Charles R. Darwin
(1809-1882): British naturalist and founder of the theory of evolution by means of natural selection, as described in his book On the Origins of Species by Means of Natural Selection (1859). He also described the process of sexual selection in his book The Descent of Man and Selection in Relation to Sex (1871) and the importance of comparative studies in the field of animal communication in his book The Expressions of Emotions in Man and Animals (1872).
Karl von Frisch
(1886-1982): Austrian physiologist and ethologist who received the Nobel Prize in 1973, along with Nikolaas Tinbergen and Konrad Lorenz. He studied the senses of bees, identified their mechanisms of communication and showed their sensitivity to ultraviolet and polarized light. In the center of his work were the study of the sensory perceptions (gestalt) of the honeybee and the way of the communication of these animals among themselves. He was one of the first who translated the meaning of the waggle dance.
William D. Hamilton
(1936-2000): British evolutionary biologist, considered one of the greatest evolutionary theorists of the 20th century. Hamilton became famous for his theoretical work expounding a rigorous genetic basis for the existence of kin selection. This insight was a key part of the development of a gene-centric view of evolution, and he can therefore be seen as one of the forerunners of the discipline of sociobiology. He also published important work on sex ratios and the evolution of sex.
Konrad Z. Lorenz
(1903-1989): Austrian zoologist, ethologist, and ornithologist often regarded as one of the founders of modern ethology and best known for his theory of instinct. He maintained that there is a fundamental distinction between the innate and the learned and emphasized that instincts are like reflexes and often produce stereotypical responses (fixed action patterns) to particular stimuli (sign stimuli). He also speculated that these behaviors are driven internally by a build-up of motivational energy under the control of an innate releasing mechanism. He shared the 1973 Nobel Prize for Physiology or Medicine with Niko Tinbergen and Karl von Frisch.
C. Lloyd Morgan
(1852-1936): British psychologist interested in the field he called "mental evolution", the borderland between intelligence and instinct. He is best remembered for coining the proposition now known as "Morgan's Canon" or "Lloyd Morgan's canon." Although no more than a specialized form of Occam's razor, it played a critical role in the growth of the prestige of behaviorism in twentieth century academic psychology. Lloyd Morgan was himself an acute observer of behavior, and provided convincing examples of cases where behavior that apparently involved higher mental processes could in fact be explained by simple trial and error learning (what we would now call operant conditioning).
Ivan P. Pavlov
(1849-1936): Russian physiologist and physician. He was awarded the Nobel Prize in Physiology or Medicine in 1904 for research pertaining to the digestive system. Pavlov was widely known for first describing the phenomenon now known as classical conditioning in his experiments with dogs.
(1907-1988): Dutch zoologist and ethologist who shared the 1973 Nobel Prize with Karl von Frisch and Konrad Lorenz for their discoveries concerning organization and elicitation of individual and social behaviour patterns in animals. Tinbergen's early work focused on the internal and external control of behavior and pioneered the use of carefully controlled experiments to elucidate the causes of behavior. His famous essay titled "On the aims and methods of ethology" (1963) noted that to understand behavior one must understand the causation, development, function and evolution of the behavior.
John B. Watson
(1878-1958): American psychologist who established the psychological school of behaviorism, after doing research on animal behavior. He believed that all behaviors of an organism are products of its past experiences and the mind is initially a blank slate (tabula rasa).
A behavior pattern that reliably develops in most individuals, promoting a function response to a releaser stimulus the first time the action is performed (Alcock). Instincts were whole patterns of behavior such as drinking, eating, fighting, courting, literally "driven from within" (Lorenz).
Fixed Action Pattern (FAP)
An innate, highly stereotyped response that is triggered by a well-defined, simple stimulus; once the pattern is activated, the response is performed in its entirety (Alcock).
Sign Stimulus (SS)
The effective component of an action or object that triggers a fixed action pattern in an animal (Alcock).
Innate Releasing Mechanism (IRM)
"A special (hypothetical) neurosensory mechanism that releases the reaction and is responsible for its selective susceptibility to a very special combination of sign stimuli" (Tinbergen).
A form of learning in which individuals exposed to certain key stimuli, usually early in life, form an association with the object and may later show sexual behavior toward similar objects (Alcock).
A precise descriptive catalog of all postures and patterns of movement an animal (species) might make in any natural context.
"In no case may we interpret an action as the outcome of the exercise of a higher mental faculty, if it can be interpreted as the exercise of one which stands lower in the psychological scale" (Morgan).
A subdiscipline of psychology that studied the sum total of an animal's responses, reactions, or adjustments to local stimuli and how past events affect future behavior (Watson).
Literally, a "blank slate" or state of the mind of an organism at birth under the theory of behaviorism.
Associative learning where the pairing of a conditioned and unconditioned stimulus to produce a unconditioned response can lead to a conditioned response in the presence of the unconditioned stimulus alone.
A kind of learning based on trial and error, in which an action or operant becomes more frequently performed if it is rewarded (Alcock).
Also direct selection. The process that occurs when individuals differ in their traits and the differences are correlated with differences in reproductive success. Natural selection can produce evolutionary change when these differences are inherited (Alcock).
A process that is identical with natural selection, except that humans control the reproductive success of alternative types within the selected population (Alcock).
The degree of genetic transmission of a trait from parents to offspring.
Any measurable aspect of an individual that arises from an interaction of the individual's genes with its environment (Alcock).
The genetic constitution of an individual; may refer to the alleles of one gene possessed by the individual or to its complete set of genes (Alcock).
A measure of the genes contributed to the next generation by an individual, often stated in terms of the number of surviving offspring produced by the individual. Direct fitness is the genes contributed by an individual via personal reproduction in the bodies of surviving offspring.
A characteristic that confers higher inclusive fitness to individuals than any other existing alternative exhibited by other individuals with the population; a trait that has spread or is spreading or is being maintained in a population as a result of natural selection (Alcock).
The sum of an individual's direct and indirect fitness; indirect fitness is the genes contributed by an individual indirectly by helping non-descendent kin, in effect creating relatives that would not have existed with the help of the individual (Alcock).
A form of natural selection that occurs when individuals vary in their ability to compete with others for mates or to attract members of the opposite sex. As with natural selection, when the variation among individuals is correlated with genetic differences, sexual selection leads to genetic changes (evolution) in the population (Alcock).
A form of sexual selection where individuals of the limiting sex (usually females) selects particular mates of the opposite sex (usually males); this special case is called female-choice.
A form of sexual selection where individuals of the non-limiting sex (usually males) compete directly for access to the limiting sex (usually females); this special case is called male-male competition.
The process that occurs when individuals differ in ways that affect their parental care or helping behavior, and thus the survival of their own offspring, or the survival of nondescendant kin (Alcock).
The process that occurs when individuals differ in their collective attributes and the differences affect the survival chances of the groups (Alcock).
A change in gene frequency (proportions) in a population over generations. These changes may be due to selection (natural, sexual, kin) or by chance events (genetic drift, gene flow, mutation).
An immediate, underlying cause based on the operation of internal mechanisms possessed by the individual; or how a behavior occurs (Alcock).
The evolutionary, historical reason why something is the way it is; or why a behavior occurs (Alcock).
A process that is identical with natural selection, except that humans control the reproductive success of alternative types within the selected population.
The process at the heart of Darwin's theory of evolution. Natural selection occurs when variants of a trait that best suit an organism to its environment, and that are heritable, increase in frequency over evolutionary time. This process requires variation, fitness differences, and heritability.
Simple rules of genetic transmission such as segregation and independent assortment that describes the transmission of one or two traits from one generation to the next - based on the discoveries of Gregor Mendel.
A procedure that allows for targeted mutagenesis resulting in individuals lacking a normal copy of one specific gene, thus allowing a detailed examination of that gene's specific influence on development, physiology and behavior.
The process that occurs when individuals differ in traits and the differences are correlated with differences in reproductive success resulting in a directional change in the mean phenotype of a population.
The process that occurs when individuals differ in traits and the differences are correlated with differences in reproductive success resulting in no net change in the mean phenotype of a population, but instead a reduction in the phenotypic variants that differ most from the population mean.
The process that occurs when individuals differ in traits and the differences are correlated with differences in reproductive success resulting in two (or more) optimal phenotypes that differ from the original population mean.
Frequency dependent selection
A form of natural (or sexual) selection in which those individuals that happen to belong to the less common of two types in the population are the ones that are more fit because of their lower frequency in the population.
A method for studying the adaptive value of alternative traits based on the recognition that phenotypes come with fitness costs and fitness benefits; an adaptation has a better cost-benefit ratio than alternative versions of that trait.
An evolutionary history via common descent.
The depiction of phylogeny by using branching tree-like diagrams.
A technique for choosing among alternative phylogenetic trees by selecting the tree that requires the fewest character changes.
Phylogenetic comparative method
A procedure based on the assumption of maximum parsimony of assigning the ancestral character states of closely related taxa.
Chemical messengers that travel via extracellular fluids to specific receptors on adjacent cell membranes.
Chemical messengers that travel via the blood to specific target tissues where they cause changes in the activities of the target tissue cells.
Chemical messengers that travel via fluids outside of the body to specific target receptors in other organisms that causes changes in the activity of the target tissue cells.
A neural cluster or an integrated set of clusters that has primary responsibility for the control of a particular behavioral activity.
A nerve cell that relays messages either from receptor neurons to the central nervous system (a sensory interneuron) or from the central nervous system to neurons commanding muscle cells (a motor interneuron).
A neural signal; a self-regenerating change in membrane electrical charge that travels the length of a nerve cell.
The point of near contact between one nerve cell and another.
Central pattern generator
A group of cells in the central nervous system that produces a particular pattern of signals necessary for a functional behavioral response.
The capacity of nerve cells and neural networks to ignore stimuli that could potentially elicit a response from them.
Cycle of activity with an approximate 24 hour period that expresses itself independent of environmental cues.
The number of light and dark hours in a 24 hour period.
An internal physiological mechanism that enables organisms to time any of a wide assortment of biological processes and activities.
Length of time from the beginning one cycle to the beginning of the next.
The cycle of activity of an individual that is expressed in a constant environment.
The re-setting of a biological clock so that an organism's activities are scheduled in keeping with local conditions.
Cycle of activity with an approximate 13-18 hour period depending on the location that expresses itself independent of environmental cues.
Cycle of activity with an approximate 28 day period that expresses itself independent of environmental cues.
Cycle of activity with an approximate 365 day period that expresses itself independent of environmental cues.
Caudomedial neostriatum is innervated by auditory neurons and shows increased ZENK gene expression when stimulated by birdsong.
Shows high levels of ZENK gene activity when first attempts to match own song to tutor's song.
Higher vocal center is the song memory center. Individuals with more songs have larger HVCs. HVC has neurons specifically tuned to the male's own song and those of familiar rivals.
Is a gene active in vocal center nuclei during song learning.
The involuntary movement of a motile organism involving a change of place toward (positive) or away (negative) from a source of stimulation. phototaxis = light, phonotaxis = sound, chemotaxis = chemical molecules, geotaxis = gravity, magnetotasis = magnetic fields.
A simple stimulus response connection believed to be unlearned and characteristic of a species.
Becoming less sensitive to stimuli over time.
Becoming more sensitive to stimuli over time.
AKA Operant conditioning
A form of learning in which individuals exposed to certain key stimuli, usually early in life, form an association with the object and may later show sexual behavior toward similar objects.
The capacity of an individual to react differently to others based on the degree to which they are genetically related.