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Evolution

Ecology and Evolutionary Biology

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Full-Text Articles in Life Sciences

Using Google Earth To Teach The Magnitude Of Deep Time, Joel D. Parker Jan 2011

Using Google Earth To Teach The Magnitude Of Deep Time, Joel D. Parker

Joel D Parker

Most timeline analogies of geologic and evolutionary time are fundamentally flawed. They trade off the problem of grasping very long times for the problem of grasping very short distances. The result is an understanding of relative time with little comprehension of absolute time. Earlier work has shown that the distances most easily understood by teachers and students are those most people can experience directly. Thus most timeline analogies are flawed by either overcompressing an experienceable time or relying on an unexperienceable distance. Under the constraint of experienceability, the best timeline to distance scale must be at least 75 miles and ...


A Major Evolutionary Transition To More Than Two Sexes?, Joel D. Parker Feb 2004

A Major Evolutionary Transition To More Than Two Sexes?, Joel D. Parker

Joel D Parker

Two recently discovered cases of genetic caste determination in social insects might provide the first example of a major evolutionary transition from two to more than two sexes. I argue here that the system can be interpreted as comprising primarily individuals requiring gametes from three parental types and having four sexes from the perspective of demographic extinction. Additionally, I show how this mating system can be seen as a major evolutionary transition. For these populations, it is apparent that the mechanism for a three- or four-sex system does not lie within the myriad of possible arrangements of chromosomes within individuals ...


Taxonomic Differences Between Birds And Mammals In Their Responses To Chemical Irritants, Russell Mason, Larry Clark, Pankaj Shah Jan 1992

Taxonomic Differences Between Birds And Mammals In Their Responses To Chemical Irritants, Russell Mason, Larry Clark, Pankaj Shah

Larry Clark

Ninety-five products are registered with the u.s. Environmental Pro­ tection Agency as bird damage control chemicals, but 38 (40%) are non­ lethal chemical repellents (Eschen and Schafer, 1986). Of these products, the active ingredients in 27 (71%) are methiocarb (a physiologic repellent that acts through food avoidance learning) or polybutene (a tactile repel­ lent). In general, chemical repellents are effective either because of aversive sensory effects (irritation), or because of post-ingestional ma­ laise (sickness). If the former, then chemicals are usually stimulants of trigeminal pain receptors (i.e., undifferentiated free nerve endings) in the nose, mouth, and eyes (Mason ...


A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark Jan 1988

A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark

Larry Clark

We develop a simple single dimension model incorporating the time and energy commitments of breeding altricial birds in an effort to understand the evolutionary constraints on parental care. We chose time as the dimension of preference, because it is a naturally bounded constraint, e.g., length of day or breeding season. The utility of the model was evaluated by comparing simulations of time allocation of various breeding scenarios for the European starling (Sturnus vulgaris) to field data. The structure of the model may prove useful in determining the evolutionary constraints on parental care imposed by the developmental pattern of chicks.