Autotomy, tail regeneration and jumping ability in Cape dwarf geckos (Lygodactylus capensis) (Gekkonidae)

Many studies have examined the effect of caudal autotomy on speed and behaviour of lizards escaping over horizontal surfaces, but there have been few studies on lizards escaping over vertical surfaces and, in particular, species that jump between surfaces.We examined jumping by the Cape dwarf gecko (Lygodactylus capensis) in terms of individuals’ varying states of tail autotomy and regeneration. Although longer jumps were less likely to be successful (i.e. the animal would not successfully grip the surface and fell to the ground), there was no difference in the distance over which animals with full and partial tails would attempt to jump. Both recently autotomized individuals and individuals with intact tails successfully jumped up to nine times their body length (snout–vent length). The jumping ability of L. capensis was therefore clearly not negatively impaired by tail loss, presumably because the geckos are using their hind legs to propel their jump. Their tails may, however, be important to control their landing as well as their locomotion on vertical surfaces. The high observed frequency of tail loss, coupled with rapid and complete regeneration (including the scansorial tail tip), suggests that caudal autotomy is an important survival tactic in this species.The University of Pretoria and Murdoch University.http://www.bioone.org/loi/afzoab201

Late Quaternary sea-level changes of the Persian Gulf

Late Quaternary reflooding of the Persian Gulf climaxed with the mid-Holocene highstand previously variously dated between 6 and 3.4 ka. Examination of the stratigraphic and paleoenvironmental context of a mid- Holocenewhale beaching allows us to accurately constrain the timing of the transgressive, highstand and regressive phases of the mid- to late Holocene sea-level highstand in the Persian Gulf. Mid-Holocene transgression of the Gulf surpassed today's sea level by 7100–6890 cal yr BP, attaining a highstand of N1 m above current sea level shortly after 5290–4570 cal yr BP before falling back to current levels by 1440–1170 cal yr BP. The cetacean beached into an intertidal hardground pond during the transgressive phase (5300–4960 cal yr BP) with continued transgression interring the skeleton in shallow-subtidal sediments. Subsequent relative sea-level fall produced a forced regression with consequent progradation of the coastal system. These new ages refine previously reported timings for the mid- to late Holocene sea-level highstand published for other regions. By so doing, they allow us to constrain the timing of this correlatable global eustatic event more accurately

Edna metabarcoding of avocado flowers: ‘Hass’ it got potential to survey arthropods in food production systems?

In the face of global biodiversity declines, surveys of beneficial and antagonistic arthropod diversity as well as the ecological services that they provide are increasingly important in both natural and agro-ecosystems. Conventional survey methods used to monitor these communities often require extensive taxonomic expertise and are time-intensive, potentially limiting their application in industries such as agriculture, where arthropods often play a critical role in productivity (e.g. pollinators, pests and predators). Environmental DNA (eDNA) metabarcoding of a novel substrate, crop flowers, may offer an accurate and high throughput alternative to aid in the detection of these managed and unmanaged taxa. Here, we compared the arthropod communities detected with eDNA metabarcoding of flowers, from an agricultural species (Persea americana—‘Hass’ avocado), with two conventional survey techniques: digital video recording (DVR) devices and pan traps. In total, 80 eDNA flower samples, 96 h of DVRs and 48 pan trap samples were collected. Across the three methods, 49 arthropod families were identified, of which 12 were unique to the eDNA dataset. Environmental DNA metabarcoding from flowers revealed potential arthropod pollinators, as well as plant pests and parasites. Alpha diversity levels did not differ across the three survey methods although taxonomic composition varied significantly, with only 12% of arthropod families found to be common across all three methods. eDNA metabarcoding of flowers has the potential to revolutionize the way arthropod communities are monitored in natural and agro-ecosystems, potentially detecting the response of pollinators and pests to climate change, diseases, habitat loss and other disturbances

Is a reduction in the individual vigilance of mothers a key evolutionary driver of group formation in white rhinos?

A key benefit and evolutionary driver of group living is reduced predation risk. In white rhinos, groups comprise adult females, their calves and one to six unrelated subadults. Subadults benefit from group living through exposure to novel areas, and protection from territorial males (i.e. ‘buddy system’). In contrast, it is unclear whether mothers benefit from group living. To determine if they benefit, or if there is simply no cost, we recorded the vigilance of white rhino mothers in different-sized groups. We predicted that as group size increased, calves would have lower predation risk and mothers would reduce their vigilance. In contrast, we found that vigilance did not decrease as group size increased. Our findings thus indicate that decreased vigilance is not a benefit that white rhino mothers gain from living in groups. Also, costs of group formation are minimal for mothers as their large body size and ability to feed on a wide range of grasses reduces competition with other group members. As a result, we suggest that the benefits obtained by subadults, coupled with the lack of costs to adult females, are the main drivers of group formation in white rhinos.We thank Ezemvelo KZN Wildlife and the staff of the Hluhluwe-iMfolozi Park for permission to undertake the study. We acknowledge funds made available by the University of Pretoria (P.W.B), and the National Research Foundation (NRF) (A.M.S.). Any opinion, findings and conclusions or recommendations expressed are those of the authors and therefore the NRF does not accept any liability in regard thereto. The experimental procedure was purely observational and noninvasive, and consistent with the University of Pretoria and South African animal ethic protocols. Finally, we thank Graham Kerley and an anonymous reviewer for their valuable comments.http://africanzoology.journals.ac.za/am2013ab201

Sexual selection and genital allometry in the Hottentot golden mole (Amblysomus hottentotus)

Under sexual selection, genitalia typically undergo rapid and divergent evolution across species and competition between the sexes over control of fertilisation may drive the co-evolution of male and female sexual traits. Sexual selection can, therefore, influence genitalia in three fundamental but non-mutually exclusive ways: (1) cryptic female choice, (2) sperm competition and (3) sexual conflict. Golden moles (Chrysochloridae) are a highly specialised family endemic to sub-Saharan Africa. We examined intraspecific genital allometry of both male and female subterranean Hottentot golden moles (Amblysomus hottentotus). Consistent with previous studies in mammals, we found positive allometry and a high coeffi- cient of variation (CV) for male genitalia. The results for female reproductive tract length of A. hottentotus contrast with the findings of previous studies as isometry was recorded. Based on the allometric relationships of both males and females presented here, we suggest that the males do not sequester females and that in the absence of visual cues the female may use penis size as an indicator of phenotypic quality.An honours bursary was awarded to T.A.R from the South African Research Chair Initiative of Mammal Behavioural Ecology and Physiology by the NRF/DST to N.C.B. The research was supported by a National Research Foundation Grant to N.C.B.http://www.elsevier.com/locate /mambiohb2016Mammal Research InstituteZoology and Entomolog

Season but not sex influences burrow length and complexity in the non-sexually dimorphic solitary Cape mole-rat (Rodentia : Bathyergidae)

Little is known about how environmental factors such as season influence burrowing activity, burrow structure or reproductive behaviour in subterranean mammals. We excavated burrow systems of male and female Georychus capensis, a solitary, subterranean rodent, in winter (wet season) and summer (dry season) to investigate whether any seasonal differences due to putative mate-seeking behaviour of males were apparent. Burrow structure did not differ between sexes, but did differ between seasons. For both sexes, summer burrows were shorter in length and covered a smaller area but explored the surrounding environment more efficiently than did winter burrows. Summer burrows had fewer mounds present indicating less expansion of the burrow systems in this season. We discuss these differences in exploration and use of the environment between seasons but not between sexes in terms of mating strategies of G. capensis and observed levels of sexual dimorphism in our populations. This study supports recent concepts regarding female competition and selection that may favour the expression of female exaggerated traits, which affect a female’s ability to acquire reproductive resources that often appear similar to that selected for by males.This research was supported by the University of Pretoria, by the SARChI Chair of Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to NCB.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7998hb2016Mammal Research InstituteZoology and Entomolog

Seasonal effects on digging activity and burrow architecture in the Cape dune mole-rat, Bathyergus suillus (Rodentia : Bathyergidae)

Most polygynous male mammals exhibit little or no parental care or involvement raising young. Instead, they invest indirectly in their own morphological and physiological attributes which enhance their chance of reproduction. Such secondary morphological sex traits may contribute to differences in the burrow architecture of fossorial mammals, such as the Cape dune mole-rat, Bathyergus suillus. Indeed, little is known about the seasonal changes in burrow architecture or differences in burrow configuration may differ between the sexes of subterranean African mole-rats (Bathyergidae). We excavated burrow systems of male and female B. suillus during the summer and the winter to investigate whether male burrow architecture reflected putative mate-seeking behaviour. We consider burrow geometry in response to mating strategies. Male burrow systems explored the environment more efficiently than females. This is presumably because of the increase in associated energetic costs of being a large male. Males produce more mounds indicating territorial behaviour even when it is energetically costly to dispose of soil onto the surface when the soil is less friable during the summer. Overall tunnel dimensions did not differ between the sexes. It appears that a change in season does not affect the geometry of the burrow system or tunnel dimensions in a climatically buffered environment.University of Pretoria, by the SARChI Chair of Mammal Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to N.C.B.http://africanzoology.journals.ac.za/am2013ab201

Applications of environmental DNA (eDNA) in agricultural systems: Current uses, limitations and future prospects

Global food production, food supply chains and food security are increasingly stressed by human population growth and loss of arable land, becoming more vulnerable to anthropogenic and environmental perturbations. Numerous mutualistic and antagonistic species are interconnected with the cultivation of crops and livestock and these can be challenging to identify on the large scales of food production systems. Accurate identifications to capture this diversity and rapid scalable monitoring are necessary to identify emerging threats (i.e. pests and pathogens), inform on ecosystem health (i.e. soil and pollinator diversity), and provide evidence for new management practices (i.e. fertiliser and pesticide applications). Increasingly, environmental DNA (eDNA) is providing rapid and accurate classifications for specific organisms and entire species assemblages in substrates ranging from soil to air. Here, we aim to discuss how eDNA is being used for monitoring of agricultural ecosystems, what current limitations exist, and how these could be managed to expand applications into the future. In a systematic review we identify that eDNA-based monitoring in food production systems accounts for only 4 % of all eDNA studies. We found that the majority of these eDNA studies target soil and plant substrates (60 %), predominantly to identify microbes and insects (60 %) and are biased towards Europe (42 %). While eDNA-based monitoring studies are uncommon in many of the world\u27s food production systems, the trend is most pronounced in emerging economies often where food security is most at risk. We suggest that the biggest limitations to eDNA for agriculture are false negatives resulting from DNA degradation and assay biases, as well as incomplete databases and the interpretation of abundance data. These require in silico, in vitro, and in vivo approaches to carefully design, test and apply eDNA monitoring for reliable and accurate taxonomic identifications. We explore future opportunities for eDNA research which could further develop this useful tool for food production system monitoring in both emerging and developed economies, hopefully improving monitoring, and ultimately food security

The tusked king cricket (Libanasidus vittatus (Kirby, 1899)( Anostostomatidae) from South Africa : morphological and molecular evidence suggest two cryptic species

An evaluation of genetic structuring and morphometric variation within tusked king crickets, Libanasidus vittatus (Kirby, 1899) from South Africa suggests two main population assemblages. Maximum likelihood (ML), Parsimony, Bayesian and phenetic analyses of mitochondrial cytochrome oxidase I (COI) sequence data recovered two well-supported clades corresponding to two biogeographically distinct populations. Canonical variates (discriminant) analysis (CVA) also showed evidence of two phenetic assemblages that correspond to the genetically delineated groups. Libanasidus vittatus is the recognized species occurring within an eastern population in South Africa (Mpumalanga and Eastern Cape Provinces), while a possible novel species occurs within a north–western population in South Africa (Limpopo and Gauteng Provinces). Using a molecular clock estimate of 2.0 % divergence per million years, suggests isolation of the two populations at ~1.65 MYA, possibly due to the formation of isolating forest pockets during the dry Pleistocene Epoch. The average genetic divergence of 3.3% between the two populations, and low migration rate estimates corresponding to less than one female migration per generation further support the presence of two cryptic tusked king cricket species in South Africa.The study was funded by the University of Pretoria and the South African National Research Foundation (NRF) under grant GUN 2053665.http://www.brill.com/insect-systematics-evolutionhb2013ab201

Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)

Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.The University of Pretoria, by the SARChI Chair of Mammal Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to NCB.http://link.springer.com/journal/114hj201