Western Range Limit Research Articles

Mayflies (Ephemeroptera) of the Great Plains. IV: South Dakota

The faunal inventory of the Great Plains state of South Dakota includes 15 families, 40 genera, and 77 species of Ephemeroptera, including the first published state records for 37 species, and 187 new county records for 64 of the species. The mayfly fauna of South Dakota includes transcontinental species, widespread species, many species that typify the central lowlands of North America, and some 18 species that find their eastern range limits in South Dakota, five species that find their northern range limits in South Dakota, and 16 species that find their western range limits in South Dakota and often additional states directly north or south of South Dakota.

Is there reduction in disease and pre‐dispersal seed predation at the border of a host plant's range? Field and herbarium studies ofCarex blanda

1 Small, isolated populations at species’ borders have been postulated to be less likely to have specialist pathogens and predators. Field and herbarium surveys were thus used to determine if two pathogens (a smut and a rust) and a pre-dispersal seed predator were less common at the western range limit of the forest sedge Carex blanda in Kansas, USA. 2 Host plant size, reproduction and density did not decline at the western border of the range. In fact, plants at two western sites had unusually large size and seed production. 3 Host populations at the edge of the range were more likely to be disease-free or lack the pre-dispersal seed predator. Where the smut, seed predator and rust were found, the proportion of infected or infested plants was not related to longitude, latitude or percentage forest cover. 4 More of the peripheral populations lacked the smut than the rust, as expected given the more localized nature of smut spore dispersal and the limited period when smut infection can occur. 5 In the adjacent, more highly forested state of Missouri, there were no geographical patterns in the incidence of the smut or seed predator in herbarium data. 6 The smut and rust increased in frequency over the 129-year span of herbarium collections. 7 Although field and herbarium distributional data were not identical (for example, smut infection was found much farther west in the field than in the herbarium data), the qualitative agreement between the two data sets suggests herbarium data can be used more broadly for studies of natural enemy distributions. 8 Limited dispersal by pathogens and seed predators is probably the reason why small, isolated western populations were less likely to have natural enemies. Peripheral host populations may thus have different ecological and evolutionary trajectories compared with more central populations. This conclusion, as well as the considerable variation among peripheral populations, is relevant to geographical studies of co-evolution and to research on climatic effects on plants inhabiting ecotonal regions.

Habitat and Distribution of the Ruffed Lemur,Varecia, North of the Bay of Antongil in Northeastern Madagascar

Abstract: Here we present information on the conservation status of ruffed lemurs (Varecia) north of the Bay of Antongil in northeastern Madagascar. Two contiguous protected areas were recently established that traverse this region via blocks of forest connected by narrow forest corridors: the Masoala National Park, which expands further to the east, and the Makira Protected Area, which expands further to the west and northwest. The two extant ruffed lemurs, Varecia variegata and V. rubra, overlapped in this region historically and, on rare occasions, hybridized. As such, land north of the Bay of Antongil is a critical part of the ruffed lemur's northern geographic range. Habitat surveys and interviews with local informants were carried out in this region to determine the extent of suitable habitat for Varecia populations, to assess the extent of human exploitation of this genus, and to obtain data on the western and northern range limits of V. rubra. Interviews indicated that there are populations of V. ...

Mid-Holocene climate and the hemlock decline: the range limit of Tsuga canadensis in the western Great Lakes region, USA

Eastern hemlock (Tsuga canadensis) expanded rapidly across Upper Peninsula Michigan from ~6500 to 5500 cal. yr BP, followed by a sudden decline of hemlock pollen percentages that lasted over 1000 years. Hemlock declined throughout its range, apparently due to insect/pathogen outbreaks, which may have been affected by regional climatic shifts. Modern analogues were used to reconstruct submillennial climatic trends from fossil pollen sites spanning the western range limit of hemlock. Reconstructions from eight sites inside the range of hemlock at the time of the decline (5400 cal. yr BP) are compared with eight sites outside the range, which should be independent of variation in hemlock pollen percentages and the non-climatic effects of insects/pathogens. Expansion of hemlock before the decline occurred at a time of increasing precipitation and January temperature. Long-term precipitation averages stabilized at ~5500 cal. yr BP and remained fairly constant throughout the period of low hemlock abundance. January temperature reconstructions decrease at the time of the hemlock decline to approximately modern values at sites inside the range, as well as at oak dominated sites just outside the range. The lower-than-modern precipitation of the mid-Holocene may have reduced hemlock's tolerance for cold stress and winter desiccation and perhaps increased its susceptibility to insects or pathogens. January temperature reconstructions for pine-dominated sites outside the pre-decline hem lock range show little change, possibly due to the insensitivity of pine-dominated pollen assemblages to small climatic fluctuations. Hemlock began a new expansion across the region after 4000 cal. yr BP as July tempera ture decreased and precipitation increased.

Late Holocene Stand-Scale Invasion by Hemlock (Tsuga canadensis) at Its Western Range Limit

Late Holocene Stand-Scale Invasion by Hemlock (Tsuga canadensis) at Its Western Range Limit

IDENTIFYING FUNCTIONAL GROUPS OF TREES IN WEST GULF COAST FORESTS (USA): A TREE-RING APPROACH

A dendroclimatic study of important tree species in the west Gulf Coastal Plain region, USA, was conducted to evaluate how climate affects tree radial growth in this southeasternmost section of the Eastern Deciduous Forest/Southern Evergreen Forest. We established an east–west transect from western Louisiana to central Texas that crossed the western range limits of each of 16 species and developed a network of 104 annual tree ring-width chronologies from 38 sites. Of the 104 chronologies, 99 series from the genera Pinus, Quercus, and Fagus were analyzed using rotated principal components analysis (RPCA). The RPCA revealed the presence of three robust phylogenetic signals in the tree-ring patterns, which partitioned the data into the Pinus species (PISP), the oak species in the black oak subgenus Erythrobalanus (QUBO), and the oak species in the white oak subgenus Leucobalanus (QUWO). The Fagus chronologies (FAGR) also loaded most highly with the QUWO series, resulting in a combined QUWO/FAGR factor. This partitioning occurred even though tree species within each phylogenetic group came from contrasting xeric and mesic sites and, in the case of the QUWO/FAGR factor, from different genera. Only in the xeric western range limits of the transect did site location begin to override the phylogenetic groupings. Consequently, responses to climate based on genetics appeared to be more important than ecological and site characteristics in determining the tree-ring patterns of the sampled species overall. We tested this hypothesis by independently modeling the dendroclimate signals in the tree-ring chronologies using monthly precipitation and maximum temperature data. The resulting climate correlation functions were subjected to RPCA as before. As we did so, the same phylogenetic groups emerged. All of the chronologies were drought sensitive. However, the phylogenetic differences in climate response were related to differences in the timing of the peak monthly responses to climate and to the differing patterns of climate response in the months prior to the current growing season. The findings of this study indicate that there is an underlying organizing principle based on genetics that determines how certain phylogenetic groups of trees respond to climate in a way that is largely independent of the site environment. At a coarse level, these phylogenetic distinctions persist even at the most stressed sites near tree range limits, though distinctions within genera start to break down. These findings therefore suggest functional groupings of tree species, which can be used in vegetation/climate models that attempt to predict realistically how such forests will respond to future climate changes.

Identifying Functional Groups of Trees in West Gulf Coast Forests (USA): A Tree-Ring Approach

A dendroclimatic study of important tree species in the west Gulf Coastal Plain region, USA, was conducted to evaluate how climate affects tree radial growth in this southeasternmost section of the Eastern Deciduous Forest/Southern Evergreen Forest. We established an east–west transect from western Louisiana to central Texas that crossed the western range limits of each of 16 species and developed a network of 104 annual tree ring-width chronologies from 38 sites. Of the 104 chronologies, 99 series from the genera Pinus, Quercus, and Fagus were analyzed using rotated principal components analysis (RPCA). The RPCA revealed the presence of three robust phylogenetic signals in the tree-ring patterns, which partitioned the data into the Pinus species (PISP), the oak species in the black oak subgenus Erythrobalanus (QUBO), and the oak species in the white oak subgenus Leucobalanus (QUWO). The Fagus chronologies (FAGR) also loaded most highly with the QUWO series, resulting in a combined QUWO/FAGR factor. This partitioning occurred even though tree species within each phylogenetic group came from contrasting xeric and mesic sites and, in the case of the QUWO/FAGR factor, from different genera. Only in the xeric western range limits of the transect did site location begin to override the phylogenetic groupings. Consequently, responses to climate based on genetics appeared to be more important than ecological and site characteristics in determining the tree-ring patterns of the sampled species overall. We tested this hypothesis by independently modeling the dendroclimate signals in the tree-ring chronologies using monthly precipitation and maximum temperature data. The resulting climate correlation functions were subjected to RPCA as before. As we did so, the same phylogenetic groups emerged. All of the chronologies were drought sensitive. However, the phylogenetic differences in climate response were related to differences in the timing of the peak monthly responses to climate and to the differing patterns of climate response in the months prior to the current growing season. The findings of this study indicate that there is an underlying organizing principle based on genetics that determines how certain phylogenetic groups of trees respond to climate in a way that is largely independent of the site environment. At a coarse level, these phylogenetic distinctions persist even at the most stressed sites near tree range limits, though distinctions within genera start to break down. These findings therefore suggest functional groupings of tree species, which can be used in vegetation/climate models that attempt to predict realistically how such forests will respond to future climate changes.

Distributional Status and Natural History Observations of the Genus Argyrodes (Araneae: Theridiidae) in Kansas

Members of the genus Argyrodes Simon (Theridiidae) are small, cryptic spiders that usually occur in the webs of other spiders. Although most species in the genus are tropical, 15 occur within the continental United States (Exline and Levi, 1962). The western or northwestern range limits of four species extend into eastern Kansas. The occurrence of the genus Argyrodes in Kansas was reported first in a checklist of spiders of the University of Kansas Kansas Ecological Reserves, in Douglas and Jefferson counties (Guarisco and Fitch 1995). Careful examination of the funnelwebs produced by members of the genus Agelenopsis (Agelenidae) revealed the presence of both Argyrodes trigonum (Hentz) and A. cancellatus (Hentz). Further field work led to the discovery of Argyrodes elevatus Taczanowski and A. pluto Banks in the southeastern part of the state. The currently known distributions of these four species in Kansas are: A. trigonum: Cherokee, Douglas, Jefferson, Labette, Montgomery A. cancellatus: Bourbon, Chautauqua, Cherokee, Crawford, Douglas, Jefferson, Labette, Montgomery, Neosho, Osage A. elevatus: Bourbon, Cherokee, Douglas, Labette, Montgomery, Woodson A. pluto: Cherokee, Labette Members of the genus Argyrodes may be difficult to locate because of their cryptic coloration, form, and behavior. Field and laboratory studies have uncovered fascinating aspects of their biology. Although occasionally building their own webs, these spiders routinely invade and reside in the webs of other spiders, where they function as commensals, competitors, kleptoparasites, scavengers, and predators (Vollrath, 1987).

Mammals of North-Central Texas

North-central Texas includes five counties along the central part of the northern border of Texas. Of the 66 kinds of mammals recorded, 59 are native species and more than a third of these find their eastern or western limits of range in the area. Eastern woodland forms occupy the eastern part of the area, and Great Plains kinds the western. The Red River permits migration of both eastern and western species. Some westward immigration of eastern mammals has occurred in recent years. North-central Texas, as here defined, includes five counties that extend eastward from the eastern base of the Texas Panhandle along the Red River and make up approximately the central third of the northern border of the state. The counties, from west to east, are: Hardeman, Wilbarger, Wichita, Clay, and Montague. The area is 150 miles from west to east and averages about 30 miles from north to south. Elements of two distinct mammalian faunas meet in north-central Texas. The land west of Hardeman County is semiarid grassland and brushland and possesses a mammalian fauna typical of the Great Plains. From Montague County eastward the land is wooded and the mammals there are more typical of the woodlands of southeastern United States. From Hardeman County to Montague County the en- vironment is transitional and there is also a transition from a fauna typical of the Great Plains to a fauna of the southeastern woodlands. Many species of mammals range completely across north-central Texas. However, more than one third of the 59 full species of native mammals here listed find their eastern or western limit of range in the five-county area here considered. The woodland vole, for example, ex- tends no farther west than Montague County, and the northern grass- hopper mouse ranges no farther east than Wichita County. Neither of these species seems to have an ecological counterpart in the opposite fauna. The eastern woodrat and the southern plains woodrat meet in Clay and Montague counties. The ranges of these two species may overlap slightly but the animals are otherwise allopatric, and doubt- less they are ecological competitors.

American Caudata. III. The Status of Pseudotriton montanus in Ohio

The presence of Pseudotriton montanus ssp. in Ohio was first reported by Walker (1933: 224), on the basis of specimens in the Ohio State Museum. Subsequently, Bishop (1941: 14) described Pseudotriton montanus diastictus from Carter County, Kentucky, and various West Virginia stations, and later extended the range of this race to include southern Ohio to the exclusion of other forms of P. montanus (1943: 386; map 45). As matters stand today, most workers follow Bishop in considering diastictus the only representative of I seudotriton montanus in Ohio. That the salamanders of southern Ohio do not fit readily into any arrangement predicated largely on specimens from adjacent areas is not surprising. The region is poorly represented in most herpetological collections, although it has been an increasingly fruitful source of novelties within the past fifteen years, yielding such unusual and important records as: the allotype and many paratypes of Plethodon ricbmondi (Netting and Mittleman, 1938), the type of Gyrinophilus porphyriticus inagnoscus (Mittleman, 1942), and the only known Ohio specimens of Plethodon wehrlei (Walker, 1933), Leiolopisma utnicolor (Stupka, 1933), and Scaphiopus h. holbrookii (Gier, 1945). This general region forms the northern and western range limit of many caudate genera and species, such as Gyrinophilus, Pseudotriton, Aneides aeneus, and Plethodon richmondi. These terminal populations are often perceptibly different from others within the range of their species, although they are not always recognizable taxonomically. Taxonomic treatments of groups including forms occurring in this region are likely not to be consonant with local conditions, unless specific attention has been given to specimens collected in southern Ohio. The status of Pseudotriton montanus ssp. is an excellent case in point. Our collecting experience in southern Ohio has produced many specimens of montanus thoroughly distinct from diastictus, at least as compared with large series of topotypic specimens from northern Kentucky, but we have seen and collected other specimens indistinguishable from diastictus. In an effort to determine the status of these Ohio specimens, we have reviewed the extant

The Ferns and Fern Allies of Missouri

The fern flora of eastern North America attains its maximum development in the number of species as well as in the luxuriant abundance of many of them, in the northeastern states and in the Appalachian Mountains. The number of species diminishes gradually westward, and most of them have disappeared in the plains states, although some few extend to the Rocky Mountains, where they meet many species from the west and south, and a few of the latter range eastward as far as the Mississippi Valley. The State of Missouri, situated about half-way between the northern and southern boundaries and somewhat east of the geographical center of the United States, embraces the western range limit of several species of ferns and fern allies. Both on account of its central geographical position and of the great diversity of its topography and of its rocks and soils, the fern flora of the state is somewhat richer and more diverse than that of most of the surrounding states. Three distinct topographical regions are found in the state, and several more or less well-marked subdivisions of these might be recognized on the basis of geological formations and soils. The three main divisions from

The Western Limit of Range for Chrysemys picta bellii

The Western Limit of Range for Chrysemys picta bellii