126 research outputs found
Equilibrium and non-equilibrium dynamics simultaneously operate in the GalĂĄpagos islands
Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galapagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galapagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms
First come, first served: Possible role for priority effects in marine populations under different degrees of dispersal potential
A Taxonomy of Causality-Based Biological Properties
We formally characterize a set of causality-based properties of metabolic
networks. This set of properties aims at making precise several notions on the
production of metabolites, which are familiar in the biologists' terminology.
From a theoretical point of view, biochemical reactions are abstractly
represented as causal implications and the produced metabolites as causal
consequences of the implication representing the corresponding reaction. The
fact that a reactant is produced is represented by means of the chain of
reactions that have made it exist. Such representation abstracts away from
quantities, stoichiometric and thermodynamic parameters and constitutes the
basis for the characterization of our properties. Moreover, we propose an
effective method for verifying our properties based on an abstract model of
system dynamics. This consists of a new abstract semantics for the system seen
as a concurrent network and expressed using the Chemical Ground Form calculus.
We illustrate an application of this framework to a portion of a real
metabolic pathway
Ab initio atomistic thermodynamics and statistical mechanics of surface properties and functions
Previous and present "academic" research aiming at atomic scale understanding
is mainly concerned with the study of individual molecular processes possibly
underlying materials science applications. Appealing properties of an
individual process are then frequently discussed in terms of their direct
importance for the envisioned material function, or reciprocally, the function
of materials is somehow believed to be understandable by essentially one
prominent elementary process only. What is often overlooked in this approach is
that in macroscopic systems of technological relevance typically a large number
of distinct atomic scale processes take place. Which of them are decisive for
observable system properties and functions is then not only determined by the
detailed individual properties of each process alone, but in many, if not most
cases also the interplay of all processes, i.e. how they act together, plays a
crucial role. For a "predictive materials science modeling with microscopic
understanding", a description that treats the statistical interplay of a large
number of microscopically well-described elementary processes must therefore be
applied. Modern electronic structure theory methods such as DFT have become a
standard tool for the accurate description of individual molecular processes.
Here, we discuss the present status of emerging methodologies which attempt to
achieve a (hopefully seamless) match of DFT with concepts from statistical
mechanics or thermodynamics, in order to also address the interplay of the
various molecular processes. The new quality of, and the novel insights that
can be gained by, such techniques is illustrated by how they allow the
description of crystal surfaces in contact with realistic gas-phase
environments.Comment: 24 pages including 17 figures, related publications can be found at
http://www.fhi-berlin.mpg.de/th/paper.htm
The combined use of reflectance, emissivity and elevation Aster/Terra data for tropical soil studies
A Critical Analysis of the Medical Model as used in the Study of Pregnancy and Childbirth
Conservation Status and Research on the Fabulous Green Sphinx of Kaua'i, Tinostoma smaragditis (Lepidoptera: Sphingidae), Including Checklists of the Vascular Plants of the Diverse Mesic Forests of Kaua'i, Hawai'i
In 1895, a moth was captured in a mountain home in Makaweli,
Kaua'i, that would captivate and elude entomologists for the next century. Tinostoma
smaragditis (Meyrick), aptly nicknamed the "Fabulous Green Sphinx
of Kaua'i" is a stunningly beautiful moth with green wings and thorax, pale
brown hind wings, and orange antennae. Eighteen individuals are known to
have been collected on Kaua'i. However, despite extensive searches in areas
around Koke'e, all the specimens discovered until the 1990s were incidental
catches, and the natural habitat and host plant of the moth remained unknown.
This study describes the results of extensive searches of the diverse mesic forests
with the aim of establishing range, habitat, and host-plant associations of the
Fabulous Green Sphinx. In February 1998 a male T smaragditis was attracted
to a mercury vapor light set up in the diverse mesic forest. Subsequently, one
other specimen was collected in a similar habitat type on another part of the
island. However, the host plant of the moth remains unknown. In this paper
we provide a history of collections, a summary of known biology, and a guide
to potential host plants, including checklists of vascular plants found in the diverse
mesic forests of two locations where T smaragditis was found, Kalalau
and Mahanaloa Valleys on Kaua'i
Speciation on a conveyor belt: sequential colonization of the hawaiian islands by Orsonwelles spiders (Araneae, Linyphiidae)
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Concurrent Sessions A: Co-Benefits of Barrier Removal: Fish Passage and Public Safety - Flood Resiliency, Aquatic Organism Passage, Critical Infrastructure, and Economics
A retrospective case study was conducted in the Upper White River subbasin in Vermont (Unthank et al 2012) that examined persistence of traditional hydraulic and stream simulation designs following the record flood flows from Tropical Storm Irene that occurred in August 2011. Analysis indicated that extensive damage to road infrastructure in this study area was largely avoided in areas where the stream simulation design approach was implemented, as did several other localized case studies from across New England. Benefit/cost analyses suggest that a relatively modest increase in initial investment to implement stream simulation designs to provide aquatic organism passage yield substantial societal benefits. When considering the overall comparative economic, social and natural resource costs to communities caused by crossing and/or road failure due to undersized road-stream crossings, adoption of stream simulation design is comparatively inexpensive when examined over a multi-year time frame. Hydraulic analysis results of stream simulation designed structures surviving Tropical Storm Irene will be presented along with a series of regulatory, policy and funding recommendations to help agencies, municipalities and communities make smart infrastructure and aquatic resource investments that reduce future road and stream crossing failures and associated impacts, and to help provide biological resilience and infrastructural persistence in the face of increased frequency and severity of flood events modeled under climate change
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