Related Experiment Videos
Unexpected patterns of plastic energy allocation in stochastic environments
Barbara Fischer1, Barbara Taborsky, Ulf Dieckmann
1Evolution and Ecology Program, International Institute for Applied Systems Analysis, Schlossplatz 1, Laxenburg, Austria. fischerb@iiasa.ac.at
The American Naturalist
|February 7, 2009
Summary
Organisms adapt energy allocation for survival and reproduction in unpredictable environments. Optimal strategies shift dramatically with energy availability, challenging traditional life-history theories.
Area of Science:
- Evolutionary Biology
- Ecology
- Life-History Theory
Background:
- Phenotypic plasticity allows organisms to benefit from varying environmental conditions.
- Optimal energy allocation is crucial for survival and reproduction in stochastic environments.
Purpose of the Study:
- To analyze an optimal energy allocation model in a stochastic environment.
- To determine the impact of environmental variability and predictability on reproductive investment and plasticity.
Main Methods:
- Utilized a general dynamic-programming model.
- Analyzed optimal energy allocation between reproduction and maintenance after maturation.
Main Results:
- Revealed non-monotonic patterns in optimal reproductive investment with changing energy availability.
- Observed that all energy is allocated to reproduction at low availability, decreasing investment at intermediate levels, and increasing again at high availability.
- Found that high environmental variability can lead to zero reproductive investment.
Conclusions:
- Optimal energy allocation strategies are complex and context-dependent, not simply increasing with resource availability.
- Results reconcile opposing predictions in life-history theory, such as 'terminal investment'.
Related Concept Videos
01:21Plastic Behavior
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and reloaded.
02:21Spontaneity
A spontaneous process is one that occurs naturally under certain conditions. A nonspontaneous process, on the other hand, will not take place unless it is “driven” by the continual input of energy from an external source. Processes have a natural tendency to occur in one direction under a given set of conditions. Water will naturally flow downhill (spontaneous process), but uphill flow (nonspontaneous process) requires outside intervention such as the use of a pump. Iron exposed to the earth’s...
01:14The Second Law of Thermodynamics
In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Scientists refer to the measure of randomness or disorder within a system as entropy. High entropy means high disorder and low energy. To better understand entropy, think of a student’s bedroom. If no energy or work were put into it, the room would quickly become messy. It would exist in a very disordered state, one of high entropy. Energy must be put...
01:10Energy Diagrams - II
Energy diagrams are important to understand the dynamics of a system. The topology of an energy diagram helps illustrate the equilibrium points of the system.
The point in the energy diagram at which the system’s potential energy is the lowest is known as the local minima. The system tends to stay in this position indefinitely unless acted upon by a net force. The slope of the potential energy diagram at the local minima is zero, indicating that zero net force is acting on the system. The slope...
The point in the energy diagram at which the system’s potential energy is the lowest is known as the local minima. The system tends to stay in this position indefinitely unless acted upon by a net force. The slope of the potential energy diagram at the local minima is zero, indicating that zero net force is acting on the system. The slope...
01:10Entropy Change in Reversible Processes
In the Carnot engine, which achieves the maximum efficiency between two reservoirs of fixed temperatures, the total change in entropy is zero. The observation can be generalized by considering any reversible cyclic process consisting of many Carnot cycles. Thus, it can be stated that the total entropy change of any ideal reversible cycle is zero.
The statement can be further generalized to prove that entropy is a state function. Take a cyclic process between any two points on a p-V diagram.
The statement can be further generalized to prove that entropy is a state function. Take a cyclic process between any two points on a p-V diagram.
00:51Energy Budgets and Reproductive Strategies
Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species reproduce only once in their lifetime, often investing most available resources into that single reproductive event. Iteroparous species, by contrast, reproduce multiple times over their lifetimes, typically allocating fewer resources to any single...