California Academy of Sciences

About: California Academy of Sciences is a archive organization based out in San Francisco, California, United States. It is known for research contribution in the topics: Genus & Population. The organization has 577 authors who have published 2153 publications receiving 70681 citations. The organization is also known as: Cal Academy & Academy of Sciences.

The velocity of climate change

Abstract: The ranges of plants and animals are moving in response to recent changes in climate. As temperatures rise, ecosystems with 'nowhere to go', such as mountains, are considered to be more threatened. However, species survival may depend as much on keeping pace with moving climates as the climate's ultimate persistence. Here we present a new index of the velocity of temperature change (km yr(-1)), derived from spatial gradients ( degrees C km(-1)) and multimodel ensemble forecasts of rates of temperature increase ( degrees C yr(-1)) in the twenty-first century. This index represents the instantaneous local velocity along Earth's surface needed to maintain constant temperatures, and has a global mean of 0.42 km yr(-1) (A1B emission scenario). Owing to topographic effects, the velocity of temperature change is lowest in mountainous biomes such as tropical and subtropical coniferous forests (0.08 km yr(-1)), temperate coniferous forest, and montane grasslands. Velocities are highest in flooded grasslands (1.26 km yr(-1)), mangroves and deserts. High velocities suggest that the climates of only 8% of global protected areas have residence times exceeding 100 years. Small protected areas exacerbate the problem in Mediterranean-type and temperate coniferous forest biomes. Large protected areas may mitigate the problem in desert biomes. These results indicate management strategies for minimizing biodiversity loss from climate change. Montane landscapes may effectively shelter many species into the next century. Elsewhere, reduced emissions, a much expanded network of protected areas, or efforts to increase species movement may be necessary.

Phylogenomics resolves the timing and pattern of insect evolution

Abstract: Insects are the most speciose group of animals, but the phylogenetic relationships of many major lineages remain unresolved. We inferred the phylogeny of insects from 1478 protein-coding genes. Phylogenomic analyses of nucleotide and amino acid sequences, with site-specific nucleotide or domain-specific amino acid substitution models, produced statistically robust and congruent results resolving previously controversial phylogenetic relations hips. We dated the origin of insects to the Early Ordovician [~479 million years ago (Ma)], of insect flight to the Early Devonian (~406 Ma), of major extant lineages to the Mississippian (~345 Ma), and the major diversification of holometabolous insects to the Early Cretaceous. Our phylogenomic study provides a comprehensive reliable scaffold for future comparative analyses of evolutionary innovations among insects.

The amphibian tree of life

Abstract: The evidentiary basis of the currently accepted classification of living amphibians is discussed and shown not to warrant the degree of authority conferred on it by use and tradition. A new taxonomy of living amphibians is proposed to correct the deficiencies of the old one. This new taxonomy is based on the largest phylogenetic analysis of living Amphibia so far accomplished. We combined the comparative anatomical character evidence of Haas (2003) with DNA sequences from the mitochondrial transcription unit H1 (12S and 16S ribosomal RNA and tRNAValine genes, ≈ 2,400 bp of mitochondrial sequences) and the nuclear genes histone H3, rhodopsin, tyrosinase, and seven in absentia, and the large ribosomal subunit 28S (≈ 2,300 bp of nuclear sequences; ca. 1.8 million base pairs; x = 3.7 kb/terminal). The dataset includes 532 terminals sampled from 522 species representative of the global diversity of amphibians as well as seven of the closest living relatives of amphibians for outgroup comparisons. The...

Approaching a state shift in Earth’s biosphere

Abstract: There is evidence that human influence may be forcing the global ecosystem towards a rapid, irreversible, planetary-scale shift into a state unknown in human experience. Most forecasts of how the biosphere will change in response to human activity are rooted in projecting trajectories. Such models tend not anticipate critical transitions or tipping points, although recent work indicates a high probability of those taking place. And, at a local scale, ecosystems are known to shift abruptly between states when critical thresholds are passed. These authors review the evidence from across ecology and palaeontology that such a transition is being approached on the scale of the entire biosphere. They go on to suggest how biological forecasting might be improved to allow us to detect early warning signs of critical transitions on a global, as well as local, scale. Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a planetary-scale ‘tipping point’ highlights the need to improve biological forecasting by detecting early warning signs of critical transitions on global as well as local scales, and by detecting feedbacks that promote such transitions. It is also necessary to address root causes of how humans are forcing biological changes.

Towards integrative taxonomy

Abstract: Delineating species boundaries correctly is crucial to the discovery of life’s diversity because it determines whether or not different individual organisms are members of the same entity. The gap in communication between the different disciplines currently involved in delimiting species is an important and overlooked problem in the so-called ‘taxonomy crisis’. To solve this problem, it is suggested that taxonomy become integrative, and this integration is seen as the real challenge for the future of taxonomy. ‘Integrative taxonomy’ is defined as the science that aims to delimit the units of life’s diversity from multiple and complementary perspectives (phylogeography, comparative morphology, population genetics, ecology, development, behaviour, etc.). Some workers have already collaborated and successfully adopted an integrative approach to taxonomy. However, it is now time for the whole discipline to evolve. A radical change in mentality is needed concerning the creation of names in order to achieve this integration and to prevent the over-abundance of both synonyms and names of doubtful application from worsening. Integrative taxonomy gives priority to species delineation over the creation of new species names. Furthermore, it is emphasized that describing morphological diversity, referred to as ‘morphodiversity’, does not require the naming of any single set of specimens. Seven guidelines are proposed to help integrative taxonomists recognize cases when species are supported by broad biological evidence and therefore are deserving of an official name. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 407‐415. ADDITIONAL KEYWORDS: biodiversity ‐ character variation ‐ DNA barcoding ‐ ecology ‐ morphodiversity ‐ phylogenetics ‐ phylogeography ‐ population biology ‐ species delineation ‐ systematics.