A Systematic revision of Southern African Aethomys Thomas, 1915 (Rodentia :muridae)

Five species of African rock rats of the genus Aethomys, A.namaquensis, A. granti, A. silindensis, A. chrysophilus and A. ineptus, are recognized in southern Africa. Morphometric analyses indicated that A. namaquensis, A. granti and A. silindensis differ markedly in cranial size and/or shape. Morphometric analyses involving cytogenetically known specimens of A. chrysophil us revealed the presence of two sympatric, morphologically similar species, A. chrysophilus and A. ineptus. This is in agreement with observations on cranial morphology and earlier investigations involving cytogenetics, protein electrophoresis and sperm morphology. Contrary to published reports, the morphometric data show that the Central African A. nyikae does not occur in southern Africa, and the single previous record from eastern Zimbabwe is probably based on a misidentification. Four subspecies, A. n. namaquensis, A. n. lehocla, A. n. alborarius and A. n. monticularis, which broadly coincide with major biomes of southern Africa, are recognized within A. namaquensis. Two subspecies, A. c. chrysophilus and A. c. imago, which broadly coincide with altitudinal limits of the eastern part of southern Africa, are recognized within A. chrysophilus. Intraspecific variation in A. ineptus is clinal, with size positively and significantly correlated with longitude. Variation within the geographically restricted A. granti suggests a southwesterly-northeasterly cline. A cladistic appraisal of phylogenetic relationships among the 11 recognized species of Aethomys in Africa, based on qualitative cranial characters, suggests the retention of Micaelamys and Aethomys as subgenera.Thesis (PhD)--University of Pretoria, 1997.Zoology and EntomologyPhDUnrestricte

Non-invasive monitoring of adrenocortical activity in free-ranging Namaqua rock mice Micaelamys namaquensis from South Africa in response to anthropogenic land use and season

Stress in animals has been linked to behavioural and physiological changes in response to environmental, social and anthropogenic stimuli. Hence, stress-related responses in animals, especially in rodents, have been used as biological indicators of ecosystem health. This study aimed to establish an enzyme immunoassay (EIA) for monitoring adrenocortical activity in free-ranging Namaqua rock mice (Micaelamys namaquensis) (Rodentia: Muridae) using faeces as a prerequisite for assessing the effects of anthropogenic land use and season on faecal glucocorticoid metabolite (fGCM) concentration. Rodents were live-trapped seasonally across four land use types: an agricultural crop farm, an agricultural livestock farm, a human-populated site, and a nature reserve; all situated in Limpopo Province, South Africa. Determined fGCM concentrations from capture and recapture events were used for biologically validating an EIA detecting steroids with a 5α-3β-11β-diol structure. Recapturing resulted in a significant overall 40% elevation of individual fGCM concentrations demonstrating the effectiveness of the chosen EIA to reliably detect glucocorticoid output in the study species. Neither land use type nor season affected fGCM concentrations in the species, suggesting that land use and season-related environmental changes do not necessarily act as stressors for M. namaquensis, presumably due to their adaptive and resilient nature. Such species can be used to identify ecosystems affected by human-mediated disturbances and allow insights into the management and restoration of these threatened ecosystems and their associated species.Centre of Excellence for Invasion Biology (CIB)http://www.wildlifebiology.orgpm2020Zoology and Entomolog

Faecal glucocorticoid metabolite concentrations and their alteration post-defaecation in African wild dogs Lycaon pictus from South Africa

Non-invasive techniques for the monitoring of animal well-being, such as faecal hormone analysis, are increasingly becoming some of the most desirable methods for addressing practical conservation questions. Despite the widespread use of faecal hormone measurements for monitoring responses to stressors and its known applicability to African wild dogs Lycaon pictus, the potential influence of time of collection post-defaecation on stress-steroid concentrations in faecal matter has not yet been investigated. In the present study, we determined the rate at which African wild dog faecal glucocorticoid metabolite (fGCM) concentrations change over a 16-day period post-defaecation, in order to provide recommendations for best sampling practice. No significant changes in fGCM concentrations were found for the first 48 h post-defaecation. However, an approximately 30% increase in fGCM concentrations were already noted between day 1 and day 2, followed by a significant 150% increase at 96 h post-defaecation. We therefore suggest that respective faecal material should be collected within the first 24 h post-defaecation to ensure the reliability of fGCM analysis. In addition, we collected baseline data denoting the fGCM concentrations of captive African wild dogs sampled across three South African captive sites. Determined baseline fGCM concentrations differed between African wild dogs at the sites sampled. These data could be used in future studies aimed at identifying the key stressor complexes perceived by captive African wild dogs in order to improve management strategies.This study was funded in part by the National Research Foundation (NRF).am2019Anatomy and PhysiologyZoology and Entomolog

Faecal glucocorticoid metabolite concentrations and their alteration post-defaecation in African wild dogs Lycaon pictus from South Africa

Non-invasive techniques for the monitoring of animal well-being, such as faecal hormone analysis, are increasingly becoming some of the most desirable methods for addressing practical conservation questions. Despite the widespread use of faecal hormone measurements for monitoring responses to stressors and its known applicability to African wild dogs Lycaon pictus, the potential influence of time of collection post-defaecation on stress-steroid concentrations in faecal matter has not yet been investigated. In the present study, we determined the rate at which African wild dog faecal glucocorticoid metabolite (fGCM) concentrations change over a 16-day period post-defaecation, in order to provide recommendations for best sampling practice. No significant changes in fGCM concentrations were found for the first 48 h post-defaecation. However, an approximately 30% increase in fGCM concentrations were already noted between day 1 and day 2, followed by a significant 150% increase at 96 h post-defaecation. We therefore suggest that respective faecal material should be collected within the first 24 h post-defaecation to ensure the reliability of fGCM analysis. In addition, we collected baseline data denoting the fGCM concentrations of captive African wild dogs sampled across three South African captive sites. Determined baseline fGCM concentrations differed between African wild dogs at the sites sampled. These data could be used in future studies aimed at identifying the key stressor complexes perceived by captive African wild dogs in order to improve management strategies.This study was funded in part by the National Research Foundation (NRF).am2019Anatomy and PhysiologyZoology and Entomolog

Faecal glucocorticoid metabolite concentrations and their alteration post-defaecation in African wild dogs Lycaon pictus from South Africa

Non-invasive techniques for the monitoring of animal well-being, such as faecal hormone analysis, are increasingly becoming some of the most desirable methods for addressing practical conservation questions. Despite the widespread use of faecal hormone measurements for monitoring responses to stressors and its known applicability to African wild dogs Lycaon pictus, the potential influence of time of collection post-defaecation on stress-steroid concentrations in faecal matter has not yet been investigated. In the present study, we determined the rate at which African wild dog faecal glucocorticoid metabolite (fGCM) concentrations change over a 16-day period post-defaecation, in order to provide recommendations for best sampling practice. No significant changes in fGCM concentrations were found for the first 48 h post-defaecation. However, an approximately 30% increase in fGCM concentrations were already noted between day 1 and day 2, followed by a significant 150% increase at 96 h post-defaecation. We therefore suggest that respective faecal material should be collected within the first 24 h post-defaecation to ensure the reliability of fGCM analysis. In addition, we collected baseline data denoting the fGCM concentrations of captive African wild dogs sampled across three South African captive sites. Determined baseline fGCM concentrations differed between African wild dogs at the sites sampled. These data could be used in future studies aimed at identifying the key stressor complexes perceived by captive African wild dogs in order to improve management strategies.This study was funded in part by the National Research Foundation (NRF).am2019Anatomy and PhysiologyZoology and Entomolog

The legacy of over a century of introductions : spread debt of rainbow trout (Oncorhynchus mykiss) in Mpumalanga Province, South Africa

DATA AVAILABILITY STATEMENT : The data that support the findings of this study are openly available in WorldClim (https://worldclim.org/); Global Biodiversity Information Facility (GBIF) (https://www.gbif.org/); Protected Areas and Conservation Areas (PACA) in South Africa (https://egis.environment.gov.za/); and the South African Department of Water Affairs (https://www.dws.gov.za/iwqs/gis_data/river/All.html). In addition, species occurrence data used in the study is available as Supplementary Material. Restrictions apply to the availability of these data, which were used under license for this study.For over a century, rainbow trout (Oncorhynchus mykiss) has been widely introduced into lakes and rivers in South Africa to create and enhance sport-fishing opportunities. Despite its long history of introduction, naturalized populations of rainbow trout are still localized to a few areas with suitable habitats and climate. This study assessed the spread debt (i.e., the increase in area invaded by invasive species over time) of rainbow trout in Mpumalanga Province, South Africa to highlight areas with known introductions, the extent of the invasion, and to identify areas that are suitable for establishment but are still invasion-free. The total river length that was predicted as suitable for rainbow trout under current climate was about ca. 3,500 km in an extension of about ca. 15,000 km. Current occupancy (river length predicted as suitable with known rainbow trout occurrence records) was ca. 1,220 km (35%) and the invasion debt was therefore estimated as 65%. While these data infer a large invasion debt, they are confounded by a lack of knowledge on sampling effort and verified true absence and should therefore be recognized as an estimate. In addition, the extent of the suitable area varied under different climate change scenarios where it was projected to decrease under RCP 4.5 scenarios and increase under the RCP 8.5 scenarios. This study demonstrates some of the difficulties of quantifying the potential future extent and impacts of biological invasions and how the invasion debt concept can be applied to provide an important link between invasion biology, management, and policy.Department of Forestry, Fisheries, and the Environment, South Africa; DSI-NRF Centre of Excellence for Invasion Biology; National Research Foundation South Africa.http://wileyonlinelibrary.com/journal/rrahj2023Mammal Research InstituteZoology and Entomolog

Faecal glucocorticoid metabolite concentrations and their alteration post-defaecation in African wild dogs Lycaon pictus from South Africa

Non-invasive techniques for the monitoring of animal well-being, such as faecal hormone analysis, are increasingly becoming some of the most desirable methods for addressing practical conservation questions. Despite the widespread use of faecal hormone measurements for monitoring responses to stressors and its known applicability to African wild dogs Lycaon pictus, the potential influence of time of collection post-defaecation on stress-steroid concentrations in faecal matter has not yet been investigated. In the present study, we determined the rate at which African wild dog faecal glucocorticoid metabolite (fGCM) concentrations change over a 16-day period post-defaecation, in order to provide recommendations for best sampling practice. No significant changes in fGCM concentrations were found for the first 48 h post-defaecation. However, an approximately 30% increase in fGCM concentrations were already noted between day 1 and day 2, followed by a significant 150% increase at 96 h post-defaecation. We therefore suggest that respective faecal material should be collected within the first 24 h post-defaecation to ensure the reliability of fGCM analysis. In addition, we collected baseline data denoting the fGCM concentrations of captive African wild dogs sampled across three South African captive sites. Determined baseline fGCM concentrations differed between African wild dogs at the sites sampled. These data could be used in future studies aimed at identifying the key stressor complexes perceived by captive African wild dogs in order to improve management strategies.This study was funded in part by the National Research Foundation (NRF).am2019Anatomy and PhysiologyZoology and Entomolog

Seasonal reproduction in the eastern rock elephant-shrew : influenced by rainfall and ambient temperature?

Because environmental conditions vary seasonally in most regions, many small mammals reproduce at a specific time of the year to maximize their reproductive success. In the tropics and subtropics, the breeding season is usually determined by the extent of the dry and rainy seasons. We investigated the seasonality of reproduction in the eastern rock elephant-shrew (Elephantulus myurus), over a 12-month period and attempted to elucidate the factors that may influence seasonal reproduction in this endemic African mammal. E. myurus breeds seasonally during the warm and wet spring and summer months and cessation of breeding occurs during the cold and dry winter months of the southern hemisphere. Pregnant females were only collected from August through to January. Ovarian size and plasma progesterone started to increase a few months prior to the first rains, were highest in October and decreased thereafter. Follicular growth and corpora body numbers corresponded to this seasonal reproductive pattern. Testes and seminiferous tubule size and plasma testosterone concentration has already started to increase during the coldest months, 2 months prior to reproductive onset in females. We propose that seasonal reproduction evolved in E. myurus because of seasonally changing food availability brought about by severe seasonal changes in rainfall and ambient temperature. The direct effects of rainfall and ambient temperature on reproduction of E. myurus are ambiguous, and we discuss other environmental factors that may trigger reproductive onset in this species.A South African Research Chair of Mammalian Behavioural Ecology and Physiology awarded to N.C. Bennett by the National Research Foundation (NRF). K. Medger acknowledges a doctoral grant from the NRF.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-799

Is reproduction of male eastern rock sengis (Elephantulus myurus) from southern Africa affected by photoperiod?

Many mammals use the change in day-length to time physiological and behavioural activities on a seasonal basis. Particularly mammals from temperate regions use photoperiod to regulate reproductive functions; however, information on the role of photoperiod in small mammals from the tropics and sub-tropics is scarce. We studied the response of the reproductive system of male eastern rock sengis (Elephantulus myurus) from southern Africa to photoperiods of differing length. Elephantulus myurus breeds seasonally during the spring and summer months of the southern hemisphere despite its subtropical distribution. It is one of only three sengi species known to breed seasonally. Fourteen male E. myurus were subjected to either long-day (LD; 16L:8D) or short-day (SD; 8L:16D) photoperiods and the photoperiodic effects on the testes, testosterone concentration and body mass were examined. Testicular volume and mass, seminiferous tubule diameter as well as body mass were not significantly different between LD and SD conditions. However, plasma testosterone concentration was significantly lower in males on LD compared to SD photoperiods. Male E. myurus may not use photoperiod as a cue to control seasonal reproductive changes. Other environmental factors such as temperature, rainfall, food abundance or social factors are possibly influencing seasonal reproduction in this species.A South African Research Chair of Mammalian Behavioural Ecology and Physiology awarded to Nigel C. Bennett by the Department of Science and Technology and the South African National Research Foundation (NRF) and K. Medger acknowledges a doctoral grant from the NRF.http://www.nrcresearchpress.com/journal/cjzZoology and Entomolog

Reproductive photoresponsiveness in male spiny mice from South Africa

Many seasonally breeding mammals use changes in photoperiod as a reliable cue to time reproduction. Photoperiodic timing assists an animal in predicting annual environmental changes in its habitat and therefore, enables it to accurately time reproductive events to the most favourable conditions. Changes in day length are more pronounced in the temperate regions and photoperiod is used as a cue for reproduction by most mammals above 30° latitude; however, a number of subtropical species also use this proximate factor to regulate their reproductive cycle. We investigated the reproductive photoresponsiveness of 14 male spiny mice (Acomys spinosissimus) from southern Africa to short-day (SD; 8 h light : 16 h dark) and long-day (LD; 16 h light : 8 h dark) photoperiods. Testicular mass and volume, seminiferous tubule diameter and plasma testosterone concentrations significantly increased in animals subjected to LD and they were regressed when the males were kept under SD. Body mass of the males was not significantly affected by the photoperiodic conditions. Although male A. spinosissimus appear to use photoperiod as a proximate factor to regulate reproduction seasonally, other environmental factors, such as rainfall, food quantity and quality as well as temperature, may regulate reproduction in A. spinosissimus in concert with photoperiod. In conclusion, the present study demonstrates the significance of photoperiodic time-measuring systems in the regulation of seasonal reproduction in a subtropical rodent.This research was funded by a South African Research Chair of Mammalian Behavioural Ecology and Physiology awarded to N.C. Bennett by the South African Department of Science and Technology (DST) and the South African National Research Foundation (NRF). K. Medger acknowledges a doctoral grant from the NRF.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7998ab201