate change will eventually take place.AFRIKAANSE OPSOMMING: Een van die grootste bedreigings vir anuran diversiteit teen die einde van die eeu is Klimaatsverandering. Wat anurans anders as ander gewerweldes maak, is hul kenmerkend klein verspreidingsgebiede en beperkte verspreidingsvermoëns. Om te voorspel hoe klimaatsverandering anurans gaan beinvloed, het wetenskaplikes die korrelatiewe-gebaseerde spesieverspreidings modelle (SDMs) gebruik. Tog word hierdie metode gekritiseer vir die simplistiese benadering van korrelasie van bekende verspreidings van klimaat veranderlikes. Die doel van hierdie studie is om met behulp van 'n multi-dissiplinêre benadering, inligting uit verskeie areas (fisiologie, prestasie en morfologie) te inkorporeer in SDMs om te help met ‘n meer akkurate voorspelling vir Suider-Afrikaanse amfibiese diere met verskillende lewens-kenmerke vir klimaatsverandering. Eerstens het ek die SDM metode gebruik om die impak van klimaatsverandering op die verspreidingsgebied van 37 nouverspreide spesies anuran van die Kaap Floristiese Streek vas te stel. Ek het korrelatiewe-SDMs gebruik vir huidige kondisies en dit gebruik op 2 tydperke in die verlede naamlik i) die Laaste Ystydperk Maksimum (LYM) en ii) die Holoseen Ystydperk Minimum (HYM). Ek het ook die metode gebruik om die tydperk tot 2080. My bevinding was dat die biotiese snelheid waarteen die KFS amfibiese gemeenskap na verwagting sal skuif is veel vinniger as historiese verpsreidingsgroei. Hierdie modelle dui verder daarop dat die KFS amfibiese gemeenskap reeds ≈ 56% verloor het van geskikte klimaatruimte sedert die LYT en dit sal na verwagting versnel onder toekomstige scenarios. Proef drie: Met soortgelyke metodes as hierbo, word die impak van klimaatsverandering vasgestel op die verspreidingsgebiede van drie wyd verspreide anuran spesies met verskillende ekologiese agtergronde: Xenopus laevis, Amietia delalandii, en Sclerophrys capensis. Ek het korrelatiewe gebaseerde SDM modelle gebruik vir huidige toestande en vir die LYM en om 2080 te voorspel. Alhoewel al drie spesies geskikte klimaat sedert die LYM verloor het, dui daarop dat A. delalandii sal na verwagting geskikte klimaat ruimte te bykry, ten minste onder twee ASM naamlik CCSM (25%) en MPI-ESM (7%), terwyl S. capensis en X. laevis verwag om geskikte klimaatruimte te verloor tot 2080. Proef vier het ek fisiologiese eksperimente gedoen om die rol van omgewingstemperatuur (Ta) en liggaamsmassa (Mb) op liggaamstemperatuur (Tb), standaard metaboliese tariewe (SMR) en verdamping waterverlies (EWL) te bepaal. Liggaamstemperatuur verhoog met 'n toename in Mb in A. delalandii en S. capensis maar nie in X. laevis. Ek het egter nie 'n beduidende effek gevind van beide Mb en seks op die geheel-dier EWL in al drie spesies. Geheel-dier SMR verhoog met 'n toename in Mb in net S. capensis. Proef vyf dan bepaal ek hoe veranderinge in temperatuur die volgende beïnvloed: i) spring - swem (snelheid en versnelling) en uithouvermoë (afstand en tyd) in verskillende. Ek het gevind daar was beduidende verskille in spesies reaksie norme net in terrestriële prestasie eienskappe. A. delalandii het beter gevaar as X. laevis in beide die spoed en versnelling eienskappe in swem en spring eksperimente, ten spyte daarvan dat X. laevis aangepas is vir akwatiese leefwyse. Sclerophrys capensis het beter gevaar as X. laevis en A. delalandii in spring uithouvermoë proe (afstand en tyd), ten spyte van veranderinge in Ta. Laastens, het ek die resultate gebruik van hierdie temperatuur-eienskap (dit wil sê, fisiologie, prestasie en morfologie) verkry in proef drie en vier in 'n ekofisiologie modellering platform. Hierdie temperatuur-eienskap verhoudings is gebruik om ruimtelik eksplisiete oppervlak modelle te bou wat gebruik word om inset lae tot huidige spesie verspreiding met behulp van Maxent model te bou. Ek het toe hierdie modelle gebruik op verspredings soortgelyk aan ASM as in proef drie. Die resultaat was dat die ekofisiologie modelleringstegnieke die verspreiding van wyd-verspreide Suid-Afrikaanse anurans akkuraat kan voorspel. Van belang is dat die modelle dui daarop dat A. delalandii meer klimaatgeskikteruimte sal verkry teen die jaar 2080, met al ASM ingesluit, terwyl X. laevis ook na verwagting meer geskikteklimaatruimte sal verkry, maar net onder MPI-ESM ASM. Sclerophrys capensis sal na verwagting geskikteklimaat ruimte verloor in dieselfde tydperk onder al die ASM. Ten slotte, Ek het getoon dat, hoewel korrelatiewe SDM's korrek is, onderliggende eienskappe soos ekofisiologie modelle ons begrip verbeter oor hoe grootskaalse klimaatveranderlikes belangrike fisiologiese eienskappe beïnvloed in die vorming van wat ons waarneem op spesieverspreidingsvlak. Benewens biologiese eienskappe en ekologiese spesialisasies, is die inkorporering van klimaatsvariasie in modelleringsprosesse ook 'n noodsaaklike aspek, aangesien ons nie verstaan het hoe klimaatsverandering uiteindelik sal plaasvind nie.Doctora

Assessing the effects of climate change on distributions of Cape Floristic Region amphibians

Climatic changes have had profound impacts on species distributions throughout time. In response, species have shifted ranges, adapted genetically and behaviourally or become extinct. Using species distribution models, we examined how changes in suitable climatic space could affect the distributions of 37 endemic frog species in the Cape Floristic Region (CFR) – an area proposed to have evolved its megadiversity under a stable climate, which is expected to change substantially in future. Species distributions were projected onto mean climate for a current period (1950 to 2000), hindcasted to palaeoclimate (Last Glacial Maximum; LGM ≈ 21 kya and Holocene Glacial Minimum; HGM ≈ 6 kya) and forecasted for two emissions scenarios (A2a and B2a) for the year 2080. We then determined the changes in area sizes, direction (longitude and latitude), fragmentation index and biotic velocity, and assessed if these were affected by life-history traits and altitude. We found that the biotic velocity at which the CFR amphibian community is expected to shift north (A2a ≈ 540.5 km/kya) and east (B2a ≈ 198 km/kya) far exceeds historical background rates (≈1.05 km/kya, north and west ≈ 2.36 km/kya since the LGM). Our models further suggest that the CFR amphibian community has already lost about 56% of suitable climate space since the LGM and this loss is expected to accelerate under future emission scenarios (A2a ≈ 70%; B2a ≈ 60%). Lastly, we found that highland species were more fragmented than lowland species between the LGM and current period, but that the fragmentation of lowland species between current and future climates is expected to increase

Shortening vehicle access permitting for mobility-impaired individuals to beaches in South Africa's National Parks

DATA AVAILABILITY : Data will be made available on request.Beach driving, generally termed off-road vehicle (ORV) use has been banned in South Africa since 2001. This was not an absolute ban as several permissible uses and permit categories still allow ORV use on beaches when specified criteria are met, though this excludes leisure driving. South African National Parks (SANParks) is responsible for permitting vehicle use on beaches under its management. One of these categories, the physically disabled permit category, allows ORV use by persons with severe, permanent mobility impairments. Although not the most effective means of providing beach access to these individuals, ORV permits are the most widely applied, affording users the same opportunities to access the coast as their able-bodied counterparts. Beach areas in the Garden Route National Park (GRNP), found within a coastal tourism node, generally see an increase in visitor numbers and requests for the above-mentioned ORV permits during austral summer holidays, often days before vehicle access is required. SANParks assessed beach sensitivity and determine acceptable ORV use areas to streamline this permitting process. Of the five sandy beach areas identified within the GRNP, eighteen percent (18 %), constituting three of the five beaches, was considered suitable for ORV use. The extent of lateral driving was determined based on Hot Spot Analysis and preliminary carrying capacities on historic ORV approvals. Turnaround time for applications at these pre-assessed sites is expected to be 2-3 calendar days, allowing visitors to the GRNP the opportunity to access the beaches upon receipt of their permit. This assessment is novel because it aims to integrate ORV access into established recreational beach-going areas instead of separating such uses. Additionally, the rapid assessment criteria are broad enough to be implemented on a national scale and can be used as informants for other coastal access applications.https://www.elsevier.com/locate/ocecoaman2026-06-27hj2024Zoology and EntomologyNon

Characterising wetland hydrology and water quality in streams and wetlands of Khalong-la-Lithunya, Lesotho

Wetland hydrology is important in understanding wetland systems, evaluating wetland functions and processes and assessing wetland conditions. Wetlands assimilate and transform pollutants and nutrients ensuring that quality water is discharged from the wetland into streams. The objective of this study was to characterise wetland hydrology and evaluate the water quality so as to determine the ecological functioning of the Khalong-la-Lithunya wetland. Wetland hydrology and water quality of the three sub-catchments were monitored from October 2015 to March 2016. Water levels in piezometers were recorded once a month and monthly water levels data for the years 2010, 2011, 2012 and 2013 previously recorded by the Millennium Challenge Account-Lesotho (MCA-L) project were integrated to this study’s data. Rainfall, piezometer and stream water were similarly obtained once every month. These were analysed for δ2H and δ18O water stable isotopes and water quality parameters determined. The estimated overall hydro-period of Khalong-la-Lithunya from the years 2010 to 2016 was 11.4% of the sampled time. The wetland showed delayed response of piezometer water levels to rainfall and additional source of water to the wetland through sub-surface flow. The isotopic composition of piezometer and stream water showed that the water gets stored in the wetland before being discharged to the stream leading to a positive interaction between ground and surface water. Most water quality parameters (Na, pH, Mg, PO4 , COD, BOD, NO3, K, Ca, EC) were higher in streams than in piezometers and were mostly within WHO permissible limits. There was a poorer water quality index in streams (59.71) when compared to that of piezometers (53.67). The principal component analysis (PCA) indicated that the parameters that were responsible for the variation in water quality were related to natural hydro-chemical processes, anthropogenic factors and geology and soil constituents. Temporally most parameters were highest during dry months. Due to a short hydro-period, a delayed interaction between surface and ground water and a poorer stream water quality index, it is concluded that the wetland was not in a good condition. Thus, it is not adequately performing its ecological function

Impact assessment with different scoring tools: How well do alien amphibian assessments match?

Classification of alien species' impacts can aid policy making through evidence based listing and management recommendations. We highlight differences and a number of potential difficulties with two scoring tools, the Environmental Impact Classification of Alien Taxa (EICAT) and the Generic Impact Scoring System (GISS) using amphibians as a case study. Generally, GISS and EICAT assessments lead to very similar impact levels, but scores from the schemes are not equivalent. Small differences are attributable to discrepancies in the verbal descriptions for scores. Differences were found in several impact categories. While the issue of disease appears to be related to uncertainties in both schemes, hybridisation might be inflated in EICAT. We conclude that GISS scores cannot directly be translated into EICAT classifications, but they give very similar outcomes and the same literature base can be used for both schemes

Global COVID-19 lockdown highlights humans as both threats and custodians of the environment

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness