Distribution of Articles published per year
(1997 - 2013)
(1997 - 2013)
Total number of journals
Article 1 Read 3 Citations Designing an Index to Reveal the Potential of Multipurpose Landscapes in Southern Africa Published: 02 December 2013
Land, doi: 10.3390/land2040705
Multipurpose mosaic (“ecoagriculture”) landscapes can serve the purpose of land sharing to combine objectives of agricultural production and biodiversity conservation. Rewarding the people who shape and maintain those landscapes could act as a mechanism to generate added-value representing an indirect payment for ecosystem services. We investigated the feasibility of such an approach in two areas in Southern Africa differing in spatial configurations, history and socio-economic context. We designed and tested a composite index describing the state of each landscape in terms of ecoagriculture criteria (conservation, production, institutions and livelihood) and ecosystem services (provisioning, regulating and cultural services). The resulting index is made up of different sets of data each comprising 40 scores, obtained from stakeholders’ participatory interviews. Ecosystem services are in general assigned more importance than ecoagriculture criteria. In both cases, cultural services receive the highest scores, whereas the lowest ones are attributed to the livelihood and institutions in the Zimbabwean and South African sites, respectively. Index values reveal that the South African site, where there is more integration between land-use units, does better in terms of a landscape performing multiple functions. Provided relevant stakeholders are involved and a certification mechanism is developed, the landscape labelling index can be used to recognize and reward the value of outstanding rural landscapes.
Article 1 Read 7 Citations Mate choice in field crickets: can females acoustically detect male body size? Published: 29 May 2009
Journal of Ethology, doi: 10.1007/s10164-009-0166-8
Females can potentially choose high-quality males by evaluating male secondary sexual traits such as acoustic signals. In field crickets (Orthoptera: Gryllidae), body size is thought to indicate male quality. Song carrier frequency (FQ) has been suggested to indicate male body size because the areas of the wing that control FQ (harp) scale with body size. However, no direct evidence showing that males can advertise their size via FQ exists for grylline crickets. Firstly, we show the lack of evidence indicating a clear relationship between FQ and body size for grylline crickets by conducting a literature review. We then calculate the three-way relationship between body size, harp size and FQ and show no relationship between FQ and body size for Gryllus bimaculatus. Eight other commonly measured song parameters also failed to indicate body size. Individual female preference functions for FQ are calculated and we demonstrate that females cannot select large males on the basis of FQ. Furthermore, we demonstrate that variation in male FQ falls within the range of female preference at the population level. Females probably cannot evaluate male body size based on the temporal and spectral properties of male calling song and alternative avenues of study are suggested.
Article 2 Reads 8 Citations Phonotactic response of female crickets on the Kramer treadmill: methodology, sensory and behavioural implications Published: 30 November 2007
Journal of Comparative Physiology A, doi: 10.1007/s00359-007-0292-0
Since population-level variation in female mating preferences can shape intraspecific communication systems within the context of sexual selection it is essential to quantify these preferences and their sources of variation. We calculated individual female response functions for four male calling song traits in the field cricket Gryllus bimaculatus, by performing untethered phonotaxis measurements on a spherical locomotor compensator (Kramer treadmill). Firstly, we quantify the population-level sources of phonotactic variation and correct for factors that adversely affect this measurement. Secondly, we develop methodology for the characterisation of individual female phonotactic response functions suitable for population-level analyses and demonstrate the applicability of our method with respect to recent literature on Orthopteran acoustic communication. Phonotaxis towards a preferred stimulus on different occasions is highly repeatable, with lower repeatabilities away from the most preferred signal traits. For certain male signal traits, female preference and selectivity are highly repeatable. Although phonotactic response magnitude deteriorated with age, preference functions of females remained the same during their lifetimes. Finally, the limitations of measuring phonotaxis using a spherical locomotor compensator are described and discussed with respect to the estimation of the selectivity of female response.
Article 2 Reads 9 Citations Conservation Implications of Genetic Differentiation in Southern African Populations of Black Rhinoceros (Diceros bicorn... Published: 01 February 1997
Conservation Biology, doi: 10.1046/j.1523-1739.1997.95180.x
We analyzed 30 protein‐coding loci of four southern African black rhinoceros populations in order to calculate fixation indices and genetic distances for the different populations. We concluded that one of these populations is of the subspecies Diceros bicornis bicornis and the other three of Diceros bicornis minor. No evidence of inbreeding within populations was found. F‐ statistics revealed significant differentiation between populations. Small genetic distances found among the four populations reveal that they are conspecific, and no evidence was found to support the claim that the populations belong to discrete subspecies. Rather, an east‐west cline in genetic characteristics appears to exist with G6pd and HB‐2 alleles peculiar to western populations and Es‐2 and GP‐3 alleles peculiar to eastern populations.Un análisis de 30 genes proteínicos se cuadro poblaciones de rinocerontes negros en Africa austral, posibilitó calcular estadísticas F y distancias genéticas entre las diferentes poblaciones. Una de estas poblaciones de rinocerontes negros es considerada como perteneciente a la sub‐specie Diceros bicornis bicornis y las otras tres a Diceros bicornis minor. No se presento evodencia de procreatión consanguínea dento de las poblaciones. Las poblaciones. Las estidísticas F presentaron una diferenciación significativa entre las poblaciones. Pequeñas distancias genéticas entre las quatro poblaciones manifiestan que partenecen a la misma especie, y no se encontró evidencia para apoyar la teoría que estos grupos pertenencen a subespecies distintas. Mas bien, una transición gradual de este a oeste fue una de las características que parecen existir con genes G6pd y HB‐2 con características a poblaciones del occidente y con genes Es‐2 y GP‐3 con características a poblaciones orientales.