The influence of desert temperature cycles on the reproductive biology of Pseudodiplorchis americanus (Monogenea)

Parasitology ◽  
1991 ◽  
Vol 103 (1) ◽  
pp. 111-120 ◽  
Author(s):  
K. Tocque ◽  
R. C. Tinsley
Keyword(s):  
Reproductive Biology ◽  
Laboratory Data ◽  
Reproductive Development ◽  
Optimal Growth ◽  
First Year ◽  
Effective Period ◽  
Temperature Regimes ◽  
Soil Temperatures ◽  
Abiotic Control ◽  
Summer Temperatures

Pseudodiplorchis americanus has an extremely brief opportunity for transmission, restricted to less than 24 h in the year when the host (Scaphiopus couchii) enters water to breed. This strict annual cycle means that invading worms have 1 year to complete reproductive development. Despite this, a large proportion of the parasite suprapopulation is not prepared for transmission at the time of host breeding. The present study correlates detailed soil temperatures for one field site in S.E. Arizona, spanning 3·5 years, with laboratory data on parasite growth and reproductive development at a series of controlled temperatures. Development is totally inhibited at 16°C. Optimal growth and development occurs at 25°C and is slower at both 20°C and a diurnal cycle fluctuating between 20 and 34°C (mean 27°C) (simulating summer temperatures experienced by host and parasite). The effective period for accumulation of infective stages by P. americanus in any one season varies according to the timing of the summer rains in consecutive years. Between 1985 and 1988, the interval between host breedings varied from 11 to 13 months and the period when temperatures were above 20°C varied from 4 to 5·5 months per year. Since the first month post-infection (p.i.) consists of pre-reproductive development, first-year worms have only 3–4·5 months to produce infective larvae. In the shortest seasons, these worms may not be able to complete reproductive preparation in time for the first opportunity for transmission. In different parts of the geographical distribution of S. couchii, different cycles of temperature, rainfall and host breeding occur; varying temperature regimes represent an important abiotic control of P. americanus reproductive biology and transmission.

An integrated approach for tracking climate-driven changes in treeline environments on different time scales in the Valle d’Aosta, Italian Alps

The Holocene ◽  
2021 ◽  
pp. 095968362110259
Author(s):  
Anna Masseroli ◽  
Giovanni Leonelli ◽  
Umberto Morra di Cella ◽  
Eric P Verrecchia ◽  
David Sebag ◽  
...  
Keyword(s):  
Integrated Approach ◽  
Early Summer ◽  
Ice Age ◽  
Limiting Factor ◽  
Alpine Treeline ◽  
Growing Seasons ◽  
Direct Measurements ◽  
Soil Temperatures ◽  
Summer Temperatures ◽  
Local Station

Both biotic and abiotic components, characterizing the mountain treeline ecotone, respond differently to climate variations. This study aims at reconstructing climate-driven changes by analyzing soil evolution in the late Holocene and by assessing the climatic trends for the last centuries and years in a key high-altitude climatic treeline (2515 m a.s.l.) on the SW slope of the Becca di Viou mountain (Aosta Valley Region, Italy). This approach is based on soil science and dendrochronological techniques, together with daily air/soil temperature monitoring of four recent growing seasons. Direct measurements show that the ongoing soil temperatures during the growing season, at the treeline and above, are higher than the predicted reference values for the Alpine treeline. Thus, they do not represent a limiting factor for tree establishment and growth, including at the highest altitudes of the potential treeline (2625 m a.s.l.). Dendrochronological evidences show a marked sensitivity of tree-ring growth to early-summer temperatures. During the recent 10-year period 2006–2015, trees at around 2300 m a.s.l. have grown at a rate that is approximately 1.9 times higher than during the 10-year period 1810–1819, one of the coolest periods of the Little Ice Age. On the other hand, soils show only an incipient response to the ongoing climate warming, likely because of its resilience regarding the changeable environmental conditions and the different factors influencing the soil development. The rising air temperature, and the consequent treeline upward shift, could be the cause of a shift from Regosol to soil with more marked Umbric characteristics, but only for soil profiles located on the N facing slopes. Overall, the results of this integrated approach permitted a quantification of the different responses in abiotic and biotic components through time, emphasizing the influence of local station conditions in responding to the past and ongoing climate change.

scholarly journals Delayed implantation in giant pandas: the first comprehensive empirical evidence

Reproduction ◽  
2009 ◽  
Vol 138 (6) ◽  
pp. 979-986 ◽  
Author(s):  
Hemin Zhang ◽  
Desheng Li ◽  
Chendong Wang ◽  
Vanessa Hull
Keyword(s):  
Reproductive Biology ◽  
Giant Panda ◽  
Reproductive Development ◽  
Mammary Glands ◽  
Strongly Correlated ◽  
Physiological Changes ◽  
Giant Pandas ◽  
Delayed Implantation ◽  
Infant Birth ◽  
First Time

Successful conservation of an endangered species relies on a good understanding of its reproductive biology, but there are large knowledge gaps. For example, many questions remain unanswered with regard to gestation and fetal development in the giant panda. We take advantage of a sample size that is unprecedented for this species (n=13) to explore patterns in reproductive development across individuals at the China Conservation and Research Center for the Giant Panda. We use ultrasound techniques on multiple giant pandas for the first time to empirically confirm what has long been suspected that pandas exhibit delayed implantation of the embryo. We also show that the duration of postfetal detection period is remarkably similar across individuals (16.85±1.34 days). Detection of fetus by ultrasound was strongly correlated to the peak in urinary progesterone (r=0.96, t=8.48, d.f.=8, P=0.0001) and swelling in the mammary glands (r=0.79, t=3.61, d.f.=8, P=0.007) and vulva (r=0.91, t=6.40, d.f.=8, P=0.0002) of adult females. When controlling for both the duration of the total gestation period and the postfetal detection period, infant birth weight was only significantly predicted by the latter (β=11.25, s.e.m.=4.98, t=2.26, P=0.05), suggesting that delayed implantation increases flexibility in the timing of birth but is not important in dictating infant growth. This study informs reproductive biology by exploring the little-studied phenomenon of delayed implantation in relationship to physiological changes in pregnant giant panda females.

Determining the content of nitrogen and some macroelements in the dry mass of perennial leguminous plants

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Željko Lakić ◽  
Mirjana Žabić ◽  
Tihomir Predić
Keyword(s):  
Dry Matter ◽  
Red Clover ◽  
Optimal Growth ◽  
Dry Mass ◽  
First Year ◽  
Random Block ◽  
Beginning Of Flowering ◽  
Set Up ◽  
Perennial Legumes ◽  
Nitrogen Phosphorus

The aim of this study was to determine the content of elements N, P, K, Ca, and Mg in the dry mass of perennial fodder legumes, mowed in the optimal growth phase. The experiment with perennial legumes of alfalfa (Medicago sativa), red clover (Trifolium pretense) and bird's-foot trefoil (Lotus corniculatus L.) was set up as a random block system in four replicates on valley-brown soil and was conducted for two years. The green mass of perennial legumes in the first and second mowing was harvested at the end of budding/ beginning of flowering phase. In the third and fourth regrowth, mowing of the biomass was done after 5 weeks. Immediately after each mowing, representative sample of green biomass was taken from each replicate of each legume tested. The content of nitrogen, phosphorus, potassium, calcium, and magnesium in the dry plant material was determined. The content of nitrogen and potassium in the fodder of alfalfa and red clover was higher in the first year of the study, which was not the case for bird's-foot trefoil. The dry matter of alfalfa on average had the highest content of nitrogen (39.8 g kg-1 DM) and calcium (19.6 g kg-1 DM), bird's-foot trefoil of phosphorus (10.6 g kg-1 DM) and potassium (26.1 g kg-1 DM), and red clover of magnesium (3.7 g kg-1 DM). In the dry mass of bird's-foot trefoil the average content of nitrogen was 39.0 g kg-1 DM, phosphorus 10.6 g kg-1 DM, potassium 26.1 g kg-1 DM, calcium 15.7 g kg-1 DM, and magnesium 3.5 g kg-1 DM.

Effects of photoperiod on reproductive development of peanut (Arachis hypogaea L.) in a cool subtropical environment. I. Field studies

1991 ◽  
Vol 42 (7) ◽  
pp. 1133 ◽  
Author(s):  
MJ Bell ◽  
G Harch
Keyword(s):  
Treatment Period ◽  
Arachis Hypogaea ◽  
Reproductive Development ◽  
Field Studies ◽  
Sowing Date ◽  
Climatic Data ◽  
Subsequent Paper ◽  
Temperature Regimes ◽  
Arachis Hypogaea L ◽  
Subtropical Environment

The effects of photoperiod on reproductive development and yield of two Virginia, one Spanish and one Valencia peanut (Arachis hypogaea L.) cultivar were investigated in the field at Kingaroy, Australia. The objective was to assess the importance of photoperiod as a limitation to post-flowering reproductive development in a cool subtropical environment. A total of five experimental sowings were made between the 1986/87 and 1988/89 growing seasons. Treatments consisted of either natural photoperiods (ranging from 11 to 14 h, depending on sowing date and growth stage) or long (16 h) photoperiods during a range of phenological stages, both pre- and post-flowering. Long photoperiods were achieved by using low intensity light from incandescent bulbs with equal extension periods in both morning and evening. Different sowing dates and seasons were used to produce a range of natural photoperiods, radiation and temperature regimes, while shadecloth was used to alter incident irradiance during the 1988/89 experiments. Photoperiod responses were significant in only one experiment (S2, 1986/87), and were due to effects of treatment during the immediate post-flowering period. Numbers of flowers, pegs and pods were reduced under long photoperiods in cv. Robut 33-1, and to a lesser extent, in cv. White Spanish. The Virginia cv. Uf 781 14-5 was unaffected. The effects of long photoperiods during this 30 day post-flowering treatment were not expressed until after the treatment period. Effects were relatively small and reproductive (pod) yields at maturity were not significantly reduced. The lack of strong photoperiod responses in the reportedly sensitive Valencia cv. NC17090 and the occurrence of the strongest response in the relatively insensitive cv. Robut 33-1 were unexpected. Analysis of climatic data from these experiments, and others reported in the literature, suggested interactions between photoperiod and temperature, with photoperiod effects being only significant at higher temperatures, i.e. in our studies, when mean daily temperature during the treatment period was 26-0�C. This finding is of considerable significance in assessing the importance of photoperiod sensitivity for cultivar adaptation to long day/subtropical environments. A subsequent paper in this series examines photoperiod x temperature interactions more closely under controlled environment conditions.

Reproductive biology of the parsley frog, Pelodytes punctatus, at the northernmost part of its range

1993 ◽  
Vol 14 (2) ◽  
pp. 131-147 ◽  
Author(s):  
M. Ohm ◽  
A.G. Toxopeus ◽  
J.W. Arntzen
Keyword(s):  
Reproductive Biology ◽  
Breeding Season ◽  
Adult Population ◽  
First Year ◽  
Adult Size ◽  
Dune System ◽  
Population Size Estimates ◽  
Coastal Dune System ◽  
Source Sink ◽  
Second Period

AbstractThe reproductive biology and population dynamics of Pelodytes punctatus were studied at the breeding season over a three year period in a coastal dune system located at the extreme northwestern border of the species' range. Adult population size estimates ranged from about 100 in the first year to 60 in the third year. Males were remarkably sedentary near the pond under artificially provided shelters. Many were observed during the most of the breeding season which lasted from mid-March or the end of March to the end of April or mid-May. Most spawning took place in the second half of March or early April. In two years out of three a second period of spawning involving fewer animals was observed in the first half of May. Both periods of spawning coincided with, or shortly followed, periods of rising median air temperature. Egg-clutches were deposited in the deepest parts of pond, mainly on submerged vegetation not reaching the surface. An average sized clutch contained approximately 360 eggs. Development of the embryos until hatching took from 4 to 14 days, depending on the ambient temperature. Larval development and growth were fast. Recently metamorphosed froglets at a size of around 18 mm were found from the end of May onwards. Juveniles may reach adult size in the autumn of the year that they were born. Adult frogs did not show a strong fidelity to the breeding pond between years. In the study area the population structure of Pelodytes punctatus seems to be best described by a source - sink model in which flourishing populations in the dunes give rise to short lived satellite populations outside the dunes.

Water and Temperature Stress Impact Fitness of Acetohydroxyacid Synthase–Inhibiting Herbicide-Resistant Populations of Eastern Black Nightshade (Solanum ptychanthum)

Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Jamshid Ashigh ◽  
François J. Tardif
Keyword(s):  
Seed Production ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Stress Conditions ◽  
Acetohydroxyacid Synthase ◽  
Eastern Black Nightshade ◽  
Black Nightshade ◽  
Reproductive Ability ◽  
Temperature Regimes ◽  
The Impact

Many substitutions in the herbicide target enzyme acetohydroxyacid synthase (AHAS) confer whole-plant resistance and may reduce plant fitness. This study was done to determine the impact of different watering and temperature regimes on the germination, growth, and seed production of eastern black nightshade populations resistant (R) to AHAS inhibitors as conferred by an Ala205Val substitution in their AHAS. Growth and reproductive ability of four R and four susceptible (S) populations were determined in growth-cabinet and greenhouse studies. The R populations had lower total berry and viable seed production per plant than S under optimal conditions because of slower berry maturation. Seed production of both S and R populations decreased under lower or higher than optimal watering regimes; however, this reduction was more pronounced for the S populations so that seed production was comparable across S and R. The R populations had significantly higher germination and vegetative growth under cooler alternating temperature regimes. Although there were no differences between R and S plants under stress conditions, under optimal growth conditions, the Ala205Val substitution comes at a significant cost in eastern black nightshade. Under optimal growth conditions and in the absence of herbicide selection, S populations should eventually dominate over R; however, the lack of fitness differences under stress conditions could enhance the persistence of the R individuals.

Senecio L. (Asteraceae) in Australia: Reproductive biology of a genus found primarily in unstable environments

1985 ◽  
Vol 33 (2) ◽  
pp. 197 ◽  
Author(s):  
M.E. Lawrence
Keyword(s):  
Exotic Species ◽  
Reproductive Biology ◽  
Seed Size ◽  
Breeding System ◽  
Seedling Establishment ◽  
Sexual Maturity ◽  
First Year ◽  
Perennial Species ◽  
Habitat Stability ◽  
Dispersal Potential

The reproductive biology of 28 native and four exotic species of Senecio is described in terms of their breeding system, longevity, habitat stability, seed size and number, dispersal potential and seedling establishment. Nineteen species (15 perennial, 2 annual, 2 ephemeral) are self-incompatible, 13 are self-compatible (4 perennial, 7 annual, 2 ephemeral) and nearly all occur in unstable environments. The success of the perennial species in unstable environments perhaps reflects the fact that they all reach sexual maturity within 1 year of germination and, provided populations of self-incompatible species are large enough, they can set seed in the first year.

Seasonal Changes in Carbohydrates in the Root of Canada thistle (Cirsium arvense) and the Disruption of these Changes by Herbicides

2006 ◽  
Vol 20 (1) ◽  
pp. 242-248 ◽  
Author(s):  
Robert G. Wilson ◽  
Alex R. Martin ◽  
Stephen D. Kachman
Keyword(s):  
Soil Temperature ◽  
Plant Density ◽  
First Year ◽  
Canada Thistle ◽  
Free Sugars ◽  
Soil Temperatures ◽  
Growth Changes ◽  
Fall Application ◽  
Sucrose Level ◽  
Made In

Roots of Canada thistle were excavated from the soil monthly from 1999 to 2001 near Scottsbluff, NE, to quantify the influence of changing soil temperature on free sugars and fructans in roots. Sucrose concentrations were low from May through August then increased in the fall and remained at high levels during winter and then declined in April as plants initiated spring growth. Changes in sucrose, 1-kestose (DP 3) and 1-nystose (DP 4) were shown to be closely associated with changes in soil temperature. During the second year of the study, average soil temperatures during the winter were colder than the first year and resulted in an increase of sucrose in Canada thistle roots. Experiments were conducted from 2001 to 2004 to determine whether there was a correlation between herbicide efficacy, time of herbicide application, and the resulting herbicide effect on root carbohydrate and Canada thistle control. Clopyralid applied in the fall reduced Canada thistle density 92% 8 months after treatment (MAT) whereas treatment made in the spring reduced plant density 33% 11 MAT. Fall application of clopyralid increased the activity of fructan 1-exohydrolase (1-FEH) in roots and was associated with a decline in sucrose, DP 4, and 1-fructofuranosyl-nystose (DP 5) 35 d after treatment (DAT). Spring application of clopyralid also resulted in a decrease of the same carbohydrates 35 DAT, but by 98 DAT, or early October, sucrose level in roots had recovered and was similar to nontreated plants. Fall application of 2,4-D or clopyralid reduced Canada thistle density 39 and 92% respectively, 8 MAT, but only clopyralid resulted in a reduction of sucrose, DP 4, DP 5, and total sugar and an increase of 1-FEH compared with nontreated plants.

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