Climate change may even test lizards' famous ability to tolerate and escape the heat -- making habitat protection increasingly vital -- according to a new study by UBC and international biodiversity experts.
The study, published today in the Proceedings of the National Academy of Sciences, looks at the heat and cold tolerance of 296 species of reptiles, insects and amphibians, known as ectotherms. The researchers discovered that regardless of latitude or elevation, cold-blooded animals across the world have similar heat tolerance limits. However, species in the tropics rely more on behaviour to survive, burrowing or finding shade to shield themselves from the sun.
"By comparing temperature tolerance limits to estimated body temperatures of animals exposed to the sun, we've found that species at low latitudes rely on shade and habitat," says UBC climate-change ecologist Jennifer Sunday, lead author on the paper. "Very few species have any extra heat tolerance."
As the world warms, most ectotherms will rely increasingly on behavioral thermoregulation, making it vital to protect migration corridors and habitats that provide shade, especially in the tropics.
Global constraints on net primary production and inorganic carbon supply during glacial and interglacial cycles
Authors:
Pelegri et al
Abstract:
Relaxation-type models have good skill at reproducing glacial-interglacial transitions in climatic variables. Here we propose a simple two-box and two-state relaxation-type model for the upper ocean (surface and permanent thermocline layers) where dissolved inorganic carbon/nutrients are supplied by the deep-ocean and through remineralization within the upper ocean. The model is tuned using genetic algorithms to simulate the atmospheric CO2 time series for the last four glacial-interglacial cycles. The fit to the data is very good, with correlations above 0.8, as the upper ocean responds to shifts in (1) the intensity of the Meridional Overturning Circulation (MOC), from off to on during the glacial-interglacial transition, and (2) the size and sign of net primary production, with respiration greatly exceeding primary production during interglacial periods and production larger than respiration during the glacial phase. The glacial-interglacial transitions are interpreted as shifts between two distinct metabolic states of the Earth system, with high/low supply of dissolved inorganic carbon and nutrients to the productive upper ocean during interglacial/glacial periods.
Constraining the Air Giants: Limits on Size in Flying Animals as an Example of Constraint-Based Biomechanical Theories of Form
Author:
1. Mike Habib (a)
Affiliation:
a. Department of Cell and Neurobiology, University of Southern California, Los Angeles, CA, USA
Abstract:
The study of biomechanics most often takes a classic adaptationist approach, examining the functional abilities of organisms in relation to what is allowed by physical parameters. This approach generally assumes strong selection and is less concerned with evolutionary stochasticity in determining the presence of biological traits. It is equally important, however, to consider the importance of constraint in determining the form of organisms. If selection is relatively weak compared to stochastic events, then the observed forms in living systems can be taken not as those shapes that were strongly selected for, so much as those forms that do not violate physical rules and therefore persist. Using the problem of maximum animal size as a case study for this alternative biomechanical philosophy, I demonstrate one example of how biomechanical approaches can be used to study constraint and consider the concept of absent forms. This alternative mindset and approach produces a complementary system to the traditional form and function approach in biomechanics. The two philosophies can be used in conjunction to better understand biological systems. I focus particularly on the maximum size of flying animals, as they are a heavily constrained class of system that has also been shaped by substantial stochasticity.
