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A comparative study of communication in six taxa of southern African elephant-shrews (macroscelididae)Faurie, Alida Susanna. January 1996 (has links)
Aspects of olfactory, auditory, visual and tactile communication were investigated in five
Elephantulus species (E. brachyrhynchus, E. edwardii, E. intuft, E. myurus, E. rupestris) and
Macroscelides proboscideus, facilitating comparisons among species and genera. The
purpose of this study was to determine whether species specific patterns of communication
could be identified in the southern African elephant-shrews.
Scent gland structure and location was investigated to determine whether species specific
differences existed and to relate gland location to marking behaviour. Prominent scent glands
were found in the oral angel, foot pads, anogenital region and tail of all elephant-shrew
specIes. Marking behaviours such as sandbathing, digging and anal dragging correlated
strongly with sent gland location, but no glandular size and/or structural differences were
apparent among the different elephant-shrew species. Species specific differences in marking
frequencies did exist among the six elephant-shrew taxa, but were unrelated to glandular
development. Choice chamber preference tests indicated that Elephantulus species preferred
conspecific odours, with males showing higher levels of discrimination than females .
Audible vocalizations and footdrumrning were investigated and compared in the sex elephant shrew taxa. Distinct differences were present in the acoustic repertoires of the southern
African elephant-shrew species. Footdrumming showed very clear species specific patterns,
and footdrumming characteristics were compared with an existing morphological phenogram
to derive a possible path of evolution for footdrumming. Visual and tactile communication were investigated by analysis of frequencies and sequences
of behavioural acts. A comparison of male-female interactions of the different taxa showed
differences in behavioural frequencies both between males and females of a species, and
among the different species. Discriminant function analysis showed clear species specific
patterns in the visual! tactile signalling systems of southern African elephant-shrews, and this
was more clearly defined in males.
Elephant-shrews showed higher levels of aggressive behaviour in interspecific encounters,
indicating a possible role of aggression as a premating isolating mechanism between species.
However, no differences in aggressive behaviour between allopatric and sympatric malefemale
interactions could be discerned. Elephant-shrew males showed high frequencies of
submissive behaviour in intraspecific encounters, which may be a strategy to reduce aggression
in conspecific females.
Species specific patterns of behaviour were found to exist in all three modes of communication
investigated, and may all act to some extent as premating isolation mechanisms between
species. However, many of these patterns are very subtle and it is suggested that a
combination of all sensory modalities act together to form each species' signalling system. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1996.
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Phylogeography of three Southern African endemic elephant-shrews and a supermatrix approach to the MacroscelideaSmit, Hanneline Adri 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The order Macroscelidea has a strict African distribution and consists of two extant subfamilies, Rhynchocyoninae with
a single genus that includes three species, and the Macroscelidinae represented by the remaining three genera,
Elephantulus that includes 10 species, and the monotypic Macroscelides and Petrodromus. On the basis of molecular,
cytogenetic and morphological evidence, Elephantulus edwardii (Cape rock elephant-shrew), the only strictly South
African endemic species, was shown to comprise two closely related taxa. A new Elephantulus taxon, described here
is reported for the first time. It has a restricted distribution in the central Nama Karoo of South Africa. Apart from
important genetic distinctions, Elephantulus sp. nov. has several relatively subtle morphological characters that
separate it from E. edwardii.
Molecular sequences from the mitochondrial cytochrome b gene and the control region of E. edwardii sensu stricto
suggests the presence of a northern Namaqua and central Fynbos clade with four evolutionary lineages identified
within the latter. The geographic delimitation of the northern and central clades corresponds closely with patterns
reported for other rock dwelling vertebrate species indicating a shared biogeographic history for saxicolous taxa in
South Africa. Elephantulus rupestris (western rock elephant-shrew) and Macroscelides proboscideus (round-eared
elephant-shrew) are two taxa with largely overlapping distributions that span the semi-arid regions of South Africa and
Namibia. Based on mitochondrial DNA sequence data E. rupestris has a structured genetic profile associated with a
habitat of rocky outcrops compared to M. proboscideus that inhabits gravel plains, where the pattern is one of isolationby–
distance. Chromosomal changes, apart from heterochromatic differences, are limited to variation in diploid number
among elephant-shrew species. These range from 2n=26 (E. edwardii; E. rupestris; Elephantulus sp. nov.; E. intufi; E.
brachyrhynchus and M. proboscideus) to 2n=28 in both Petrodromus tetradactylus and E. rozeti to 2n=30 in E. myurus.
Cross-species chromosome painting (Zoo-Fluorescence in situ hybridization or zoo-FISH) of E. edwardii flow-sorted
probes that correspond to the five smaller sized autosomes (8-12) and the X chromosome showed no evidence of
synteny disruption among Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus and M. proboscideus, and
reinforced the G-banding observations underscoring the conservative karyotypes in these species.
A comprehensive phylogeny including all described elephant-shrew species is presented for the first time. A multigene
supermatrix that included 3905 bp from three mitochondrial (12S rRNA, valine tRNA, 16S rRNA) and two nuclear
segments (Von Willebrand factor [vWF] and exon 1 of the interphotoreceptor retinoid binding protein [IRBP]) was
analysed. Cytogenetic characters, previously described morphological, anatomical and dental features as well as
allozyme data and penis morphology were evaluated and mapped to the molecular topology. The molecular findings
did not support a monophyletic origin for the genus Elephantulus and suggests that both the monotypic Petrodromus
and Macroscelides should be included in Elephantulus. Molecular dating suggests that an arid-adapted
Macroscelidinae lineage dispersed from east Africa at ~11.5 million years ago via the African arid corridor to southwestern
Africa. Subsequent speciation events within the Macroscelidinae are coincidental with three major periods of
aridification of the African continent. / AFRIKAANSE OPSOMMING: Die orde Macroscelidea het ’n verspreiding beperk tot Afrika en sluit twee bestaande subfamilies in, die
Rhynchocyoninae wat drie spesies binne ’n enkele genus insluit en die Macroscelidinae verteenwoordig deur drie
genera, Elephantulus (10 spesies) en die monotipiese Macroscelides en Petrodromus. Gebaseer op molekulêre,
sitogenetiese en morfologiese bewyse, bestaan E. edwardii, tot op datum die enigste streng endemiese Suid-
Afrikaanse klaasneusspesie, uit twee nabyverwante taksa. Die nuwe Elephantulus takson, hierin beskryf, het ’n
beperkte verspreiding in die sentraal Nama Karoo van Suid-Afrika. Afgesien van belangrike genetiese bewyse wat die
beskrywing van die nuwe spesie ondersteun, word Elephantulus sp. nov. gekenmerk deur ’n aantal subtiele
morfologiese karakters wat dit onderskei van E. edwardii.
Binne E. edwardii sensu stricto, het mitochondriale molekulêre volgordes beduidende substruktuur aangedui regoor die
spesies se verspreiding. Die data het die teenwoordigheid van ’n noordelike Namakwa en sentrale Fynbos klade
aangetoon met vier evolusionêre lyne binne die laasgenoemde. Die geografiese skeiding van die noordelike en
sentrale klades stem grootliks ooreen met patrone in ander rotsbewonende vertebraat spesies, wat op ’n gedeelde
biogeografiese verlede in Suid-Afrika dui. Elephantulus rupestris (westelike klipklaasneus) en Macroscelides
proboscideus (ronde-oor klaasneus) is twee taksa met verspreidings wat grootliks oorvleuel in die semi-woestyn streke
van Suid-Afrika en Namibië. Mitochondriale DNS volgorde-bepaling dui op ’n gestruktueerde genetiese profiel binne E.
rupestris, geassosieer met ’n habitat van rotskoppies, in vergelyking met ’n isolasie-deur-afstand patroon wat M.
proboscideus, wat op gruisvlaktes aangetref word, karakteriseer. Chromosoom verandering, afgesien van
heterochromatiese verskille, is beperk tot ’n strukturele verandering van ‘n diploïede getal van 26 (E. edwardii; E.
rupestris; Elephantulus sp. nov.; E. intufi; E. brachyrhynchus en M. proboscideus) tot 2n=28 in beide Petrodromus
tetradactylus asook E. rozeti en 2n=30 in E. myurus. Kruis-spesies chromosoom fluoressent hibridisasie (“zoo-FISH”)
van die vloei-sorteerde merkers toegewys tot die vyf kleiner grootte outosome (8-12) asook die X chromosoom van E.
edwardii tot metafase chromosome van Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus en M. proboscideus
het geen bewyse getoon van sintenie-verbreking nie en versterk G-bandbepaling waarnemings wat die konserwatiewe
kariotipes in hierdie spesies ondersteun.
‘n Volledige evolusionêre filogenie, verteenwoordigend van alle erkende klaasneusspesies, word vir die eerste keer
voorgestel. As sulks is ’n multigeen supermatriks wat gebaseer is op 3905 bp van drie mitochondriale (12S rRNA,
valien tRNA, 16S rRNA) en twee nukluêre segmente (Von Willebrand faktor [vWF] en ekson 1 van die
interfotoreseptor-retinoïed-bindende proteïen [IRBP]) ingesluit. As toevoeging, is nuwe sitogenetiese data, voorheen
beskryfde morfologiese, anatomiese en dentale karakters sowel as data van allosieme-analises en penis morfologie
ge-evalueer en nie-molekulêre ondersteuning aangedui op die molekulêre topologie. Die molekulêre bevindinge
ondersteun nie ’n monofiletiese oorsprong vir Elephantulus nie en stel voor dat beide die monotipiese Petrodromus en
Macroscelides ingesluit moet word in die genus Elephantulus. Molekulêre datering stel voor dat ’n dor-aangepasde
Macroscelidinae lyn versprei het vanaf oos Afrika ~11.5 miljoen jaar gelede deur die “droeë Afrika korridor” tot in suidwestelike Afrika. Verdere spesiasie gebeurtenisse binne die Macroscelidinae kan nouliks geassosieer word met
drie groot periodes van verdorring in Afrika.
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Thermoregulation in free-ranging African-endemic small mammals : the rock elephant shrew, Elephantulus myurus and the lesser bushbaby, Galago moholi.Mzilikazi, Nomakwezi. January 2005 (has links)
Endothermy in birds and mammals is invariably associated with homeothermy. However, homeothermy can only be maintained if sufficient energy is obtained to meet the animals' maintenance budget. In mammals, daily torpor and hibernation have evolved to conserve energy when energy inputs from the environment are insufficient to meet maintenance requirements. Several studies have suggested that daily torpor and hibernation do not represent distinct physiological responses but are components of a continuum of heterothermy. Under laboratory conditions, even within phylogenetically ancient eutherian mammals, such as elephant shrews, it is unclear whether daily torpor or hibernation is used. Furthermore, an interpretation of the torpor patterns observed under laboratory conditions is complicated by the fact that torpor patterns often differ between laboratory and free-ranging conditions. Within the more recent mammal lineages, torpor has been observed in strepsirrhine primates. The occurrence of torpor in strepsirrhines is interesting as it pertains to arguments relating to the colonization of Madagascar by
strepsirrhine primates as well as implications for human physiology. The first aim of this study was to investigate and quantify parameters that
characterize torpor in a phylogenetically ancient eutherian mammal
(Macroscelidae: Elephantulus myurus) under free-ranging conditions. This was done mainly to resolve whether daily torpor and hibernation were physiologically discrete responses. The second aim was to investigate torpor occurrence in a more recently evolved eutherian mammal (Primates: Galago moholi). The objective was to gain insights into the phylogenetic distribution of torpor and to provide a physiological verification of torpor occurrence in a mainland strepsirrhine relative to arguments about the colonization of Madagascar. I measured body temperatures in three monthly cycles between May 2001 - May 2002 in 22 free-ranging E. myurus. I recorded a total of 467 torpor bouts throughout the study period. The elephant shrews were capable of daily torpor throughout the year, with torpor most prevalent during winter and correlated with ambient temperature, photoperiod and invertebrate abundance. Only two torpor
bouts were observed during summer. I suggest that although torpor use was most prevalent during winter, summer torpor might also be important for energy conservation in this species during drought years. This highlights the need for long-term physiological data in free-ranging animals.
The mean torpor Tbmin and the mean bout length for the whole year were
in the range expected for daily heterotherms. However, there was some
marginal overlap with hibernation characteristics; a few torpor bouts were longer than 24 hrs in duration indicating that the animals were capable of
opportunistically extending torpor bouts longer than 24 hours in response to unpredictable energetic shortfalls. Tbmin also decreased below 10°C. However, a consideration of behavioural and ecological factors argues against hibernation in E. myurus. Instead, these results support the idea of a physiological continuum for heterothermy. A return to normothermic body temperatures requires considerable energy expenditure, and this is perceived to be one of the major disadvantages of torpor. E. myurus offset the high cost of arousal from low body temperatures by using exogenous passive heating. This is achieved by coupling of the timing of arousal with ambient temperature cycles. Laboratory studies that quantify torpor energetics are usually conducted under constant temperature conditions and are likely to underestimate the energetic benefits accrued through the use of ambient temperature cycles during arousal. Torpor is often displayed during the animal's rest phase. However, nocturnal small mammals that utilize passive heating to assist arousal from torpor may enter torpor during the nighttime, thus effectively advancing the onset of the rest phase. I investigated the functional significance of daily and seasonal
rhythms of body temperature in normothermic and torpid free-ranging E. myurus.
Daily patterns of Tb, in normothermic E. myurus suggested polyphasic Tb patterns that nevertheless indicated a rest phase coincident with the daytime. I suggested that the principal benefit of a flexible daily rhythm of Tb, is that it facilitated torpor use during the nighttime and arousal by passive exogenous heating using ambient temperature cycles.
It has been suggested that the evolution of endothermy precluded the
need for homeothermic mammals to be sensitive to Ta cycles because they could maintain physiological function despite fluctuations in the ambient temperature. Elephant shrews utilize passive heating and provide excellent models with which to investigate whether mammals can entrain their body temperature rhythms to ambient temperature cycles. I experimentally tested whether food restricted E. myurus can entrain torpor cycles to shifts in the Ta cycle while holding the light-dark cycle constant. Food restriction and short photoperiod were only sufficient to induce torpor in E. myurus if photoperiod and Ta, cycles are in phase with each other. Shifting the cold T, into the photophase prevented the expression of torpor. I concluded that the body temperature rhythm is most probably tightly coupled with the photoperiod cycle and that although Ta and photoperiod usually act synergistically in nature, photoperiod is probably the stronger zeitgeber.
The evolution of endothermy is thought to have been facilitated by the
advent of endothermic energy sources such as brown adipose tissue (BAT), the principal site of nonshivering thermogenesis (NST). Rock elephant shrews are amongst the smallest members of the Afrotheria, the most basal of the eutherian lineage. I determined whether the phylogenetic placement of E. myurus and reliance on passive heating might result in a decreased capacity for NST relative to other eutherians. I investigated the capacity for NST in winter acclimated E. myurus by measuring the thermogenic response to noradrenalin (NA) injection. I used phylogenetically independent analyses to compare E. myurus NST capacity
with other eutherians. E. myurus had an NST capacity that was no different from other eutherian mammals. Although they displayed a NST capacity that was 74% of that expected on the basis of body mass, this value was not significantly different from phylogenetically independent allometric predictions. Although heterothermy is almost always considered in the context of how the environment affects function , its use may offer insights into topics such as island biogeography and species dispersal. For example, there have been suggestions that heterothermy might have played an important role in the successful colonization of Madagascar by strepsirrhine primates. To my knowledge no studies exist as yet that provide a physiological verification of this suggestion. Currently no data exist on thermoregulation and heterothermy in any free-ranging African strepsirrhines. The lesser bushbaby, Galago moholi, is a small nocturnal strepsirrhine primate that experiences severe winters and drastic
food reduction during winter and is a candidate employer of torpor. I measured body temperatures of 11 free-ranging lesser bushbabies, Galago moholi, captured at different times between February 2002 - September 2003. I did not record any incidents of heterothermy throughout the study period. Why does G. moholi not employ heterothermy? I consider several alternatives; phylogenetic placement, physiological and ecological factors that might preclude the use of torpor in this species. I suggest that the breeding pattern observed in G. moholi obviates torpor use whilst increasing fecundity, which would be adaptive if the animals are confronted with high predation risks. Much is currently known about the advantages of torpor use. This study highlights the need to consider and investigate those physiological, ecological and phylogenetic factors that might constrain species from utilizinq heterothermy. Furthermore, this study highlights the potential for thermoregulatory studies to offer insights into topics as widely separated as evolution of endothermy to species dispersal and island biogeography. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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