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Data from: Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities

Hummingbirds are important pollinators of many native Neotropical plants but their abundance and diversity in landscapes dominated by intensive human uses such as agriculture have rarely been examined, despite such land-uses prevailing in the tropics. We examined how tropical deforestation affects hummingbird community structure in premontane forest patches embedded in a tropical countryside of Coto Brus Canton, Costa Rica. We captured hummingbirds in fourteen landscapes representing a gradient in patch size and forest amount, and tested for the effects of these variables on (1) hummingbird captures at flowers (pollinator availability); (2) species richness; and (3) filtering of functional traits. After accounting for sampling effects, both hummingbird availability and species richness declined by 40% and 50%, respectively, across the gradient in deforestation that we observed (9–66% forest within 1000 m). Focal patch size was the strongest predictor, even after statistically accounting for the amount of forest and matrix composition of landscapes. These reductions in availability and richness were well predicted by functional traits; morphologically specialized species with the capacity to transport long-distance outcrossed pollen and low functional redundancy within the pollinator network showed the greatest sensitivity to landscape change. We hypothesize that declines in hummingbird availability, diversity, and functional traits are important mechanisms driving the observed pollen limitation of ornithophilous flowers in fragmented tropical landscapes. Efforts to conserve large forest patches and enhance matrix permeability are critical for maintaining forest hummingbird communities and pollination services under current and predicted deforestation regimes.

opencc-zeroMar 2022View details →

From nature reserve to mosaic management: improving matrix survival, not permeability, benefits regional populations under habitat loss and fragmentation

Although matrix improvement in fragmented landscapes is a promising conservation measure, matrix permeability (willingness of an organism to enter the matrix) and movement survival in the matrix are usually aggregated. Consequently, it is unknown which matrix property needs to be improved. It also remains unclear whether matrix upgrading from dispersal passage to providing reproduction opportunities has large conservation benefits and whether there are interactive effects between habitat and matrix management. We examined matrix effects on regional populations across a gradient of habitat loss and fragmentation using simulation experiments that integrated demographic processes and movement modeling based on circuit theory. We separately modified the levels of matrix permeability and movement survival to evaluate their individual effects. We also altered the amount and configuration of not only habitat but also improved matrix to assess their effects on population vital rates (size, survival and density). In binary landscapes comprising habitat and unimproved matrix, matrix movement survival had larger effects on population vital rates than matrix permeability. Increasing movement survival increased vital rates, yet, increasing matrix permeability decreased vital rates. Increased permeability required corresponding increased movement survival to offset potential negative population outcomes. When subsets of the matrix functioning as dispersal passage only (where no reproduction opportunities existed) were improved, increasing matrix permeability but holding movement survival constant reduced all vital rates, especially with increasing habitat fragmentation. In contrast, when movement survival increased, vital rates increased given strong habitat fragmentation. The benefits of upgrading dispersal passage to provide reproduction opportunities for population survival were greatest when habitat amount was moderate. We also found synergetic effects between amounts of habitat and improved matrix, and the benefits of matrix improvement were promoted when improvement was achieved in a spatially aggregated manner. Synthesis and applications: Matrix improvement and connectivity modeling aimed at increasing movement survival will likely bring larger conservation benefits than those for improving permeability alone. Buffering and connecting habitat remnants with improved matrix could provide benefits as long as movement survival is increased. Simultaneous implementation of habitat management and matrix improvement would yield synergistic conservation benefits.

publicMar 2022View details →

From nature reserve to mosaic management: improving matrix survival, not permeability, benefits regional populations under habitat loss and fragmentation

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publicAug 2017View details →

Data from: Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities

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Data from: Climate change and human colonization triggered habitat loss and fragmentation in Madagascar.

The relative effect of past climate fluctuations and anthropogenic activities on current biome distribution is subject to increasing attention, notably in biodiversity hot spots. In Madagascar, where humans arrived in the last ~4 to 5,000 years, the exact causes of the demise of large vertebrates that cohabited with humans are yet unclear. The prevailing narrative holds that Madagascar was covered with forest before human arrival and that the expansion of grasslands was the result of human-driven deforestation. However, recent studies have shown that vegetation and fauna structure substantially fluctuated during the Holocene. Here, we study the Holocene history of habitat fragmentation in the north of Madagascar using a population genetics approach. To do so, we infer the demographic history of two northern Madagascar neighbouring, congeneric and critically endangered forest dwelling lemur species—Propithecus tattersalli and Propithecus perrieri—using population genetic analyses. Our results highlight the necessity to consider population structure and changes in connectivity in demographic history inferences. We show that both species underwent demographic fluctuations which most likely occurred after the mid-Holocene transition. While mid-Holocene climate change probably triggered major demographic changes in the two lemur species range and connectivity, human settlements that expanded over the last four millennia in northern Madagascar likely played a role in the loss and fragmentation of the forest cover.

opencc-zeroDec 2017View details →

Data from: Habitat fragmentation, not habitat loss, drives the prevalence of blood parasites in a Caribbean passerine

Habitat destruction due to human land-use activities is well recognized as a central threat to biodiversity. However, there is still debate about the relative influence of its two components, habitat loss and habitat fragmentation, mostly because few studies have been able to disentangle their respective effects. We studied mechanisms by which habitat destruction might influence the prevalence of vector-transmitted haemosporidian blood parasites of the genera Plasmodium and Haemoproteus the Lesser Antillean Bullfinch, Loxigilla noctis, on the Caribbean islands of Guadeloupe and Martinique . Starting from a large set of environmental descriptors (including metrics reflecting habitat loss, habitat fragmentation and landscape heterogeneity; as well as other variables not linked to habitat destruction, such as climatic conditions), we used PLS regression analyses to determine which variables were driving parasite prevalence on the islands. Our results showed that variables related to forest destruction were much more influential than other factors for all parasites analyzed on both islands. Remarkably, the effects documented were almost exclusively due to forest fragmentation, as opposed to habitat loss. This positive effect of forest fragmentation on blood parasite prevalence is proposed to happen through its effects on insect vectors and/or host biology. Increased understanding of the role of habitat fragmentation as a driver of parasitic diseases can help anticipate future effects and limit the risk of emergence and proliferation of wildlife pathogenic outbreaks and zoonosis through informed landscape planning.

opencc-zeroDec 2015View details →

Data from: Trait-associated loss of frugivores in fragmented forest does not affect seed removal rates

Seed dispersal by frugivorous animals forms the basis for regeneration of numerous plant species. Habitat fragmentation has been found to be one major factor perturbing frugivore communities and dependent plant species. Yet, community-wide consequences of fragmentation for both frugivore and plant communities are still hardly understood. Here, we studied the effects of habitat fragmentation on the seed removal by frugivorous birds and mammals from nine fleshy-fruited plant species in Białowieża Forest (Eastern Poland). This last relict of old-growth lowland forest in Europe poses an exceptional reference site for studying the impact of habitat fragmentation on seed dispersal processes in temperate forest ecosystems. In particular, (i) we tested for associations between forest fragmentation and response traits of frugivores, that is forest specialization and body mass; (ii) we studied the relationship between frugivore response and effect traits, that is centrality (number of consumed plant species) and interaction type (mutualistic vs. antagonistic); and (iii) we assessed the feedback of fragmentation-induced changes on plant–frugivore interactions and seed removal rates. We found that fragmentation led to shifts in the frugivore community, associated with the response traits forest specialization and body mass, with fewer forest specialists and large-bodied frugivores in fragmented than in continuous forests. However, forest generalists and small-bodied frugivores were more central in the plant–frugivore associations than forest specialists and large-bodied frugivores. Therefore, the loss of vulnerable species did not result in reduced seed removal rates in fragmented compared with continuous forest. Synthesis. These results indicate that seed removal may be relatively robust in spite of shifts in the frugivore community in forest fragments. The correlation between response and effect traits of frugivores highlights the importance of forest generalists and small-bodied frugivores for maintaining dispersal processes in fragmented forests in temperate regions. Yet, future studies should aim at quantifying the consequences of seed disperser loss on other aspects of dispersal, such as long-distance dispersal, spatial patterns of seed deposition, seed germination and plant regeneration.

Data from: Continental divide: predicting climate-mediated fragmentation and biodiversity loss in the boreal forest

Climate change threatens natural landscapes through shifting distribution and abundance of species and attendant change in the structure and function of ecosystems. However, it remains unclear how climate-mediated variation in species' environmental niche space may lead to large-scale fragmentation of species distributions, altered meta-population dynamics and gene flow, and disrupted ecosystem integrity. Such change may be especially relevant when species distributions are restricted either spatially or to a narrow environmental niche, or when environments are rapidly changing. Here, we use range-wide environmental niche models to posit that climate-mediated range fragmentation aggravates the direct effects of climate change on species in the boreal forest of North America. We show that climate change will directly alter environmental niche suitability for boreal-obligate species of trees, birds and mammals (n=12), with most species ranges becoming smaller and shifting northward through time. Importantly, species distributions will become increasingly fragmented, as characterized by smaller mean size and greater isolation of environmentally-suitable landscape patches. This loss is especially pronounced along the Ontario-Québec border, where the boreal forest is narrowest and roughly 78% of suitable niche space could disappear by 2080. Despite the diversity of taxa surveyed, patterns of range fragmentation are remarkably consistent, with our models predicting that spruce grouse (Dendragapus canadensis), boreal chickadee (Poecile hudsonicus), moose (Alces americanus) and caribou (Rangifer tarandus) could have entirely disjunct east-west population segments in North America. These findings reveal potentially dire consequences of climate change on population continuity and species diversity in the boreal forest, highlighting the need to better understand: 1) extent and primary drivers of anticipated climate-mediated range loss and fragmentation; 2) diversity of species to be affected by such change; 3) potential for rapid adaptation in the most strongly-affected areas; and 4) potential for invasion by replacement species.

opencc-by-4.0Aug 2024View details →

zenodo32/100

Variation in species' dispersal capacities amplifies effects of habitat loss and fragmentation on biodiversity loss

Simulation data and model belonging to the manuscript 'Variation in species’ dispersal capacities amplifies effects of habitat loss and fragmentation on biodiversity loss', by Monique de Jager and Edwin Pos. The folder 'Generated data' holds the generated simulation data. The folder 'Model' contains the 2-dimensional, semi-spatial, near-neutral, individual-based model. A description of the model can be found in the file 'README.md'.

Data from: A degradation debt? large-scale shifts in community composition and loss of biomass in a tropical forest fragment after 40 years of isolation

Habitat loss and fragmentation are among the biggest threats to tropical biodiversity and associated ecosystem services. We examined forest dynamics in a mid-elevation 365-ha fragment in southern Costa Rica. The fragment was isolated in the mid-1970s and belongs to the Las Cruces Biological Station. A 2.25-ha permanent plot was established in the center of the old-growth forest (>400 m to nearest edge boundary) and all plants >5 cm DBH were censused, mapped, and identified to species in two surveys taken ~5–6 years apart (>3,000 stems/survey). Although the reserve maintains high species richness (>200 spp.), with many rare species represented by only one individual, we document a strong shift in composition with a two-fold increase in the number of soft-wooded pioneer individuals. The dominant late-successional understory tree species, Chrysochlamys glauca (Clusiaceae), and most species in the Lauraceae, declined dramatically. Turnover was high: 22.9% of stems in the first survey were lost, and 27.8% of stems in the second survey represented new recruits. Mean tree diameter decreased significantly and there was a 10% decrease in overall biomass. Such alteration has been documented previously but only in smaller fragments or within ~100 m of an edge boundary. Further penetration into this fragment was perhaps driven by a progressive invasion of disturbance-adapted species into the fragment's core over time; the loss of once-dominant late successional species could be a contributing factor. The pattern found is of particular concern given that such fragments represent a substantial portion of today's remaining tropical habitat; further studies in similar-sized fragments that have been isolated for similar prolonged periods are called for.

opencc-by-4.0Sep 2023View details →

zenodo32/100

Neutral model data from "Fragmentation mitigates biodiversity loss immediately after habitat destruction"

Raw community data from the manuscript "Fragmentation mitigates biodiversity loss immediately after habitat destruction." The folder contains text files of raw community data from the neutral model. Filenames contain the parameter values used in the simulation of that community. In the text files, each number is a different species and its position in the vector indicates its x, y coordinate in the 2D map. See <a href="https://github.com/cmsmith91/fragmentation/blob/main/python_code/neutral_mod-amarel15june2021.py">code</a> in the manuscript github repository.

ClinicalTrials.gov32/100

Sperm DNA Fragmentation in Recurrent Pregnancy Loss

ClinicalTrials.gov study NCT02572154. IPD Sharing: Not stated. Countries: 1. Publications: 1.

restrictedIPD-UNDECIDEDFeb 2026View details →

publicAug 2010View details →

Data from: The effect of habitat fragmentation on the genetic structure of a top predator: loss of diversity and high differentiation among remnant populations of Atlantic Forest jaguars (Panthera onca)

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