Thesis (M. S.)--Biomedical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Boyan, Barbara; Committee Member: Bonassar, Lawrence; Committee Member: Sambanis, Anthanassios; Committee Member: Schwartz, Zvi; Committee Member: Wick, Timothy.

Thesis (M.S.)--Georgia Southern University, 2006. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 89-95) and appendices.

In many terrestrial mammals, males are generally larger than females. Since shrews are the smallest living terrestrial mammals, specimens of the shrew Sorex cinereus cinereus from north central Minnesota were studied to determine if size differences between sexes also occurred at this extreme. Comparisons were based on measurements of external body lengths and individual lengths of upper quadrant locomotive muscles. External differences showed neither males nor females were consistently larger. The results from analysis of variance on individual muscle lengths showed very few significant differences between individual muscles. Those muscles that did show a significant difference were not grouped In a way that would suggest a significance due to a function specific to either sex. This study suggests that in these shrews, unlike many other living terrestial mammals, males are not larger than females.

Leptochelia dubia is a dioecious tube-building tanais, which broods its young and exhibits marked sexual dimorphism. The species is widely distributed in the Pacific, Atlantic, Mediterranean and Indian Oceans, but to date there are no published accounts of its ecology. L. dubia is one of the most abundant of the small Crustacea in Tomales Bay, where it may attain densities of 30,000/m2 in soft bottom communities.

No description available.

No description available.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005. / The Dwarf Crag Lizard, Pseudocordylus nebulosus, is one of several relict ectotherm species associated with the mistbelt of the Cape folded mountain belt. Prior to this study, it was only known from a single locality in the Hottentots Holland Mountains. In this study, the distribution range and microhabitat preferences of P. nebulosus were determined and resource partitioning among the three melanistic cordylids (C. oelofseni, P. capensis and P. nebulosus), co-occurring in this area, investigated. Using the locality where P. nebulosus was first discovered as centerpoint, surveys were conducted in all directions and the occurrence of all three melanistic species recorded. The previous known range of P. nebulosus, of only 0.04 km2, was extended to 11 km2. Of the three melanistic cordylids, P. nebulosus has by far the smallest range, completely overlapping with the ranges of both the other two melanistic cordylids. Pseudocordylus nebulosus was found to show a distinct affinity for water bodies such as mountain streams and seepage areas. Distinct differences in resource partitioning were found among the three species regarding crevice selection, which will prevent any significant competition during periods of environmental stress. Cordylus oelofseni preferred small crevices at ground level, P. capensis preferred large rock structures high above ground level and P. nebulosus utilized intermediate sized rock structures. Because of its relatively small range and melanistic colour, P. nebulosus could be a key indicator species of environmental change. Although the lack of objective fire management and global warming may be immediate threats to the survival of this species, possible illegal collection due to the easy access via the popular hiking trail in the area, is probably less significant a threat than was previously thought. Although its known range has been extended considerably, it is recommended that the Vulnerable status of P. nebulosus be maintained. This study provides baseline data that could be useful in future monitoring programmes to predict declines and fluctuations. In the second part of this study, the aim is to provide information about sexual dimorphism in P. nebulosus and to discuss the observed variation in sexual size dimorphism among montane cordylids. Data were recorded for all P. nebulosus individuals encountered in the Landdroskop area (Hottentots Holland Mountains), irrespective of size and sex. The total sample of 87 lizards recorded, consisted of 26 adult males, 49 adult females and 12 indeterminates. Size at sexual maturity was determined at 60 mm snout-vent length (SVL) for both sexes. The highly female-biased adult sex ratio recorded for P. nebulosus, is considered to be due to sampling error, gravid females probably basking more than males, making them easier to locate during searches. Generation glands were found to be present in males only and the number present was significantly correlated to body size. Both adult males and adult females possessed active femoral glands, but males had significantly more than females. Females were found to reach larger body sizes than males, but adult males had relatively larger heads than females. No significant difference in scar frequency was found between the male and female samples. Variation in sexual size dimorphism among montane cordylids is discussed and the need for more comprehensive data pointed out. The female-biased sexual size dimorphism in P. nebulosus and its sister species, P. capensis, is tentatively ascribed to fecundity selection for offspring to be large at birth in order to survive in a predictable unfavourable environment at high altitudes. Sexual dimorphism in head size is ascribed to sexual selection, males probably being territorial as in many other cordylids.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: PELOMEDUSA SUBRUFA is a freshwater turtle widely distributed throughout Africa and Madagascar, and is described as a Tropical to Sub-tropical species. 1 examined the female and male reproductive cycles of P. subrufa, over a 20-month period to determine whether they display a typical Tropical to Sub-tropical type reproductive cycle (pre-nuptial) or a typical Temperate Zone type reproductive cycle (post-nuptial). Blood and tissue samples were collected from wild specimens captured in the Western Cape, South Africa and these samples were supplemented by tissue samples obtained from museum specimens. In female P. subrufa seasonal variation in related circulating reproductive hormones in the plasma (estradiol, progesterone, and testosterone) were analyzed using validated ELISA kits. Plasma vitellogenin (yolk precursor produced in liver) was measured using a newly developed universal vitellogenin ELISA for vertebrates (UNIVTG). Ovarian follicles were measured (± 0.1 mm) and female ovaries were staged macroscopically (non-active, pre-vitellogenic, vitellogenic, gravid), and results were confirmed via histological sectioning of ovaries and oviducts. Females exhibited a cyclic reproductive pattern, with distinct phases of follicular enlargement (vitellogenesis), ovulation and a gravid period. Seasonal timing of the reproductive cycle coincided with those of other temperate zone freshwater turtles. Vitellogenic recrudescence began in summer (late December), and continued unabated through winter with ovulation occurring in the following spring (September-October). My data suggested that P. subrufa females mostly lay a single clutch of eggs during the late-spnng summer period (September through January). Clutch size varied between 7 -3 7 eggs, with the number of eggs being significantly correlated with maternal body size (r = 0.82, P < 0 001). Plasma estradiol and plasma vitellogenin concentrations peaked once during the ovarian cycle, typically coinciding with the period of early- to mid-vitellogenesis in late summer. Plasma testosterone varied throughout the year, but significant increases were measured during the ovulation and mating period in spring. Plasma progesterone concentrations were significantly elevated during the gestation period prior to ovi-position in mid-summer (December). In male P. subrufa spermatogenesis in mature specimens was distinctly seasonal and timing of the reproductive cycle coincided with those of other temperate zone freshwater turtles. Spermatogemc recrudescence began in summer, following emergence from a winter hibernation period (brumation) and spring mating. Peak testicular volume and maximum spermiogemc activity occurred in late summer and early autumn. Testicular regression commenced in autumn through winter. Spermatozoa were abundant in the ducti epididymi throughout the year. Plasma testosterone concentrations peaked once during the testicular cycle, typically coinciding with spermio genes is in late summer, early autumn. Ducti epididymi diameter showed significant variation throughout the year, whereas the epithelial cell height showed no significant seasonal variation. Peak secretory activity coincided with spermiogemc activity and high circulating testosterone concentrations in late summer, early autumn. Testicular recrudescence was correlated with increasing ambient air temperatures, photopenod and summer rainfall, whereas testicular regression, during late autumn, corresponded conversely with decreasing ambient air temperatures, photopenod and rainfall. Female and male reproductive cycles were asynchronous in that the peak spermatogenic activity occurred in autumn at the time when most females were depositing yolk in growing ovarian follicles. Therefore, adult females displayed a typical postnuptial vitellogemc cycle and adult males displayed a typical post-nuptial spermatogenic cycle. Differences between sexes in body size are common in many animals, and the African helmeted turtle is no exception. Sexual size dimorphism (SSD) in P. subrufa was pronounced, and using principal component analysis, it was clear that adult male P. subrufa was significantly larger than adult females. Using carapace length as the measure of body size (covariate), adult males, adult females, and juveniles differed significantly in absolute size of the carapace width, carapace depth, plastron length, plastron width, and head depth. However, there was no significant difference between adult males, adult females and juveniles in head width and head length. Therefore, adult males were larger than adult females in the seven traits measured, except in carapace depth where the females were significantly larger In the occurrence of ontogenetic growth patterns, the adults grow at a slower rate than juveniles in plastron length. There was no significant difference between adults and juveniles in shell width, however in depth, the adults grow at a faster rate when compared to the juveniles. Adults significantly grow at a faster rate than juveniles in absolute head size as well. However, when these traits were used as a whole data set (eight traits measured), there was no difference in growth rate between adults of either sex. Similarly, there was no significant difference in adults compared to juveniles in shell size, however, adults grow at a faster rate than juveniles in absolute body size and head size. Differences in body size, and in the size of traits such as shell measurements and head measurements relative to absolute body size, were assessed to clarify SSD of P. subrufa in South Africa. / AFRIKAANSE OPSOMMING: PELOMEDUSA SUBRUFA is ‘n varswaterskilpad wat wyd verspreid oor Afrika en Madagascar voorkom en word beskryf as ‘n Tropiese tot Sub-tropiese spesies. Die manlike en vroulike voortplantingspatroon van P. subrufa is oor ‘n tydperk van 20 maande bestudeer om vas te stel of hul voortplanting ooreenstem met ‘n tipiese tropiesie tot sub-tropiese voortplantingspatroon of ‘n tipiese gematigde-sone voortplantingspatroon. Waterskilpaaie is uit damme in die Wes-Kaap, Suid-Afnka gevang en bloed- en weefselmonsters is versamel. Materiaal en data is aangevul deur weefselmonsters van waterskilpaaie wat in museumversamelings gehuisves word. Ovarium follikels in P. subrufa wyfies is gemeet en die wyfies se ovanums is makroskopies gegradeer (onaktief, pre-vitellogenies, vitellogemes, dragtig) en resultate is deur histologiese snitte van die ovaria en ovidukte bevestig. Wyfies vertoon ‘n sikliese voortplantingspatroon, met duidelike fases van follikulere groei (vetllogenese), ovulasie en dragtigheid. Sirkulerende voortplantingshormone in die bloedplasma (estradiol, progesteroon en testosteroon) is ook geanaliseer met behulp van gevalideerde hormoonspesifieke ELISA bepalings. Plasma vitellogeen (‘n dooiervoorloper wat in die lewer vervaardig word) konsentrasies is ook bepaal met ‘n nuut ontwikkelde, universele (spesifiek vir werweldiere) vitellogeen ELISA (UNIVTG). Seisoenale tydsberekemng van die voortplantingsiklus het ooreengestem met die van ander varswaterskilpaaie vanuit die Gemagtigde-sone. Vitellogenese het in die somer begin en duur voort deur die grootste gedeelte van die somer, herfs en winter gevolg deur ovulasie in die daaropvolgende lente (September - Oktober). Die data ingewin stel voor d a t/5. subrufa wyfies meestal een broeisel eiers tydens laat lente-somer le (September tot Januane). Broeiselgrootte het gewissel tussen 7-37 eiers, met die hoeveelheid eiers wat beduidend met moederlike liggaamsgrootte gekorreleer was (r = 0.82, P < 0.001). Plasma estradiol en vitellogeen konsentrasies het een keer tydens die ovariumsiklus gepiek, en gewoonlik saamgeval met vroee tot middel vitellogenese in die laat somer. Plasma testosteroon het dwarsdeur die jaar gevarieer, maar beduidende toenames is gemeet tydens ovulasie en die paartydperk in die lente. Plasma progesteroon konsentrasies was beduidend hoer tydens dragtigheid kort voor eierlegging in die middel van die somer (Desember). In volwasse P. subrufa mannetjies was spermatogenese sterk seisoenaal en het die voortplantingsiklus ooreengestem met die van ander varswaterskilpadspesies wat in die gematigde streke voorkom. Na ‘n oorwinteringsperiode (brumasie), volg die panngstydperk gedurende die lente. ‘n Nuwe spermatogemese siklus het in die somer begin. Maksimale spermatogeniese aktiwiteit en testis-volume word in die laat somer en vroee herfs bereik. Testikulere regressie neem in aanvang in die herfs en duur voort tot na paringstyd in die lente. Tydens testikulere regressie word spermatosoe in die ducti epididymi gestoor. Plasma testosteroon konsentrasies het in die laat somer en vroee herfs gedurende die testikulere siklus, spermiogenese (sperm produksie fase), gepiek. Die grootte (omtrek) van die ducti epididymi het beduidende vanasie dwarsdeur die jaar getoon, terwyl epiteel selhoogtes geen beduidende seisoenale vanasie getoon het nie. Piek sekretonese aktiwiteit het saamgeval met spermiogeniese aktiwiteit en hoe vlakke van sirkulerende testosteroon tydens laat somer en vroee herfs. Testikulere groei het goed gekorreleer met toenemende omgewingstemperatuur, fotopenode en reenval, terwyl testikulere regressie in herfs met ‘n daling in omgewingstemperature, fotopenode en reenval gekorrespondeer het. Die vroulike en manlike voortplantingspatrone was nie goed ge-sinkroniseerd nie, deurdat piek spermatogeniese aktiwiteit tydens herfs voorgekom het, gedurende die tyd waann meeste wyfies besig was om dooier in groeiende ovarium follikels neer te le. Daarteenoor vertoon die mannetjies testikulere regressie tydens die pre-ovulatoriese fase en ovulasie penode van die wyfies. Dus toon volwasse wyfies ‘n tipiese gematigde sone vitellogeniese patron en volwasse mannetjies ‘n tipiese gematigde sone spermatogeniese patroon. ‘n Verskil in liggaamsgrootte tussen die geslagte is 'n algemene verskynsel by baie diere en P. subrufa is geen uitsondering me. Daar was wesenlike geslagtelike grootteverskille (SSD) in P. subrufa en ‘n hoofkomponent analise (PC A) het getoon dat daar beduidende morfometnese verskille tussen volwasse mannetjies en wyfies was. Deur karapakslengte as 'n maatstaf vir liggaamsgrootte te gebruik (mede-veranderlike), het volwasse mannetjies, volwasse wyfies en onvolwassenes beduidend verskil ten opsigte van absolute grootte van hul karapaksbreedte, karapaksdiepte, plastronlengte, plastronbreedte en kopdiepte. Geen beduidende verskil in kopbreedte en koplengte in volwasse mannetjies, volwasse wyfies en onvolwassenes is gevind nie. Derhalwe was volwasse mannetjies groter as volwasse wyfies in sewe van die liggaamseienskappe wat gemeet is, buiten vir karapaksdiepte waar die wyfies beduidend groter was. In terme van die voorkoms van ontogenetiese groeipatrone het volwassenes teen ‘n stadiger tempo as onvolwassenes in plastronlengte toegeneem. Daar was geen beduidende verskil in die groeitempo van dopbreedte tussen volwassenes en onvolwassenes nie, alhoewel dopdiepte van volwassenes teen ‘n vinniger tempo gegroei het as die van onvolwassenes. Absolute kopgrootte van volwassenes het ook teen ‘n vinniger tempo gegroei as in onvolwassenes. Wanneer hierdie eienskappe as ‘n volledige datastel gebruik word (al agt gemete eienskappe), wil dit voorkom asof daar geen verskil in groeitempo van volwassenes van die onderskeidelike geslagte is me. Daar was geen beduidende verskil tussen volwassenes en onvolwassenes, ten opsigte van dopgrootte nie, alhoewel volwassenes klaarblyklik teen ‘n vinniger tempo in liggaamsgrootte en kopgrootte toeneem. Verskille in liggaamsgrootte en grootte van ander veranderlikes, soos byvoorbeeld dop- en kop-eienskappe, relatief tot absolute liggaamsgrootte, word aangebied om geslagsdimorfisme in P. subrufa vir die eerste keer te beskryf.

Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science. / Breeding was observed in the foam nest frog, Chiromantis xerampelina, over three breeding seasons The mating pattern was characterized by an extended breeding season with a male-biased operational sex ratio and asynchronous and unpredictable female arrival. At more than 90% of nests, from one to seven unpaired males ('peripheral males') gathered around the amplexing pair during nest construction. Those peripheral males closest to the pair competed 'With each other, and with the amplexing male, to position their cloacae against the female's cloaca during oviposition bouts. In a detailed study of a single population, over 80% of males were observed as peripheral males, and 57% of males were observed both in amplexus and as peripheral males. Male mating success and participation at nests was unrelated to size or weight. Chorus participation was the best predictor of male, mating success and participation at nests. The most plausible explanation for the presence of peripheral males was a sperm competition hypothesis; namely that peripheral males compete with the amplexing male for fertilizations by shedding sperm into the nest. I collected data on body mass and testis mass for 13 African anurans. Using additional published data on 19 Japanese anurans, an allometric relationship between body mass and testis mass was calculated. using 16 genera as independent data points. This revealed that C. xerampelina have testes fourteen times heavier than predicted on the basis of body mass. This is consistent with a trend seen in several taxa where testis size is related to the intensity of sperm competition. An additional experiment, in which the arnplexing male was prevented from shedding sperm into the nest, showed that peripheral males are capable of fertilizing eggs. I conclude that peripheral males are engaged in an opportunistic alternative mating tactic involving sperm cosnpetition. More than half the observed females bred polyandrously, some mating with up to three males, This was the result of amplexing males dismounting between nesting sessions, and males displacing one another from amplexus. / Andrew Chakane 2018

Thesis (Ph. D.)--University of Chicago, Faculty of the Division of the Biological Sciences and the Pritzker School of Medicine, Department of Ecology and Evolution, June 2001. / Includes bibliographical references. Also available on the Internet.