Photoperiod and population density interact to affect reproductive and immune function in male prairie voles

1996 ◽  
Vol 270 (3) ◽  
pp. R571-R577 ◽  
Author(s):  
R. J. Nelson ◽  
J. B. Fine ◽  
G. E. Demas ◽  
C. A. Moffatt
Keyword(s):  
Population Density ◽  
Immune Function ◽  
High Density ◽  
Adrenal Function ◽  
Day Length ◽  
Low Density ◽  
Prairie Voles ◽  
Extrinsic Factors ◽  
Short Day ◽  
Long Day

Seasonal breeding of rodents is often associated with changes in adrenal function; altered adrenal function could account, in part, for seasonal changes in immune function and, ultimately, influence seasonal fluctuations in survival. Animals commonly monitor the annual change in photoperiod to ascertain the time of year and to make appropriate seasonal adjustments in physiology and behavior. Several extrinsic factors affect reproductive responsiveness to photoperiod. The interaction between population density and reproductive and adrenal responsiveness to photoperiod was assessed in the present experiment. Adult male prairie voles (Microtus ochrogaster) were maintained individually for 10 wk in long [light:dark (LD) 16:8] or short (LD 8:16) photoperiods in rooms with either high (10.96 animals/m3) or low (0.18 animals/m3) population densities. Regardless of population density, short-day voles regressed the size of their reproductive organs; reproductive organ masses were higher in long-day voles housed in high-density compared with low-density rooms. Paired adrenal masses were reduced in short-day voles, but were unaffected by population density; serum corticosterone concentrations were significantly elevated in short-day compared with long-day animals. In both photoperiods, basal blood corticosterone levels were higher in voles from low-density compared with high-density rooms. Splenic masses were unaffected by day length, but were elevated among high-density animals. Similarly, serum immunoglobulin (IgG) levels were elevated among high-density animals. These results suggest that population density per se, in the absence of behavioral interactions, can affect reproductive size, and possibly function, in long-day conditions, and that prairie voles, which are highly social, exhibit higher corticosterone and lower IgG levels in low compared with high densities. These results may be important in understanding arvicoline population fluctuations, as well as improving animal husbandry practices in the lab.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

Effects of population density on female and male burrow characteristics in the fiddler crab, Uca bengali Crane, 1975

Crustaceana ◽  
2015 ◽  
Vol 88 (12-14) ◽  
pp. 1283-1299 ◽  
Author(s):  
Fahmida Wazed Tina ◽  
Mullica Jaroensutasinee ◽  
Krisanadej Jaroensutasinee
Keyword(s):  
Body Size ◽  
Population Density ◽  
Fiddler Crab ◽  
High Density ◽  
The Other ◽  
Low Density ◽  
Density Effects ◽  
Egg Incubation ◽  
Other Hand ◽  
Males And Females

We examined the effects of population density on body size and burrow characteristics ofUca bengaliCrane, 1975. We predicted that (1) males in high-density areas (HD) should be larger in size and build higher quality burrows than males in low-density areas (LD), and (2) HD females should be larger in size, but build lower quality burrows than LD females, as HD females can find higher numbers of good quality male burrows around them for breeding and egg incubation. Our results showed that males and females in HD were larger in size than those in LD. Since HD males were larger in size, they built higher quality burrows than males in LD. On the other hand, even though LD females were smaller in size than HD ones, they built higher quality burrows than HD females. Our results thus indicate that density effects both body size and burrow characteristics.

A method for induction and quantification of diapause entry in the swede midge (Diptera: Cecidomyiidae)

2012 ◽  
Vol 144 (6) ◽  
pp. 792-800 ◽  
Author(s):  
Lauren E. Des Marteaux ◽  
Marc B. Habash ◽  
Jonathan M. Schmidt ◽  
Rebecca H. Hallett
Keyword(s):  
Diapause Induction ◽  
Day Length ◽  
Retrieval Method ◽  
Short Day ◽  
Long Day ◽  
Rearing Conditions ◽  
Swede Midge ◽  
Pupal Mortality ◽  
Contarinia Nasturtii ◽  
Cool Conditions

AbstractInduction of diapause under laboratory conditions is a valuable tool for the study of dormancy in economic pests such as the swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae). In the present study, diapause in larval swede midge was achieved via manipulation of rearing photoperiod and temperature. Frequency of diapause was assessed by sieve separation of diapause cocoons from pre-sifted peat substrate following emergence of pupating individuals. Mean diapause frequency for swede midge larvae reared under cool conditions with short day length or cool conditions with decreasing day lengths were 45.2% and 19.5%, respectively. Only 1.2% of swede midge reared under warm, long day length conditions entered diapause. A small percentage of larvae neither pupated nor entered diapause and remained in substrate long after other individuals had emerged as adults. This behaviour was more prevalent under cool and short or decreasing day length rearing conditions. Approximately 76% of the larvae used for diapause induction were recovered with the present larval and cocoon retrieval method, and premature (larval and pupal) mortality averaged 18.2%. Although diapause occurred in the present study, conditions resulting in higher diapause frequencies should be investigated and attempts should be made to improve survival and recovery of individuals.

scholarly journals Effects of Diaphorina citri Population Density on Daily Timing of Vibrational Communication Calls: Potential Benefits in Finding Forage

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 182
Author(s):  
Richard W. Mankin ◽  
Rikin Patel ◽  
Mason Grugnale ◽  
Ethan Jetter
Keyword(s):  
Population Density ◽  
Chemical Cues ◽  
Reproductive Fitness ◽  
High Density ◽  
Vibrational Communication ◽  
Low Density ◽  
Diaphorina Citri ◽  
Conspecific Density ◽  
Potential Benefits ◽  
Communication Calls

Adult Diaphorina citri (ACP) use visual and chemical cues to locate young citrus flush shoots on which they forage and oviposit, and they use vibrational communication duetting calls as cues to help locate mates. For individual pairs, calling and mating usually peaks between 10:00 and 15:00. To explore whether call rates (calls/h) are affected by interactions with nearby conspecifics, rates were compared in small citrus trees on which either 5 or 25 ACP female and male pairs had been released at 17:00 for later recording from sunrise (06:00) to 22:00. Final ACP locations were noted 40 h after release. Call rates were similar in both treatments during normal mating hours. However, rates were significantly higher for low- than high-density treatments between 06:00 and 10:00, which suggests calling during this period may be affected by conspecific density. Both sexes aggregated on flush at both densities. We discuss the potential that ACP producing calls near sunrise, outside of normal mating hours, might benefit from gains in reproductive fitness in low-density contexts if they call not only to locate mates but also to locate preferred flush—in which case, co-opting of vibrations to disrupt both mating and foraging may be feasible.

scholarly journals Responses of earliness and lateness genes for heading to different photoperiods, and specific response of a gene or a pair of genes to short day length in rice

Hereditas ◽  
2019 ◽  
Vol 156 (1) ◽  
Author(s):  
Birendra Bahadur Rana ◽  
Misa Kamimukai ◽  
Mukunda Bhattarai ◽  
Yohei Koide ◽  
Masayuki Murai
Keyword(s):  
Genetic Factors ◽  
Day Length ◽  
Specific Response ◽  
Near Isogenic Lines ◽  
Heading Time ◽  
Short Day ◽  
Long Day ◽  
Days To Heading ◽  
Important Trait ◽  
Spring Sowing

Abstract Background Heading time is an important trait for regional and seasonal adaptabilities in rice, and is controlled by genetic factors in relation with environmental factors, mainly day length and temperature. The following genes controlling heading were examined for their responses to six different environmental conditions involving different day lengths using five early near-isogenic lines (NILs) of T65-R and three late NILs of T65wx: two earliness genes, Ef1 and Efx controlling basic vegetative phase (BVG), and m-Ef1, the enhancer to the former gene; and two lateness genes, Se1-pat(t) and se-pat controlling photo-sensitivity and BVG, respectively. T65-R and T65-T were different accessions of Taichung 65. T65wx is a NIL of T65-T carrying wx. Results The five early NILs of T65-R were in the order of ER50 (Ef1, Efx, m-Ef1) < ER40 (Ef1, m-Ef1) ≤ ER20 (Ef1, Efx) < ER1 (Ef1) ≤ ER21 (Efx) < T65-R regarding days to heading (DTH) under two spring-sowing and one summer-sowing paddy field (PF) conditions. The three late NILs of T65wx were in the order of LF3 (Se1-pat(t)) ≤ LF2 (Se1-pat(t), se-pat) ≤ T65wx < LF1 (se-pat) under two short-day conditions (10-h photoperiod condition with artificial-light and natural short-day condition from autumn to winter). The NILs and T65wx were in the order of T65wx < LF3 < LF1 < LF2 under the two spring-sowing PF (long day) conditions. T65-R (Ac-ef1) was 2.8 or 5.1 days earlier in DTH than T65-T (ac-ef1) under the two spring-sowing PF conditions. However, T65-R was 19 and 10 days earlier than T65-T under the two short-day conditions. Conclusions Earliness gene(s) and their combinations reduced DTH regardless of photoperiod lengths. Se1-pat(t) increased DTH under long-day conditions but decreased it under short-day conditions, while se-pat elongated DTH under both short-day and long-day conditions indicating that se-pat is responsible for BVG. The se-pat increased DTH by adding its effect over that of Se1-pat(t) under long-day conditions. However, this increasing effect of DTH by se-pat was almost completely masked when it coexisted with Se1-pat(t) under the short-day conditions. Notably, the response of Ac-ef1 to day length was found to delay heading under the short-day conditions.

scholarly journals Four Hour Temporal Relation of 5-HTP and L-DOPA Induces Inhibitory Responses in Recrudescing Gonad of Indian Palm Squirrel (Funambulus pennantii)

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Ranjana Jaiwal ◽  
C. M. Chaturvedi
Keyword(s):  
Environmental Factors ◽  
Basic Mechanism ◽  
Inhibitory Effect ◽  
Temporal Relation ◽  
Day Length ◽  
Short Day ◽  
Long Day ◽  
Testicular Recrudescence ◽  
Neurotransmitter Activity ◽  
Seasonally Breeding

Daily injections of L-dihydroxyphenylalanine (L-DOPA, dopamine precursor) given 4 h after 5-hydroxytryptophan (5-HTP, serotonin precursor) induced inhibitory responses in recrudescing gonad (in the first week of December) of Indian palm squirrel, a seasonally breeding subtropical animal. Other temporal relations (L-DOPA given at 0, 8, 12, 16, and 20 h after 5-HTP administration) did not show any effect on the recrudescing gonad. This inhibitory effect of 4 h was evident under short day length (6 : 18) group but was masked by the increasing day length of nature (NDL, late December onwards) and increased photoperiod of long day group (16 : 8). It is apparent that seasonal testicular recrudescence of Indian palm squirrel during short day length by 4 h relation of 5-HTP and L-DOPA is not a pharmacological effect but actually is an alteration of seasonality in this annually breeding mammal. It seems that endogenous mechanism controlling seasonal testicular recrudescence of Indian palm squirrel is reset by timed daily injections of these neurotransmitter drugs. It is suggested that in spite of different environmental factors (photoperiod, humidity, etc.) used by different species to time their annual reproduction, basic mechanism of seasonality appears to be the same, that is, the temporal synergism of neurotransmitter activity.

Effects of shortened day length upon translocation and starch accumulation by maize, wheat, and pangola grass leaves

1982 ◽  
Vol 60 (8) ◽  
pp. 1304-1309 ◽  
Author(s):  
Richard C. Sicher ◽  
William G. Harris ◽  
Diane F. Kremer ◽  
N. Jerry Chatterton
Keyword(s):  
Carbon Assimilation ◽  
Pool Size ◽  
Day Length ◽  
Starch Accumulation ◽  
Leaf Extracts ◽  
Sucrose Transport ◽  
Chase Period ◽  
Short Day ◽  
Long Day ◽  
Total Pool

Rates of leaf starch accumulation in maize, wheat, and pangola grass were approximately doubled when plants were shifted from long to short day lengths, 4 days prior to measurement. There were only small changes in carbon assimilation rates and specific leaf weights. After a brief exposure to 14CO2 and after a 2-h-chase period, total label was higher in leaves of long to short day length than in long day length plants. Most of the increased 14C radioactivity in leaf extracts of long to short day length plants was recovered in the starch, protein, and neutral fractions. The translocation of 14C-labeled assimilates to roots was less in long to short day length then in long day length plants. Sucrose was increased in leaves and decreased in roots following a shift from long to short day lengths. The above findings indicated that the accumulation of assimilates in leaves of long to short day length plants was due in part to a lowered rate of sucrose transport. The rate of sucrose movement was not directly proportional to its total pool size in source leaves.

INFLUENCE OF BREED, BIRTH DATE, AGE AND BODY WEIGHT ON TESTICULAR MEASUREMENTS OF GROWING RAMS MAINTAINED IN A CONTROLLED ENVIRONMENT

1983 ◽  
Vol 63 (4) ◽  
pp. 835-847 ◽  
Author(s):  
J. N. B. SHRESTHA ◽  
P. S. FISER ◽  
G. A. LANGFORD ◽  
D. P. HEANEY
Keyword(s):  
Body Weight ◽  
Continuous Light ◽  
Skinfold Thickness ◽  
Day Length ◽  
Birth Date ◽  
Short Day ◽  
Scrotal Circumference ◽  
Long Day ◽  
Expanded Metal ◽  
Time Of Breeding

Testicular measurements, including scrotal circumference (SC), testis length (TL), testis width (TW), scrotal skinfold thickness (ST) and tonometer score (TS), and body weight (BW) were collected from 233 rams of three synthetic strains, Suffolk and Finnish Landrace breeds, at 6, 8 and 10 mo of age, at the time of first breeding in September 1981 (11–13 mo) and second breeding in April 1982 (18–21 mo). Rams were exposed to continuous light from birth to weaning (21 ± 3 days of age), to a long day-length (16 h light: 8 h darkness) from weaning to 6 mo and then to a short day-length (9 h light: 15 h darkness) to the time of breeding. Subsequently, the rams were exposed to 4 mo of long day-length followed by a 4 mo of short day-length. All rams were hysterectomy derived, housed indoors year-round on expanded metal floors in windowless barns and reared artificially. Breed, birth date, age of ram and body weight were found to have important effects (P < 0.05) on testicular measurements of growing rams, whereas, age of dam and litter size effects were absent (P > 0.05). In general, meat-type sire breeds (Strain 1 and Suffolk) had larger SC, TL, TW and BW when compared to the fecund sheep breeds (Finnish Landrace, Strains 2 and 3). Testicular measurements and BW of Finnsheep rams were smaller when compared to all other rams examined. The significance of breed and birth date effects varied as the ram progressed in age. Testicular measurements and BW increased with age of ram from 6 to 8 mo but TS showed no change. SC and BW increased substantially at 18–21 mo (April) compared to 11–13 mo (September), whereas TL, TW, ST and TS declined. SC, TL and TW were significantly correlated with each other at all ages. ST and TS were independent traits with no significant relationship to SC, TL, TW and BW. Key words: Sheep, testicular measurements, breed, birth date, age of ram, body weight

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