27 research outputs found
The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts
Biodiversity continues to decline in the face of increasing anthropogenic pressures
such as habitat destruction, exploitation, pollution and introduction of
alien species. Existing global databases of species’ threat status or population
time series are dominated by charismatic species. The collation of datasets with
broad taxonomic and biogeographic extents, and that support computation of
a range of biodiversity indicators, is necessary to enable better understanding of
historical declines and to project – and avert – future declines. We describe and
assess a new database of more than 1.6 million samples from 78 countries representing
over 28,000 species, collated from existing spatial comparisons of
local-scale biodiversity exposed to different intensities and types of anthropogenic
pressures, from terrestrial sites around the world. The database contains
measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35)
biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains
more than 1% of the total number of all species described, and more than
1% of the described species within many taxonomic groups – including flowering
plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans
and hymenopterans. The dataset, which is still being added to, is
therefore already considerably larger and more representative than those used
by previous quantitative models of biodiversity trends and responses. The database
is being assembled as part of the PREDICTS project (Projecting Responses
of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk).
We make site-level summary data available alongside this article. The full database
will be publicly available in 2015
Variación Entre Poblaciones en la Supervivencia Mensual y Anual De la Rama Ártica de Baja California, Pseudacris Hypochondriaca curta, en Oasis del Desierto de Baja California Sur, México
Survival is an important component of the demography of an animal. We estimated monthly and annual survival probabilities of three populations of the Baja California Treefrog (Pseudacris hypochondriaca curta) inhabiting desert oases of Baja California Sur, Mexico. We used data from a two-year mark recapture study to estimate survival. Recapture probabilities varied widely among months and there was no clear temporal pattern underlying the fluctuations. Annual survival was 27 and 29% for two populations and 1% for the third population. This implies that the populations, particularly the third one, can persist only if there is steady and high recruitment. With annual survival as low as 1–29%, a lack of recruitment could quickly cause local extinction. Because immigration seems unlikely in these populations due to their isolation from other breeding populations, recruits must be produced locally. Non-native fish, crayfish, and frogs that prey on tadpoles may therefore be a threat for the persistence of the populations.La supervivencia es un componente importante de la demografía de un animal. Estimamos las probabilidades mensuales y anuales de supervivencia de tres poblaciones de la brecha de Baja California (Pseudacris hypochondriaca curta) que habitan oasis del desierto de Baja California Sur, México. Utilizamos datos de un estudio de recaptura de marca de dos años para estimar la supervivencia. Las probabilidades de recaptura variaron ampliamente entre meses y no hubo patrón temporal claro subyacente a las fluctuaciones. La supervivencia anual fue de 27 y 29% para dos poblaciones y 1% para la tercera población. Esto implica que las poblaciones, particularmente la tercera, sólo pueden persistir si hay reclutamiento constante y alto. Con una supervivencia anual tan baja como 1-29%, la falta de reclutamiento podría causar rápidamente la extinción local. Debido a que la inmigración parece poco probable en estas poblaciones debido a su aislamiento de otras poblaciones reproductoras, los reclutas deben ser producidos localmente. Los peces no nativos, cangrejos de río y ranas que se alimentan de renacuajos pueden ser una amenaza para la persistencia de las poblaciones
Among-population variation in monthly and annual survival of the Baja California Tree Frog, Pseudacris hypochondriaca curta, in desert oases of Baja California Sur, Mexico
Survival is an important component of the demography of an animal. We estimated monthly and annual survival probabilities of three populations of the Baja California Treefrog (Pseudacris hypochondriaca curta) inhabiting desert oases of Baja California Sur, Mexico. We used data from a two-year mark recapture study to estimate survival. Recapture probabilities varied widely among months and there was no clear temporal pattern underlying the fluctuations. Annual survival was 27 and 29% for two populations and 1% for the third population. This implies that the populations, particularly the third one, can persist only if there is steady and high recruitment. With annual survival as low as 1–29%, a lack of recruitment could quickly cause local extinction. Because immigration seems unlikely in these populations due to their isolation from other breeding populations, recruits must be produced locally. Non-native fish, crayfish, and frogs that prey on tadpoles may therefore be a threat for the persistence of the populations