Lincoln P. Brower

Bio: Lincoln P. Brower is an academic researcher from Sweet Briar College. The author has contributed to research in topics: Monarch butterfly & Danaus. The author has an hindex of 53, co-authored 127 publications receiving 7733 citations. Previous affiliations of Lincoln P. Brower include University of Florida & University of California, Davis.

Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk?

Abstract: During the 2009-2010 overwintering season and following a 15-year downward trend, the total area in Mexico occupied by the eastern North American population of overwintering monarch butterflies reached an all-time low. Despite an increase, it remained low in 2010-2011. 2. Although the data set is small, the decline in abundance is statistically signifi- cant using both linear and exponential regression models. 3. Three factors appear to have contributed to reduce monarch abundance: degra- dation of the forest in the overwintering areas; the loss of breeding habitat in the Uni- ted States due to the expansion of GM herbicide-resistant crops, with consequent loss of milkweed host plants, as well as continued land development; and severe weather. 4. This decline calls into question the long-term survival of the monarchs' migra- tory phenomenon. Resumen. 1. Durante la temporada invernal 2009-2010, y siguiendo una tenden- cia a la baja de 15 anos, la superficie total ocupada por mariposas monarca en Mexico, provenientes del este America del Norte, llegoa su punto mas bajo. A pesar de su incremento, dicha superficie siguiosiendo baja en 2010-2011. 2. Aunque que el conjunto de datos disponibles es aun pequeno, esta disminucion de la abundancia de mariposas es estadisticamente significativa, tanto si se usan modelos de regresion lineales como exponenciales. 3. Hay tres factores que parecen haber contribuido con esta tendencia de reduc- ciond el numero de mariposas: la degradacion de bosque en las areas de invernacion en Mexico; la perdida de habitat de reproduccion en los Estados Unidos, debido a la expansiond e cultivos geneticamente modificados resistentes a herbicidas, con la consiguiente perdida de las plantas hospederas de algodoncillo, y por continuos cambios en el uso del suelo no favorables para ellas; y, las recientes condiciones cli- maticas severas. 4. Esta disminucion hace que nos cuestionemos sobre la posibilidad de superviven- cia a largo plazo del fenomeno migratorio de las mariposas monarca.

Understanding and misunderstanding the migration of the monarch butterfly (Nymphalidae) in North America: 1857-1995

Abstract: Since 1857, amateurs and professionals have woven a rich tapestry of biological information about the monarch butterfly's migration in North America. Huge fall migrations were first noted in the midwestern states, and then eastward to the Atlantic coast. Plowing of the prairies together with clearing of the eastern forests promoted the growth of the milkweed, Asclepias syriaca, and probably extended the center of breeding from the prairie states into the Great Lakes region. Discovery of overwintering sites along the California coast in 1881 and the failure to find consistent overwintering areas in the east confused everyone for nearly a century. Where did the millions of monarchs migrating southward east of the Rocky Mountains spend the winter before their spring remigration back in to the eastern United States and southern Canada? Through most of the 20th century, the Gulf coast was assumed to be the wintering area, but recent studies rule this out because adults lack sufficient freezing resistance to survive the recurrent severe frosts. Seizing the initiative after C. B. Williams' (1930) review of monarch migration, Fred and Norah Urquhart developed a program that gained the interest of legions of naturalists who tagged and released thousands of monarchs to trace their migration. Just as doubts in the early 1970s over whether there really were overwintering aggregations of the eastern population, on 2 January 1975 two Urquhart collaborators, Kenneth and Cathy Brugger, discovered millions of monarchs overwintering high in the volcanic mountains of central Mexico. This allowed a synthesis of the biology of this remarkable insect, including its migration and overwintering behaviors, its spread across the Pacific Ocean to Australia, its coevolution with milkweeds, and its elaborate milkweed-derived chemical defense which probably makes possible the dense aggregations during the fall migration and at the overwintering sites. Many important questions remain. Can monarchs migrate across the Gulf of Mexico? Can they migrate at night? Do they exploit strong tailwinds? Do they migrate to Central America? Do they overwinter elsewhere in Mexico or Central America? How much interchange is there between the eastern and western North American populations? How important is the fall migration along the Atlantic coast compared to the migration west of the Appalachian Mountains? What causes annual fluctuations in the size of the fall migrations? Beautiful and mysterious, the monarch's overwintering colonies in Mexico rank as one of the great biological wonders of the world. Unfortunately, these colonies are the monarch's Achilles' heel because of human population growth and deforestation in the tiny Oyamel fir forest enclaves. Additional risks arise from the increasing use of herbicides across North America which kill both larval and adult food resources. As a result, the migratory and overwintering biology of the eastern population of the monarch butterfly has become an endangered biological phenomenon. Without immediate implementation of effective conservation measures in Mexico, the eastern migration phenomenon may soon become biological history. In writing this paper for Charles Remington's honorarial issue of the Journal of the Lepidopterists' Society, fond memories flood forth of my days as his graduate student at Yale University from 1953 to 1957. My very first seminar lecture was on the migration of the monarch butterfly, Danaus plexippus (L.), and this set the stage for what will soon be 40 years of studying diverse aspects of the biology of this VOLUME 49, NUMBER 4 305 fascinating creature (reviews in Brower 1977a, 1984, 1985a, 1985b, 1986, 1987b, 1988, 1992). The present paper reconstructs the history of understanding the migration of the monarch butterfly in North America. To my knowledge, a detailed analysis of the ideas and the people who developed them has never been attempted. The story, a result of the combined observations of professional and amateur lepidopterists over more than a century, reflects the spirit in which Charles Remington, then a graduate student at Harvard, and his friend and colleague Harry Clench founded The Lepidopterists' Society in 1947 (Clench 1977). My purpose is to weave together the strands, to follow some of the red herrings, and to discuss several aspects of the migration biology that are still incompletely understood. Timely resolution of these questions should enhance efforts to preserve the monarch's mass migratory and overwintering behaviors which, regrettably, have become an endangered biological phenomenon (Brower & Pyle 1980, Brower & Malcolm 1989, 1991). The first great student of the monarch butterfly was Charles Valentine Riley, who emigrated from England and rose to lead midwestern, and then national entomology in the USA (Packard 1896, Essig 1931). In addition to being a first rate scientist, Riley was a talented artist who beautifully illustrated his descriptions of insect natural histories, and he fostered the English tradition of collating and publishing letters from a diversity of field observers, including many on the migration of the monarch. Anecdotal science on the monarch predominated well into the 20th century. In 1930, C. B. Williams of Edinburgh University reviewed monarch migration in his book, The Migration of Butterflies, which he periodically updated (Williams 1938, 1958, Williams et al. 1942). Shortly after the founding of The Lepidopterists' Society, Williams (1949:18) called for information from members and defined questions for much of the migration research that would follow: \"What happens to the butterflies that fly through Texas in the fall? Do they go on to Mexico? If so, do they hibernate there, or remain active, or breed?\" University of Toronto entomologist Fred A. Urquhart and his wife Norah took up the Williams challenge in 1940 and began tracing the fall migration of the monarch via a long-term tagging program, which would come to involve more than 3,000 research associates (Urquhart 1941,1952,1960,1978,1979,1987, Anon. 1955). The Urquharts communicated with their collaborators through an annual newsletter, published numerous papers on monarch biology, and carried on the tradition of incorporating amateurs' notes in their writings. According to Urquhart and Urquhart (1994), the final newsletter to their Insect Migration Association was issued as Volume 33 in 1994. Speculations about the destination of the eastern monarch migration 306 JOURNAL OF THE LEPIDOPTERISTS' SOCIETY became increasingly confused throughout the first three quarters of the 20th century because of the mysterious disappearance of what had to be vast numbers of butterflies that annually bred over an area of at least three million square kilometers. Many tortuous hypotheses were devised until resolution came in Urquhart's August 1976 National Geographic article announcing the discovery of the phenomenal overwintering aggregations in Mexico. This culmination of the Urquharts' lifetime efforts was one of the great events in the history of lepidopterology. FIRST OBSERVATIONS OF THE FALL MIGRATION: REPORTS FROM KANSAS TO CONNECTICUT Aside from a possible sighting of monarchs migrating in eastern Mexico during one of Christopher Columbus's expeditions (Doubleday & Westwood 1846-1852:91), D'Urban (1857) was apparently the first to report a migration of monarch butterflies. He described the butterflies appearing in the Mississippi Valley in \"such vast numbers as to darken the air by the clouds of them\" (p. 349). During September 1867 in southwestern Iowa, Allen (in Scudder & Allen 1869) described monarchs gathered in several groves of trees bordering the prairie \"in such vast numbers, on the lee sides of trees, and particularly on the lower branches, as almost to hide the foliage, and give to the trees their own peculiar color\" (p. 331). Although this clustering behavior was initially interpreted as a means of avoiding strong prairie winds, it soon became evident that it was associated with large southward movements of monarchs in the fall. The first collated evidence of massive fall migrations was published in 1868 by two American entomologists, Benjamin Dann Walsh and Charles Valentine Riley, who had independently emigrated from England to Illinois and were both keen to establish entomology as a science useful to farmers. Additionally, as evidenced in Darwin's correspondence (in F. Darwin and Seward 1903a:248-251, 1903b:385-386), Walsh and Riley were both influenced by The Origin of Species (Darwin 1859). Walsh, born in 1808, developed his interest in insects when he was nearly 50 years old, and launched his career in 1865 as associate editor of the Practical Entomologist in which he wrote, reprinted and edited numerous articles and letters, and answered letters from curious people and farmers besieged by insect pests. Within a decade he became the first Illinois State Entomologist (Riley 1870, Darwin and Seward 1903a). In contrast, Riley, born in 1843, had left his family home in England at the age of 17. By the time he was 20, he had begun publishing entomological notes in the Chicago-based Prairie Farmer (Ashmead 1895) and shortly thereafter became the journal's prolific entomological editor. In September 1868 the two men founded The American Entomologist, which Riley continued after Walsh died prematurely in VOLUME 49, NUMBER 4 307 1869 (Riley 1870). In 1868 Riley was appointed State Entomologist of Missouri, in 1876 he moved to Washington, D.C. to become Chief of the newly founded U.S. Entomological Commission, and shortly thereafter he founded the Smithsonian Institution's insect collections. Beginning in 1864, Riley used the Prairie Farmer to establish a correspondence network with midwestern farmers who were plagued by the migratory Rocky Mountain Locust. Combining his observations and high quality drawings with the information in hundreds of letters from farmers and lay

Plant poisons in a terrestrial food chain.

Abstract: palatability to avian predators, and because of the close larval food plant association of the entire subfamily, Danainae, with the classically poisonous plant families, Asclepiadaceae and Apocyanaceae.1-3 These plants contain digitalis-like cardiac glycosides which are of extreme potency as vertebrate heart toxins.1 4-6 In order to test the molecular-sequestering hypothesis, it is of great importance that the insect be holomettabolous to show definitively that the plant poisons are assimilated by the adult. In contrast, hemimetabolous insects such as grasshoppers could utilize gut storage of the plant material. Furthermore, in the absence of complete metamorphosis in terrestrial insects, the adult food is likely to be the same as or similar to that of the nymph, with the result that the imago is not a pristine entity as far as food intake is concerned. Use of the monarch butterfly avoided

Ecological Chemistry and the Palatability Spectrum

Abstract: A new bioassay for comparing the palatability to avian predators of monarch butterflies reared on various asclepiadaceous food plants containing cardiac glycosides indicates a palatability spectrum. The monarchs reared on one plant species are six times as emetic as those fed another, while those raised on an asclepiad which lacks cardiac glycosides are not emetic at all.

Butterflies and plants: a study in coevolution

Abstract: One of the least understood aspects of population biology is community evolution-the evolutionary interactions found among different kinds or organisms where exchange of genetic information among the kinds is assumed to be minimal or absent. Studies of community evolution have, in general, tended to be narrow in scope and to ignore the reciprocal aspects of these interactions. Indeed, one group of organisms is all too often viewed'as a kind of physical constant. In an extreme example a parasitologist might not consider the evolutionary history and responses of hosts, while a specialist in vertebrates might assume species of vertebrate parasites to be invariate entities. This viewpoint is one factor in the general lack of progress toward the understanding of organic diversification. One approach to what we would like to call coevolution is the examination of patterns of interaction between two major groups of organisms with a close and evident ecological relationship, such as plants and herbivores. The considerable amount of information available about butterflies and their food plants make them particularly suitable for these investigations. Further, recent detailed investigations have provided a relatively firm basis for statements about the phenetic relationships of the various higher groups of Papilionoidea (Ehrlich, 1958, and unpubl.). It should, however, be remembered that we are considering the butterflies as a model. They are only one of the many groups of herbivorous organisms coevolving with plants. In this paper, we shall investigate the relationship between butterflies and their food

The dilemma of plants: To grow or defend.

Abstract: Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially in relation to defenses against herbivores. Phenotypic and life history theories are unified within the growth-differentiation balance (GDB) framework, forming an integrated system of theories explaining and predicting patterns of plant defense and competitive interactions in ecological and evolutionary time. Plant activity at the cellular level can be classified as growth (cell division and enlargement) of differentiation (chemical and morphological changes leading to cell maturation and specialization). The GDB hypothesis of plant defense is premised upon a physiological trade-off between growth and differentiation processes. The trade-off between growth and defense exists because secondary metabolism and structural reinforcement are physiologically constrained in dividing and enlarging cells, and because they divert resources from the production of new leaf area. Hence the dilemma of plants: Th...

Citation classic - optimal foraging - a selective review of theory and tests

Abstract: Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Climate Warming and Disease Risks for Terrestrial and Marine Biota

Abstract: Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline

The Role of Disturbance in Natural Communities

Abstract: Two features characterize all natural communities. First, they are dynamic systems. The densities and age-structures of populations change with time, as do the relative abundances of species; local extinctions are commonplace (37). For many communities, a self-reproducing climax state may only exist as an average condition on a relatively large spatial scale, and even that has yet to be rigorously demonstrated (36). The idea that equilibrium is rarely achieved on the local scale was expressed decades ago by a number of forest ecologists (e.g. 10 1, 168). One might even argue that continued application of the concept of climax to natural systems is simply an exercise in metaphysics (41). While this view may seem extreme, major climatic shifts often recur at time intervals shorter than that required for a community to reach competitive equilibrium or alter the geographical distributions of species (6, 21, 43, 76, 92). Climatic variation of this kind influences ecological patterns over large areas, sometimes encompassing entire continents. Other agents of temporal change in natural communities operate over a wide range of smaller spatial scales (47, 242). Second, natural communities are spatially heterogeneous. This statement is true at any scale of resolution (242), but it is especially apparent on what is commonly referred to as the regional scale. (By region I mean an area that potentially encompasses more than one colonizable patch.) Across any land or seascape, one observes a mosaic of patches identified by spatial discontinuities in the distributions of populations (153, 159, 161, 231, 239, 240). Closer examination often reveals a smaller-scale patchwork of same-aged individuals (e.g. 85-87, 101, 146, 199,204,217-220,235,246). Discrete patch boundaries sometimes reflect species-specific responses to