Cheryl A. Logan

Autumnal territorial aggression is independent of plasma testosterone in mockingbirds

Mockingbirds (Mimus polyglottos) show intense territorial activity in the autumn as newcomers attempt to establish space within resident populations. Examination of autumnal territorial behavior showed that unmated males sing more and engage in more territorial fights than mated males. Newcomers that have just acquired space also sing more and show more territorial fights than birds resident to the population for at least one prior season. Among established residents, the average number of territorial fights was greater in birds that shared more territory boundaries with new residents. Radioimmunoassay of plasma samples taken from males during the molt and following the onset of territorial defense showed that during both periods plasma concentrations of testosterone (T), dihydrotestosterone (DHT), and estradiol were basal or below the sensitivity of the assay system. Moreover, groups of males that differed in song and territorial aggression did not differ in plasma concentrations of T, DHT, or luteinizing hormone (LH). Hormone analyses confirm measurements on several other avian species suggesting that sex steroid concentrations are low in the fall and winter and that variations in aggressive behavior at this time of year may be unrelated to LH and androgen levels. Our observations contribute to a growing body of work in temperate passerines indicating that the role of androgens in mediating aggressive challenge may be restricted to the breeding season. The possible hormonal basis (if any) of song and territorial aggression in mockingbirds outside the breeding season remains obscure.

Song playback initiates nest building during clutch overlap in mockingbirds, Mimus polyglottos

Abstract Mockingbirds commonly show clutch overlap, initiating work on a subsequent brood while older young remain dependent on parental care. Several days before the male begins to build a new nest, he resumes singing. The result is a cyclic pattern of singing in which song ceases during the nestling period and recurs each time the male builds a nest. To determine if song can stimulate renesting in the presence of dependent young, and thereby regulate the amount of clutch overlap, mated males were played song earlier in the breeding cycle than they would normally begin to sing. Experimental pairs were played 140 min of mockingbird song per day in their territories beginning at nestling day 6 and continuing through the onset of renesting. They began nest building sooner and built more before the older young fledged than either males that heard no song or two that heard brown thrasher, Toxastoma rufum, song. In several pairs hearing mockingbird song, nest building continued after the stimulus song ceased, and the female laid in the nest begun in response to song. The amount of nest building was positively correlated with the males initial aggressive reaction to the speaker playing song, but unrelated to the amount of his own song production. These data constitute the first demonstration in the field of the role of passerine song in re-initiating breeding in established pairs.

Testosterone stimulates reproductive behavior during autumn in mockingbirds (Mimus polyglottos)

Mockingbirds normally secrete little or no testosterone during the period of autumnal territoriality. To determine the behavioral effects of exogenously administered testosterone, 20-mm lengths of Silastic tubing filled with crystalline testosterone were implanted into free-living resident mockingbirds during the autumn. Control residents were given sealed empty implants. Focal animal sampling showed that T-implanted males sang significantly more than controls. Perhaps as a consequence, a significantly greater percentage of the T-implanted males acquired mates. Though nest building does not naturally occur in autumn, T-implanted males also showed significantly more nest building than control males. However, T-implanted males only built if there was a female in the territory, suggesting a synergy between the presence of testosterone and social cues provided by the female. Examination of the effects of testosterone on territorial aggression showed that despite the high levels of territorial activity common in this species in autumn, territorial fights were unaffected by the presence of testosterone. One aggressive call, known to function in fall territorial defense, was significantly decreased in T-implanted versus control males. The presence of fall testosterone appears to stimulate a number of reproductive activities in mockingbirds, leaving autumnal aggressive interactions either unchanged or decreased. We discuss the application of these data to the effects of testosterone on the mockingbirds reproductive behavior during the breeding season.

The altered rationale for the choice of a standard animal in experimental psychology: Henry H. Donaldson, Adolf Meyer, and "the" albino rat.

The mid 20th-century dominance of albino rats in nonhuman experimental psychology research often presumed that the animal embodied fundamental psychological processes that could generalize to a wide range of vertebrates. The author describes the conceptual basis for the original choice of white rats by the 2 individuals most responsible for establishing rats as a prominent animal model in the life sciences at the turn of the century: Henry H. Donaldson and Adolf Meyer. The author stresses the comparative rationale that justified their choice and argues that they sought generality through attention to diversity and species differences. Their approach contrasts sharply with the later view of the rat as a generic animal model that could represent similarities shared by all vertebrates. It is suggested that the change resulted from an emphasis on standardization produced by the growing industrialization of the life sciences in America.

The legacy of Adolf Meyer's comparative approach: Worcester rats and the strange birth of the animal model.

The breeding of albino rats had an enormous impact on experimental psychology in the twentieth century: Rats were, and for many questions still remain, the “standard animal” for laboratory research in neurology, psychology, and physiology. Albert Meyer was one of the figures most responsible for developing the albino rat as an experimental model. Despite Meyer’s pioneering work with albino rats, his rat research has received only sparse attention. Little is known about the way in which the animal served Meyer’s more famous psychiatric program. In this article, the author discusses the role that albino rats played in Meyer’s animal research. He then turn to the contrast between the way in which Meyer viewed the animal’s role in research and the way rats were later used as a laboratory “standard” to assure scientific generality. This comparison highlights the changes that occurred in comparative psychology in the twentieth century, and it further clarifies some of the concerns associated with the use of animal models today.

Eugen Steinach: The First Neuroendocrinologist

In 1936, Eugen Steinach and colleagues published a work that brought steroid biochemistry to the study of sexual behavior and, using synthetic androgens and estrogens, foreshadowed by an astonishing 4 decades the discovery of the central role of estrogen in the sexual behavior of male rats. We offer an English translation of that paper, accompanied by historical commentary that presents Steinach as a pioneer in reproductive neuroendocrinology. His work 1) established the interstitial cells as the main source of mammalian gonadal hormones; 2) launched the hypothesis that steroid hormones act on the brain to induce sexual behavior and that chronic gonadal transplants produce sexual reversals in physiology and behavior; 3) demonstrated the influence of sensory stimulation on testicular function; and finally 4) spearheaded the development of synthetic commercial hormones for clinical use in humans. Although its applications were controversial, Steinachs research was confirmed by many, and his concepts were applied to fields such as oncology and vascular disease. His contemporaries lauded his research, as indicated by his 7 Nobel Prize nominations. But Steinachs basic research was rarely acknowledged as the field flourished after 1950. The translation and our commentary attempt to reverse that neglect among behavioral neuroendocrinologists and clarify his central role as a founder of the neuroendocrinology of sexual behavior and reproduction.

Developmental Analysis in Behavioral Systems The Case of Bird Song

Empirically informed debate about the convergence of nature and nurture in the development of behavior has contributed greatly to our understanding of behavioral origins. Nowhere are the issues and concerns more clearly drawn than in the contemporary literature on the development of bird By now, most participants in the debate agree on the fundamentals at issue: both organismic (genes, embryology) and environmental (acoustical, social, ecological) influences are involved in song development, and each influence contributes to a causal network within the context of the limitations placed on it by other elements in that network. It is misleading to segregate out the “parts” that result from one influence versus those that result from another and attempt to uncover the “pure” manifestation of each. Such an approach assumes an additive relation among causal influences in which each operates in isolation just as it would in concert with others. Many students of behavioral development now argue that this assumption is inaccurate. No such pure isolation of separate influences is possible. Rather, development proceeds in patterns of interconnectedness, and song results from relationships among varying sets of influences. No one influence need universally pervade the process of development; and often their history of interconnectedness is as or more important than the nature of any single influence. Despite widespread agreement on general perspectives hard won by 20 years of difficult and dedicated research, there is little consensus on where our efforts to understand song development should go next. On the one hand, Timothy Johnston criticizes the common attempt to distinguish between innate elements of song that are presumed to be under genetic control from those produced by experiential influences. He argues that this tradition commits the study of bird song to “an outmoded view of behavioral development that seeks to attribute elements of behavior separately to one of two sources: genetic information and environmental information [p. 6171 .’I On the other hand, while Peter Marler acknowledges that “all behaviour develops out of genomic-environment interactions”2 (p. 43), he also states that “scientific crippling inhibitions about acknowledging genetic contributions to behav-

Controlling and culturing diversity: experimental zoology before World War II and Vienna's Biologische Versuchsanstalt.

Founded in Vienna in 1903, the Institute for Experimental Biology pioneered the application of experimental methods to living organisms maintained for sustained periods in captivity. Its Director, the zoologist Hans Przibram, oversaw until 1938, the attempt to integrate ontogeny with studies of inheritance using precise and controlled measurements of the impact of environmental influences on the emergence of form and function. In the early years, these efforts paralleled and even fostered the emergence of experimental biology in America. But fate intervened. Though the Institute served an international community, most of its resident scientists and staff were of Jewish ancestry. Well before the Nazis entered Austria in 1938, these men and women were being fired and driven out; some, including Przibram, were eventually killed. We describe the unprecedented facilities built and the topics addressed by the several departments that made up this Institute, stressing those most relevant to the establishment and success of the Journal of Experimental Zoology, which was founded just a year later. The Institutes diaspora left an important legacy in North America, perhaps best embodied by the career of the developmental neuroscientist Paul Weiss.

Engrams and biological regulation: What was “wrong” with organic memory?

The idea that offspring could inherit attributes or dispositions that their parents had acquired is associated with the thinking of Jean-Baptiste Lamarck. But the early twentieth century saw several attempts to modernize the concept as a form of “organic” memory. I focus on one uncommonly comprehensive attempt, that of the German morphologist Richard Semon. Semon’s case is instructive because, despite an evidence-based approach that drew on cell biology, neurophysiology, and evolution, his idea was strongly resisted. Some critics failed even to address his central claim. I use criticisms of Semon’s attempt to explore some philosophical, social, and scientific barriers that combined to facilitate the decline of modernized notions of organic memory in the first half of the twentieth century, especially as applied to the science of heredity.

Behavioral inhibition induced by ingestion in sea anemones (Anthopleura elegantissima)

Following tests for initial responsiveness, the suppressive effect of ingestion ofArtemia salina on the contraction response of the sea anemone,Anthopleura elegantissima, was assessed. During testing, repeated presentations of a water-stream stimulus occurred over a period of 70 min. All subjects also underwent control testing in which the water-stream sequence was presented in the absence of priorArtemia ingestion. Significant suppression of oral disk contraction to the water stream was observed followingArtemia ingestion with and without water exchange during testing. The relationship of this finding to similar results obtained withHydra is discussed.