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Relationships between abiotic environment, plant functional traits, and animal body size at Mount Kilimanjaro, Tanzania.

ABSTRACT: The effect-response framework states that plant functional traits link the abiotic environment to ecosystem functioning. One ecosystem property is the body size of the animals living in the system, which is assumed to depend on temperature or resource availability, among others. For primary consumers, resource availability may directly be related to plant traits, while for secondary consumers the relationship is indirect. We used plant traits to describe resource availability along an elevational gradient on Mount Kilimanjaro, Tanzania. Using structural equation models, we determined the response of plant traits to changes in precipitation, temperature and disturbance with and assessed whether abiotic conditions or community-weighted means of plant traits are stronger predictors of the mean size of bees, moths, frugivorous birds, and insectivorous birds. Traits indicating tissue density and nutrient content strongly responded to variations in precipitation, temperature and disturbance. They had direct effects on pollination and fruit traits. However, the average body sizes of the animal groups considered could only be explained by temperature and habitat structure, not by plant traits. Our results demonstrate a strong link between traits and the abiotic environment, but suggest that temperature is the most relevant predictor of mean animal body size. Community-weighted means of plant traits and body sizes appear unsuitable to capture the complexity of plant-animal interactions.

SUBMITTER: Schellenberger Costa D

PROVIDER: S-EPMC5358856 | biostudies-other | 2017

REPOSITORIES: biostudies-other

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Relationships between abiotic environment, plant functional traits, and animal body size at Mount Kilimanjaro, Tanzania.

Schellenberger Costa David D Classen Alice A Ferger Stefan S Helbig-Bonitz Maria M Peters Marcell M Böhning-Gaese Katrin K Steffan-Dewenter Ingolf I Kleyer Michael M

PloS one 20170320 3

The effect-response framework states that plant functional traits link the abiotic environment to ecosystem functioning. One ecosystem property is the body size of the animals living in the system, which is assumed to depend on temperature or resource availability, among others. For primary consumers, resource availability may directly be related to plant traits, while for secondary consumers the relationship is indirect. We used plant traits to describe resource availability along an elevationa ...[more]

PMID: 28319155

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Project description:Morphological and molecular analyses of plant-parasitic nematodes (PPN) from 12 sugarcane plantation sites of Tanganyika Planting Company (TPC) Limited in Kilimanjaro region of Tanzania revealed the presence of six PPN genera, i.e. Helicotylenchus, Hemicycliophora, Pratylenchus, Rotylenchulus, Scutellonema, and Tylenchorhynchus. The genera with the highest densities and present in virtually all samples were Pratylenchus and Rotylenchulus, and the most important species appeared to be R. parvus, P. zeae, T. crassicaudatus, and T. ventrosignatus. A total sequences of 11 partial ITS, 15 D2-D3 of 28S, and 6 partial 18S of rRNA gene, and 7 partial COI gene of mtDNA of these species were obtained in this study. Morphology and molecular data comparisons between the Tanzanian R. parvus and the South African R. parvus indicated that R. parvus is a cryptic species complex. Based on the results of morphological and molecular analyses of T. crassicaudatus and T. agri from China, Haiti, Indonesia, Iran, Niger and the USA, T. agri syn. n. is proposed as a junior synonym of T. crassicaudatus.Morphological and molecular analyses of plant-parasitic nematodes (PPN) from 12 sugarcane plantation sites of Tanganyika Planting Company (TPC) Limited in Kilimanjaro region of Tanzania revealed the presence of six PPN genera, i.e. Helicotylenchus, Hemicycliophora, Pratylenchus, Rotylenchulus, Scutellonema, and Tylenchorhynchus. The genera with the highest densities and present in virtually all samples were Pratylenchus and Rotylenchulus, and the most important species appeared to be R. parvus, P. zeae, T. crassicaudatus, and T. ventrosignatus. A total sequences of 11 partial ITS, 15 D2-D3 of 28S, and 6 partial 18S of rRNA gene, and 7 partial COI gene of mtDNA of these species were obtained in this study. Morphology and molecular data comparisons between the Tanzanian R. parvus and the South African R. parvus indicated that R. parvus is a cryptic species complex. Based on the results of morphological and molecular analyses of T. crassicaudatus and T. agri from China, Haiti, Indonesia, Iran, Niger and the USA, T. agri syn. n. is proposed as a junior synonym of T. crassicaudatus.

Project description:BackgroundOrganism biomass is one of the most important variables in ecological studies, making biomass estimations one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry mass or ash-free dry mass (hereafter 'DM' vs. 'AFDM') per sample; a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like body size or wet (fresh) mass. Another common way of estimating AFDM (one of the most accurate but also time-consuming estimates of biologically active tissue mass) is the use of AFDM/DM ratios as conversion factors. So far, however, these ratios typically ignore the possibility that the relative mass of biologically active vs. non-active support tissue (e.g., protective exoskeleton or shell)-and therefore, also AFDM/DM ratios-may change with body size, as previously shown for taxa like spiders, vertebrates and trees.MethodsWe collected aquatic, epibenthic macroinvertebrates (>1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), body dry mass and ash-free dry mass for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDM/DM ratio per taxon.ResultsFor most taxa, non-linear regression models describing the power relationship between body size and (i) DM and (ii) AFDM fit the data well (as indicated by low SE and high R2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDM/DM ratios.DiscussionThe good fit of the modelled power relationships suggests that the constants reported here can be used to quickly estimate organism dry- and ash-free dry mass based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for taxon-specific relationships, and the potential dangers associated with ignoring body size. The negative influence of body size on the AFDM/DM ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDM/DM (and presumably also AFDM/wet mass) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism body mass.

Project description:IntroductionMental health disorders in pregnant women living with HIV are associated with poor maternal and child outcomes, and undermine the global goals of prevention of mother-to-child transmission of HIV (PMTCT). This study aimed to determine prevalence of depression and anxiety and identify factors associated with these common mental health disorders among HIV-infeced pregnant women in Tanzania.MethodsWe enrolled 200 pregnant women living with HIV from antenatal care clinics in the Kilimanjaro region. Women were eligible if they were in the second or third trimester of pregnancy and had been in PMTCT care for a minimum of one month. Data were collected via interviewer administered surveys. Participants self reported depression symptoms (Edinburgh Postnatal Depression Scale, EPDS) and anxiety symptoms (Brief Symptom Index, BSI). Multivariate logistic regression models examined factors associated with depression, anxiety, and comorbid depression and anxiety.Results25.0% of women met screening criteria for depression (EPDS ?10). Depression was significantly associated with being single (aOR = 4.2, 95% CI = 1.1-15.5), food insecurity (aOR = 2.4, 95% CI = 1.0-6.4), and HIV shame (aOR = 1.2, 95% CI = 1.1-1.3). 23.5% of participants met screening criteria for anxiety (BSI ?1.01). Anxiety was associated with being single (aOR = 3.6, 95%CI = 1.1-11.1), HIV shame (aOR = 1.1, 95% CI = 1.1-1.2) and lifetime experience of violence (aOR = 2.3, 95% CI = 1.0-5.1). 17.8% of the sample met screening criteria for both depression and anxiety. Comorbid depression and anxiety was associated with being single (aOR = 4.5, 95%CI = 1.0-19.1), HIV shame (aOR = 1.2, 95%CI = 1.1-1.3) and lifetime experience of violence (aOR = 3.4, 95% CI = 1.2-9.6).ConclusionDepression and anxiety symptomatology was common in this sample of pregnant women living with HIV, with a sizable number screening positive for comorbid depression and anxiety. In order to successfully engage women in PMTCT care and support their well-being, strategies to screen for mental health disorders and support women with mental illnesses are needed.

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Relationships between abiotic environment, plant functional traits, and animal body size at Mount Kilimanjaro, Tanzania.

Publications

Relationships between abiotic environment, plant functional traits, and animal body size at Mount Kilimanjaro, Tanzania.

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