scholarly journals Population productivity of wedgefishes, guitarfishes, and banjo rays: inferring the potential for recovery

2019 ◽  
Author(s):  
Brooke M. D’Alberto ◽  
John K. Carlson ◽  
Sebastián A. Pardo ◽  
Colin A. Simpfendorfer
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Maximum Size ◽  
Population Increase ◽  
Population Recovery ◽  
High Demand ◽  
Over Exploitation

AbstractRecent evidence of widespread and rapid declines of wedgefishes, guitarfishes, and banjo ray populations (Order Rhinopristiformes), driven by a high demand for their fins in Asian markets and the quality of their flesh, raises concern about their risk of over-exploitation and extinction. Using life history theory and incorporating uncertainty into a modified Euler-Lotka model, maximum intrinsic rates of population increase (rmax) were estimated for nine species from the four families of rhinopristiforms. Estimates of medianrmaxvaried from −0.04 to 0.60 year−1among the nine species, but generally increased with increasing maximum size. In comparison to 115 other species of chondrichthyans for whichrmaxvalues were available, the families Rhinidae and Glaucostegidae are relatively productive, while most species from Rhinobatidae and Trygonorrhinidae had relatively lowrmaxvalues. If the demand for their high value products can be addressed, then population recovery for this species is likely possible but will vary depending on the species.

scholarly journals Diagnosing the dangerous demography of manta rays using life history theory

2013 ◽  
Author(s):  
Nicholas K Dulvy ◽  
Sebastián A. Pardo ◽  
Colin A. Simpfendorfer ◽  
John K. Carlson
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Extinction Risk ◽  
Somatic Growth ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Population Declines ◽  
Demographic Information ◽  
Age At Maturity ◽  
Manta Ray

The directed harvest and global trade in the gill plates of mantas, and other mobulid rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography in the context of other sharks and rays. Despite the limited availability of data, we use life history theory and comparative analysis to develop plausible ranges of somatic growth rate, annual pup production and age at maturity to estimate risk of extinction (maximum intrinsic rate of population increase rmax) using a variant of the classic Euler-Lotka model. Manta ray rmax is most sensitive to the length of the reproductive cycle, and the median rmax of 0.11 year-1(CI: 0.089-0.137) is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information. In common with other unprotected, unmanaged, high-value large-bodied species with low or very low productivity, manta rays are unlikely to sustain unmonitored, unregulated exploitation and may face increasing local and regional extinction risk.

scholarly journals Diagnosing the dangerous demography of manta rays using life history theory

2013 ◽  
Author(s):  
Nicholas K Dulvy ◽  
Sebastián A. Pardo ◽  
Colin A. Simpfendorfer ◽  
John K. Carlson
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Extinction Risk ◽  
Somatic Growth ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Population Declines ◽  
Demographic Information ◽  
Age At Maturity ◽  
Manta Ray

The directed harvest and global trade in the gill plates of mantas, and other mobulid rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography in the context of other sharks and rays. Despite the limited availability of data, we use life history theory and comparative analysis to develop plausible ranges of somatic growth rate, annual pup production and age at maturity to estimate risk of extinction (maximum intrinsic rate of population increase rmax) using a variant of the classic Euler-Lotka model. Manta ray rmax is most sensitive to the length of the reproductive cycle, and the median rmax of 0.11 year-1(CI: 0.089-0.137) is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information. In common with other unprotected, unmanaged, high-value large-bodied species with low or very low productivity, manta rays are unlikely to sustain unmonitored, unregulated exploitation and may face increasing local and regional extinction risk.

scholarly journals Flexibility in an emergency life-history stage: acute food deprivation prevents sickness behaviour but not the immune response

2020 ◽  
Vol 287 (1929) ◽  
pp. 20200842
Author(s):  
Kathryn Wilsterman ◽  
Mattina M. Alonge ◽  
Darcy K. Ernst ◽  
Cody Limber ◽  
Lisa A. Treidel ◽  
...  
Keyword(s):  
Life History ◽  
Immune Responses ◽  
Food Deprivation ◽  
Life History Theory ◽  
Network Models ◽  
Life History Stage ◽  
Sickness Behaviour ◽  
Single Organism ◽  
Multiple Challenges

The emergency life-history stage (ELHS) can be divided into two subcategories that describe distinct, coordinated responses to disease- or non-disease-related physiological challenges. Whether an individual can simultaneously express aspects of both subcategories when faced with multiple challenges is poorly understood. Emergency life-history theory suggests that disease- and non-disease-related responses are coordinated at the level of the whole organism and therefore cannot be expressed simultaneously. However, the reactive scope and physiological regulatory network models suggest that traits can be independently regulated, allowing for components of both disease- and non-disease-related responses to be simultaneously expressed within a single organism. To test these ideas experimentally, we subjected female zebra finches to food deprivation, an immune challenge, both, or neither, and measured a suite of behavioural and physiological traits involved in the ELHS. We examined whether the trait values expressed by birds experiencing simultaneous challenges resembled trait values of birds experiencing a single challenge or if birds could express a mixture of trait values concurrently. We find that birds can respond to simultaneous challenges by regulating components of the behavioural and immune responses independently of one another. Modularity within these physio-behavioural networks adds additional dimensions to how we evaluate the intensity or quality of an ELHS. Whether modularity provides fitness advantages or costs in nature remains to be determined.

Interrelationships of factors of social development are more complex than Life History Theory predicts

2019 ◽  
Vol 42 ◽  
Author(s):  
Boris Kotchoubey
Keyword(s):  
Life History ◽  
Social Development ◽  
Life History Theory ◽  
Strong Correlations ◽  
Behavioral Features

Abstract Life History Theory (LHT) predicts a monotonous relationship between affluence and the rate of innovations and strong correlations within a cluster of behavioral features. Although both predictions can be true in specific cases, they are incorrect in general. Therefore, the author's explanations may be right, but they do not prove LHT and cannot be generalized to other apparently similar processes.

scholarly journals Five reasons COVID-19 is less severe in younger age groups

2020 ◽  
Author(s):  
Paul W Turke
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Age Of Onset ◽  
Age Groups ◽  
Medical Community ◽  
System Function ◽  
The Third ◽  
Immune System Function ◽  
Age Related ◽  
Younger Age

Abstract The severity of COVID-19 is age-related, with the advantage going to younger age groups. Five reasons are presented. The first two are well-known, are being actively researched by the broader medical community, and therefore are discussed only briefly here. The third, fourth, and fifth reasons derive from evolutionary life history theory, and potentially fill gaps in current understanding of why and how young and old age groups respond differently to infection with SARS-CoV-2. Age of onset of generalized somatic aging, and the timing of its progression, are identified as important causes of these disparities, as are specific antagonistic pleiotropic tradeoffs in immune system function.

scholarly journals A Review on Polymer Nanocomposites and Their Effective Applications in Membranes and Adsorbents for Water Treatment and Gas Separation

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 139
Author(s):  
Oluranti Agboola ◽  
Ojo Sunday Isaac Fayomi ◽  
Ayoola Ayodeji ◽  
Augustine Omoniyi Ayeni ◽  
Edith E. Alagbe ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Polymer Nanocomposites ◽  
Gas Separation ◽  
Rapid Growth ◽  
Dye Removal ◽  
Anthropogenic Activities ◽  
Polymer Nanocomposite ◽  
Population Increase ◽  
Nanocomposite Membranes

Globally, environmental challenges have been recognised as a matter of concern. Among these challenges are the reduced availability and quality of drinking water, and greenhouse gases that give rise to change in climate by entrapping heat, which result in respirational illness from smog and air pollution. Globally, the rate of demand for the use of freshwater has outgrown the rate of population increase; as the rapid growth in town and cities place a huge pressure on neighbouring water resources. Besides, the rapid growth in anthropogenic activities, such as the generation of energy and its conveyance, release carbon dioxide and other greenhouse gases, warming the planet. Polymer nanocomposite has played a significant role in finding solutions to current environmental problems. It has found interest due to its high potential for the reduction of gas emission, and elimination of pollutants, heavy metals, dyes, and oil in wastewater. The revolution of integrating developed novel nanomaterials such as nanoparticles, carbon nanotubes, nanofibers and activated carbon, in polymers, have instigated revitalizing and favourable inventive nanotechnologies for the treatment of wastewater and gas separation. This review discusses the effective employment of polymer nanocomposites for environmental utilizations. Polymer nanocomposite membranes for wastewater treatment and gas separation were reviewed together with their mechanisms. The use of polymer nanocomposites as an adsorbent for toxic metals ions removal and an adsorbent for dye removal were also discussed, together with the mechanism of the adsorption process. Patents in the utilization of innovative polymeric nanocomposite membranes for environmental utilizations were discussed.

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