Biomedical subjects

Henrique M Pereira

Publications and source records attributed to Henrique M Pereira.

5 recordsLinked to original sources

PubMed2026

Increasing bird diversity in a landscape in transition.

Rural depopulation across Mediterranean uplands has driven farmland extensification and landscape transitions, yet their medium-term impacts on birds remain poorly understood. We resurveyed 213 selected 2 km × 2 km grid cells in the Côa River basin (western Iberia) in 2023-2024, following protocols comparable to those applied in 1999-2005, ensuring consistent sampling across periods. Median alpha diversity increased by five species, a 28% gain, with total abundance rising as common taxa became more widespread. Gains were predominantly driven by forest-associated and generalist species, while farmland specialists showed stagnation or slight declines. We discuss how landscape transitions contributed to these biodiversity patterns including lower human density, reduced grazing pressure, and altered disturbance regimes. However, significant avian diversity gains occurred within apparently stable forest-cover mosaics, potentially masking broader ecological shifts.

Animals↗

PubMed2006

Modeling biodiversity dynamics in countryside landscapes.

The future of biodiversity hinges to a great extent on the conservation value of countryside, the growing fraction of Earth's surface heavily influenced by human activities. How many species, and which species, can persist in such landscapes (and analogous seascapes) are open questions. Here we explore two complementary theoretical frameworks to address these questions: species-area relationships and demographic models. We use the terrestrial mammal fauna of Central America to illustrate the application of both frameworks. We begin by proposing a multi-habitat species-area relationship, the countryside species-area relationship, to forecast species extinction rates. To apply it, we classify the mammal fauna by affinity to native and human-dominated habitats. We show how considering the conservation value of countryside habitats changes estimates derived from the classic species-area approach We also examine how the z value of the species-area relationship affects extinction estimates. Next, we present a framework for assessing the relative vulnerability of species to extinction in the countryside, based on the Skellam model of population dynamics. This model predicts the minimum area of contiguous native habitat required for persistence of a species, which we use as an indicator of vulnerability to habitat change. To apply the model, we use our habitat affinity classification of mammals and we estimate life-history parameters by species and habitat type. The resulting ranking of vulnerabilities is significantly correlated with the World Conservation Union (IUCN) Red List assessment.

Animals↗

PubMed2005

Towards the global monitoring of biodiversity change.

Governments have set the ambitious target of reducing biodiversity loss by the year 2010. The scientific community now faces the challenge of assessing the progress made towards this target and beyond. Here, we review current monitoring efforts and propose a global biodiversity monitoring network to complement and enhance these efforts. The network would develop a global sampling programme for indicator taxa (we suggest birds and vascular plants) and would integrate regional sampling programmes for taxa that are locally relevant to the monitoring of biodiversity change. The network would also promote the development of comparable maps of global land cover at regular time intervals. The extent and condition of specific habitat types, such as wetlands and coral reefs, would be monitored based on regional programmes. The data would then be integrated with other environmental and socioeconomic indicators to design responses to reduce biodiversity loss.

Animals↗

PubMed2002

Socially stable territories: the negotiation of space by interacting foragers.

This article presents a theory of territoriality that integrates optimal foraging and conflict resolution through negotiation. Using a spatially explicit model of a sit-and-wait forager, we show that when resources are scarce, there is a conflict between foragers: there is not enough space for all individuals to have optimal home ranges. We propose that a division of space that solves this conflict over resources is the outcome of a negotiation between foragers. We name this outcome the socially stable territories (SST). Using game theory we show that in a homogenous patch occupied by two interacting foragers, both individuals receive identical energy yields at the socially stable territories; that is, there is economic equity. Economic inequity can arise in a heterogeneous patch or from asymmetries in fighting abilities between the foragers. Opportunity costs play a role in reducing economic inequity. When the asymmetry in fighting abilities is very large, a negotiated division of space is not possible and the forager with lowest fighting ability may be evicted from the habitat patch. A comparison between territories and overlapping home ranges shows that energy yields from territories are generally higher. We discuss why there are instances in which individuals nevertheless overlap home ranges.

Animals↗

PubMed2002

The intranuclear mobility of messenger RNA binding proteins is ATP dependent and temperature sensitive.

After being released from transcription sites, messenger ribonucleoprotein particles (mRNPs) must reach the nuclear pore complexes in order to be translocated to the cytoplasm. Whether the intranuclear movement of mRNPs results largely from Brownian motion or involves molecular motors remains unknown. Here we have used quantitative photobleaching techniques to monitor the intranuclear mobility of protein components of mRNPs tagged with GFP. The results show that the diffusion coefficients of the poly(A)-binding protein II (PABP2) and the export factor TAP are significantly reduced when these proteins are bound to mRNP complexes, as compared with nonbound proteins. The data further show that the mobility of wild-type PABP2 and TAP, but not of a point mutant variant of PABP2 that fails to bind to RNA, is significantly reduced when cells are ATP depleted or incubated at 22 degrees C. Energy depletion has only minor effects on the intranuclear mobility of a 2,000-kD dextran (which corresponds approximately in size to 40S mRNP particles), suggesting that the reduced mobility of PABP2 and TAP is not caused by a general alteration of the nuclear environment. Taken together, the data suggest that the mobility of mRNPs in the living cell nucleus involves a combination of passive diffusion and ATP-dependent processes.

Active Transport, Cell Nucleus↗