Subalpine Population Research Articles

Population structure, genetic variation and morphological diversity in indigenous sheep of Ethiopia

We investigated genetic and morphological diversity and population structure of 14 traditional sheep populations originating from four ecological zones in Ethiopia (sub-alpine, wet highland, sub-humid lowland and arid lowland). All animals (n = 672) were genotyped for 17 microsatellite markers and scored for 12 morphological characters. The sheep were initially classified as fat-tailed (11 populations), thin-tailed (one population) and fat-rumped sheep (two populations). These classifications are thought to correspond to three consecutive introduction events of sheep from the Near-East into East Africa. For the 14 populations, allelic richness ranged from 5.87 to 7.51 and expected heterozygosity (H(E)) from 0.66 to 0.75. Genetic differentiations (F(ST) values) between all pairs of populations, except between sub-alpine populations, were significantly different from zero (P < 0.001). Cluster analysis of morphological characters and a dendrogram constructed from genetic distances were broadly consistent with the classification into fat-tailed, thin-tailed and fat-rumped sheep. Bayesian cluster analysis using microsatellite markers indicated that there has been further genetic differentiation after the initial introduction of sheep into Ethiopia. Investigation of factors associated with genetic variation showed that an isolation-by-distance model, independently of other factors, explained most of the observed genetic variation. We also obtained a strong indication of adaptive divergence in morphological characters, patterns of morphological variation being highly associated with ecology even when the effect of neutral genetic divergence (F(ST)) was parcelled out in partial Mantel tests. Using a combination of F(ST) values, Bayesian clustering analysis and morphological divergence, we propose a classification of Ethiopian sheep into six breed groups and nine breeds.

A comparison of the physiology, anatomy and ribosomal DNA in alpine and subalpine populations of the lichen Nephroma arcticum—the effects of an eight-year transplant experiment

Thalli of Nephroma arcticum were transplanted between and within a high-elevation alpine heath (1100 m) and a low-elevation subalpine mountain birch forest (380 m) in northern Swedish Lapland and harvested after eight years. Statistically significant differences (P < 0.05) were found between control samples for dark respiration rates, photon use efficiencies (apparent quantum yields) and light compensation points (all were higher in the high-altitude population). The following traits were significantly affected by transplanting: (1) epicortex thickness, (2) upper cortex thickness in the low-altitude population, (3) maximum photosynthetic rates, (4) dark respiration rates and (5) light compensation point. Of these malleable traits, all reduce the differences between the controls although there seems to be over-compensation in maximum net photosynthesis and under-compensation in dark respiration rate of the low-altitude population. Conservative traits, i.e., those that did not change significantly with transplantation were: (1) thallus thickness, (2) algal layer thickness, (3) algal cell diameter and (4) light saturation level. Small, yet significant differences in anatomy and physiology suggest that an ecotypic differentiation was established although the two internal transcribed DNA spacers ITS 1 and ITS 2 showed no corresponding variation between the populations.

Variations with altitude in reproductive traits and resource allocation of three Tibetan species of Ranunculaceae

We investigated the adaptive response of alpine plants to elevational gradients by examining reproductive traits and resource allocation of three species of Ranunculaceae with contrasting mating systems in alpine and subalpine populations on the eastern QinhaiTibetan Plateu. The results showed that (i) at alpine sites, the self-incompatible Trollius ranunculoides Hemsley tended to become limited by pollination rather than by nutrient availability, although the self-compatible Anemone rivularis var. flore-minore Maxim. Fl. Tang. and A. obtusiloba D.Don. seemed not to be limited by pollen availability; (ii) influences on the reproduction of these three species induced by high altitude were seen in different reproductive characters, and the influences were, to some extent, dependent on the plant. Female investment in the self-compatible A. rivularis and A. obtusiloba was influenced by altitude and plant size; with a much lower carpel number per flower and larger mean seed size in A. rivularis, and a much higher carpel number per flower and smaller mean seed size in A. obtusiloba, at a higher altitude. Floral investment in the self-incompatible T. ranunculoides was also influenced by altitude and plant size, with a smaller single-flower size and larger seed at the higher altitude. Results also showed that (iii) reproductive allocation to flowering and fruiting did not always decrease with altitude as predicted. This may be due to higher nutrient availability in soil at alpine sites. (iv) Although self-pollination may be an assurance mechanism alleviating pollination limitation, changes in allocation pattern, (i.e. the male-biased floral sexual allocation in A. rivularis and the higher allocation to attractive structure in A. obtusiloba) seem to promote pollinator visits at the high altitude.

Phenolics and condensed tannins in relation to altitude in neotropical Pteridium spp : A field study in the Venezuelan Andes

Two species of neotropical bracken, Pteridium caudatum (L.) Maxon ( P.c.) and P. arachnoideum (Kaulf.) ( P.a.), thrive dominantly in habitats extending from near the sea level to the Andean alpine zone around 3000 m altitude. The scope of sources of stress associated with elevation has three main components: plant competition for resources, activity of herbivores/pathogens, and climate. The contribution of each component varies greatly from place to place and bracken must respond with considerable physiological/genetic plasticity to maintain its dominant status in all these habitats. Phenolic compounds have a number of properties for plant adaptation to evolutionary selective forces of biotic and climatic nature, in particular with reference to their protective role against excessive solar radiation. We have examined the second of these properties by studying the dynamics of low (LMP) and high (HMP) molecular weight phenolics in neotropical bracken ferns in two groups of field experiments: (1) their variation during the phenologic development of blades in sympatric populations of both bracken species to examine the synthesis and allocation of these materials under similar conditions of competition, predation and solar UV-B radiation; (2) the contents of LMP and HMP in six bracken populations of P.c. along its typical altitudinal range [1180–2140 m above sea level (asl)] and six additional populations of P.a. (1880–3190 m asl), which grows at higher elevations in the western Andes of Venezuela, to investigate the phenolics’ response to the ecological gradients associated with elevation in these plants. From series (1), we recorded the progressive accumulation of both types of phenolics with frond expansion, and hence increased surface of lamina exposed to sunlight, in P.c. and P.a. However, phenolics in mature blades of P.a. were 1.6 (LMP) and 3.26 (HMP) greater in amount than in P.c. From series (2), synthesis and accumulation of LMP was found to be independent of altitude, except for the subalpine population of P.a. at 3190 m asl, where a 167% increment of the average contents was recorded. By contrast, the levels of HMP correlated positively with elevation in both bracken species. The independent response of both types of phenolics to solar radiation may be interpreted as either more effective and metabolically cost-effective protection of HMP against UV-B light than LMP or differential light activation of key steps in the biosynthesis of HMP and LMP in bracken.

Treatments to improve seed germination of Arnebia benthamii: an endangered medicinal herb of high altitude Himalaya

Methods for breaking dormancy and thereby improving germination of Arnebia benthamii (Wall. ex G.Don) Johnston, an endangered medicinal herb of the high altitude Himalayas were investigated. Seeds collected from two populations (alpine and subalpine) were subjected to various treatments, viz; cold stratification (chilling and chilling + gibberellic acid), plant growth substances (gibberellic acid, 6 benzylaminopurine and a Naphthaleneacetic acid) and nitrogenous compounds (thiourea and KNO 3 ). Both the populations differed significantly (p<0.001) in response to various pretreatments. In the alpine population, thiourea (50 mM) significantly (p<0.05) improved germination over that of the control (thiourea 96%; control 42%), whereas in the subalpine population chilling (14 d) resulted in a significant (p<0.05) improvement in germination over that of the control (chilling 14 d, 62%; control 13 %). Reasons for variation in the responses of the two populations and among treatments are discussed.

Reproductive Correlates of Abdominal Fat Body Mass in Niveoscincus ocellatus, a Skink with an Asynchronous Reproductive Cycle

The relationship between the annual cycle of energy storage, in the form of abdominal fat bodies, and reproduction was studied in lowland and subalpine populations of the viviparous skink, Ni- veoscincus ocellatus. This species displays an unusual asynchronous reproductive pattern in which male and female preparations for reproduction are separated temporally, thereby providing an opportunity to clarify our understanding about the energy demands of squamate reproduction. Abdominal fat bodies in both sexes showed distinct annual cycles that were positively correlated with resource availability, peaking in summer. In males, fat body mass was correlated positively with testes development and negatively with plasma testosterone concentrations and mating behavior. This is in contrast to the patte obsernved in species with synchronous breeding cycles, where there is generally a negative relationship between testis size and lipid storage. We concluded that N. ocellatus is able to produce spermatozoa and develop abdominal fat reserves concurrently, and therefore testis size is unlikely to be constrained by energetic costs. In contrast, mating behavior appears to rely on stored energy, even though this results in reduced fat reserves for winter hi- bernation. Female fat bodies were smallest in midspring, coinciding with the end of vitellogenesis and early pregnancy. Vitellogenesis and early pregnancy appear to be energetically expensive and are reliant on stored energy in this species. Large fat bodies at the end of pregnancy in both populations are surprising given the reported high costs of reproduction. Two factors may contribute to this: resource availability may be greater in late summer, and the energetic costs associated with pregnancy appear to be highest in the early to midstages of gestation.

Density-dependent variation in reproductive success in a terrestrial orchid

Within population variation in plant density can affect reproductive success and breeding systems. We examined such effects in Listera cordata R. Br., a north temperate terrestrial orchid, in a subalpine population in Colorado, USA. Hand pollinations showed that L. cordata was self-compatible as all pollinations produced fruits. Cross-pollinations differed significantly from self-pollinations, and had a higher number of seeds per capsule and higher % of fertilized ovules. Together they could compensate for the transmission advantage of self-pollinations. Average number of flowers per inflorescence was 4.2–4.4 and average fruit set was 20.7–23.7%. By establishing 36 plots with varying plant densities (1, 4, 8 and 16) and emasculating all flowers in target plants of a set of 20 plots, we estimated density effects on fruit and seed production. Plant density had no effect on the amount of reproduction except in reduced seed production of highly dispersed plants. Our results suggest that inbreeding depression may be an important selective factor in L. cordata. Further studies are needed to define its role in the evolution of mating systems in this species.

Variations in reproductive traits at inflorescence and flower levels of an arctic legume, Astragalus alpinus L.: Comparisons between a subalpine and an alpine population

AbstractThe reproductive traits of Astragalus alpinus L. between a subalpine and an alpine population in northern Sweden were compared. This species was physiologically self‐incompatible and mainly pollinated by bumblebees. Mean flower size was larger and anthesis was longer in the alpine population than in the subalpine population. There were no significant differences in ovule fertilization rate and seed predation rate per inflorescence between the populations. However, the abortion rate of fertilized ovules was higher in the alpine population, probably because of resource limitation. The difference in seed production per inflorescence was small between the populations. Dense ovule packing within each flower may have compensated for the lower fruit production in the alpine population, where pollinator activity was low. Although the alpine population produced a smaller number of mature seeds per inflorescence, total seed mass per inflorescence did not differ between the populations due to larger seed size in the alpine population. Within an inflorescence, upper flowers had a smaller size, a relatively larger allocation to stamens, lower seed production (for both populations) and higher pollen viability (only for the alpine population) than did lower flowers. Thus, reproductive values through male and female functions may differ among flowers within an inflorescence.

The Demographic Cost of Reproduction and Its Consequences in Balsam Fir (Abies balsamea).

It is an axiom of life-history theory that reproduction involves age-specific costs in terms of survival or future reproduction. The measurement of costs of reproduction in plants is difficult, and few field studies have measured these costs in terms of fitness or demographic components, thus creating a hiatus between theory and data. In this article, we describe methods for overcoming the problem, illustrated by a field study of balsam fir. We used serial correlation and a permutation test to detect growth costs of reproduction and show how these translate into demographic costs when relative tree size (and therefore growth) is critical to survival. Using chronosequences, we reconstructed the age- and size-specific dynamics of a subalpine population of Abies balsamea. A matrix model describing these dynamics was then used to estimate age- and size-specific probabilities of future survival to maturity ([Formula: see text]). By using a regression model of the relationship between tree size, age, and [Formula: see text], we were able to estimate the maximum age-specific demographic cost of reproduction for trees of all ages. The shape of the age-specific cost curve for A. balsamea may explain why, contrary to a previously published hypothesis, age at first reproduction in A. balsamea does not vary between wave-regenerating and normal populations.

Length of the Larval Cycle of Ascaphus truei in Coastal Streams of the Redwood Region, Northern California

Length of the Larval Cycle of Ascaphus truei in Coastal Streams of the Redwood Region, Northern California

High Frequency of Extra-Pair Paternity in a Dense and Synchronous Population of Willow Warblers Phylloscopus trochilus

Genetic parentage was studied in a Norwegian, sub-alpine population of Willow Warblers Phylloscopus trochilus by means of multilocus DNA fingerprinting. We found that 33% (36/109) of the offspring were unrelated to the putative father, and that one additional offspring was unrelated to both putative parents. Altogether 50% (10/20) of the broods contained illegitimate young. The distribution of extra-pair paternity was bimodal, with several broods containing many extra-pair offspring. These results contrast markedly with a previous study of the same species, reporting no cases of mismatched parentage in a Swedish lowland population. Potentially, the high frequency of extra-pair paternity could be attributed to a higher breeding density and/or synchrony in our study population. Cuckolded males had a lower body mass, but no shorter tarsi or wings, than non-cuckolded males. This suggests that a male's loss of paternity is somehow related to his body condition. The data set includes five broods in which the pair male was permanently removed on the day the first egg was laid. There was no tendency that the manipulation increased the

Seasonal variation in size and nutrient content of eggs of the land snail Arianta arbustorum

Summary Variation in size and nutrient content of eggs deposited in successive batches is a life-history aspect that has received little attention. We examined the size and nutrient content of eggs laid in successive batches by the land snail Arianta arbustorum. Snails from three populations (a lowland, a subalpine and an alpine locality in Switzerland) differed in number of batches produced, clutch size, egg size and nutrient concentration and energy content of eggs. This was partly due to differences in shell size, since reproductive characters of A. arbustorum scale with shell size. In the first batch snails from the lowland and subalpine population laid eggs that had a higher protein concentration (28.1%) than snails from the alpine population (25.6%). Similarly, eggs from the first batch did not differ in carbon concentration in the lowland and subalpine population, whereas eggs from the alpine population had a lower concentration. Clutch size tended to decrease in successive egg batches in all populations. Egg size increased over the reproductive season in snails from the lowland population, whereas no seasonal change was observed in the subalpine and alpine population. Protein concentration decreased in successive batches in the lowland and alpine population but tended to increase in the subalpine population. Carbon concentration decreased over the season in the lowland population but not in the other two populations. This indicates (1) egg characteristics show different changes in successive batches in different snail populations, and (2) the trade-off clutch size vs. egg size can be influenced by alterations of the nutrient concentration and energy content of eggs.

Early flowers ofBartsia alpina(Scrophulariaceae) and the visitation by bumblebees

Phenology and insect visitation of early flowers of Bartsia alpina, a perennial herb, in a subalpine population in northern Sweden, were investigated to find causes for low seed set in early flowers. Bumblebees are the only visitors of B. alpina; they collect pollen and nectar. Flower phenologies of several bumblebee visited species and their nectar standing crops were measured. Flowering of Bartsia started simultaneously with Astragalus frigidus while Pedicularis lapponica was nearly out of flower. Early blooming flowers of Bartsia received fewer visits than later blooming ones. The large volumes of nectar with a high sugar concentration in early flowers indicate that bumblebees neglect or fail to discover early blooming flowers of Bartsia. Early in the season seven bumblebees species visited Bartsia but later on Bombus pascuorum was dominant. This species was also an important visitor of Astragalus. A rather low percentage of the pollen loads contained only Bartsia pollen, 27-28%, during early and peak flowering of Bartsia. Corbicular loads of B. pascuorum, the most frequent visitor of Bartsia, often contained Bartsia but also contained Astragahus pollen and to a lesser extent Ericaceae pollen (probably of Andromeda polifolia). The large variation in composition of corbicular loads indicated that bumblebees were not faithful to Bartsia only and that several plant species were visited by the same individuals. Bumblebee visitation of Bartsia and Pedicularis during a single trip may result in heterospecific pollen deposition which may lower seed set in Bartsia. Bumblebee visitation of Bartsia and Astragalus during a single trip may not result in heterospecific pollen deposition on Bartsia flowers due to the deposition of Bartsia pollen on the dorsal and Astragalus pollen on the ventral side of the body of bumblebees. Low seed set of early blooming flowers of B. alpina was probably due to low visitation rates by bumblebees. In addition, seed set of early flowers may be low due to heterospecific pollen depositions but this also may occur later in the season if the composition of corbicular loads is considered. After artificial heterospecific pollinations seed set decreased as compared with pure pollinations.

Movements and Home Ranges of Feral Pigs (Sus Scrofa) in Kosciusko National Park, New South Wales.

The movements of a subalpine population of feral pigs were examined at Kosciusko National Park in southeastern New South Wales. Sufficient data were collected to estimate the home-range area of 20 pigs on the basis of 782 telemetry and trap locations. Mean (+/- s.d.) home-range size (minimum convex polygon method) for males (35.0 t 22.2 km*2) was significantly greater than that for females (1 1.1 +/- 5.2 km*2). Use of capture-recapture distances to estimate home-range size was considered inappropriate. A test for nomadism suggests that, although home ranges of pigs in this environment were larger than those reported for other pigs in Australia, the pigs were essentially sedentary. Management implications for this population are discussed.

Terrestrial development in the Tasmanian frog, Bryobatrachus nimbus (Anura: Myobatrachinae): larval development and a field staging table

The moss froglet Bryobatrachus nimbus is a recently described terrestrial breeding and direct anuran from southwestern Tasmania. A 17-stage table based on changes in external was developed in order to calculate development rates and larval lifespan. This staging demonstrated that development was not predominantly intracapsular as earlier reported. Instead, larvae hatch from the capsule two to three months after oviposition and continue development in the nest within a homogenous, capsule-derived fluid. This reproductive mode was previoulsy known in Australia only in the Geverinia rosea complex from southwestern Australia. This paper describes the larval life-history of a subalpine population and presents data on clutch size, ovum and capsule diameters and the duration of larval development. Capsule size is almost twice that recorded for any other Australian anuran, while the larval lifespan is the longest known for any terrestrial breeding Australian species. Metamorphosis occurs approximately 12 months after oviposition.

Seasonal movement patterns in a subalpine population of the tiger salamander, Ambystoma tigrinum nebulosum

Seasonal movements of a subalpine population of metamorphic tiger salamanders, Ambystoma tigrinum nebulosum, were explored from 1990 to 1992. Metamorphic adults bred in permanent and semipermanent habitats during June of each year. After breeding, soma individuals returned to the terrestrial environment, but many remained and congregated in nonpermanent ponds. Metamorphic adults in nonpermanent ponds included those that moved from permanent ponds, those that bred and remained in semipermanent ponds, and those that did not breed but migrated from the terrestrial environment after the breeding season. Dietary analyses indicated that metamorphic adults in nonpermanent ponds have significantly greater numbers, biomass, and calories of prey in their gut than the few metamorphic adults remaining in permanent ponds. This difference was due to the presence of fairy shrimp (Branchinecta coloradensis), which composed 91 % of metamorphic adult diets in nonpermanent ponds and accounted for three times the average caloric value of all prey in gut samples from metamorphic adults in permanent ponds. Intraspecific competition also may have contributed to movement into nonpermanent ponds: post-breeding densities of metamorphic adults in permanent ponds were inversely related to the densities of other morphs (paedo-morphic adults and large larvae). We conclude that metamorphic A. t. nebulosum in this population utilize nonpermanent ponds after the breeding season because of the abundance of high-quality aquatic prey and reduced competition from con-specific morphs.

The Demography of Feral Pigs (Sus Scrofa) in Kosciusko National Park, New South Wales.

The demography of a sub-alpine population of feral pigs was examined at Kosciusko National Park in south-eastern New South Wales. Reproductive data and age structures indicated a seasonal pattern of breeding, most births occurring in summer and autumn. It is proposed that a decreasing availability of high protein food in the autumn and winter months caused reduced rates of conception. Sows produced 0.84 litters per year with postnatal mortality as high as 85%. The population appeared relatively stable at a density of 1.6 pigs kg-2. Hunting, although illegal in a national park, removed 4.4-15.4% of pigs each year. The overall health and body condition of pigs was good, with no evidence of heavy parasitic burdens or disease. Age-specific body weight and body length in this study were greater than those reported for pigs in semi-arid wester New South Wales.

Seasonal Patterns of Photosynthesis in Alpine and Subalpine Populations of the Lichen Nephroma arcticum

Photosynthetic characteristics of an alpine and a subalpine population of Nephroma arcticum, assumed to represent different ecotypes, were measured to investigate possible adaptations to their respective environments. The light compensation levels in the alpine population were consistently higher than those in the subalpine ones, and the chlorophyll contents of the former were, on average, about half those of the latter, reflecting the differences in light regimes between sites. In both populations, altitude accounted for a significant part of the variation in photosynthesis at suboptimal thallus water contents assumed to correspond to levels resulting from normal in-situ hydration (...)

WHOLE- AND PART-FLOWER SELF-POLLINATION IN GLYCINE CLANDESTINA AND G. ARGYREA AND THE EVOLUTION OF AUTOGAMY.

The overall rate of self-fertilization can be viewed as the sum of two distinct processes: 1) self-pollination of all ovules in a flower (whole-flower self-pollination); and 2) self-pollination of some of the ovules in a flower, occurring together with outcrossing of the remaining ovules (part-flower self-pollination). In some situations these processes may be equated with different modes of self-pollination. A model of the mating system in which the progeny of separate fruits serve as the unit of observation is presented. The model partitions the overall rate of self-pollination into components attributable to whole- and part-flower selfing. When the mating system is estimated using information on marker genotypes from chasmogamous fruits in two species of Glycine together with the whole- and part-flower selfing model, the results indicate that the chasmogamous flowers in a subalpine population of G. clandestina underwent a significant level of whole-flower selfing, whereas in another, lower elevation population of G. clandestina and in a subtropical population of G. argyrea, they did not. This difference is thought to be related to the contrast in the variability of environmental conditions for insect-mediated pollination between the habitats sampled. In particular, the large component of whole-flower selfing observed in the subalpine population of G. clandestina may be due to self-pollination that is induced during periods unfavorable to insect-mediated pollination. It can be demonstrated that such induced selfing will be selected whenever environmental conditions are such that pollinator activity limits seed set, and moreover that induced selfing can result in the selection of overall levels of self-pollination that are intermediate between 0 and 1. Monte Carlo simulation is employed to show that ignoring the correlation of self-fertilization events that result from whole- and part-flower selfing may lead to biased estimates of mating system parameters.

Pollination of Dianthus superbus L.

Pollination of Dianthus superbus L. was studied in a subalpine population in the Swiss Alps (San Bernardino Pass, 1,700m) in 1987 and 1988. Pollinators of this well known and beautiful plant are reported here for the first time. The flowers were visited exclusively by migratory nocturnal hawkmoths ( Herse convolvuli L.) in 1987, but in 1988 native noctuid moths were the most frequent flower visitors. The deeply divided and brightly coloured petals, calyx length and the strong sweet scent produced in the evening and distinctly weaker during the daytime suggest that Dianthus superbus is adapted to crepuscular and nocturnal hawkmoths rather than to noctuid moths. It is not especially adapted to diurnal hawkmoths and clearly not pollinated by butterflies as stated so far in the literature. Nectar is sucrose dominant with moderate sugar and amino acid concentrations and corresponds well with the syndrome of hawkmoth pollination. The observations are discussed with respect to both the plant and its pollinators.