scholarly journals GENETIC AND NON-GENETIC VARIABILITY IN TEMPERATURE TOLERANCE OF THE COPEPODEURYTEMORA AFFINISIN FIVE TEMPERATURE REGIMES

1982 ◽  
Vol 162 (3) ◽  
pp. 233-245 ◽  
Author(s):  
BRIAN P. BRADLEY ◽  
PHYLLIS A. KETZNER
Keyword(s):  
Genetic Variability ◽  
Temperature Tolerance ◽  
Temperature Regimes

Variability in temperature-dependent germination in eastern black nightshade (Solanum ptycanthum)

1991 ◽  
Vol 69 (7) ◽  
pp. 1463-1470 ◽  
Author(s):  
L. A. Hermanutz ◽  
S. E. Weaver
Keyword(s):  
Genetic Variability ◽  
Cultural Practices ◽  
Germination Rate ◽  
Base Temperature ◽  
Range Limit ◽  
Temperature Dependent ◽  
Marginal Populations ◽  
Solanum Ptycanthum ◽  
Temperature Regimes ◽  
Response To Temperature

The colonization potential of the northwardly migrating weed Solanum ptycanthum was evaluated by comparing germination profiles of southern agrestal populations with northern marginal populations sampled from both ruderal and agrestal habitats. Under laboratory conditions, the seed from five maternal families from each population was subjected to six light:dark temperature regimes from 18:8 to 40:30 °C and germination rate (time to 50% germination) and final percent germination were monitored. The base temperature and thermal time (degree-days) required for 50% germination were calculated. Seeds from southern agrestal populations germinated over a broader temperature range than northern agrestal populations but had similar rates of germination, base temperatures, and thermal times. At the northern range limit, ruderal populations germinated faster and had smaller thermal times than agrestal populations but had similar base temperatures. Delayed emergence in agrestal habitats may be a response to cultural practices. Seeds from northern populations were heavier than southern populations. Plasticity of germination response to temperature did not differ between populations. The observed levels of genetic variability in all germination parameters suggest that future range expansion would be possible. Key words: temperature-dependent germination, agrestal, ruderal, marginal populations, genetic variability, plasticity.

scholarly journals The physiological consequences of varied heat exposure events in adultMyzus persicae: a single prolonged exposure compared to repeated shorter exposures

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2290 ◽  
Author(s):  
Behnaz Ghaedi ◽  
Nigel R. Andrew
Keyword(s):  
High Temperature ◽  
Recovery Time ◽  
Prolonged Exposure ◽  
Heat Exposure ◽  
Temperature Tolerance ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Exposure Group ◽  
Temperature Regimes ◽  
Heating Event

The study of environmental stress tolerance in aphids has primarily been at low temperatures. In these cases, and in the rare cases of high temperature tolerance assessments, all exposures had been during a single stress event. In the present study, we examined the physiological consequences of repeated high temperature exposure with recovery periods between these stress events inMyzus persicae. We subjected individuals to either a single prolonged three hour heating event, or three one hour heating events with a recovery time of 24 h between bouts. Aphids exposed to repeated bouts of high temperatures had more glucose and higher expression of proteins and osmolyte compounds, such as glycerol, compared to the prolonged exposure group. However, aphids exposed to the repeated high temperature treatment had reduced sources of energy such as trehalose and triglyceride compounds than the prolonged exposure group. Recovery time had more physiological costs (based on production of more protein and consumption of more trehalose and triglyceride) and benefits (based on production of more osmolytes) in repeated high temperature treatments. As aphids are known to respond differently to constant versus ‘natural’ fluctuating temperature regimes, conclusions drawn from constant temperature data sets may be problematic. We suggest future experiments assessing insect responses to thermal stress incorporate a repeated stress and recovery pattern into their methodologies.

scholarly journals Regional environmental conditions determine tolerance to future warming of a marine macroalgae forests

2018 ◽  
Author(s):  
Jana Verdura ◽  
Sonia de Caralt ◽  
Jorge Santamaria ◽  
Alba Vergés ◽  
Luisa Mangialajo ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Temperature Tolerance ◽  
Marine Macroalgae ◽  
Marine Habitat ◽  
Mediterranean Populations ◽  
Temperature Regimes ◽  
Conservation Actions ◽  
The Mediterranean

Abstract: In the Mediterranean Sea, many species of Cystoseira, which are important habitat-forming species on shallow rocky bottoms, have gone missing from many coastal areas, impairing essential ecosystem services. Cystoseira crinita forests thrive in very shallow waters from sheltered environments and are currently regressing in several European shores. In the actual scenario of ocean warming it is essential to determine the vulnerability of these populations to thermal stress in order to design future conservation actions. Since the response of this macroalgae to thermal stress may be site-specific, here we compared the thermal tolerance of populations dwelling in the coldest and warmest areas of the Mediterranean Sea. We show that C. crinita populations from warmer areas (Eastern Mediterranean) had a temperature tolerance threshold 2ºC higher than Northwestern Mediterranean populations. There is a strong correlation between the observed differential phenotypic responses and the local temperature regimes experienced by each population. This is the first evidence for the role of thermal history in shaping the thermotolerance responses marine habitat-forming macroalgae under contrasting temperature environments. Financial support from EU2020 (R+I) under grant agreement No 689518 (MERCES) and MINECO (CGL2016-76341-R).

Genetic variability in reaction norms between farmed and wild backcrosses of Atlantic salmon (Salmo salar)

2009 ◽  
Vol 66 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Tamara L. Darwish ◽  
Jeffrey A. Hutchings
Keyword(s):  
Genetic Variability ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Second Generation ◽  
Common Garden ◽  
Early Life History ◽  
Reaction Norms ◽  
Adaptive Responses ◽  
Atlantic Salmon Salmo Salar ◽  
Temperature Regimes

Adaptive responses to environmental heterogeneity may vary among populations. Genetic variability in reaction norms might account for population differences in the ability to respond to environmental change and may reflect local adaptation. Reaction norms for early life history traits were compared among three population crosses of Atlantic salmon ( Salmo salar ). Two comprised second-generation backcrosses introgressed with either farmed or wild genes; the third comprised individuals from a second-generation, pure wild cross. Using a common-garden experimental protocol, each cross was exposed to three temperature regimes. Plasticity in embryonic development, growth, survival, and body size was measured from fertilization up to 24 weeks of exogenous feeding. Reaction norms differed markedly among crosses, irrespective of whether individuals interbred with those whose genes originated from another wild population or from a cultured population. We find that introgression involving individuals with comparatively few genetic differences can change reaction norms. If plasticity represents an adaptive response to local environments, then changes to reaction norms resulting from interbreeding between populations are unlikely to have a beneficial effect on fitness.

scholarly journals Influence of temperature on germination of new buffelgrass (Cenchrus ciliaris) genotypes

2021 ◽  
Author(s):  
Abdulrahman A. Al-Soqeer ◽  
Abdulaziz A. Alqarawi ◽  
Mohamed I. Motawei ◽  
Soleman M. Al-Otayk
Keyword(s):  
Seed Germination ◽  
Genetic Variability ◽  
High Tolerance ◽  
Cenchrus Ciliaris ◽  
Storage Duration ◽  
Influence Of Temperature ◽  
Temperature Regimes ◽  
Influence Of Temperature On ◽  
Arid Rangelands ◽  
High Level

Buffelgrass (Cenchrus ciliaris) is widely grown in tropical and sub-tropical arid rangelands around the globe because of its high tolerance to drought and high level of nutrients. In the present study, the seed germination response of 12 buffelgrass genotypes (nine collected accessions and three introduced varieties) was tested to record the various effects of storage duration and temperature treatments on germination. Five constant temperature treatments (15, 20, 25, 30 and 35°C) and two storage durations (12 and 24 months) were used. The studied buffelgrass genotypes responded differently to the different storage durations and temperature regimes, suggesting the importance of genotype assessment under different environments. The highest germination percentages were recorded for genotype BUR-1 at 20°C (45%) after 12 months. No germination occurred after 12 months at low constant temperatures (15°C) for all genotypes except BUR-1, BUR-2 and UIA. Therefore, there is a large genetic variability among buffelgrass genotypes for seed germination, which could permit improvement by selection and breeding.

scholarly journals Regional environmental conditions determine tolerance to future warming of a marine macroalgae forests

2018 ◽  
Author(s):  
Jana Verdura ◽  
Sonia de Caralt ◽  
Jorge Santamaria ◽  
Alba Vergés ◽  
Luisa Mangialajo ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Temperature Tolerance ◽  
Marine Macroalgae ◽  
Marine Habitat ◽  
Mediterranean Populations ◽  
Temperature Regimes ◽  
Conservation Actions ◽  
The Mediterranean

Abstract: In the Mediterranean Sea, many species of Cystoseira, which are important habitat-forming species on shallow rocky bottoms, have gone missing from many coastal areas, impairing essential ecosystem services. Cystoseira crinita forests thrive in very shallow waters from sheltered environments and are currently regressing in several European shores. In the actual scenario of ocean warming it is essential to determine the vulnerability of these populations to thermal stress in order to design future conservation actions. Since the response of this macroalgae to thermal stress may be site-specific, here we compared the thermal tolerance of populations dwelling in the coldest and warmest areas of the Mediterranean Sea. We show that C. crinita populations from warmer areas (Eastern Mediterranean) had a temperature tolerance threshold 2ºC higher than Northwestern Mediterranean populations. There is a strong correlation between the observed differential phenotypic responses and the local temperature regimes experienced by each population. This is the first evidence for the role of thermal history in shaping the thermotolerance responses marine habitat-forming macroalgae under contrasting temperature environments. Financial support from EU2020 (R+I) under grant agreement No 689518 (MERCES) and MINECO (CGL2016-76341-R).

Photoinhibition of Photosynthesis and Its Recovery in Two Maize Hybrids Varying in Low Temperature Tolerance

1989 ◽  
Vol 16 (2) ◽  
pp. 189 ◽  
Author(s):  
DH Greer ◽  
AK Hardacre
Keyword(s):  
Low Temperature ◽  
Temperature Tolerance ◽  
O2 Evolution ◽  
Photoinhibition Of Photosynthesis ◽  
Temperature Dependent ◽  
Maize Hybrids ◽  
Low Temperature Tolerance ◽  
Temperature Regimes ◽  
Subsequent Exposure ◽  
Time Courses

Photoinhibition of photosynthesis was induced in intact leaves of two maize hybrids that differed in low temperature tolerance by exposing the leaves to a photon irradiance (PI) of 1500 �mol m-2s-1 at temperatures of 10, 15 and 20°C. Hybrid A665 × H99 (CBD) is adapted to the U.S.A. Corn Belt and is intolerant of cool conditions, while NZlA × 5-113 (CT) is of high-altitude tropical origin and tolerant of low temperatures. Each hybrid was grown at two temperature regimes of 22/18 and 16/14°C at a PI of 700 �mol m-2s-1. Recovery from photoinhibition was followed at the same temperatures and at a PI of 20�mol m-2s-1. In either case the time-courses of photoinhibition and recovery were monitored by measuring chlorophyll fluorescence at 692 nm and 77K and the photon yield of photosynthetic O2 evolution. Chronic photoinhibition resulting from growth at the moderate PI and at 16/ 14°C was apparent in both hybrids but was more severe in the CBD hybrid. Additional photoinhibition, induced by subsequent exposure to high light, was highly temperature-dependent with increasing severity at lower temperatures. The CT hybrid was more susceptible to this photoinhibition but photoinhibition in the CBD hybrid was more temperature-dependent than in the CT hybrid. Susceptibility to photoinhibition was, therefore, not apparently related to the degree of low temperature tolerance in these maize hybrids. Induced photoinhibition was readily reversible though recovery was temperature-dependent with the most recovery at the higher temperature. Recovery in these hybrids was not impeded by temperatures as low as 10°C as it is in other species and there was no difference between the hybrids in their ability to recover. However, differences in chronic rather than induced photoinhibition conformed to a greater extent with the ability of these maize hybrids to tolerate low temperature.

Genetic variation for stomatal conductance in upland cotton as influenced by heat-stressed and non-stressed growing regimes

2008 ◽  
Vol 56 (1) ◽  
pp. 11-19 ◽  
Author(s):  
H. Rahman ◽  
N. Murtaza ◽  
K. Shah ◽  
A. Qayyum ◽  
I. Ullah ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Stomatal Conductance ◽  
Genetic Variability ◽  
Combining Ability ◽  
Upland Cotton ◽  
Recurrent Selection ◽  
Effect Of Temperature ◽  
Temperature Regimes ◽  
Breeding Programmes ◽  
The Impact

Stomatal conductance is an important heat avoidance mechanism and its association with higher yield and heat resistance has been established in Pima cotton. Experiments were carried out on upland cotton under heat-stressed and non-stressed greenhouse and field regimes, to understand the impact of heat-stressed and non-stressed environments on the genetic and combining ability variations for stomatal conductance. The experimental material comprised 8 upland cotton cultivars and their 15 F 1 cross combinations obtained in a line × tester mating arrangement. The results showed high genetic variability for stomatal conductance in a single environment, but low genetic variability across environments, due to the higher magnitude of the environmental interaction, especially that caused by temperature regimes. The interaction effect of temperature regimes also substantially modified general and specific combining ability variations for stomatal conductance. The relative contributions of general and specific combining abilities to total phenotypic variation for stomatal conductance also underwent a great change across field temperature regimes. The non-stressed regime favoured the expression of genes causing the additive type of genetic variability. The heat-stressed field regime, however, favoured the expression of both additive and non-additive types of genetic variation for stomatal conductance in upland cotton. Recurrent selection for the accumulation of favourable genes for general combining ability under non-stressed conditions was suggested for improving stomatal conductance in applied cotton breeding programmes.

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