Effects of simulated herbivory on growth and reproduction of two beach annuals, Cakile edentula and Corispermum hyssopifolium

1992 ◽  
Vol 70 (12) ◽  
pp. 2467-2475 ◽  
Author(s):  
Kevin E. Gedge ◽  
M. A. Maun
Keyword(s):  
Reproductive Output ◽  
Natural Habitat ◽  
Critical Time ◽  
Insect Herbivores ◽  
Compensatory Response ◽  
Large Numbers ◽  
Cakile Edentula ◽  
Specialist Insect ◽  
Heavy Damage ◽  
Growth And Reproduction

Cakile edentula var. lucustris (sea rocket) and Corispermum hyssopifolium (bugseed) are two annual flowering plants that grow on the sandy shores of the Great Lakes. This habitat is extremely unpredictable and plants are subject to grazing by a number of insect herbivores as well as browsing by white-tailed deer. The objectives of these studies were to estimate the extent of herbivore damage under natural conditions, to determine the most vulnerable stage of damage, and to examine the compensatory ability of each species to tolerate herbivory. Greenhouse experiments showed that both species were able to compensate for low to moderate levels of artificial defoliation. However, high levels near the time of anthesis reduced the growth and reproductive output of both species. Similar experiments in the field revealed that although the critical time of damage was still the same, the plants were less able to tolerate herbivory. Cakile edentula plants exposed to natural herbivory in an unsprayed cabbage field were quickly attacked by large numbers of specialist insect herbivores and completely defoliated in 11 days. The fact that such damage does not occur in its natural habitat suggests that Cakile edentula escapes heavy damage because insects are unable to locate these populations along the shoreline. Key words: white-tailed deer, defoliation intensity, defoliation stage, compensatory response, indeterminate growth.

Competition in Plant Communities

Ecology ◽  
2012 ◽  
Author(s):  
Paul A. Keddy ◽  
James Cahill
Keyword(s):  
Experimental Design ◽  
Plant Communities ◽  
Managed Forests ◽  
Negative Effects ◽  
Large Numbers ◽  
Multiple Species ◽  
Choice Of Species ◽  
Intensity Of Competition ◽  
Plant Coexistence ◽  
Growth And Reproduction

Competition is generally understood to refer to the negative effects on plant growth or fitness caused by the presence of neighbors, usually by reducing the availability of resources. Competition can be an important factor controlling plant communities, along with resources, disturbance, herbivory, and mutualisms. Since all plants require a few basic elements, the resource involved is generally light, water, nitrogen, or phosphorus, depending upon the species and the location. The effects of competition are widespread and easily observed in mixtures of crops and managed forests, which is why weeding and thinning are practiced. Competition is also widespread in native habitats, from deserts to wetlands, and is known to have important—indeed crucial—effects upon recruitment, growth, and reproduction. In the late 1800s, Darwin wrote extensively about the importance of competition in nature, particularly its role in driving natural selection. Thereafter, interest in the phenomenon grew. Many experiments with both crops and wild species were conducted. Models of competitive interactions were also constructed, with the number and size of the models increasing rapidly with the advent of computers in the 1970s. Because the word competition has a common usage in English, what it represents in biological systems is frequently assumed, rather than explicitly stated, leading to misunderstanding. Care must be taken in using or interpreting the word without specifying what kind of competition is being investigated, as different forms of competition can have different types of consequences. For example, competition may be looked at from the perspective of an individual, a population, or a species, it may be symmetric or asymmetric, and it can occur among single or multiple species simultaneously. Experimental design carries its own assumptions, which are often not stated in published articles. One of the most difficult tasks in exploring published studies is the need to sift through large numbers of experiments in which investigators have haphazardly selected (a pair of) species and grown them in mixture, without adequately justifying their choice of species or the experimental design. Another difficult task is distinguishing between models that, at least in principle, have measurable inputs or make measurable predictions (or both) and those that do not and cannot be tested. Overall, the very ease of growing plants in mixture, as well as the ease of making new models, may have made some people careless, with the result that basic questions are remaining unaddressed. Ongoing issues of importance include mechanisms of competition, types of competition, effects of competition on plant coexistence, and the intensity of competition under different sets of conditions.

Respiratory Adaptations of the Fingernail Clams Sphaerium occidentale and Musculium securis to Ephemeral Habitats

1983 ◽  
Vol 40 (6) ◽  
pp. 783-791 ◽  
Author(s):  
Paul M. McKee ◽  
Gerald L. Mackie
Keyword(s):  
Oxygen Uptake ◽  
Life Histories ◽  
Natural Habitat ◽  
Pond Water ◽  
Temperature Acclimation ◽  
Early Summer ◽  
Temporary Pond ◽  
Obligate Aerobe ◽  
Fingernail Clams ◽  
Growth And Reproduction

Experiments performed on seasonal collections of the pisidiids Sphaerium occidentale and Musculium securis from a temporary pond suggest that respiratory adaptations are related to the specific life histories of the two species. Sphaerium occidentale lives up to 3 yr and all age classes aestivate during dry periods, while M. securis lives for about 1 yr and only newborn aestivate. Both species are iteroparous and reproduce primarily in late spring and early summer. Oxygen uptake rates at field temperature and Q10 values are low in both species during hibernation and aestivation, indicating respiratory stability and energy conservation. These rates and respiratory coefficients peak in spring during maximal growth and reproduction. Respiration in M. securis is more independent of temperature than in S. occidentale, reflecting the requirement of the former to complete growth and reproduction more quickly. Both animals show temperature acclimation patterns permitting early activity in spring and, thus, a more efficient exploitation of the short aquatic season. This pattern is more pronounced in the shorter lived M. securis. During aestivation, M. securis is a facultative anaerobe, while S. occidentale is an obligate aerobe. Neither species displays an oxygen debt following aestivation when immersed in water. Arousal from aestivation, as indicated by oxygen uptake, is delayed when clams are introduced to pond water. This apparently inhibits a premature resumption of activity and decreases the likelihood of desiccation in the natural habitat.

scholarly journals Critical Time Course of Right Frontoparietal Involvement in Mental Number Space

2013 ◽  
Vol 25 (3) ◽  
pp. 465-483 ◽  
Author(s):  
Elena Rusconi ◽  
Martynas Dervinis ◽  
Frederick Verbruggen ◽  
Christopher D. Chambers
Keyword(s):  
Time Course ◽  
Posterior Parietal Cortex ◽  
Inferior Frontal Gyrus ◽  
Critical Time ◽  
Single Pulse ◽  
Random Order ◽  
Number Line ◽  
Sampling Interval ◽  
Snarc Effect ◽  
Large Numbers

Neuropsychological, neurophysiological, and neuroimaging studies suggest that right frontoparietal circuits may be necessary for the processing of mental number space, also known as the mental number line (MNL). Here we sought to specify the critical time course of three nodes that have previously been related to MNL processing: right posterior parietal cortex (rPPC), right FEF (rFEF), and right inferior frontal gyrus (rIFG). The effects of single-pulse TMS delivered at 120% distance-adjusted individual motor threshold were investigated in 21 participants, within a window of 0–400 msec (sampling interval = 33 msec) from the onset of a central digit (1–9, 5 excluded). Pulses were delivered in a random order and with equal probability at each time point, intermixed with noTMS trials. To analyze whether and when TMS interfered with MNL processing, we fitted bimodal Gaussian functions to the observed data and measured effects on changes in the Spatial–Numerical Association of Response Codes (SNARC) effect (i.e., an advantage for left- over right-key responses to small numbers and right- over left-key responses to large numbers) and in overall performance efficiency. We found that, during magnitude judgment with unimanual key-press responses, TMS reduced the SNARC effect in the earlier period of the fitted functions (∼25–60 msec) when delivered over rFEF (small and large numbers) and rIFG (small numbers); TMS further reduced the SNARC effect for small numbers in a later period when delivered to rFEF (∼200 msec). In contrast, TMS of rPPC did not interfere with the SNARC effect but generally reduced performance for small numbers and enhanced it for large numbers, thus producing a pattern reminiscent of “neglect” in mental number space. Our results confirm the causal role of an intact right frontoparietal network in the processing of mental number space. They also indicate that rPPC is specifically tied to explicit number magnitude processing and that rFEF and rIFG contribute to interfacing mental visuospatial codes with lateralized response codes. Overall, our findings suggest that both ventral and dorsal frontoparietal circuits are causally involved and functionally connected in the mapping of numbers to space.

scholarly journals FISSION IN THE ZOANTHARIA PALYTHOA CARIBAEORUM (Duchassaing and Michelotii, 1860) POPULATIONS: A LATITUDINAL COMPARISON

2016 ◽  
Vol 36 ◽  
Author(s):  
Alberto Acosta ◽  
Ana M. González
Keyword(s):  
Colony Size ◽  
Reproductive Output ◽  
Abiotic Factors ◽  
Regional Studies ◽  
Fission Process ◽  
Palythoa Caribaeorum ◽  
Large Numbers ◽  
Small Colony ◽  
The Relationship ◽  
Brazilian Populations

There are few regional studies attempting to compare the asexual reproductive output of marine populations, particularly when they are exposed to different environmental conditions. In this study we compared Caribbean and Southwestern Atlantic Palythoa caribaeorum populations in terms of ramet production, the minimum colony size for fission, and the relationship between fission frequency and colony size. Fission process was quantified in Ponta Recife and Praia Portinho, Sao Paulo, Brazil, and in Punta de Betín, Colombia, during the summer (December-January) of 1997 and 1998, respectively. Fission started at small colony size in both populations studied (> 4 cm2). The number of ramets produced per colony increased with colony size in Brazil and Colombia. Colombian zoanthids produced more ramets by fission than Brazilian populations. The populations shared early reproduction characteristics, and production of large numbers of ramets, which increased with colony size, even though they differed in fission frequency. Fission seems to be a conservative trait in P. caribaeorum, although its expression could vary depending on habitat conditions related to biotic and / or abiotic factors.

scholarly journals Propagation for the Conservation of Pityopsis ruthii, an Endangered Species from the Southeastern United States

HortScience ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 194-200 ◽  
Author(s):  
Phillip A. Wadl ◽  
Timothy A. Rinehart ◽  
Adam J. Dattilo ◽  
Mark Pistrang ◽  
Lisa M. Vito ◽  
...  
Keyword(s):  
Endangered Species ◽  
Natural Habitat ◽  
Basal Medium ◽  
Single Individual ◽  
In Vitro Multiplication ◽  
Large Numbers ◽  
Lateral Shoots ◽  
Genetic Swamping ◽  
Germination Techniques

Pityopsis ruthii is an endangered species endemic to the Hiwassee and Ocoee Rivers in Tennessee. As part of a recovery effort focused on P. ruthii, vegetative propagation and in vitro multiplication and seed germination techniques were developed. Plants were vegetatively propagated using greenhouse stock plants and wild-collected stems. Rooting occurred with and without auxin treatments but was greatest when 0.1% indole-3-butyric acid (IBA) talc was applied to the vegetative cuttings; rooting was lowest when flowering stems were used. Pro-Mix BX substrate provided the most consistent rooting. In vitro multiplication was accomplished by the removal of lateral shoots from in vitro-grown plants that were rooted on Murashige and Skoog (MS0) basal medium with 270 clones produced from a single individual after 4 months. Nineteen clones were transplanted and secured with bonded fiber matrix into their natural habitat and 14 survived for 1 year. To avoid genetic swamping of native populations with the introduction of large numbers of genetically identical individuals through clonal propagation, seed-based propagation efforts were explored. Open-pollinated seeds were collected, disinfested and germinated, and seedlings established on MS medium. Seeds were submersed in 70% ethanol for 1 minute and briefly flamed. Seeds were surface-sterilized in a range [10% to 50% (v/v)] Clorox® bleach solutions with vigorous shaking for 20 minutes, rinsed three times in sterile water, and germinated on MS0. Removal of pappus from seeds was required for successful disinfestations, but the bleach concentration was not critical. Successful propagation is a step toward the conservation and recovery of P. ruthii and should allow future reintroduction projects.

SEAGRASS RESTORATION: AN UPDATE FROM TRANG PROVINCE, SOUTHWESTERN THAILAND

2017 ◽  
Author(s):  
Prasert Tongnunui ◽  
Prasert Tongnunui ◽  
Woraporn Tarangkoon ◽  
Woraporn Tarangkoon ◽  
Parichat Hukiew ◽  
...  
Keyword(s):  
Survival Rate ◽  
Habitat Restoration ◽  
Natural Habitat ◽  
Donor Site ◽  
Limiting Factor ◽  
Seagrass Bed ◽  
Asexual Propagation ◽  
Enhalus Acoroides ◽  
Large Numbers ◽  
Sexual Propagation

Natural disasters may adversely affect coastal resources potentially leading to coastal habitat restorations that incorporate stakeholders and the general public. Appropriate methodologies for habitat restoration are developed to ensure the outcomes of this project. Currently, seagrass bed restoration by means of asexual and sexual propagation techniques have been used worldwide. However, the experience of seagrass (Enhalus acoroides) habitat restoration in Trang Province noted that to accomplish this project’s strategies involved the application of restoration techniques along with public and stakeholder participation. The application of asexual propagation, specifically the collection of single shoots from donor seagrasses and subsequent transplantation, is a convenient tool. However, from this project results, this process still has conceptual problems as from the large numbers of single shoots collected from donor seagrasses, the survival rate was relatively low. Furthermore, this process was complicated by conflicting interests between local communities near to the donor site and the project’s organizers. In order to reduce said conflicts, other techniques to balance stakeholder interests were instigated by this project, namely the development of both asexual and sexual propagation techniques. This project initiated a sexual propagation technique by the collection of wild seeds of Enhalus acoroides that were subsequently grown in the laboratory before natural habitat transplantation. This project results showed that seeds can be grown rapidly and can be cultured in large numbers. However, this development technique has a limit on rearing time because seedlings were found to be in decline after the third month of the experiment. These problems were compounded by a limiting factor that pushed the project’s organizers to decide to transplant seagrasses from the laboratory to the wild whether a time was seasonally suitable or unsuitable, the planting activity still done forward. This matter may have enhanced the low survival rate situation after seagrass transplantation to the wild. If there is a need to recover a seagrass bed, the above culture and transplantation methodologies should be used in conjunction with repeated periodic plantings until natural ecological function has been restored. In conclusion, further research should be instigated to improve the cultivation method for producing ready to plant seedlings and to improve methods of project operation.

The First Farmers

2013 ◽  
Author(s):  
T. Douglas Price
Keyword(s):  
Near East ◽  
Natural Habitat ◽  
Coastal Region ◽  
Wild Plants ◽  
Human Society ◽  
Way Of Life ◽  
Large Numbers ◽  
Major Turning Point ◽  
Wild Sheep ◽  
Spread Of Agriculture

The origins and spread of agriculture and a Neolithic way of life marked a major turning point in the evolution of human society. Farming changed everything. Our heritage as food collectors, consuming the wild products of the earth, extends back millions of years. Nevertheless, at the end of the Pleistocene some human groups began to produce their own food rather than collect it, to domesticate and control wild plants and animals, achieving what is perhaps the most remarkable transformation in our entire human past. Agriculture is a way of obtaining food that involves domesticated plants and animals. But the transition to farming is much more than simple herding or cultivation. It also entails major, long-term changes in the structure and organization of the societies that adopt this new way of life, as well as a totally new relationship with the environment. Hunters and gatherers largely live off the land in an extensive fashion, generally exploiting diverse resources over a broad area; farmers intensively use a smaller portion of the landscape and create a milieu that suits their needs. With the transition to agriculture, humans began to truly change their environment. Cultivation of plants and herding of animals, village society, and pottery did not originate in Europe. Domestication arrived from the ancient Near East. The Neolithic began in southwest Asia some 11,000 years ago and eventually spread into the European continent, carried by expanding populations of farmers. The mountains of western Iran and southern Turkey and the uplands of the Levant (the coastal region of the far eastern part of the Mediterranean, from the northeastern Sinai Peninsula through modern Israel, Lebanon, and Syria, and west along the modern Turkish coast) form an elevated zone somewhat cooler and wetter than much of the Near East. The area has been described as the Fertile Crescent. A variety of wild plants grow in abundance. This region was the natural habitat of many of the wild ancestors of the first species of plants and animals to be domesticated at the end of the Pleistocene: the wild wheats and barleys, the wild legumes, and the wild sheep, goats, pigs, and cattle that began to be exploited in large numbers at the origins of agriculture.

scholarly journals We Are What We Eat: A Stoichiometric and Ecometabolomic Study of Caterpillars Feeding on Two Pine Subspecies of Pinus sylvestris

2018 ◽  
Vol 20 (1) ◽  
pp. 59
Author(s):  
Albert Rivas-Ubach ◽  
Josep Peñuelas ◽  
José Hódar ◽  
Michal Oravec ◽  
Ljiljana Paša-Tolić ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Tissue Concentration ◽  
Trophic Levels ◽  
Food Sources ◽  
Thaumetopoea Pityocampa ◽  
Insect Herbivores ◽  
Plant Host ◽  
Total Variability ◽  
Specialist Insect ◽  
C:P Ratios

Many studies have addressed several plant-insect interaction topics at nutritional, molecular, physiological, and evolutionary levels. However, it is still unknown how flexible the metabolism and the nutritional content of specialist insect herbivores feeding on different closely related plants can be. We performed elemental, stoichiometric, and metabolomics analyses on leaves of two coexisting Pinus sylvestris subspecies and on their main insect herbivore; the caterpillar of the processionary moth (Thaumetopoea pityocampa). Caterpillars feeding on different pine subspecies had distinct overall metabolome structure, accounting for over 10% of the total variability. Although plants and insects have very divergent metabolomes, caterpillars showed certain resemblance to their plant-host metabolome. In addition, few plant-related secondary metabolites were found accumulated in caterpillar tissues which could potentially be used for self-defense. Caterpillars feeding on N and P richer needles had lower N and P tissue concentration and higher C:N and C:P ratios, suggesting that nutrient transfer is not necessarily linear through trophic levels and other plant-metabolic factors could be interfering. This exploratory study showed that little chemical differences between plant food sources can impact the overall metabolome of specialist insect herbivores. Significant nutritional shifts in herbivore tissues could lead to larger changes of the trophic web structure.

scholarly journals Heterothermy is associated with reduced fitness in wild rabbits

2017 ◽  
Vol 13 (12) ◽  
pp. 20170521 ◽  
Author(s):  
Shane K. Maloney ◽  
Maija K. Marsh ◽  
Steven R. McLeod ◽  
Andrea Fuller
Keyword(s):  
Body Temperature ◽  
Oryctolagus Cuniculus ◽  
Reproductive Output ◽  
Core Body Temperature ◽  
The Body ◽  
The Core ◽  
Temperature Rhythm ◽  
Body Temperature Rhythm ◽  
Core Body ◽  
Growth And Reproduction

An increase in variation in the 24 h pattern of body temperature (heterothermy) in mammals can be induced by energy and water deficits. Since performance traits such as growth and reproduction also are impacted by energy and water balance, we investigated whether the characteristics of the body temperature rhythm provide an indication of the reproductive success of an individual. We show that the amplitude of the daily rhythm of body temperature in wild rabbits ( Oryctolagus cuniculus ) prior to breeding is inversely related to the number of pregnancies in the subsequent seven months, while the minimum daily body temperature is positively correlated to the number of pregnancies. Because reproductive output could be predicted from characteristics of the core body temperature rhythm prior to the breeding season, we propose that the pattern of the 24 h body temperature rhythm could provide an index of animal fitness in a given environment.

scholarly journals Fresh and Dry Weight Relations Are Predictors of Cycas micronesica Seed Age

Horticulturae ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 29
Author(s):  
Thomas E. Marler ◽  
Christopher A. Shaw
Keyword(s):  
Dry Weight ◽  
Insect Herbivores ◽  
Seed Traits ◽  
Fresh Weight ◽  
Historical Source ◽  
Absolute Value ◽  
Seed Age ◽  
Specialist Insect ◽  
Total Seed ◽  
Substantial Change

Cycas micronesica is a foundation species in several Micronesian islands and its seeds have been a historical source of starch for the island residents. The species has become endangered by invasive specialist insect herbivores and conservationists struggle with the inability to estimate the age of observed seeds. To inform this agenda, we evaluated numerous Cycas micronesica seed traits to determine if any exhibited a relationship with age and a substantial change in absolute value. Of the 30 direct and derived seed traits that we evaluated, most of them were non-linear and exhibited minimal change after about 12 months in age. The only traits that emerged as unambiguous estimators of age were the quotients derived as gametophyte fresh weight/total seed fresh weight and sarcotesta dry weight/sclerotesta dry weight. These two simple metrics can be used to accurately estimate seed age for this arborescent cycad species.

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