scholarly journals Life-history patterns of fishes in the Hellenic Seas

Web Ecology ◽  
2000 ◽  
Vol 1 (1) ◽  
pp. 1-10 ◽  
Author(s):  
K. I. Stergiou
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Feeding Habits ◽  
Information Age ◽  
Adult Mortality ◽  
Quantitative Information ◽  
Fish Prey ◽  
Fish Stocks ◽  
Similar Information ◽  
Life History Patterns

Abstract. The available quantitative information (age, growth, maturation and mortality) for 103 fish stocks in Hellenic Seas was analysed here in the context of life-history theory and compared with similar information from other areas of the world. The results showed that the fish species and stocks inhabiting Hellenic waters are generally small in size, have low longevity, mature at an early age and size, and probably suffer high adult mortality rates. Such a pattern most probably is an adaptation to the synergetic combination of highly oligotrophic conditions and high subtropical temperatures prevailing in Hellenic waters and is consistent with life-history theory. Finally, the auximetric grid was used to compare the growth of four species, each represented by more than six stocks. The results revealed that the growth spaces occupied by the four species reflect their strikingly different feeding habits, especially with respect to the size of prey and the relative importance of fish prey to their diet.

Can commercial fishing cause evolution? Answers from guppies (Poecilia reticulata)

2005 ◽  
Vol 62 (4) ◽  
pp. 791-801 ◽  
Author(s):  
David N Reznick ◽  
Cameron K Ghalambor
Keyword(s):  
Life History ◽  
Body Size ◽  
Life Histories ◽  
Life History Theory ◽  
Poecilia Reticulata ◽  
Mortality Rates ◽  
Adult Mortality ◽  
Commercial Fisheries ◽  
Commercial Fishing ◽  
Rate Of Evolution

Life history theory predicts that high adult mortality rates select for earlier maturity and increased reproduction. If such evolution occurs in response to the commercial exploitation of natural fish populations, then the correlated reduction in body size would reduce the yield of the fishery. Earlier maturity and reduced body size are seen in commercially exploited populations. Here, we compare the life histories of natural populations of guppies (Poecilia reticulata) from Trinidad that live in either high- or low-predation environments, which serve as surrogates for the presence or absence of commercial fishing. We can quantify mortality rate and life history variables, including age and size at maturity, in the laboratory and in nature. We have manipulated mortality rates in nature and measured the rate of evolution. High mortality selects for earlier maturity at a smaller size, as observed in commercial fisheries and as predicted by theory. Furthermore, the nature and magnitude of predator-induced mortality are comparable to those caused by commercial fishing. The rate of evolution in guppies predicts similar evolution in commercial fisheries on a time scale of decades. These attributes support arguments that humans, like predators, have acted as an agent of selection when exploiting populations of fish.

scholarly journals Diet and divergence of introduced smallmouth bass (Micropterus dolomieu) populations

2005 ◽  
Vol 62 (8) ◽  
pp. 1720-1732 ◽  
Author(s):  
Erin S Dunlop ◽  
Judi A Orendorff ◽  
Brian J Shuter ◽  
F Helen Rodd ◽  
Mark S Ridgway
Keyword(s):  
Life History ◽  
Food Availability ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Adult Mortality ◽  
Smallmouth Bass ◽  
Individual Growth ◽  
Common Source ◽  
Large Prey ◽  
Micropterus Dolomieu

We examine the degree and causes of divergence in growth and reproduction in two populations of smallmouth bass (Micropterus dolomieu) introduced a century ago. Despite a common source, the Provoking Lake population now has a higher population density and slower growing individuals than the Opeongo Lake population. Using this system, we test the predictions of life history theory that delayed maturation and reduced reproductive investment are expected in high density populations with slow individual growth rates. Observations on both populations run directly counter to the aforementioned expectations. Instead, Provoking males have smaller sizes and younger ages at nesting and higher gonad masses than Opeongo males; Provoking females have smaller sizes at maturity, larger egg sizes, and higher ovarian dry masses than Opeongo females. Temperature, food availability, diet ontogeny, young-of-the-year mortality, and adult mortality were examined as plausible contributors to the divergence. Results suggest that low food availability, likely caused or mediated by intraspecific competition for prey, and lack of large prey in the diet are contributing to the slow growth, increased reproductive investment, and higher mortality following reproduction in Provoking. This study provides insight into the processes that produce rapid divergence of life history in a species exhibiting parental care.

AQUATIC COLEOPTERA OF PEATLANDS AND MARSHES IN CANADA

1987 ◽  
Vol 119 (S140) ◽  
pp. 99-132 ◽  
Author(s):  
David J. Larson
Keyword(s):  
Life History ◽  
Species Composition ◽  
Feeding Habits ◽  
Water Beetles ◽  
Future Needs ◽  
Water Beetle ◽  
Wetland Water ◽  
Life History Patterns ◽  
Common Future ◽  
Rich Fauna

AbstractA rich fauna of water beetles, comprising 11 families and 485 species, occurs in Canadian peatlands and marshes. These beetles are diverse with respect to morphology, feeding habits, life-history patterns, and even in the degree to which they occur in water. Major adaptations to peatland and marsh habitats are described. Based on species composition, the following regional communities of marsh-inhabiting beetles are recognized: arctic, boreal, Cordilleran, grasslands, and eastern temperate. Peatlands possess a community of beetles similar to that of boreal marshes but contain enough unique elements to warrant separate recognition. However, based on water beetle distribution, it is not possible to subdivide peatlands into bog and fen communities because these habitats have many species in common. Future needs for research on wetland water beetles are identified.

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.

Relationships between temperature and Pacific hake distribution vary across latitude and life-history stage

2020 ◽  
Vol 639 ◽  
pp. 185-197 ◽  
Author(s):  
MJ Malick ◽  
ME Hunsicker ◽  
MA Haltuch ◽  
SL Parker-Stetter ◽  
AM Berger ◽  
...  
Keyword(s):  
Life History ◽  
Environmental Effects ◽  
Environmental Conditions ◽  
Vancouver Island ◽  
Additive Models ◽  
Life History Stage ◽  
Fish Stocks ◽  
Merluccius Productus ◽  
Multiple Dimensions ◽  
Effects Of Temperature

Environmental conditions can have spatially complex effects on the dynamics of marine fish stocks that change across life-history stages. Yet the potential for non-stationary environmental effects across multiple dimensions, e.g. space and ontogeny, are rarely considered. In this study, we examined the evidence for spatial and ontogenetic non-stationary temperature effects on Pacific hake Merluccius productus biomass along the west coast of North America. Specifically, we used Bayesian additive models to estimate the effects of temperature on Pacific hake biomass distribution and whether the effects change across space or life-history stage. We found latitudinal differences in the effects of temperature on mature Pacific hake distribution (i.e. age 3 and older); warmer than average subsurface temperatures were associated with higher biomass north of Vancouver Island, but lower biomass offshore of Washington and southern Vancouver Island. In contrast, immature Pacific hake distribution (i.e. age 2) was better explained by a nonlinear temperature effect; cooler than average temperatures were associated with higher biomass coastwide. Together, our results suggest that Pacific hake distribution is driven by interactions between age composition and environmental conditions and highlight the importance of accounting for varying environmental effects across multiple dimensions.

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.

Sign in / Sign up

Export Citation Format

Share Document