Lindie Janse van Rensburg - Academia.edu (original) (raw)

Lindie  Janse van Rensburg

Uploads

Papers by Lindie Janse van Rensburg

Research paper thumbnail of A morphological analysis of weevils from sub-Antarctic Prince Edward Islands: an assessment of ecological influences

The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-... more The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-free Prince Edward Islands represent ideal ecosystems for addressing questions relating to the partitioning of potential influences of anthropogenic changes, such as climate change and alien species on ecosystem functioning. Consequently, weevil species were used in the present investigation to address questions of morphological change over time with reference to climate change and mouse predation. As a prelude to the assessment of morphological changes over time, the six currently recognised weevil species, namely, Bothrometopus randi, B. parvulus, B. elongatus, Ectemnorhinus similis, E. marioni and Palirhoeus eatoni from both Marion and Prince Edward Islands were confirmed by morphometric analyses. However, the taxonomic status of Ectemnorhinus weevil species on both islands is much more complex than previously considered. A multi-faceted approach based on both morphometric and molecul...

Research paper thumbnail of The reproductive biology of Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

Cryptomys hottentotus pretoriae is a co-operatively breeding rodent that exhibits seasonal breedi... more Cryptomys hottentotus pretoriae is a co-operatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive tract morphometrics, ovarian histology and plasma oestrogen and progesterone concentrations were studied in 189 females from 49 colonies. Although the birth of the offspring is confined to the months of May through to November, qualitative analysis of ovarian histology revealed that females retained reproductive function during the summer non­ breeding period (December March) . Seasonal differences were found in ovarian morphometrics and progesterone and oestrogen concentrations which are associated with enhanced follicular activation in April and May and subsequent conceptions from May tlu"ough to November during the breeding period. The continuance of ovarian function during the non-breeding period as evidenced by the production of corpora lutea in reproductive females parallels the situation found in the male membe...

Research paper thumbnail of The endogenous rhythm of plasma melatonin and its regulation by light in the highveld mole-rat (Cryptomys hottentotus pretoriae): a microphthalmic, seasonally breeding rodent: Melatonin rhythm in C. hottentotus pretoriae

Research paper thumbnail of A morphological analysis of weevils from sub-Antarctic Prince Edward Islands: an assessment of ecological influences

... Student: Lindie Janse van Rensburg1 Supervisors: Prof Christian T. Chimimba1,2 & ... more ... Student: Lindie Janse van Rensburg1 Supervisors: Prof Christian T. Chimimba1,2 & Dr Armanda D. Bastos1,2 Departments: 1Department of Zoology & Entomology, University of Pretoria, Pretoria, 0002 South Africa ... Tame the dragon and the gift is yours.” Noela Evans ...

Research paper thumbnail of The reproductive biology of Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

Research paper thumbnail of A morphological analysis of weevils from sub-Antarctic Prince Edward Islands: an assessment of ecological influences

The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-... more The ecologically sensitive, but relatively simple sub-Antarctic mouse-colonised Marion and mouse-free Prince Edward Islands represent ideal ecosystems for addressing questions relating to the partitioning of potential influences of anthropogenic changes, such as climate change and alien species on ecosystem functioning. Consequently, weevil species were used in the present investigation to address questions of morphological change over time with reference to climate change and mouse predation. As a prelude to the assessment of morphological changes over time, the six currently recognised weevil species, namely, Bothrometopus randi, B. parvulus, B. elongatus, Ectemnorhinus similis, E. marioni and Palirhoeus eatoni from both Marion and Prince Edward Islands were confirmed by morphometric analyses. However, the taxonomic status of Ectemnorhinus weevil species on both islands is much more complex than previously considered. A multi-faceted approach based on both morphometric and molecul...

Research paper thumbnail of The reproductive biology of Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

Cryptomys hottentotus pretoriae is a co-operatively breeding rodent that exhibits seasonal breedi... more Cryptomys hottentotus pretoriae is a co-operatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive tract morphometrics, ovarian histology and plasma oestrogen and progesterone concentrations were studied in 189 females from 49 colonies. Although the birth of the offspring is confined to the months of May through to November, qualitative analysis of ovarian histology revealed that females retained reproductive function during the summer non­ breeding period (December March) . Seasonal differences were found in ovarian morphometrics and progesterone and oestrogen concentrations which are associated with enhanced follicular activation in April and May and subsequent conceptions from May tlu"ough to November during the breeding period. The continuance of ovarian function during the non-breeding period as evidenced by the production of corpora lutea in reproductive females parallels the situation found in the male membe...

Research paper thumbnail of The endogenous rhythm of plasma melatonin and its regulation by light in the highveld mole-rat (Cryptomys hottentotus pretoriae): a microphthalmic, seasonally breeding rodent: Melatonin rhythm in C. hottentotus pretoriae

Research paper thumbnail of A morphological analysis of weevils from sub-Antarctic Prince Edward Islands: an assessment of ecological influences

... Student: Lindie Janse van Rensburg1 Supervisors: Prof Christian T. Chimimba1,2 & ... more ... Student: Lindie Janse van Rensburg1 Supervisors: Prof Christian T. Chimimba1,2 & Dr Armanda D. Bastos1,2 Departments: 1Department of Zoology & Entomology, University of Pretoria, Pretoria, 0002 South Africa ... Tame the dragon and the gift is yours.” Noela Evans ...

Research paper thumbnail of The reproductive biology of Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

Log In