Animal-defined resources reveal nutritional inadequacies for woodland caribou during summer–autumn

Populations of woodland caribou (Rangifer tarandus caribou) are declining throughout their range and many are at risk of extirpation, yet the role of nutrition in these declines remains poorly understood, in part owing to a lack of information about available nutritional resources during summer. We quantified rates of intake of digestible protein and digestible energy by tame caribou foraging in temporary enclosures in the predominant plant communities of northeastern British Columbia, Canada, during summer–autumn and compared intake rates to daily requirements for protein and energy during lactation. We tested hypotheses related to the nutritional adequacy of the environment to support nutritional requirements during lactation (with and without replenishment of body reserves) and simulated scenarios of foraging by caribou in these plant communities to better understand how wild caribou could meet nutritional demands on these landscapes. Nutritional resources varied among plant communities across seasonal, ecological, and successional gradients; digestible energy intake per minute and per day were significantly greater in younger than older forests; dietary digestible energy and per-minute and daily intake of digestible protein were greater, though not significantly so, in younger than older forests; and dietary digestible protein was greater in older than younger forests, though differences were not significant. Tame caribou were unable to satisfy protein and energy requirements during lactation, even without replenishment of body reserves, at most sites sampled. Further, foraging simulations suggested widespread nutritional inadequacies on ranges of wild caribou. Selection for habitats offering the best nutrition may mitigate some nutritional inadequacies, but given low availability of vegetation communities with high nutritional value, performance (e.g., calf production, growth, replenishment of body fat and protein) of caribou may be depressed at levels of nutrition documented herein. Our results, coupled with recent measurements of body fat of wild caribou in northeastern British Columbia, refute the hypothesis that the nutritional environment available to caribou during summer in northeastern British Columbia is adequate to fully support nutritional demands of lactating caribou, which has implications to productivity of caribou populations, recovery, and conservation.     

Loss of autumn colors under domestication: A byproduct of selection for fruit flavor?

According to the coevolution hypothesis the red autumn leaves of certain tree species are a warning signal towards insects that lay their eggs on the trees. A recent study has shown that red leaves are common in wild varieties of apple (Malus pumila) but not in cultivated varieties. This suggests that autumn colors have been lost during domestication due to relaxed selection against insects. The few varieties with red leaves have small fruits, similar to their wild ancestors, which shows that they have been under less effective artificial selection. As expected by the coevolution hypothesis these red varieties are very susceptible to an insect-borne disease, fire blight. Here I report further data on the loss of autumn colors under domestication. Since red leaf color is correlated with red fruit flesh color, if red fruit flesh has more astringent taste it is possible that loss of autumn colors is not only due to relaxed selection against insect, but also to direct artificial selection against astringent taste. However even varieties with yellow flesh turn out to have astringent taste. Moreover, while red fruit flesh is common in cultivated varieties with red leaves, it is very rare in wild varieties. It is unclear, therefore, whether loss of autumn color under domestication was a byproduct of artificial selection against red fruit flesh.Key words: coevolution, autumn colors, signaling, apple, Malus pumila, domestication, artificial selection, germplasm     

Spring‐autumn variations in hemispheric asymmetry

Abstract

48 right‐handed subjects performed verbal and spatial hemifield tachistoscopic tasks, half of them during spring and the other half during autumn. Results showed increased visual field advantage both in performance speed and accuracy in the right visual field during spring and in the left visual field during autumn. This suggests a seasonal‐hemispheric shift favouring the left hemisphere during spring and the right hemisphere during autumn, and provides a clue to understanding seasonal variations in mood and affective states as related to variations in cognitive style.     

What do red and yellow autumn leaves signal?

The widespread phenomenon of red and yellow autumn leaves has recently attracted considerable scientific attention. The fact that this phenomenon is so prominent in the cooler, temperate regions and less common in warmer climates is a good indication of a climate-specific effect. In addition to the putative multifarious physiological benefits, such as protection from photoinhibition and photo-oxidation, several plant/animal interaction functions for such coloration have been proposed. These include (1) that the bright leaf colors may signal frugivores about ripe fruits (fruit flags) to enhance seed dispersal; (2) that they signal aphids that the trees are well defended (a case of Zahavi’s handicap principle operating in plants); (3) that the coloration undermines herbivore insect camouflage; (4) that they function according to the “defense indication hypothesis,” which states that red leaves are chemically defended because anthocyanins correlate with various defensive compounds; or (5) that because sexual reproduction advances the onset of leaf senescence, the pigments might indicate to sucking herbivores that the leaves have low amounts of resources. Although the authors of hypotheses 3, 4, and 5 did not say that bright autumn leaves are aposematic, since such leaves are chemically defended, unpalatable, or both, we suggest that they are indeed aposematic. We propose that in addition to the above-mentioned hypotheses, autumn colors signal to herbivorous insects about another defensive plant property: the reliable, honest, and critical information that the leaves are about to be shed and may thus cause their mortality. We emphasize that all types of defensive and physiological functions of autumn leaves may operate simultaneously.     

Habitat selection by capercaillie in summer and autumn: Is bilberry important?

The use of habitat by female and male adult capercaillie Tetrao urogallus during summer and autumn was studied by comparing the distribution of radio locations of birds with the availability of habitat at forest stand, home range and landscape level in an area of the Bavarian Alps, Germany. Capercaillie preferred forests with structural features typical of their main distribution range, the boreal forest: they selected large patches of old forest with moderate canopy cover of about 50%, and a well developed field layer with high proportions of bilberry Vaccinium myrtillus. Hens selected both home ranges and sites within home ranges in old forest. Ranges selected by cocks did not differ from availability in the study area, but they preferred old forest within their ranges. The size of home ranges was negatively related to bilberry cover both in hens and cocks. The distribution of bilberry also determined habitat use by capercaillie at the landscape scale. The study demonstrated that bilberry is the major determinant of the selection of habitat by capercaillie in landscapes with sparse and fragmentary cover of ericaceous shrubs, such as central Europe.     

Spring and autumn territoriality in song sparrows: same behavior, different mechanisms?

Vertebrates show a diverse array of social behaviors associatedwith territoriality. Field and laboratory experiments indicatethat underlying themes—including mechanisms—mayexist. For example in birds, extensive evidence over many decadeshas implicated a role for testosterone in the activation ofterritorial aggression in reproductive contexts. Territorialityat other times of the year appeared to be independent of gonadalhormone control. One obvious question is—why this diversityof control mechanisms for an apparently similar behavior? Controlof testosterone secretion during the breeding season must balancethe need to compete with other males (that tends to increasetestosterone secretion), and the need to provide parental care(that requires lower testosterone concentrations). Regulationof aggressive behaviors by testosterone in the non-breedingseason may incur substantial costs. A series of experimentson the male song sparrow, Melospiza melodia morphna, of westernWashington State have revealed possible mechanisms to avoidthese costs. Song sparrows are sedentary and defend territoriesin both breeding and non-breeding seasons. Dominance interactions,territorial aggression and song during the non-breeding seasonare essentially identical to those during the breeding season.Although in the non-breeding season plasma testosterone andestradiol levels are very low, treatment with an aromatase inhibitordecreases aggression and simultaneous implantation of estradiolrestores territorial behavior. These data suggest that the mechanismby which testosterone regulates territorial behavior at theneural level remains intact throughout the year. How the hormonalmessage to activate such behavior gets to the brain in differentseason does, however, appear to be different.     

Can the capacity for isoprene emission acclimate to environmental modifications during autumn senescence in temperate deciduous tree species <Emphasis Type="Italic">Populus tremula</Emphasis>?

Changes in isoprene emission (Φ_isoprene), and foliage photosynthetic (A) rates, isoprene precursor dimethylallyldiphosphate (DMADP), and nitrogen and carbon contents were studied from late summer to intensive leaf fall in Populus tremula to gain insight into the emission controls by temperature and endogenous, senescence-induced, modifications. Methanol emissions, characterizing degradation of cell wall pectins, were also measured. A rapid reduction in Φ_isoprene and A of 60–70% of the initial value was observed in response to a rapid reduction of ambient temperature by ca. 15°C (cold stress). Later phases of senescence were associated with further reductions in Φ_isoprene and A, with simultaneous major decrease in nitrogen content. However, during episodes of temperature increase, A and in particular, Φ_isoprene partly recovered. Variation in Φ_isoprene during senescence was correlated with average temperature of preceding days, with the highest degree of explained variance observed with average temperature of 6 days. Throughout the study, methanol emissions were small, but a large burst of methanol emission was associated with leaf yellowing and abscission. Overall, these data demonstrate that the capacity for isoprene emission can adjust to environmental conditions in senescing leaves as well, but the responsiveness is low compared with mid-season and is also affected by stress.     

Are babies better in autumn or spring? The consequences of extending gestation in a biennially reproducing viviparous lizard

Niveoscincus microlepidotus, the southern snow skink, is a biennially reproducing alpine viviparous lizard with an extremely protracted gestation period: embryos are fully developed in autumn, but held over winter so that offspring are born in spring. The obvious benefits for offspring survival of delaying birth until spring have been demonstrated previously. To examine the consequences of deferred parturition for offspring characteristics, we compared neonates obtained in autumn by dissection with neonates born naturally in the spring. Our results demonstrate that deferral of parturition until spring represents a trade-off between key offspring characteristics (spring neonates exhibit lower growth rates, reduced sprint speed after birth, reduced condition and decreased energy reserves) and offspring size [spring neonates are heavier (wet mass) and longer (snout-vent length)]. Furthermore, when females are placed into cold experimental conditions in spring around the time of natural parturition, this species is able to defer parturition for an additional 4 weeks with no significant effect on offspring characteristics. Our results provide further evidence that flexibility in birth date provides a significant advantage to viviparous lizards living in cold climates.     

Estimated copepod production rate and structure of mesozooplankton communities in the coastal Barents Sea during summer–autumn 2007

The southern Barents Sea is considered to be the most productive area in the Arctic Ocean; however, there are no assessments of daily production rates in the coastal waters. During the summer and autumn of 2007, we investigated the variation of mesozooplankton community structure relative to environmental conditions at 12 coastal stations. Copepods dominated the total zooplankton biomass and abundance during both periods. Diversity indices and the total biomass of zooplankton communities differed significantly between the two seasons. Cluster analyses revealed two distinct groups of stations which were associated with Ura Bay and the adjacent open sea, respectively. Daily production rates of the copepod species examined were calculated using three methods based on: (1) a temperature-dependent equation and (2) two multiple regressions that consider temperature, body weight, and chlorophyll a concentration. Significant seasonal differences for daily production rates were found using all three model equations (p?<?0.05): 358?±?188–1,775?±?791 versus 198?±?85–1,584?±?559?μg?dry?mass?m^?3?day^?1. Results of principal components analyses demonstrated that the abundance and biomass of herbivorous species were related to variation in chlorophyll a concentration while the abundance and biomass of other species (omnivorous copepods and Ctenophora) were related mainly with water temperature and salinity. Mesozooplankton biomass was higher during this study relative to previous studies. Computed copepod production rates were higher compared with other Arctic seas confirming a high productive potential of the coastal southern Barents Sea.     

Satellite tracking of two Montagu’s Harriers (Circus pygargus): dual pathways during autumn migration

Autumn migration routes of two Dutch female Montagu’s Harriers (Circus pygargus) were documented for the first time using satellite telemetry. Both migrated to their African wintering area—one via the Straits of Gibraltar through the Mediterranean and the other via Italy/Tunisia. The rate of travel was comparable to values reported for larger raptor species.     

The extensive bloom of alternate-stage Prymnesium polylepis (Haptophyta) in the Baltic Sea during autumn–spring 2007–2008

During autumn 2007, an unusual increase in an algal species belonging to the order Prymnesiales was observed throughout the Baltic Sea Proper during routine national monitoring. Electron microscopical examination of the blooming species showed two types of flat scales – small and large – that resembled those of the alternate stage of Prymnesium polylepis. No spine-bearing scales were found. The 18S rDNA sequence data (n?=?20, c. 1500?bp) verified the species identification as P. polylepis. There was up to 0.5% (7?bp) variability in the P. polylepis partial 18?S rDNA sequences from the Baltic Sea. These environmental sequences differed by 0–0.35% (0–4?bp) from cultured P. polylepis (isolate UIO036), and by 1.0–3.7% from other available Prymnesium sequences. The number of cells assumed to be P. polylepis began to increase in October 2007 coincidently with significantly calm and dry weather, and at their maximum the cells accounted for over 80% of the total phytoplankton biovolume in December–January. During February–April 2008, 95% of the Prymnesiales cells were in the size class of P. polylepis (>6?µm). The species attained bloom concentrations (>1?×?10⁶?cells?l^–1) from March to May 2008. The species was observed throughout the Baltic Sea, except the Bothnian Bay, Gulf of Riga and the Kattegat. No toxic effects of the bloom were observed.     

The diet of Antarctic fur seals, Arctocephalus gazella, at King George Island, during the summer–autumn period

The diet of non-breeding male Antarctic fur seals, Arctocephalus gazella, was investigated at Stranger Point, King George Island, by scat analysis from February to April 1996. Overall, krill and fish were the most frequent prey, occurring in an average of 97% and 69% of samples (n=128), followed by cephalopods (12%). Myctophids constituted almost 90% of the fish predated, with Electrona antarctica and Gymnoscopelus nicholsi being the most abundant and frequent species consumed. All fish taxa identified were krill-feeding species suggesting that seals foraged primarily on krill and opportunistically on fish species associated with krill swarms. A seasonal change observed in the relative proportions of the different fish prey taxa indicates that fur seals spent more time foraging over the shelf in summer and off the shelf in autumn. During the study period, commercial fishing in the area was not based upon any of the fish identified in this study.     

Is fecundity in plaice (Pleuronectes platessa L.) down‐regulated in response to reduced food intake during autumn?

The effect of controlling food intake during the autumn, which is the time of late vitellogenesis, on fecundity, atresia and follicle and ovary growth was examined for plaice Pleuronectes platessa . Eighteen fish were kept in individual pens and either fed on a high or low ration diet. Fish which increased in whole body condition exhibited an increase in carcass condition which means that when food intake is sufficient to maintain whole body condition some resources are used as storage. Follicle growth rate was positively correlated with change in Fulton's condition and total atresia was negatively correlated with change in Fulton's condition. Thus, the rate of vitellogenesis was dependent on the availability of an exogenous food source. Fecundity at the end of the experiment was positively correlated with mass and total length. Food intake had no effect on relative fecundity; however, fish which had a lower food intake lost mass and had a greater intensity of atresia, lowering their absolute fecundity. One fish in a very low condition at the start of the experiment skipped spawning and one fish exhibited a decrease in average follicle diameter during the experiment which is hypothesized to be a prelude to mass atresia.     

Polyphenol gene expression and changes in anthocyanins and polyphenols in the skin of ‘Braeburn’ apples after the autumn application of prohexadione-calcium

Prohexadione-calcium (Pro-Ca) transient inhibits 2-Oxoglutarate-dependent dioxygenases and causes significant changes in the flavonoid spectrum of apple. In the present study the influence of two autumn preharvest applications of Pro-Ca on the polyphenol metabolism in apple peel during the advanced maturation was investigated. Pro-Ca was sprayed in two doses, approximately five and 3 weeks before the technological maturity. Changes in the concentrations of hydroxycinnamic acids, dihydrochalcones, flavonols, flavanols and anthocyanins as well as their related gene expression and enzyme activities in the apple peel were monitored six times during the advanced maturation until the technological maturity of the fruits. To evaluate its influence on red coloration differences in the chromatic values a*, h° and L* between the treated and untreated apples were monitored. The parameters showed a temporary effect of Pro-Ca on the intensity of red coloration, which was not detected anymore at the technological maturity of apples. The application of Pro-Ca decreased the flavanone 3-hydroxylase activity and slightly inhibited activities of all the enzymes analyzed. Concomitantly, the concentrations of anthocyanins in the peel of the treated apples decreased, whereas the concentrations of hydroxycinnamic acids, dihydrochalcones and flavan 3-ols increased. Flavonol concentrations, however, remained unchanged. The expression of ANS, ANR, FGT and MYB10 was downregulated after the Pro-Ca treatment. The results indicate that the autumn application of Pro-Ca modulates the biosynthetic pathway resulting in distinct changes in the flavonoid composition in the apple peel of ‘Braeburn’ apples. However, the changes are temporary and are generally suspended during apple storage.     

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