The influence of food resources on life history in Columbian ground squirrels

1985 ◽  
Vol 63 (9) ◽  
pp. 2105-2109 ◽  
Author(s):  
F. Stephen Dobson ◽  
Julia D. Kjelgaard
Keyword(s):  
Body Weight ◽  
Life History ◽  
Litter Size ◽  
Life History Theory ◽  
Experimental Manipulation ◽  
Food Resources ◽  
Ground Squirrels ◽  
Life History Characteristics ◽  
Columbian Ground Squirrels ◽  
Two Populations

Life history characteristics were studied experimentally in Columbian ground squirrels (Spermophilus columbianus) at two elevations in the Rocky Mountains of southwestern Alberta, Canada, from 1981 to 1984. In two populations with supplemented food resources, survival of young increased, age at maturity of females decreased, litter size increased, and spring body weight increased in comparison with an initial unmanipulated period and with two populations monitored for reference. For individual ground squirrels, litter size and spring body weight increased under supplementation. Thus, life history characteristics exhibited phenotypically plastic responses to experimental manipulation of food resources. Life history patterns changed among natural ground squirrel populations at different elevations and these changes were likely due to changes in food resources. A general prediction of life history theory that reproductive effort should be highest in years favorable for juvenile survivorship was supported by the experimental results. The results did not support predictions from interspecific studies of changes in life history characteristics that scale to body weight.

scholarly journals Trade-off between offspring mass and number: the lightest offspring bear the costs

2020 ◽  
Vol 16 (2) ◽  
pp. 20190707
Author(s):  
Joanie Van de Walle ◽  
Andreas Zedrosser ◽  
Jon E. Swenson ◽  
Fanie Pelletier
Keyword(s):  
Life History ◽  
Litter Size ◽  
Phenotypic Variation ◽  
Reproductive Strategy ◽  
Life History Theory ◽  
Brown Bear ◽  
Offspring Size ◽  
Trade Off ◽  
The Relationship

Life-history theory predicts a trade-off between offspring size and number. However, the role of intra-litter phenotypic variation in shaping this trade-off is often disregarded. We compared the strength of the relationship between litter size and mass from the perspective of the lightest and the heaviest yearling offspring in 110 brown bear litters in Sweden. We showed that the mass of the lightest yearlings decreased with increasing litter size, but that the mass of the heaviest yearling remained stable, regardless of litter size. Consistent with a conservative reproductive strategy, our results suggest that mothers maintained a stable investment in a fraction of the litter, while transferring the costs of larger litter size to the remaining offspring. Ignoring intra-litter phenotypic variation may obscure our ability to detect a trade-off between offspring size and number.

Growth and its relationship to the initial annual cycle of the golden-mantled ground squirrel, Spermophilus lateralis

1981 ◽  
Vol 59 (6) ◽  
pp. 865-871 ◽  
Author(s):  
John A. Phillips
Keyword(s):  
Litter Size ◽  
Annual Cycle ◽  
Ground Squirrel ◽  
Growth And Development ◽  
Reproductive Effort ◽  
Ground Squirrels ◽  
Active Season ◽  
Spermophilus Lateralis ◽  
Significant Difference ◽  
Two Populations

Thirty-eight litters of golden-mantled ground squirrels (Spermophilus lateralis), from two populations that experienced different lengths of active season, were born and raised in the laboratory. Growth and development in young were inversely related to litter size. Offspring from smaller litters were both able to attain their prehibernation peak of body mass sooner and hibernate after fewer days of homeothermy than squirrels from larger litters. Young that remained homeothermic throughout the initial overwintering period were always from large litters and among the slowest growing littermates. Fecundity was lower in females from the temporally compressed environment. There was no significant difference between populations in the nutrition provided by mothers to their litters. The results suggest that reproductive effort is more conservative in populations of ground squirrels that experience short seasons of activity, yet this conservatism allows the offspring of those populations to reach independence and attain the prehibernation state of preparedness at an earlier age than their counterparts from populations of more moderate climates.

scholarly journals Life cycle of natural populations of Metriocnemus (Inermipupa) carmencitabertarum Langton & Cobo 1997 (Diptera: Chironomidae) in The Netherlands: indications for a southern origin?

2017 ◽  
pp. 55-66
Author(s):  
Jan Kuper
Keyword(s):  
Life History ◽  
Body Size ◽  
The Netherlands ◽  
Ambient Temperature ◽  
Larval Development ◽  
Seasonal Pattern ◽  
Water Levels ◽  
Water Volume ◽  
Life History Characteristics ◽  
Two Populations

The life-history and behaviour of the chironomid Metriocnemus (Inermipupa) carmencitabertarum was studied for three years and a comparison was made between two populations in the Netherlands. Key life-history characteristics are reported, including the number of generations (2-5 generations) and duration of larval development (19-55 days). Life-history characteristics differed between the two populations and between generations within a population. These differences were likely related to differences in competitors (mainly Chironomus riparius Meigen) and thermal characteristics of the habitat from variations in water volume and ambient temperature. Results suggested a diapause in summer, when water levels dropped, and not in winter. A clear seasonal pattern in body size was found with pupal length increasing steeply at the beginning of the summer. The increase in body size was positively correlated with mean ambient temperature during larval development. This correlation is in contrast with the Temperature-Size Rule (TSR) in ectotherms, which postulates a negative correlation between temperature and adult body size. The chance of ectotherm predators being present in the habitat is low, which may explain this feature. Life history characteristics supported a recent northward range expansionfor M. (I.) carmencitabertarum due to warmer winters. If correct, it is predicted that the species will be found in Scotland and northern Germany and/or southern Denmark in the near future.

scholarly journals Differential reproductive responses to stress reveal the role of life-history strategies within a species

2013 ◽  
Vol 280 (1771) ◽  
pp. 20132090 ◽  
Author(s):  
J. Schultner ◽  
A. S. Kitaysky ◽  
G. W. Gabrielsen ◽  
S. A. Hatch ◽  
C. Bech
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Life History Strategies ◽  
Short Term ◽  
Food Shortages ◽  
Investment In Reproduction ◽  
Response To Stress ◽  
Environmental Events ◽  
Two Populations

Life-history strategies describe that ‘slow’- in contrast to ‘fast’-living species allocate resources cautiously towards reproduction to enhance survival. Recent evidence suggests that variation in strategies exists not only among species but also among populations of the same species. Here, we examined the effect of experimentally induced stress on resource allocation of breeding seabirds in two populations with contrasting life-history strategies: slow-living Pacific and fast-living Atlantic black-legged kittiwakes. We tested the hypothesis that reproductive responses in kittiwakes under stress reflect their life-history strategies. We predicted that in response to stress, Pacific kittiwakes reduce investment in reproduction compared with Atlantic kittiwakes. We exposed chick-rearing kittiwakes to a short-term (3-day) period of increased exogenous corticosterone (CORT), a hormone that is released during food shortages. We examined changes in baseline CORT levels, parental care and effects on offspring. We found that kittiwakes from the two populations invested differently in offspring when facing stress. In response to elevated CORT, Pacific kittiwakes reduced nest attendance and deserted offspring more readily than Atlantic kittiwakes. We observed lower chick growth, a higher stress response in offspring and lower reproductive success in response to CORT implantation in Pacific kittiwakes, whereas the opposite occurred in the Atlantic. Our findings support the hypothesis that life-history strategies predict short-term responses of individuals to stress within a species. We conclude that behaviour and physiology under stress are consistent with trade-off priorities as predicted by life-history theory. We encourage future studies to consider the pivotal role of life-history strategies when interpreting inter-population differences of animal responses to stressful environmental events.

Litter Size in Columbian Ground Squirrels (Spermophilus columbianus)

1980 ◽  
Vol 61 (2) ◽  
pp. 237-244 ◽  
Author(s):  
J. O. Murie ◽  
D. A. Boag ◽  
V. K. Kivett
Keyword(s):  
Litter Size ◽  
Ground Squirrels ◽  
Spermophilus Columbianus ◽  
Columbian Ground Squirrels

Maternal influences on reproduction in two populations of Columbian ground squirrels

2009 ◽  
Vol 79 (2) ◽  
pp. 325-341 ◽  
Author(s):  
Amy L. Skibiel ◽  
F. Stephen Dobson ◽  
Jan O. Murie
Keyword(s):  
Ground Squirrels ◽  
Maternal Influences ◽  
Columbian Ground Squirrels ◽  
Two Populations

Inheritance of key life-history traits in crosses between northern and southern populations of the cabbage beetle Colaphellus bowringi (Coleoptera: Chrysomelidae)

2021 ◽  
pp. 1-9
Author(s):  
Hai-Min He ◽  
Jian-Jun Tang ◽  
Li-Li Huang ◽  
Shao-Hui Wu ◽  
Yuan Peng ◽  
...  
Keyword(s):  
Growth Rate ◽  
Weight Loss ◽  
Body Weight ◽  
Life History ◽  
Development Time ◽  
Life History Traits ◽  
Weight Growth ◽  
Almost All ◽  
Two Populations ◽  
Two Hybrid

Abstract A southern population (S) from Xiushui County (29°1′N, 114°4′E) and a northern population (N) from Shenyang city (41°48′N, 123°23′E) of the cabbage beetle, Colaphellus bowringi vary greatly in their life-history traits, and may serve as an excellent model with which to study the inheritance of life-history traits. In the present study, we performed intraspecific hybridization using the two populations, comparing the key life-history traits (fecundity, development time, body weight, growth rate, and sexual size dimorphism (SDD)) between the two populations (S♀ × S♂ and N♀ × N♂) and their two hybrid populations (S♀ × N♂ and N♀ × S♂ populations) at 19, 22, 25, and 28°C. Our results showed that there were significant differences in life-history traits between the two parental populations, with the S population having a significantly higher fecundity, shorter larval development time, larger body weight, higher growth rate, and greater weight loss during metamorphosis than the N population at almost all temperatures. However, these life-history traits in the two hybrid populations were intermediate between those of their parents. The life-history traits in the S × N and N × S populations more closely resembled those of the maternal S population and N population, respectively, showing maternal effects. Weight loss for both sexes was highest in the S population, followed by the S × N, N × S, and N populations at all temperatures, suggesting that larger pupae lost more weight during metamorphosis. The changes in SSD with temperature were similar between the S and the S × N populations and between the N and the N × S populations, also suggesting a maternal effect. Overall, our results showed no drastic effect of hybridization on C. bowringi, being neither negative (hybrid inferiority) nor positive (heterosis). Rather, the phenotypes of hybrids were intermediate between the phenotypes of their parents.

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