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Nigel C. Bennett - One of the best experts on this subject based on the ideXlab platform.
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Foraging in the subterranean social Damaraland mole-rat, Cryptomys damarensis: an investigation into size-dependent Geophyte utilization and foraging patterns
Canadian Journal of Zoology, 2003Co-Authors: Mandy Barnett, Nigel C. Bennett, Steven R. Telford, Jennifer U. M. JarvisAbstract:The foraging behaviour of captive colonies of the Damaraland mole-rat, Cryptomys damarensis, was investigated in an artificial soil-filled burrow system provided with three tray patches that varied in bulb and corm (i.e., Geophyte) density and size. Members of two founder colonies (comprising three and four mole-rats) were exposed to resource patches that varied in food profitability (both size and density of Geophytes). There was no preference for excavating any of the patches with different densities or sizes of Geophytes. The larger Geophytes were preferentially stored and the smaller ones preferentially eaten both on encounter and within the food store. The duration of handling and rate of consumption of Geophytes by 15 animals of various body sizes from three colonies were recorded. Handling time was related to the size of the Geophytes. Small Geophytes were less profitable to consume. It was concluded that the mole-rats generally followed the qualitative predictions of optimal foraging theory but fe...
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Foraging in the subterranean social highveld mole-rat ( Cryptomys hottentotus pretoriae ): an investigation into mass-dependent Geophyte use and foraging patterns
Journal of Zoology, 2003Co-Authors: G.p. Malherbe, Nigel C. Bennett, A. S. SchoemanAbstract:The foraging behaviour of captive colonies of the highveld mole-rat Cryptomys hottentotus pretoriae was investigated in an artificial soil-filled burrow system provided with four trays (patches) that varied in Geophyte density and mass. An initial trial involving empty trays (only soil) revealed that there was no preference for any specific tray. There were no statistically significant preferences for excavating in any of the patches of different Geophyte density. No preferences were evident for excavation in patches containing Geophytes of different mass classes. Empty patches seemed to be preferred over patches containing Geophytes when combinations of Geophyte density/mass were investigated. The duration of handling and the rate of consumption of Geophytes were recorded for 23 individuals of two mass classes. Handling time of Geophytes was not related to mole-rat sex, but was strongly linked to mole-rat mass class. Handling time of Geophytes was related to Geophyte mass class. Small Geophytes were less profitable to consume. These findings are considered in light of optimal foraging theory and the situation in the field. It was concluded that the mole-rats generally followed the qualitative predictions of optimal foraging theory, although falling short of being energy maximizers.
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Coefficients of digestibility and nutritional values of Geophytes and tubers eaten by southern African mole‐rats (Rodentia: Bathyergidae)
Journal of Zoology, 1995Co-Authors: Nigel C. Bennett, Jennifer U. M. JarvisAbstract:Subterranean rodents have high energy requirements when they are excavating their burrows. This study investigates the energy available to, and the efficiency with which it can be extracted by, four species of bathyergid mole-rats fed natural diets ranging from the underground storage organs of Geophytes to grass roots and leaves. The digestibility coefficients of Geophytes ranged from 53% for the fibrous tuber of the gemsbok cucumber to 95–7% for corms and bulbs. One species, Bathyergus suillus whose diet consists of over 80% grass, had a digestibility coefficient of 87% on an all grass diet. All species had similar coefficients of digestibility of > 90% when fed on a uniform diet of sweet potato. Bulbs and corms had a low fibre content (3–3–4%), high calorific value (15–16kJ/g) and high digestibility coefficients (95–7–96%) and on this diet the mole-rats maintained their body mass. Food of lower digestibility tended to have a high fibre content (8–2–45%) and, with the exception of B. suillus, although the mole-rats consumed a greater quantity of food, they lost mass. The sweet potato had a low fibre content (4–1 %) but was energetically very similar to bulbs and corms (15–5 kJ/g). Geophytes which have low fibre contents are generally small (1–20 g), whereas Geophytes with high fibre contents are much larger (30–2000 g) and often occur in more arid zones.
Stephen D. Hopper - One of the best experts on this subject based on the ideXlab platform.
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Soil and plant outcomes of harvesting a Noongar staple Geophyte in south-western Australia
Biological Journal of the Linnean Society, 2020Co-Authors: Alison Lullfitz, Carol Pettersen, Lynette Knapp, Stephen D. HopperAbstract:Abstract Geophytes are a considerable component of Southwest Australian flora and thus, unsurprisingly, feature heavily in the diets and culture of Noongar First Nations people of this old, climatically buffered, infertile landscape-dominated global biodiversity hotspot. Of ~650 Geophyte species recorded in south-western Australia, 90 are known traditional Noongar foods. Despite the significant role of Geophytes in Noongar traditional lives, there is little published knowledge of the ecological effects of harvesting Geophytes. We measured and observed soil and plant outcomes of tuber harvest for two Noongar staple species of Platysace Bunge to test whether it improved soil conditions for plant growth and/or aided tuber availability, as suggested for other Australian Aboriginal root crops. Harvesting of Platysace deflexa led to increases in some soil nutrient levels and, unexpectedly, to an increase in bulk density. Platysace deflexa stem abundance was restored to the pre-harvest level within 1 year post-harvest, whereas tuber weight and volume were less than pre-harvest levels after 2 years. A post-harvest increase in the proportion of small tubers in crops suggests that harvest has a renewing and homogenizing effect on tubers. Site-based differences in post-harvest P. deflexa and Platysace trachymenioides quantity of tubers were consistent with preferential harvest of some populations by present-day Noongar families and their ancestors.
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Monocotyledonous Geophytes: comparison of south-western Australia with other areas of mediterranean climate
Australian Journal of Botany, 2003Co-Authors: R. F. Parsons, Stephen D. HopperAbstract:Recent data on monocotyledonous Geophytes from south-western Australia are compiled and compared with those from other areas of mainly mediterranean climate, especially California, Chile and Victoria, Australia. South-western Australia has a high monocot Geophyte diversity of 496 species (7% of an estimated native flora of 7100 vascular species), like Victoria (12%) and the Cape region (14%). As in Victoria, orchids are by far the most important group, with c. 400 species, including those likely to be described once ongoing taxonomic research is completed. South-western Australia has higher Geophyte numbers than Victoria in all families considered, but a lower Geophyte percentage because of a much higher vascular species total. Among south-western Australian non-orchid Geophytes, as in Victoria, the most common storage organ is tuberous roots, followed by corms then bulbs and rhizomes, whereas in California bulbs are by far the most common. The presence of microGeophytes with seed-like storage organs is a special feature seen in several phylogenetically unrelated lineages in the south-western Australian and Victorian geophytic flora, especially on granite outcrops. Divergent phylogenetic history is undoubtedly a major factor underlying striking differences between the monocot Geophytes of mediterranean Australia, California, Chile, South Africa and Mediterranean countries. Further studies, particularly on the last two regions, will enable better elucidation of these patterns.
A. S. Schoeman - One of the best experts on this subject based on the ideXlab platform.
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Foraging in the subterranean social highveld mole-rat ( Cryptomys hottentotus pretoriae ): an investigation into mass-dependent Geophyte use and foraging patterns
Journal of Zoology, 2003Co-Authors: G.p. Malherbe, Nigel C. Bennett, A. S. SchoemanAbstract:The foraging behaviour of captive colonies of the highveld mole-rat Cryptomys hottentotus pretoriae was investigated in an artificial soil-filled burrow system provided with four trays (patches) that varied in Geophyte density and mass. An initial trial involving empty trays (only soil) revealed that there was no preference for any specific tray. There were no statistically significant preferences for excavating in any of the patches of different Geophyte density. No preferences were evident for excavation in patches containing Geophytes of different mass classes. Empty patches seemed to be preferred over patches containing Geophytes when combinations of Geophyte density/mass were investigated. The duration of handling and the rate of consumption of Geophytes were recorded for 23 individuals of two mass classes. Handling time of Geophytes was not related to mole-rat sex, but was strongly linked to mole-rat mass class. Handling time of Geophytes was related to Geophyte mass class. Small Geophytes were less profitable to consume. These findings are considered in light of optimal foraging theory and the situation in the field. It was concluded that the mole-rats generally followed the qualitative predictions of optimal foraging theory, although falling short of being energy maximizers.
Jennifer U. M. Jarvis - One of the best experts on this subject based on the ideXlab platform.
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Foraging in the subterranean social Damaraland mole-rat, Cryptomys damarensis: an investigation into size-dependent Geophyte utilization and foraging patterns
Canadian Journal of Zoology, 2003Co-Authors: Mandy Barnett, Nigel C. Bennett, Steven R. Telford, Jennifer U. M. JarvisAbstract:The foraging behaviour of captive colonies of the Damaraland mole-rat, Cryptomys damarensis, was investigated in an artificial soil-filled burrow system provided with three tray patches that varied in bulb and corm (i.e., Geophyte) density and size. Members of two founder colonies (comprising three and four mole-rats) were exposed to resource patches that varied in food profitability (both size and density of Geophytes). There was no preference for excavating any of the patches with different densities or sizes of Geophytes. The larger Geophytes were preferentially stored and the smaller ones preferentially eaten both on encounter and within the food store. The duration of handling and rate of consumption of Geophytes by 15 animals of various body sizes from three colonies were recorded. Handling time was related to the size of the Geophytes. Small Geophytes were less profitable to consume. It was concluded that the mole-rats generally followed the qualitative predictions of optimal foraging theory but fe...
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Coefficients of digestibility and nutritional values of Geophytes and tubers eaten by southern African mole‐rats (Rodentia: Bathyergidae)
Journal of Zoology, 1995Co-Authors: Nigel C. Bennett, Jennifer U. M. JarvisAbstract:Subterranean rodents have high energy requirements when they are excavating their burrows. This study investigates the energy available to, and the efficiency with which it can be extracted by, four species of bathyergid mole-rats fed natural diets ranging from the underground storage organs of Geophytes to grass roots and leaves. The digestibility coefficients of Geophytes ranged from 53% for the fibrous tuber of the gemsbok cucumber to 95–7% for corms and bulbs. One species, Bathyergus suillus whose diet consists of over 80% grass, had a digestibility coefficient of 87% on an all grass diet. All species had similar coefficients of digestibility of > 90% when fed on a uniform diet of sweet potato. Bulbs and corms had a low fibre content (3–3–4%), high calorific value (15–16kJ/g) and high digestibility coefficients (95–7–96%) and on this diet the mole-rats maintained their body mass. Food of lower digestibility tended to have a high fibre content (8–2–45%) and, with the exception of B. suillus, although the mole-rats consumed a greater quantity of food, they lost mass. The sweet potato had a low fibre content (4–1 %) but was energetically very similar to bulbs and corms (15–5 kJ/g). Geophytes which have low fibre contents are generally small (1–20 g), whereas Geophytes with high fibre contents are much larger (30–2000 g) and often occur in more arid zones.
Pavel Veselý - One of the best experts on this subject based on the ideXlab platform.
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Nutrient reserves may allow for genome size increase: evidence from comparison of Geophytes and their sister non-geophytic relatives.
Annals of botany, 2013Co-Authors: Pavel Veselý, Petr Bureš, Petr ŠmardaAbstract:The genome size of an organism is determined by its capacity to tolerate genome expansion, given the species' life strategy and the limits of a particular environment, and the ability for retrotransposon suppression and/or removal. In some giant-genomed bulb Geophytes, this tolerance is explained by their ability to pre-divide cells in the dormant stages or by the selective advantage of larger cells in the rapid growth of their fleshy body. In this study, a test shows that the tendency for genome size expansion is a more universal feature of Geophytes, and is a subject in need of more general consideration. Differences in monoploid genome sizes were compared using standardized phylogenetically independent contrasts in 47 sister pairs of geophytic and non-geophytic taxa sampled across all the angiosperms. The genome sizes of 96 species were adopted from the literature and 53 species were newly measured using flow cytometry with propidium iodide staining. The Geophytes showed increased genome sizes compared with their non-geophytic relatives, regardless of the storage organ type and regardless of whether or not vernal Geophytes, polyploids or annuals were included in the analyses. The universal tendency of Geophytes to possess a higher genome size suggests the presence of a universal mechanism allowing for genome expansion. It is assumed that this is primarily due to the nutrient and energetic independence of Geophytes perhaps allowing continuous synthesis of DNA, which is known to proceed in the extreme cases of vernal Geophytes even in dormant stages. This independence may also be assumed as a reason for allowing large genomes in some parasitic plants, as well as the nutrient limitation of small genomes of carnivorous plants.
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RESEARCH IN CONTEXT Genome size and DNA base composition of Geophytes: the mirror of phenology and ecology?
2012Co-Authors: Pavel Veselý, Petr Bureš, Petr SAbstract:† Background and Aims Genome size is known to affect various plant traits such as stomatal size, seed mass, and flower or shoot phenology. However, these associations are not well understood for species with very large genomes, which are laregly represented by geophytic plants. No detailed associations are known between DNA base composition and genome size or species ecology. † Methods Genome sizes and GC contents were measured in 219 Geophytes together with tentative morphoanatomical and ecological traits. † Key Results Increased genome size was associated with earliness of flowering and tendency to grow in humid conditions, and there was a positive correlation between an increase in stomatal size in species with extremely large genomes. Seed mass of Geophytes was closely related to their ecology, but not to genomic parameters. Genomic DNA GC content showed a unimodal relationship with genome size but no relationship with species ecology. † Conclusions Evolution of genome size in Geophytes is closely related to their ecology and phenology and is also associated with remarkable changes in DNA base composition. Although geophytism together with producing larger cells appears to be an advantageous strategy for fast development of an organism in seasonal habitats, the drought sensitivity of large stomata may restrict the occurrence of Geophytes with very large genomes to regions not subject to water stress.
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Genome size and DNA base composition of Geophytes: the mirror of phenology and ecology?
Annals of botany, 2011Co-Authors: Pavel Veselý, Petr Bureš, Petr Šmarda, Tomáš PavlíčekAbstract:Background and Aims Genome size is known to affect various plant traits such as stomatal size, seed mass, and flower or shoot phenology. However, these associations are not well understood for species with very large genomes, which are laregly represented by geophytic plants. No detailed associations are known between DNA base composition and genome size or species ecology. Methods Genome sizes and GC contents were measured in 219 Geophytes together with tentative morphoanatomical and ecological traits. Key Results Increased genome size was associated with earliness of flowering and tendency to grow in humid conditions, and there was a positive correlation between an increase in stomatal size in species with extremely large genomes. Seed mass of Geophytes was closely related to their ecology, but not to genomic parameters. Genomic DNA GC content showed a unimodal relationship with genome size but no relationship with species ecology. Conclusions Evolution of genome size in Geophytes is closely related to their ecology and phenology and is also associated with remarkable changes in DNA base composition. Although geophytism together with producing larger cells appears to be an advantageous strategy for fast development of an organism in seasonal habitats, the drought sensitivity of large stomata may restrict the occurrence of Geophytes with very large genomes to regions not subject to water stress.