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Shifts in climate foster exceptional opportunities for species radiation: the case of South african geraniums.

ABSTRACT: Climate change is often assumed to be a major driver of biodiversity loss. However, it can also set the stage for novel diversification in lineages with the evolutionary ability to colonize new environments. Here we tested if the extraordinary evolutionary success of the genus Pelargonium was related to the ability of its species to capitalize on the climate niche variation produced by the historical changes in southern Africa. We evaluated the relationship between rates of climate niche evolution and diversification rates in the main Pelargonium lineages and disentangled the roles of deep and recent historical events in the modification of species niches. Pelargonium clades exhibiting higher ecological differentiation along summer precipitation (SPP) gradients also experienced higher diversification rates. Faster rates of niche differentiation in spatially structured variables, along with lower levels of niche overlap among closely related species, suggest recent modification in species niches (e.g. dispersal or range shift) and niche lability. We suggest that highly structured SPP gradients established during the aridification process within southern Africa, in concert with niche lability and low niche overlap, contributed to species divergence. These factors are likely to be responsible for the extensive diversification of other lineages in this diversity hot spot.

SUBMITTER: Martinez-Cabrera HI

PROVIDER: S-EPMC3866268 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Shifts in climate foster exceptional opportunities for species radiation: the case of South african geraniums.

Martínez-Cabrera Hugo I HI Peres-Neto Pedro R PR

PloS one 20131217 12

Climate change is often assumed to be a major driver of biodiversity loss. However, it can also set the stage for novel diversification in lineages with the evolutionary ability to colonize new environments. Here we tested if the extraordinary evolutionary success of the genus Pelargonium was related to the ability of its species to capitalize on the climate niche variation produced by the historical changes in southern Africa. We evaluated the relationship between rates of climate niche evoluti ...[more]

PMID: 24358250

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Project description:BackgroundThe prevention of mother-to-child transmission (PMTCT) program in South Africa is now successful in ensuring HIV-free survival for most HIV-exposed children, but gaps in PMTCT coverage remain. The study objective was to identify missed opportunities for prevention of mother-to-child transmission of HIV using the four PMTCT stages outlined in National Guidelines.MethodsThis descriptive study enrolled HIV-exposed children who were below the age of 7 years and therefore born during the South African PMTCT era. The study site was in Gauteng, South Africa and enrolment was from June 2009 to May 2010. The clinical history was obtained through a structured caregiver interview and review of medical records and included socio-demographic data, medical history, HIV interventions, infant feeding information and HIV results. The study group was divided into the "single dose nevirapine" ("sdNVP") and "dual-therapy" (nevirapine & zidovudine) groups due to PMTCT program change in February 2008, with subsequent comparison between the groups regarding PMTCT steps during the preconception stage, antenatal care, labor and delivery and postpartum care.ResultsTwo-hundred-and-one HIV-exposed children were enrolled: 137 (68%) children were HIV infected and 64 (32%) were HIV uninfected. All children were born between 2002 and 2009, with 78 (39%) in the "sdNVP" and 123 (61%) in the "dual-therapy" groups. The results demonstrate significant improvements in antenatal HIV testing and PMTCT enrolment, known maternal HIV diagnosis at delivery, mother-infant antiretroviral interventions, infant HIV-diagnosis and cotrimoxazole prophylaxis. Missed opportunities without improvement include pre-conceptual HIV-services and family planning, tuberculosis screening, HIV disclosure, psychosocial support and postnatal care. Not receiving consistent infant feeding messaging was the only PMTCT component that worsened over time.ConclusionsMultiple missed opportunities for optimal PMTCT were identified, which collectively increase children's risk of HIV acquisition. Although HIV-testing and antiretroviral interventions improved, all PMTCT components need to be optimized to reach the goal of total pediatric HIV elimination.

Project description:AimClimate change can lead to decreased climatic suitability within species' distributions, increased fragmentation of climatically suitable space, and/or emergence of newly suitable areas outside present distributions. Each of these extrinsic threats and opportunities potentially interacts with specific intrinsic traits of species, yet this specificity is seldom considered in risk assessments. We present an analytical framework for examining projections of climate change-induced threats and opportunities with reference to traits that are likely to mediate species' responses, and illustrate the applicability of the framework.LocationSub-Saharan Africa.MethodsWe applied the framework to 195 sub-Saharan African amphibians with both available bioclimatic envelope model projections for the mid-21st century and trait data. Excluded were 500 narrow-ranging species mainly from montane areas. For each of projected losses, increased fragmentation and gains of climate space, we selected potential response-mediating traits and examined the spatial overlap with vulnerability due to these traits. We examined the overlap for all species, and individually for groups of species with different combinations of threats and opportunities.ResultsIn the Congo Basin and arid Southern Africa, projected losses for wide-ranging amphibians were compounded by sensitivity to climatic variation, and expected gains were precluded by poor dispersal ability. The spatial overlap between exposure and vulnerability was more pronounced for species projected to have their climate space contracting in situ or shifting to distant geographical areas. Our results exclude the potential exposure of narrow-ranging species to shrinking climates in the African tropical mountains.Main conclusionsWe illustrate the application of a framework combining spatial projections of climate change exposure with traits that are likely to mediate species' responses. Although the proposed framework carries several assumptions that require further scrutiny, its application adds a degree of realism to familiar assessments that consider all species to be equally affected by climate change-induced threats and opportunities.

Dataset Information

Shifts in climate foster exceptional opportunities for species radiation: the case of South african geraniums.

Publications

Shifts in climate foster exceptional opportunities for species radiation: the case of South african geraniums.

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