Paul D Heideman

William & Mary | WM · Department of Biological Sciences

The photoperiodic response of many temperate zone rodents, including white-footed mice (Peromyscus leucopus), is a heritable life-history trait with underlying physiological variation. Previous studies of intact male P. leucopus utilized two wild-derived bidirectional selection lines, a short photoperiod responsive (R) line selected for reproductiv...

Under natural conditions, many aspects of the abiotic and biotic environment vary with time of day, season or even era, while these conditions are typically kept constant in laboratory settings. The timing information contained within the environment serves as critical timing cues for the internal biological timing system, but how this system drive...

Drawing by learners can be an effective way to develop memory and generate visual models for higher-order skills in biology, but students are often reluctant to adopt drawing as a study method. We designed a non classroom intervention that instructed introductory biology college students in a drawing method, minute sketches in folded lists (MSFL),...

The evolution of brain function in the regulation of physiology may depend in part upon the numbers and locations of neurons. Wild populations of rodents contain natural genetic variation in the inhibition of reproduction by winter-like short photoperiod, and it has been hypothesized that this functional variation might be due in part to heritable...

Subject Areas: health and disease and epidemiology, ecology, environmental science The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology , behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agricu...

In natural populations, genetic variation in seasonal male sexual behaviour could affect behavioural ecology and evolution. In a wild-source population of white-footed mice, Peromyscus leucopus, from Virginia, U.S.A., males experiencing short photoperiod show high levels of genetic variation in reproductive organ mass and neuroendocrine traits rela...

Two continuing puzzles in clock biology are the synchronizing mechanisms (zeitgebers) for endogenous circannual clocks in tropical organisms and the neuroendocrine sources of heritable variation in annual timing in natural populations. Tropical species of mammals are often as highly seasonal as temperate zone mammals. In many bats, these may be reg...

This article is part of a Special Issue "Energy Balance". Natural populations display a variety of reproductive responses to environmental cues, but the underlying physiology that causes these responses is largely unknown. This study tested the hypothesis that heritable variation in reproductive traits can be described by heritable variation in con...

Heritable variation in metabolic traits is likely to affect fitness. In this study, white-footed mice from wild-derived photoresponsive [R, infertile in short day length (SD)] and non-photoresponsive (NR, fertile in SD) selection lines were maintained under short-day (SD 8Light:16Dark), sub-thermoneutral conditions (22 or 12 °C). Mice had significa...

A naturally variable life-history trait with underlying physiological variation is the photoperiodic response of many temperate-zone rodents, including white-footed mice (Peromyscus leucopus (Rafinesque, 1818)). Male P. leucopus were obtained from a short photoperiod responsive (R) line, artificially selected for reproductive suppression in short-d...

Natural genetic variation in reproduction and life history strategies is a manifestation of variation in underlying regulatory neuronal and endocrine systems. A test of the hypothesis that genetic variation in luteinizing hormone (LH) level could be related to a life history trait, seasonal reproduction, was conducted on artificial selection lines...

A key question in the evolution of life history and in evolutionary physiology asks how reproductive and other life-history traits evolve. Genetic variation in reproductive control systems may exist in many elements of the complex inputs that can affect the hypothalamic-pituitary-gonadal (HPG) or reproductive axis. Such variation could include numb...

Hypothalamic genes involved in food intake and growth regulation were studied in F344 rats in response to photoperiod. Two sub-strains were identified: F344/NHsd (F344/N) and F344/NCrHsd (F344/NCr); sensitive and relatively insensitive to photoperiod respectively. In F344/N rats, marked, but opposite, changes in the genes for neuropeptide Y (NPY) (...

Seasonal environments favor the timing, of reproduction to match seasons when Successful reproduction is most likely. Most species of temperate zone mammals suppress reproduction in winter using changes in day length as a cue. In many species, individuals vary genetically in how strongly they respond to these seasonal cues. Individuals also may mod...

Variation in circadian rhythms and nocturnality may, hypothetically, be related to or independent of genetic variation in photoperiodic mediation of seasonal changes in physiology and behavior. We hypothesized that strain variation in photoperiodism between photoperiodic F344 rats and nonphotoperiodic Harlan Sprague Dawley (HSD) rats might be cause...

The evolution of mammalian brain function depends in part on levels of natural, heritable variation in numbers, location, and function of neurons. However, the nature and amount of natural genetic variation in neural traits and their physiological link to variation in function or evolutionary change are unknown. We estimated the level of within-pop...

Although most temperate-zone mammals are seasonal breeders, many populations display variation in winter reproductive phenotype. For most mammals, the primary environmental cues regulating reproductive status are food availability and photoperiod, and these two factors can interact in their effect. Low food availability is primarily thought to supp...

1.The pineal hormone melatonin influences thermoregulation in many species, but the mechanism of action is unknown.2.We tested whether melatonin could act directly on the primary thermoregulatory control center in the preoptic area and anterior hypothalamus (PO/AH), using a white-footed mouse tissue slice preparation.3.PO/AH neurons were classified...

The exploration of many of the fundamental features of mammalian behavioral neuroendocrinology has benefited greatly throughout the short history of the discipline from the study of highly inbred, genetically characterized rodents and several other "traditional" exemplars. More recently, the impact of genomic variation in the determination of compl...

Responsiveness to changing photoperiods from summer to winter seasons is an important but variable physiological trait in most temperate-zone mammals. Variation may be due to disorders of melatonin secretion or excretion, or to differences in physiological responses to similar patterns of melatonin secretion and excretion. One potential cause of no...

Natural variation in neuroendocrine traits is poorly understood, despite the importance of variation in brain function and evolution. Most rodents in the temperate zones inhibit reproduction and other nonessential functions in short winter photoperiods, but some have little or no reproductive response. We tested whether genetic variability in repro...

Reproductive costs can affect survival and future reproduction. In winter and in short photoperiods, some individuals within populations of temperate‐zone rodents inhibit reproduction and decrease food intake, while others do not. Two lines derived from a natural population of White‐Footed Mice and selected to maintain or inhibit reproduction in sh...

Laboratory rats have been generally considered non-photoresponsive, but strains of laboratory rats have been found to be variable for this trait. Young males of both the Fischer (F344) and Brown Norway strains (BN) suppress reproductive development, food intake and body mass in short winter photoperiod (short days (SD); 8 h light:16 h darkness), an...

Variation in complex physiological pathways has important effects on human function and medical treatment. Complex pathways involve cells at multiple locations, which serve different functions regulated by many genes and include complex neuroendocrine pathways that regulate physiological function. One of two competing hypotheses regarding the effec...

Differences among species and among years in reproductive seasonality (the tendency for clusters of events to fall at approximately the same point in each year) and synchrony (amount of clustering of events within a year) have been intensively studied in bats, but are difficult to assess. Here, we use randomization methods with circular statistics...

Although laboratory rats are often considered classic nonseasonal breeders, peripubertal rats of two inbred strains, F344 and BN, have both reproductive and nonreproductive responses to short photoperiods. Unmanipulated adult rats have not been reported to have robust responses to short photoperiod alone, although several treatments can induce phot...

Rattus norvegicus has been considered nonphotoperiodic, but Fischer 344 (F344) rats are inhibited in growth and reproductive development by short photoperiod (SD). We tested photoresponsiveness of the genetically divergent Brown Norway (BN) strain of rats. Peripubertal males were tested in long photoperiod or SD, with or without 30% food reduction....

Many temperate-zone species use photoperiod as an environmental cue to regulate reproductive timing. Strains of laboratory rats differ in their responsiveness to photoperiod, with the Fischer 344 (F344) strain being the most responsive known. F344 rats and closely related strains that differ in photoresponsiveness may be useful models to study the...

In laboratory-bred rodent populations, intraspecific variation in circadian system organization is a known cause of individual variation in reproductive photoresponsiveness. The authors sought to determine whether circadian system variation accounted for individual variation in reproductive photoresponsiveness in a single, highly genetically variab...

Reproductive and life-history strategies vary tremendously among bats, even within species. Understanding the nature of this variation and the evolution of these strategies requires an understanding of the mechanisms responsible. This chapter reviews what is known about environmental factors that affect reproduction in bats in the context of both u...

In laboratory-bred rodent populations, intraspecific variation in circadian system organization is a known cause of individual variation in reproductive photoresponsiveness. The authors sought to determine whether circadian system variation accounted for individual variation in reproductive photoresponsiveness in a single, highly genetically variab...

Photoperiod is the major regulator of reproduction in temperate-zone mammals. Laboratory rats are generally considered to be nonphotoresponsive, but young male Fischer 344 (F344) rats have a uniquely robust response to short photoperiods of 8 h of light. Rats transferred at weaning from a photoperiod of 16 h to photoperiods of < 14 h of light slowe...

Phenotypic variation in reproductive response to photoperiod is typical of many temperate-zone populations of rodents. This variation could be due either to genetic variation in photoresponsiveness or phenotypic plasticity within populations genetically homogeneous for photoresponsiveness. At least some of this variation has been shown to be geneti...

Photoperiod is an environmental cue used by many temperate-zone species to regulate their reproductive timing. Within species, the degree of reproductive photoresponsiveness can vary widely both among and within populations. The neuroendocrine mechanisms causing this individual variation in photoresponsiveness are unknown. Using selected lines from...

Laboratory rats generally do not respond reproductively to short days (SD) unless they are given treatments that unmask reproductive inhibition in SD. While young Fischer 344 (F344) rats are unusual among rat strains in that SD substantially inhibit their reproductive response, the inhibition is not as strong as in the classically photoresponsive s...

Laboratory rats generally do not respond reproductively to short days (SD) unless they are given treatments that unmask reproductive inhibition in SD. While young Fischer 344 (F344) rats are unusual among rat strains in that SD substantially inhibit their reproductive response, the inhibition is not as strong as in the classically photoresponsive s...

Mammals respond to electrolyte and water imbalance by a variety of neural and endocrine mechanisms that regulate water and salt intake and loss. We used the expression of c-fos and Fos-related antigens to indicate neuronal activation in hypothalamic neurons of members of an outbred laboratory population of white-footed mice (Peromyscus leucopus) de...

Ptenochirus jagori (Megachiroptera, Pteropodidae) is a tropical cynopterine fruit bat restricted to the Philippine islands. Samples of bats were obtained over 4 years, and reproductive tracts were preserved and examined using standard histological techniques. Reproductive status also was recorded for bats captured, marked, and released. A facultati...

Laboratory rats are considered to be reproductively unresponsive to photoperiod because photoperiod treatments do not induce robust reproductive responses. Groups of 15 young male Fischer 344 (F344) rats were tested for effects of long (16L:8D) and short (8L:16D) photoperiods on testicular development and body mass. Two weeks of short photoperiod i...

It has been hypothesized that pineal structure and function might differ between temperate zone and tropical species of mammals because of lower amplitudes of seasonal change in photoperiod and, in some areas, less seasonal climatic variation. Anoura geoffroyi produce a single offspring in November or December of each year on the Caribbean island o...

The effects of social cues from adult conspecifics on the rate of sexual maturity were studied in a tropical rodent, the cane mouse (Zygodontomys brevicauda), in the laboratory. Several aspects of the biology of this species have suggested that it might be atypical in that young females may not accelerate or decelerate their rate of reproductive de...

Most species of mammals live in the tropics, and many breed seasonally, but little is known about the regulation of their seasonal cycles. Males of a tropical bat, Anoura geoffroyi (Order Chiroptera, Family Phyllostomidae), from 10 degrees latitude in Trinidad, were studied to test the role of photoperiod in regulating seasonal reproduction in the...

Otopteropus cartilagonodus (Megachiroptera, Pteropodidae) is a rare, small-bodied cynopterine bat endemic to Luzon Island in the Philippine Archipelago. Twenty-two female and seven male O. cartilagonodus were collected during March and May of 1988. Observations were made on early embryonic development and the morphology of ovaries, uteri, and teste...

The cane mouse (Zygodontomys brevicauda) breeds year-round on the hot llanos of Venezuela, only 8 degrees above the equator. The reproductive responses of the males of this species to heat were compared with those of a temperature zone rodent, the white-footed mouse (Peromyscus leucopus). When tested at different ambient temperatures, the movement...

Data from a laboratory colony of Peromyscus nudipes founded with individuals trapped at 10°N latitude near Monte verde, Costa Rica, were compared with published and new data on the same population in the wild as a basis for assessing phenotypic plasticity in lifehistory characteristics. Mean litter size was almost identical in the wild and in the l...

Empirical data suggest that reproductive photoresponsiveness occurs in some populations of mammals above 13 degrees of latitude, but may be absent in populations from 0 degrees to 10 degrees of latitude. The present experiments examined the degree to which the low amplitude of change in photoperiod in the tropics constrains mammals from using dayle...

A total of 48 indigenous species are known to occur on the three islands: 45, 30, and 25 from Leyte, Biliran, and Maripipi, respectively. All but three of these species occur on the large neighboring island of Mindanao. The exceptions include a widespread but rarely captured vespertilionid bat and two rodents that have sister-species on Mindanao. A...

Anoura geoffroyi (Chiroptera, Phyllostomidae, Glossophaginae), Geoffroy's hairy-legged long-tongued bat, were collected from September 1984 to August 1985, and these bats were found to breed seasonally in the wild on Trinidad, West Indies, at 10 degrees N latitude. Histological examination of these samples indicated that females became pregnant in...

A population of cloud forest mice (Peromyscus nudipes) at latitude 10 degrees N near Monteverde, Costa Rica, was sampled four times by live-trapping twice during the 7-8 month wet season and twice during the 4-5 month dry season in 1989 and 1990. Body weights were lower during the early part of the dry season in males and throughout the dry season...

Cane mice (Zygodontomys brevicauda) are year-round breeders in Venezuela. As shown previously, these animals are not reproductively responsive to variation in photoperiod. In the present experiments, male cane mice were maintained on long or short day lengths (16L:8D or 8L:16D, respectively) and challenged with each of three experimental treatments...

Laboratory colonies of the Neotropical muroid rodent Zygodontomys brevicauda have been employed in studies of arbovirus epidemiology and are currently the subjects of experimental research on tropical mammalian reproductive physiology and evolutionary quantitative genetics. Captive-bred litters typically consist of 4 or 5 pups weighing 3-4 g each a...

Wild populations of Peromyscus are often composed of individuals that vary greatly in their reproductive response to photoperiod. A population of white-footed mice (P. leucopus) from Michigan (43 degrees N) was subjected to mass selection in the laboratory both for and against reproductive photoresponsiveness for four generations. The first generat...

Traditionally, the adaptive value of mammalian white fat stores is considered in relation to long-term needs such as providing protection against the vagaries of winter or signalling the reproductive system when energy reserves are sufficient to risk pregnancy. As shown here, the fat stores of young house mice could not serve such needs. Despite pr...

Descendants of a sample of cane mice (Zygodontomys brevicauda) trapped at 8 degrees latitude in Venezuela were tested for reproductive photoresponsiveness. This species breeds continuously, year around, despite living in a seasonally harsh habitat. At 50 days of age there were no differences in the weights of the testes or seminal vesicles or in sp...

These studies focused on the phenomenon of "catch-up" pubertal development. Circulating levels of several hormones were characterized in 8-wk-old female rats whose growth and reproductive development had been blocked before puberty by restricting their food intake. Some of these females were fed ad libitum for 24 h to initiate rapid pubertal develo...

Of the six species of free-tailed bats from selected sites in northwestern Yucatan, Molossus sinaloae was taken most frequently, followed in order by Eumops glaucinus, Molossus ater, Eumops bonariensis, Promops centralis, and Tadarida laticaudata. Tile roof roost data for M. ater, M. sinaloae, and E. bonariensis showed some aggregation and, for the...

In submontane rainforest on Negros Island, C Philippines, temporal variation in the percentage of plants in flower or fruit was generally less than 2-fold. Temporal variation in abundance of flowers or fruits was up to 4-fold among some months. A peak in flowering during the dry season and early part of the wet season was due to temporal variation...

a3 Department of Biology, Silliman University, Dumaguete, Negros Oriental, 6501, Philippines(Accepted September 26 1988)

Thirteen species of megachiropteran bats were captured in primary forest at 830–1000 m on Negros Island in the central Phillippines; 1229 individuals were marked and released. Individuals of six species were recaptured, for an overall recapture rate of 13%. For these six species, mean movement distance ranged from 0.16 to 0.75 km. For the two speci...

Trapping and netting of small mammals on a land-bridge island (Leyte) and on an oceanic island (Negros) revealed similar patterns of elevational change in abundance and species richness. Fruit bats (Pteropodidae) reached their greatest local densities in agricultural areas, and were least abundant in montane mossy forest. The fruit bats found to be...

A long delay in post-implantation embryonic development was detected in Fischer's pygmy fruit bats (palaeotropical fruit bats of the suborder Megachiroptera), the first time such a delay has been demonstrated outside the bat suborder Microchiroptera. Samples of bats were obtained from the Philippines over 5 years, and reproductive tracts were prese...

In climatically seasonal habitats, favourable periods for reproduction may be simply determined by large annual changes in temperature or rainfall. In contrast, in climatically less seasonal habitats, reproductive timing may be determined by a wide variety of seasonal factors. Three hypotheses regarding reproductive timing were tested for a fruit b...

Thesis (Ph. D.)--University of Michigan, 1987. Includes bibliographical references (p. 306-320). Photocopy.