DISTRIBUTION AND SYSTEMATICS OF THE FRESHWATER GENUS TUOMEYA (RHODOPHYTA,BATRACHOSPERMACEAE)1

Twenty-seven populations of Tuomeya, including the types of Tuomeya fluviatilis Harvey and Baileya americana Kützing, were analyzed from the entire known range of the genus: northern Newfoundland to northern Florida and east of the Mississippi River. Key morphological features were examined in detail since it has been recently proposed that Tuomeya should be reduced to a section of the genus Batrachospermum. Our observations confirmed the presence of several characteristics unique to Tuomeya: gametophyte development from a basal mass of undifferentiated cells rather than a chantransia stage, pseudoparenchymatous growth, and carpogonia with obliquely to perpendicularly attached trichogynes. Based on these findings, we conclude that the genus Tuomeya should be retained. Using multivariate morphometrics, two groupings were found that differed significantly in plant length (X = 14.1 and 24.1 mm, respectively). However, since there was no other morphometric, environmental, or geographic basis for separation of the groupings, only one species is recognized, T. americana (Kützing) Papenfuss. Populations tend to occur in large streams (>2.8 m wide) with low ion content (≤ 100 μS · cm^?1).     

Multi-unit Recording Methods to Characterize Neural Activity in the Locust (Schistocerca Americana) Olfactory Circuits

Detection and interpretation of olfactory cues are critical for the survival of many organisms. Remarkably, species across phyla have strikingly similar olfactory systems suggesting that the biological approach to chemical sensing has been optimized over evolutionary time¹. In the insect olfactory system, odorants are transduced by olfactory receptor neurons (ORN) in the antenna, which convert chemical stimuli into trains of action potentials. Sensory input from the ORNs is then relayed to the antennal lobe (AL; a structure analogous to the vertebrate olfactory bulb). In the AL, neural representations for odors take the form of spatiotemporal firing patterns distributed across ensembles of principal neurons (PNs; also referred to as projection neurons)^2,3. The AL output is subsequently processed by Kenyon cells (KCs) in the downstream mushroom body (MB), a structure associated with olfactory memory and learning^4,5. Here, we present electrophysiological recording techniques to monitor odor-evoked neural responses in these olfactory circuits.First, we present a single sensillum recording method to study odor-evoked responses at the level of populations of ORNs^6,7. We discuss the use of saline filled sharpened glass pipettes as electrodes to extracellularly monitor ORN responses. Next, we present a method to extracellularly monitor PN responses using a commercial 16-channel electrode³. A similar approach using a custom-made 8-channel twisted wire tetrode is demonstrated for Kenyon cell recordings⁸. We provide details of our experimental setup and present representative recording traces for each of these techniques.     

Long-distance relocation of nestboxes reduces nest predation by Pine Marten Martes martes

Capsule Clutches of hole-nesting passerines suffer less predation if nestboxes are moved by 800–3000 m.

Aims To see if Pine Marten predation upon clutches of insectivorous birds increases with the age of nestboxes and to see if predation is affected by the distance nestboxes are relocated from the plots where predation occurred the previous year.

Methods The study was undertaken in two habitats of central Italy (deciduous and Holm Oak wood). In each habitat, nestboxes were placed and relocated in order to have plots with: new (first year of placement) or old (second year of placement) nestboxes; short (100 m) or long-distance (800–3000 m) relocated nestboxes following previous predation.

Results After controlling for habitat, hole-nester density, competition with snakes and nestbox age, the plots with nestboxes replaced at a short distance from the original location suffered higher predation pressure. Pine Marten predation was higher in plots with older nestboxes. A high predation rate was observed in nestboxes replaced in plots where they had not been present for one year and where they had been heavily preyed on in past years.

Conclusion To reduce the risks of predation by mammals, the relocation of old nestboxes should be carried out at a long distance from plots where predation had previously occurred.     

American marten (Martes americana) in the Pacific Northwest: population differentiation across a landscape fragmented in time and space

American marten (Martes americana) have a close association with mature temperate forests, a habitat that expanded throughout the Pacific Northwest as glaciers receded at the end of the Pleistocene. Similar to several other forest-associated mammals in North America (e.g. black bear), genetic analysis of the marten shows a deep phylogeographical subdivision that reflects populations with distinctive evolutionary histories. Using a suite of 14 microsatellite markers, we explored the genetic structure of marten populations in two reciprocally monophyletic clades in the Pacific Northwest identified previously as M. caurina and M. americana by mitochondrial haplotypes and morphology. Microsatellite phylogeographical patterns were congruent with mitochondrial analyses. These independent data sets shed light upon hybridization patterns, population structure and evolutionary histories. Hybridization between M. caurina and M. americana individuals was documented in two regions of sympatry (Kuiu Island in southeastern Alaska and southern Montana). Northern insular populations of M. caurina exhibited higher differentiation and lower variability relative to northern populations of M. americana. Greater divergence among M. caurina populations may reflect longer isolation and persistence in coastal forest habitat that was fragmented by rising sea level in the early Holocene. Lower differentiation among northern M. americana populations and close relationship to other continental M. americana populations may reflect more recent expansion into the Pacific Northwest and/or continued gene flow among populations. Differentiation among M. caurina populations was attributed to habitat fragmentation (i.e. rising sea level), as opposed to isolation-by-distance; oceanic straits pose significant barriers to gene flow among M. caurina populations and between populations of M. caurina and M. americana.     

Genetic variation and structure of fisher (Martes pennanti) populations across North America

Fishers are mid-sized forest carnivores indigenous to North America that experienced sharp population declines from the early 1800s through to the mid-1900s. To evaluate levels of genetic variation within and subdivision among northern fisher populations 459 individuals were genotyped using 13 microsatellite loci. Genetic diversity was found to be slightly lower in re-introduced populations than in adjacent indigenous populations. Furthermore, fisher populations revealed much more genetic structuring than two closely related mustelids. Further investigation is needed to determine if fishers are more philopatric than martens and wolverines or if barriers to dispersal explain the levels of structure identified in this study.     

Seed dispersal by Japanese marten <Emphasis Type="Italic">Martes melampus</Emphasis> in the subalpine shrubland of northern Japan

The functions of carnivorous mammals as seed dispersers were studied during a snow-free period of 2 years in the subalpine shrubland of northern Japan. Mammal appearances, which were recorded using three automatic cameras, were dominated by Japanese marten, Martes melampus (Wagner), followed by three carnivores (ermine, red fox, and raccoon dog) and two other mammals (field mouse and Japanese hare). Fecal analysis revealed that the martens dispersed seeds of 11 species (eight woody and three herbaceous plants), which included a vine species that is an inhabitant of lower elevation sites. Fruit weight and size, and flesh weight and volume of the fleshy-fruited species foraged by the martens were significantly greater than those that were not foraged. These facts indicate that the marten plays a key role as a relatively long-distance seed disperser for major component species with large and flesh-rich fruits in the subalpine shrubland.     

Factors Affecting Landscape Occupancy by Fishers in North-Central British Columbia

ABSTRACT To better understand distribution and density of fishers (Martes pennanti) in industrial forests of north-central British Columbia, Canada, we examined factors affecting the probability of a potential home range being occupied by 10 radiotagged resident fishers in the Sub-Boreal Spruce biogeoclimatic zone between 1996 and 2000. Percentage of a home range in wetlands and recently logged (within past 12 yr) best predicted likelihood of occupancy by each fisher. Probability of a home range area being occupied by a resident fisher decreased with increasing amounts of wetlands and recent logging present in the area. We estimated that a 5% increase in wetlands or recent logging decreased the relative probability of occupancy of a potential home range by 50%. The accelerated rate of timber harvest in forests affected by mountain pine beetle (Dendroctonus ponderosae) infestations may have substantial implications for the ability of the landscape of central British Columbia to support sustainable populations of fishers.     

Rapid Homogenization of Multiple Sources: Genetic Structure of a Recolonizing Population of Fishers

Abstract: Fishers (Martes pennanti) were extirpated from much of southern Ontario, Canada, prior to the 1950s. We hypothesised that the recent recolonization of this area originated from an expansion of the population in Algonquin Provincial Park, which historically served as a refuge for fishers. To test this hypothesis, we created a sampling lattice to encompass Algonquin and the surrounding area, and we collected contemporaneous DNA samples. We sampled fishers from each of 35 sites and genotyped them at 16 microsatellite loci. Using a Bayesian assignment approach, with no a priori geographic information, we inferred 5 discrete genetic populations and used genetic population assignment as a means to cluster sites together. We concluded that the Algonquin Park fisher population has not been a substantial source for recolonization and expansion, which has instead occurred from a number of remnant populations within Ontario, Quebec, and most recently from the Adirondacks in New York, USA. The genetic structure among sampling sites across the entire area revealed a pattern of isolation-by-distance (IBD). However, an examination of the distribution of genetic structure (F_ST/1^- F_ST) at different distances showed higher rates of gene flow than predicted under a strict IBD model at small distances (40 km) within clusters and at larger distances up to 100 km among clusters. This pattern of genetic structure suggests increased migration and gene flow among expanding reproductive fronts.