Maternal expenditure in the polygynous and monomorphic guanaco: suckling behavior, reproductive effort, yearly variation, and influence on juvenile survival

From 1981 to 1984, a field study of reproductive strategies of Lemmus sibiricus and Dicrostonyx groenlandicus in high-arctic tundra was undertaken at Igloolik Island and the Melville Peninsula, Northwest Territories. Both species of lemmings were scarce in 1981 and 1982 and increased rapidly in abundance in 1983 and 1984. In 1983, D. groenlandicus began breeding in March under the snow, whereas L. sibiricus did not commence breeding until meltoff in early June. Breeding in L. sibiricus was coincident with the appearance of the first sprouts of Dupontia fisheri and Carex stans, two of its preferred monocotyledonous food plants. A survey of tundra plants revealed that 6-methoxybenzoxlazolinone (6-MBOA) was present in the monocotyledons that are the preferred food plants of L. sibiricus, but not in those that are not preferred. With one exception, stoloniferous species contained 6-MBOA but caespitose species did not. Dupontia fisheri showed considerable yearly variation in 6-MBOA content, consistent with low and high population years for L. sibiricus. None of the dicotyledons preferred by D. groenlandicus contained 6-MBOA. Laboratory assays demonstrated that L. sibiricus responds reproductively (increased uterine mass) to 6-MBOA, but D. groenlandicus does not. We conclude that D. groenlandicus uses photoperiod to cue its reproductive effort, while plant chemical cues are an important component of the reproductive strategy of L. sibiricus.

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Spring-loaded reproduction: effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)

Canadian Journal of Zoology ◽

10.1139/cjz-2012-0334 ◽

2013 ◽

Vol 91 (7) ◽

pp. 473-479 ◽

Cited By ~ 17

Author(s):

M. Pachkowski ◽

S.D. Côté ◽

M. Festa-Bianchet

Keyword(s):

Population Size ◽

Body Condition ◽

Rangifer Tarandus ◽

Reproductive Effort ◽

Low Density ◽

Female Fecundity ◽

Conservative Strategy ◽

Maternal Expenditure ◽

Population Sizes ◽

Hypoderma Tarandi

In many ungulates, female fecundity is affected by body condition and has important effects on population dynamics. In some species, females adopt a conservative strategy, reducing reproductive effort when population density is high. We investigated what factors affect the probability of gestation in adult female caribou (Rangifer tarandus (L., 1758)) from the Rivière-George herd in northern Quebec and Labrador over 5 years that spanned various population sizes and trends. Similar to other populations of migratory caribou, the probability that a female was pregnant in spring increased with body mass and percent body fat. The probability of gestation appeared to be reduced by high infestation of warbles (Hypoderma tarandi (L., 1758)). The proportion of females pregnant varied between years and was lower at high population size. Females of similar mass, however, were pregnant regardless of whether the population was increasing at low density, had reached a peak, or was declining. Compared with other ungulates that reduce maternal expenditure at high density, female caribou of the Rivière-George herd may have a risk-prone reproductive strategy.

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Effects of Natal Departure and Water Level on Survival of Juvenile Snail Kites (Rostrhamus Sociabilis) in Florida

The Auk ◽

10.1093/auk/121.3.894 ◽

2004 ◽

Vol 121 (3) ◽

pp. 894-903

Author(s):

Victoria J. Dreitz ◽

Wiley M. Kitchens ◽

Donald L. DeAngelis

Keyword(s):

Environmental Factors ◽

Food Resources ◽

Water Levels ◽

Natal Dispersal ◽

Lifetime Reproductive Success ◽

Juvenile Survival ◽

Wet Season ◽

Juvenile Period ◽

Yearly Variation ◽

Rostrhamus Sociabilis

Abstract Survival rate from fledging to breeding, or juvenile survival, is an important source of variation in lifetime reproductive success in birds. Therefore, determining the relation-ship between juvenile survival and environmental factors is essential to understanding fitness consequences of reproduction in many populations. With increases in density of individuals and depletion of food resources, quality of most habitats deteriorates during the breeding season. Individuals respond by dispersing in search of food resources. Therefore, to understand the influence of environmental factors on juvenile survival, it is also necessary to know how natal dispersal influences survival of juveniles. We examined effects of various environmental factors and natal dispersal behavior on juvenile survival of endangered Snail Kites (Rostrhamus sociabilis) in central and southern Florida, using a generalized estimating equations (GEEs) approach and model selection criteria. Our results suggested yearly effects and an influence of age and monthly minimum hydrologic levels on juvenile Snail Kite survival. Yearly variation in juvenile survival has been reported by other studies, and other reproductive components of Snail Kites also exhibit such variation. Age differences in juvenile survival have also been seen in other species during the juvenile period. Our results demonstrate a positive relationship between water levels and juvenile survival. We suggest that this is not a direct linear relationship, such that higher water means higher juvenile survival. The juvenile period is concurrent with onset of the wet season in the ecosystem we studied, and rainfall increases as juveniles age. For management purposes, we believe that inferences suggesting increasing water levels during the fledging period will increase juvenile survival may have short-term benefits but lead to long-term declines in prey abundance and possibly wetland vegetation structure.

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Production of asari (Manila) clams, Ruditapes philippinarum, during the period of harvest decrease in the 2000s in the Banzu tidal area, Tokyo Bay

Aquatic Living Resources ◽

10.1051/alr/2020016 ◽

2020 ◽

Vol 33 ◽

pp. 14

Author(s):

Mitsuharu Toba ◽

Jun Kakino ◽

Kazuo Tada ◽

Yutaka Kobayashi ◽

Hideharu Tsuchie

Keyword(s):

Field Investigation ◽

Ruditapes Philippinarum ◽

Management Style ◽

Seed Stock ◽

Tokyo Bay ◽

Yearly Variation ◽

Culture Area ◽

Stock Biomass ◽

Tidal Area ◽

High Level

In Tokyo Bay, the harvestable quantity of asari (Manila) clams Ruditapes philippinarum has been decreasing since the late 1990s. We conducted a field investigation on clam density in the Banzu culture area from April 1988 to December 2014 and collected records spanning January 1986 to September 2017 from relevant fisheries cooperative associations to clarify the relationship between the temporal variation in stock abundance and the production activities of fishermen. The yearly variation in clam abundance over the study period was marked by larger decreases in the numbers of larger clams. A large quantity of juvenile clams, beyond the biological productivity of the culture area, may have been introduced as seed stock in the late 1980s despite the high level of harvestable stock. The declines in harvested quantity began in the late 1990s and may have been caused by decreases in harvestable stock despite the continuous addition of seed stock clams. The harvested quantity is likely to be significantly dependent upon the wild clam population, even within the culture area, as the harvestable quantity was not correlated with the quantity of seed stock introduced during the study period. These declines in harvested quantity may have resulted from a decreasing number of operating harvesters due to the low level of harvestable stock and consequently reduced profitability. Two findings were emphasized. A certain management style, based on predictions of the contributions of wild and introduced clams to future stock biomass, is essential for economically-feasible culturing. In areas with less harvestable stock, actions should be taken to maintain the incomes of harvesters while avoiding overexploitation, even if the total harvest quantity decreases.

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High Reproductive Effort and Low Recruitment Rates of European Beech: Is There a Limit for the Superior Competitor?

Polish Journal of Ecology ◽

10.3161/15052249pje2015.63.2.004 ◽

2015 ◽

Vol 63 (2) ◽

pp. 198-212 ◽

Cited By ~ 8

Author(s):

Jerzy Szwagrzyk ◽

Georg Gratzer ◽

Hanna Stępniewska ◽

Janusz Szewczyk ◽

Bojana Veselinovic

Keyword(s):

Reproductive Effort ◽

European Beech ◽

High Reproductive Effort

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Perceived mate competition risk influences the female mate choice and increases the reproductive effort in the annual killifish Millerichthys robustus

Ethology Ecology & Evolution ◽

10.1080/03949370.2021.1893827 ◽

2021 ◽

pp. 1-13

Author(s):

Omar Domínguez-Castanedo

Keyword(s):

Mate Choice ◽

Reproductive Effort ◽

Female Mate Choice ◽

Mate Competition ◽

Female Mate ◽

Annual Killifish

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Seed provenance determines germination responses of Rumex crispus (L.) under water stress and nutrient availability

Journal of Plant Ecology ◽

10.1093/jpe/rtz034 ◽

2019 ◽

Vol 12 (6) ◽

pp. 949-961 ◽

Cited By ~ 3

Author(s):

María Pérez-Fernández ◽

Carole P Elliott ◽

Alex Valentine ◽

José Antonio Oyola

Keyword(s):

Reproductive Effort ◽

Agricultural Soils ◽

Inorganic Nitrogen ◽

Seedling Emergence ◽

Plant Mortality ◽

Rumex Crispus ◽

Reciprocal Transplantation ◽

Transplantation Experiment ◽

Germination Trial ◽

Western Spain

Abstract Aims Seeds of Rumex crispus from six provenances were studied in relation to their germination under drought and presence of nitrogen in the germination and emergence media. We also investigated whether adaptation to soil increases the ability of the species to colonize and establish in contrasting environments along a longitudinal gradient in western Spain by means of a reciprocal transplantation experiment. Methods We conducted a germination trial in the lab to test for the germination responses to water scarcity along a polyethylene glycol gradient and to varying concentrations of nitrogen compounds. Simultaneously reciprocal transplantations experiment was conducted, where seeds from six provenances were grown in the soils from the very same provenances. Seedling emergence, survivorship and fitness-related variables were measured in all plots. Important Findings We found that R. crispus has a cold-stratification requirement that enhances its germination. Significant differences between the six provenances were detected for time-to-germination, total seedling emergence, plant mortality and reproductive effort in all the experiments. The differences between provenances with respect to germination were confirmed by the significant statistical analyses of the variance, thus providing evidence that seeds from parent plants grown in different environmental conditions have an intrinsically different abilities to germinate and establish. Soil nitrogen content where seed germination and seedlings establish also play an important role in their performance in terms of survivorship and reproduction, being the higher levels of inorganic nitrogen and of microbial biomass those that increased biomass production, enhanced inflorescence formation and reduced plant mortality. We conclude that one of the main reasons for the spread and maintenance of R. crispus would be the increased levels of nitrogen in agricultural soils.

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