Site characteristics and habitat requirements of the endangered dwarf bear-claw poppy ( Arctomecon humilis Coville, Papaveraceae)

Arctomecon humilis Cov. is a narrow endemic, confined to gypsiferous substrates derived from the Shnabkaib Member of the Moenkopi Formation in southwestern Utah. The characteristics of seven A. humilis sites were studied to define habitat requirements of the species. Both physical and biotic aspects of the habitat were analyzed; geology, soil chemistry, and physical properties, as well as vascular and nonvascular plant communities, were studied. Chemical and physical properties of these soils vary considerably from those supporting adjacent desert-shrub communities. The dominant vascular species on A. humilis sites are shadscale and Mormon tea. It was found that A. humilis occurred in portions of the habitat where shrubs were relatively less dense. A soil-surface, cryptogamic community contributed 84% or more of the total living cover on sites that supported A. humilis . Species composition of the cryptogamic community was highly similar among sites. Likewise, composition of the cryptogamic cover was similar when random samples were compared with samples centered on A. humilis plants. The Purgatory Flat site, which does not support the poppy, seems inseparable from A. humilis sites, in respect to soil characteristics and composition of the associated plant cover. There is reason to believe an A. humilis population could be established at the Purgatory Flat site.     

Reproductive biology and strategies of nine meloid beetles from Central Europe (Coleoptera: Meloidae)

The reproductive biology of meloid species from Central Europe is investigated by means of laboratory breeding experiments. They show that the total reproductive potential of meloids, with up to 40,000 eggs, largely exceeds prior data. Furthermore, the number of laid eggs strongly relates to the way by which the triungulins find their host. Clutch size correlates significantly with the size of the beetle, while egg size is independent of this. Both clutch size and egg size decrease with each oviposition. For some species, reproductive data are used to demonstrate how they have adapted to their habitat and to point out existing trade‐offs. Based on the obtained results and on an evaluation of the relevant literature, three types of reproductive strategy can be distinguished within the meloids: (1) very high reproductive rates of open field species with phoretic larvae; (2) average reproductive rates of forest populations of species with phoretic larvae and of species the larvae of which search the nests of their hosts actively; and (3) small to average reproductive rates of those species depositing their clutches in the immediate proximity of their hosts' nests.     

Alkaloidal relationships in the genus Arctomecon (Papaveraceae) and herbivory in A. humilis

The previously reported alkaloids (including protopines, benzophenanthridines, tetrahydrobenzylisoquinolines, and protoberberines) of the genus Arctomecon (Papaveraceae) are discussed in relation to their distribution in the plant kingdom, in the Papaveraceae, and among the three species of Arctomecon . The biological activity of these alkaloids is discussed, and possible implications for herbivore and plant-insect interactions in A. humilis are presented.     

Food habits and dietary overlap of nongame insectivorous fishes in Flint Creek, Oklahoma, a western Ozark foothills stream

Insectivorous fishes were sampled from March, 1983 to February 1984, in Flint Creek, Delaware Co., Oklahoma. There was insignificant habitat segregation between Etheostoma spectabile and E. punctulatum and seasonal habitat partitioning between Cottus carolinae and both darters. Mature E. spectabile ate primarily chironomids and mayflies, whereas juveniles fed primarily on microcrustaceans. Mature E. punctulatum consumed fewer Ephemerella and Leptophlebia than E. spectabile , feeding on Stenonema and other crustaceans. Juvenile E. punctulatum fed mainly on amphipods and mayflies, and juvenile E. spectabile ate primarily microcrustaceans. Cottus carolinae elected primarily mayflies in spring - summer and chironomids in January - February. Coefficients of dietary overlap were highest between larger E. spectabile and juvenile E. punctulatum and lowest between immature E. spectabile and mature E. punctulatum . Overlap between the two darters was significantly correlated with differences in mean prey size (p E. spectabile was also significantly correlated to differences in mean prey sizes. Etheostoma spectabile generally preferred smaller prey than E. punctulatum . All three species avoided Stenelmis . Cottus carolinae avoided microcrustaceans. The study showed that resource partitioning among these three insectivorous fishes is affected by complex interactions of habitat and prey electivity, and prey size selectivity.         

Habitat utilization by juvenile hawksbill turtles (Eretmochelys imbricata,Linnaeus, 1766) around a shallow water coral reef

Contemporary studies of sea turtle diving behaviour are generally based upon sophisticated techniques such as the attachment of time depth recorders. However, if the risks of misinterpretation are to be minimized, it is essential that electronic data are analysed in the light of first-hand observations. To this aim, we set out to make observations of juvenile hawksbill turtles (Eretmochelys imbricata, Linnaeus, 1766) foraging and resting in a shallow water coral reef habitat around the granitic Seychelles (4°'S, 55°'E). Data were collected from six study sites characterized by a shallow reef plateau (<5 m) and a flat sandy area at the base of the reef face (<10 m). Observation data were categorized into the following behaviours: (1) stationary foraging; (2) active foraging; (3) resting; and (4) assisted resting. Central to this investigation was the development of a technique for accurately estimating the size of sea turtles in situ based upon previously tested techniques for reef fishes. This revealed that through calibration, the curved carapace length (CCL) of marine turtles can be consistently estimated to within 10 cm of their actual size. Although rudimentary, this has advantages for assessing the residency or absence of specific life history stages from particular environments. Indeed, our data supported previous claims that following the reproductive season, adult hawksbills in the region may move away from the nesting beaches to alternative foraging grounds whilst immature turtles (following the pelagic juvenile stage) may opt to reside in areas close to their natal beaches. With regards to habitat utilization, juvenile hawksbills displayed an alternating pattern of short, shallow foraging dives followed by deeper, longer resting dives. These findings are consistent with previous electronic studies of free-range diving in this species and suggest that the maximization of resting duration may be an important factor driving this behaviour.     

Distribution and ecological characteristics of Lewisia longipetala (Piper) Clay, a high-altitude endemic plant

Lewisia longipetala (Piper) Clay is a high-altitude endemic found in the northern Sierra Nevada. The characteristics of 12 sites with L. longipetala , which represent all known populations, were studied to define habitat requirements of the species. Meso- and microscale characteristics of the habitat were examined, including characteristics of the associated plant community. Average plant size and plant density of L. longipetala were also determined for each population. Similar measurements were made on 6 populations of Lewisia pygmaea (A. Gray) Robinson, a more common Lewisia . Populations of L. longipetala that had larger plants and higher plant density were associated with gently sloped, north-facing sites that were near large, persistent snowbanks and had low vegetative cover. Plant species associated with populations of L. longipetala were similar among the 12 sites and were indicative of mesic, rocky alpine sites. These types of plant communities found near persistent snowbanks are often termed snow-bed vegetation. In contrast, L. pygmaea was found to be less site specific. Lewisia pygmaea was found adjacent to or interspersed with L. longipetala at 5 sites, but was found in areas associated with a higher percentage of herbaceous cover and a wider variety of species. This integration of ecological community information for L. longipetala populations contributes to the interim management and long-term monitoring of this species by providing needed information concerning its habitat and environmental specificity.     

Reproductive characteristics of Elaphe quadrivirgata (Serpentes: Colubridae) from ecologically dissimilar main island and island populations

We compared reproductive characteristics of a snake (Elaphe quadrivirgata) from two geographically distinct populations, which differ considerably in habitat use and diet. Snakes in Shiga Prefecture, in the central western area of the main island of Japan, occupy open rice fields and predominantly eat frogs. Snakes on Yakushima Island, in southwestern Japan, occupy a forest environment and mainly eat lizards. Maternal body size of snakes from Yakushima was significantly smaller than that of snakes from Shiga. Oviposition date was significantly later in snakes from Yakushima than in those from Shiga, and the former laid a smaller number of considerably elongated eggs than the latter. Relative clutch mass was significantly higher in the Shiga than in the Yakushima population, but egg mass in relation to maternal body mass of the latter was larger than that of the former. Hatchlings of Yakushima were larger than those of Shiga. This size difference in hatchlings was not fully explained by differences in egg size. These differences in reproductive characteristics between the two populations do not seem to be a consequence of morphological constraints of dam snakes. Instead, we presume that the differences in reproductive characteristics reflect local adaptations.     

Dynamics of a dwarf bear-poppy ( Arctomecon humilis ) population over a sixteen-year period

A population of the dwarf bear-poppy ( Arctomecon humilis Coville, Papaveraceae) at Red Bluff, Washington County, Utah, was monitored twice annually between 1987 and 2002. This is a narrowly endemic, gypsophilous species that has been formally listed as endangered since 1979. During the 16 years of observation, density of this species has fluctuated between 3 and 1336 individuals on the 0.07-ha monitoring plot. Moderate to large recruitments of seedlings occurred in 1992, 1995, and 2001. Seedling recruitments from a large, long-lived seed bank are triggered by abundant precipitation during the February-April period. At least 5.0 cm of rainfall is required during that interval to produce any seedlings. Seedlings experienced considerable mortality in the 1st few months of life in all observed cases. The average seedling initiated in the very large recruitment event of 1992 survived for only 2.6 years. Seedlings in that cohort that were alive 1 year after germination had an average longevity of 4.6 years. None of the seedlings that emerged in 1992 were still alive in October 2002. Mortality in this species was poorly correlated with fluctuations in precipitation or temperature. No epidemics of parasites or herbivores were observed. Mortality in the species appears to be caused by a variety of factors acting over a cohort's lifetime.     

Demographic and environmental relations of two rare Astragalus species endemic to Washington County, Utah: Astragalus holmgreniorum and A. ampullarioides

Two endemic locoweeds of Washington County, Utah, Astragalus holmgreniorum and A. ampullarioides , were recently listed as federally endangered plant species (Federal Register 2001). They both occur in few, small populations surrounded by increasing human activity in the St. George, Utah, area. Demographic and habitat studies have been ongoing since 1992 and results of those studies are presented here. Astragalus holmgreniorum (Holmgren locoweed) is presently limited to 1 larger population and 2 smaller, isolated populations on the eastern and western edges of its range. It is a short-lived perennial that grows primarily on the Virgin limestone member of the Moenkopi Formation. Density of A. holmgreniorum over the 10-year study averaged about 2 plants per m 2 . The number of living plants of this species perhaps never exceeds 10,000. In drought years A. holmgreniorum populations are as much as 95% smaller than in years with adequate water, and few plants produce flowers that successfully contribute to the seed bank. Astragalus ampullarioides (Shivwits locoweed) occurs in 4 populations where plant density fluctuated between 0.5 and 4.8 per m 2 during our study period (average = 2.6). This locoweed is restricted to clay soils of the Chinle Formation. Direct threats to both Astragalus species include widespread urbanization, road construction, population fragmentation, and off-highway vehicle use. Indirect threats include competition from aggressive, introduced annual species such as Bromus rubens, B. tectorum, Malcolmia africana , and Erodium cicutarium . Our data show that 3 of 4 species most closely associated with these Astragalus species are introduced. Studies of seed banks and reproduction biology, as well as continued monitoring of these Astragalus species, are critically needed. Studies of the consequences of competition from alien and native species on seedling establishment of these locoweeds are especially needed.     

Relationship of diurnal habitat use of native stream fishes of the eastern Great Basin to pPresence of introduced salmonids

Introduced brown trout, Salmo trutta , are common to many streams of western North America. However, the ecological interactions between brown trout and native stream fishes are not well understood, particularly the nature and extent of antipredator responses of native species. We examined the effects of brown trout presence on diurnal habitat use by 2 small native fishes at a mesohabitat scale (e.g., pool, riffle, run, backwater, etc.). Adult and juvenile southern leatherside chub ( Lepidomeda aliciae , formerly Gila copei ) and juvenile mountain sucker ( Catostomus platyrhynchus ) were located in main channel pools in the absence of brown trout, but they were found almost exclusively in backwaters and cutoff pools (i.e., off-channel habitats) in streams where brown trout were abundant. Off-channel habitat appears to provide a refuge for native fishes in streams with abundant brown trout populations. Altered or degraded streams may not include sufficient off-channel refuge habitats to allow coexistence of native species and introduced brown trout.     

Occurrence, persistence, and expansion of saltcedar ( Tamarix spp.) populations in the Great Plains of Montana

Saltcedar ( Tamarix spp.), a shrub native to Eurasia, is associated with major alterations to wetland and riparian systems in the southwestern United States. Since the 1960s saltcedar has been naturalized in northern states of the U.S. where its growth potential and impacts are not well known. Here, we describe the occurrence, age, size, and relative cover of saltcedar populations in several river basins in central eastern Montana, USA, to identify potential patterns of spread across the region and changes in individual populations as they age. Stands were aged according to the oldest saltcedar individuals and were sampled for dominant plant cover and soil properties. Multiple introductions appear to have occurred in Montana, with the oldest stands occurring on the Bighorn River in southern Montana. Saltcedar absolute and relative cover and stand area increased significantly with stand age, while native tree and shrub relative cover remained low across all stand ages. These results suggest that saltcedar stands establish where woody natives are not abundant and that they persist and expand over time. Although soil salinity remained constant, soil pH decreased with saltcedar stand age, indicating a possible effect of organic matter inputs. An analysis of annual wood increment of saltcedar and sandbar willow (a native with analogous growth form) stems along a latitudinal gradient showed that stem growth of both species did not differ significantly among regions. Stem growth decreased inversely with elevation for both species while growth responses to elevation did not differ between species. Our results show an increase in number of populations and continued viability of these populations. Mechanisms of saltcedar increases in this region are yet to be determined. Anthropogenic influences, such as saltcedar plantings, watershed alterations (e.g., river flow control), and habitat disturbances (e.g., cattle grazing or habitat clearing) may facilitate its spread in similar climates of the Great Plains.     

Growth and demography of one population of the lizard Sceloporus mucronatus mucronatus

We report on growth and demography of Sceloporus mucronatus mucronatus , a lizard subspecies endemic to central Mexico. We characterize the life history of this subspecies, provide quantitative information relevant to conservation, and add to the growing literature on the diversity of life histories in the genus Sceloporus . We calculated body growth rates and fitted them to the Von Bertalanffy, the logistic-by-length, and the logistic-by-weight growth models. The Von Bertalanffy model provided the best fit, and we used it to analyze the growth pattern. Growth rates were similar during the 1st year of life in both sexes, but after that point males grew faster and reached maturity earlier (20 months) than females (31 months). We used a population projection matrix to model population dynamics during 2003–2004 and found a positive population growth rate (λ = 1.769). However, based on the projected stable size-class vector ( w ), this population does not appear to have reached stability, and it might be currently experiencing considerable interannual fluctuations. Elasticity values showed that the transition from the juvenile stage to the 1st adult stage was the vital rate that contributes the most to population growth rate, followed by fecundity and stasis of the 1st reproductive category. While total elasticities for demographic processes were similar, elasticities per size class showed the relatively high importance of small adults in comparison to juveniles and large adults. The restriction of this endemic subspecies to central Mexico, where human activities and consequent habitat destruction are increasing, demands further quantitative evaluation and monitoring of populations, even though our results indicate a potential for population growth.     

Historic expansion of Juniperus occidentalis (western juniper) in southeastern Oregon

The chronology of Juniperus occidentalis (western juniper) expansion in eastern Oregon, the effect of plant canopy and interspace on J. occidentalis seedling establishment and growth rates, and the age of J. occidentalis maximum reproductive potential were determined. Measurements were recorded in twenty-two 0.4-ha plots established in sagebrush-grassland communities and six 0.1-ha plots in Populus tremuloides (quaking aspen) communities. J. occidentalis began increasing during the 1880s in stands containing > 130 yr old. Relatively steady establishment ensued into the 1950s and then began to progress at a geometric rate in the 19602. J. occidentalis encroachment into aspen stands began between 1910 and 1920. The largest proportion of juvenile trees established beneath Artemisia species in sagebrush-grassland communities. J. occidentalis trees appeared to reach full reproductive potential at > 50 yr of age. The ratio of male:female trees increased from 1.7 in scattered J. occidentalis stands to 3.8 in closed stands. The initiation of J. occidentalis encroachment during the late 1800s coincides with optimal climatic conditions for Juniperus berry production and establishment, reduced fire-return intervals, and heavy livestock grazing. The accelerated increase in J. occidentalis expansion since 1960 may be due to the continued absence of fire, abundant woody plant cover, and the large increase in J. occidentalis seed production.     

LIX.—Description of a species of Palæmon from near Sydney,probably either a new species or the adult form of Palæmon (Eupalæmon) danæ, Heller

Summary

Plagues of small mammals in Australia are nearly confined to rodents, both native and introduced. Only in the arid regions do small marsupials reach plague numbers.

Records of plagues have been found as early as 1845, but in many of them there is insufficient information to identify the species involved.

Plagues can develop under three main conditions, namely (a) when species are introduced into new environments, (b) in the artificial environment of crop plants, and (c) in the natural environment.

There are records of the introduced Rattus rattus forming plagues. On colonizing Lord Howe Island in 1918 the species built up to plague numbers in two years. On other islands the species is likely to have built up large populations also. Of various reported plagues on the Australian mainland, Rattus rattus has been identified definitely on only one occasion, in western New South Wales in 1887. There are earlier reports of the introduced rats and mice occurring in large numbers in unsettled areas, but it seems more likely that the animals were native species, wrongly identified, than introduced species which had spread into the areas concerned.

Two groups of species build up to plague numbers in the artificial environment of crop plants. These are Rattus conatus and some other native species which infest sugar-cane in Queensland, and Mus musculus which often infests wheatfields but also forms plagues in other habitats. Both groups infect the crop from a neighbouring natural habitat. Detailed ecological studies have been carried out on both these types of infestation. Reports of dispersal of plagues of Mus musculus need investigation.

Mus musculus can form plagues over a wide range of habitats, from the arid regions of central Australia to the high rainfall areas of tropical Queensland. The status of the form inhabiting the arid regions needs study.

The arid regions of Australia provide a special environment in which live a number of species of small mammals, both eutherians (rodents) and marsupials. In this habitat breeding occurs when there is a sufficient rainfall, and is not regulated at its extremes by an annual climatic cycle. Some of the riverine lands within the region receive drainage from outside, and this modifies the relationship with rainfall in the Lake Eyre Basin particularly. Under favourable conditions several species of the small mammals can build up to plague numbers. In this they appear to differ markedly from the small mammals of other deserts of the world. The special features of the Australian arid environment which allow this are unknown.

Plagues of Rattus villosissimus are generated in the tablelands to the south of the Gulf of Carpentaria, and hordes of the rodents disperse in large numbers, mostly moving out of the home territory along the course of rivers draining it to the south, and sometimes also to the north. The little information available concerning the populations suggests similarities with the cyclic changes which take place in populations of voles and lemmings in the northern hemisphere. There is no good information about the period of recurrence of the plagues, present records showing a range from three to seventeen years.

The little information available about the plagues of small mammals in Australia suggests parallels with such plagues elsewhere. The common factors are a small size, an herbivorous (? or insectivorous) diet, a high reproductive potential and a polymorphism which permits quick adaptation to the different population structures found under different population densities.     

The reproductive ecology of the Tahoe sucker, Catostomus tahoensis, in Pyramid Lake, Nevada

The Tahoe sucker spawns in Pyramid Lake from April to August at lake temperatures of 11.7 to 22.7 C. The spawning population is comprised of a large lake spawning group and a numerically smaller river running group. The river running group is smaller in length and was not considered during this study. The sex ratio of sampled suckers significantly favored the females. This is the result of the longer life of females and greater mortality of males during spawning. &nbsp; Pyramid Lake Tahoe suckers reach sexual maturity at two to three years of age; however, those in Lake Tahoe do not mature until four or five years of age. The size at sexual maturity is different in both populations, which suggests that size or rate of growth rather than age determines sexual maturity. &nbsp; The fecundity of Tahoe suckers is positively correlated with fork length, weight, and age. Additional analysis showed that a better correlation occurred between fish size (either length or net weight) and total ovary weight. We believe that fish size is primarily correlated with total reproductive tissue produced and secondarily with fecundity. A comparison of the Pyramid Lake population and the Lake Tahoe population demonstrated that size, not age, is the most important determinant of Tahoe sucker fecundity.     

Progenesis as a principle in meiofauna evolution

The interstitial meiofaunal taxa may have evolved in very different ways, which are shortly discussed and schematically represented. Several taxa reveal the possibility of an evolutionary pathway by early maturation of larvae or juvenile stages of large size species with a pelago-benthic life-cycle. This presumed progenetic (= neotenic) evolution can be sustantiated in, for example, various Polychaeta and Crustacea by larval or juvenile morphological features. The progenetic origin of several of these taxa is also strongly supported by morphological series, of which species conforming well with typical larvae form the endpoint. The monophyletic origin of similar progenetic taxa, however, is only proved with difficulties. The theoretical available phylogenetic reconstructions for a series of progenetic taxa are discussed. It is emphasized that progenetic evolution is not regressive or degenerate but novel morphological features like derived reproductive organs are characteristic indications of the progenetic origin of a species. In general, progenesis may have a significant role in the evolution of higher taxa in the interstitial habitat.     

Decapod Crustacea from the International Indian Ocean Expedition: The species of Funchalia (Penaeidae) and their post-larvae

Summary

Information is sparse on the ecology of the larval and juvenile stages of the lobster (Homarus gammarus (L.)). A knowledge of the distribution and particularly the abundance of this species is vital for the development of stock-recruitment theory. Attempts were therefore made to determine the distribution of juvenile lobsters in the field by Scuba diving and the fishing of small mesh traps.

As these initial attempts were of very limited success, lobsters were reared in the laboratory to study their substrate preferences and behaviour. Juvenile lobsters (～8 mm carapace length) selected coarse substrates which offered suitable crevices, or burrowed extensively in fine, cohesive mud. The rock crevice habitat is widely used by adult lobsters, but the construction of complex mud burrows has not previously been described for this genus. The burrowing behaviour of juvenile lobsters and the structure of the burrows are discussed. Juvenile lobsters appear to have wide habitat tolerances enabling them to inhabit a variety of substrate types. The estimation of juvenile lobster abundance is likely to be extremely difficult.     

Comparative population biology of Uca rapax (Smith, 1870) (Brachyura,Ocypodidae) from two subtropical mangrove habitats on the Brazilian coast

The structure of two populations of the fiddler crab Uca rapax in two subtropical mangrove habitats near Ubatuba, State of São Paulo, Brazil were compared. The size–frequency distribution, sex ratio, and recruitment were evaluated. Sampling was performed monthly from April 2001 to March 2002 in the Itamambuca and Ubatumirim habitats. Crabs were caught manually for 15?min by two collectors during low tide. The carapace width of each crab was measured with a digital caliper, and the sex and ovigerous state were recorded. The median size of the carapace width of males was greater than that of females at both sites (P<0.05). The median size of the crabs from Itamambuca was larger than at Ubatumirim (P<0.05). Only 28 ovigerous females were obtained from both mangroves, which suggested that females might remain in their burrows during the incubation period. The highest recruitment pulse occurred in winter for both populations, probably as a consequence of high reproductive activity during summer. The sex ratio in the size classes showed an anomalous pattern, with a higher frequency of females in the intermediate size classes. This may be related to a greater energy requirement for reproduction in females, thus delaying growth. The variable environmental conditions to which Uca rapax populations are subject appear to act directly or indirectly on the population, causing variations in growth and reproductive processes in the different populations investigated here.     

Ecology and conservation of the endangered quillwort Isoetes sinensis in China

Isoetes sinensis Palmer is an East Asia endemic fern that faces impending extirpation from the expansive area of Mainland China. Presently, only two natural populations are known to exist in this vast region. Both populations have decreased by about 50% within the last 4 years. This reduction is most probably related to the decline in the size of the wetlands since reproductive activity, spore production, and recruitment were noticeably lower at the microsites occurring in smaller ponds. The decline in population size seems to be associated with succession from marsh to dry land at the habitats of both populations. The study revealed that individuals in both populations produced copious numbers of spores suggesting adequate fecundity, furthermore high levels of spore germination were obtained in laboratory experiments. However, inefficient spore dispersal appears to have contributed to the limited spread of the species. The sex ratio in both populations was male‐biased. Several factors are identified here as posing a threat to Isoetes sinensis populations in China, chiefly the loss of habitat due to infrastructure construction and competition with adventive weed species for establishment on available sites. Disturbance by introduced mammals during browsing and trampling by livestock farm workers, as well as tourists, further contribute to the diminishing numbers of Isoetes sinensis at the study sites.