scholarly journals Size-based ecological interactions drive food web responses to climate warming

2018 ◽  
Author(s):  
Max Lindmark ◽  
Jan Ohlberger ◽  
Magnus Huss ◽  
Anna Gårdmark
Keyword(s):  
Life History ◽  
Body Size ◽  
Food Web ◽  
Population Size ◽  
Climate Warming ◽  
Size Structure ◽  
Physiological Responses ◽  
Size Variation ◽  
Food Chains ◽  
Ecological Interactions

AbstractPredicting the impacts of climate change on animal populations and communities requires understanding of feedbacks between direct physiological responses and indirect effects via ecological interactions. Food-dependent body growth and within-species size variation have major effects on dynamics of populations and communities through feedbacks between individual performance and population size structure. Moreover, evidence suggests a link between temperature and population size structure, but we lack an understanding of how this is mediated by species interactions when life history processes are food-dependent. Here, we use a dynamic stage-structured biomass model with food-, size- and temperature-dependent life history processes to assess how temperature affects coexistence, stability and size structure in a tri-trophic food chain. We show that predator biomass densities decline with warming either gradually or in the form of collapses, depending on which consumer life stage they predominantly feed on. Collapses occur when warming destabilizes the community and induces alternative stable states via Allee effects, which emerge when predators promote their own food source through predation. By contrast, warming at low temperatures stabilizes the community as limit cycles turn to fixed point dynamics, unless predators feed only on juveniles. Elevated costs of being large in warmer environments accelerate the decline in predator persistence and mean body size of the community. These results suggest that predator persistence in warmer climates may be lower than previously acknowledged when accounting for size- and food-dependence of life history processes, and that interactions within and between species can mediate the effects of warming on food web stability.SignificanceClimate warming is altering the dynamics and structure of aquatic ecosystems worldwide. Predicting food web reorganization under rising temperatures requires an understanding of physiological responses and ecological interactions of organisms, both of which depend on body size. We show that size variation within species, food-dependent growth and ecological interactions critically affect how food chains respond to warming. Specifically, warming can stabilize or destabilize food chains and expose predators to increased risk of sudden collapses, resulting in alternative stable food web states. Increasing temperatures can cause abrupt reductions in mean community body size, primarily due to loss of top predators. The potential loss of biodiversity and shifts in ecosystem stability are among the major challenges caused by a warming climate.

scholarly journals Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9792
Author(s):  
Aluwani Nengovhela ◽  
Christiane Denys ◽  
Peter J. Taylor
Keyword(s):  
Life History ◽  
Body Size ◽  
Climate Warming ◽  
Life History Traits ◽  
Vegetation Type ◽  
Reproductive Rate ◽  
Temporal Changes ◽  
Temporal Response ◽  
Extrinsic Factors ◽  
African Species

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

scholarly journals Resurgence of an apex marine predator and the decline in prey body size

2019 ◽  
Vol 116 (52) ◽  
pp. 26682-26689 ◽  
Author(s):  
Jan Ohlberger ◽  
Daniel E. Schindler ◽  
Eric J. Ward ◽  
Timothy E. Walsworth ◽  
Timothy E. Essington
Keyword(s):  
Life History ◽  
Body Size ◽  
Chinook Salmon ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Size Structure ◽  
Economic Value ◽  
Killer Whales ◽  
Selective Predation ◽  
Marine Predator

In light of recent recoveries of marine mammal populations worldwide and heightened concern about their impacts on marine food webs and global fisheries, it has become increasingly important to understand the potential impacts of large marine mammal predators on prey populations and their life-history traits. In coastal waters of the northeast Pacific Ocean, marine mammals have increased in abundance over the past 40 to 50 y, including fish-eating killer whales that feed primarily on Chinook salmon. Chinook salmon, a species of high cultural and economic value, have exhibited marked declines in average size and age throughout most of their North American range. This raises the question of whether size-selective predation by marine mammals is generating these trends in life-history characteristics. Here we show that increased predation since the 1970s, but not fishery selection alone, can explain the changes in age and size structure observed for Chinook salmon populations along the west coast of North America. Simulations suggest that the decline in mean size results from the selective removal of large fish and an evolutionary shift toward faster growth and earlier maturation caused by selection. Our conclusion that intensifying predation by fish-eating killer whales contributes to the continuing decline in Chinook salmon body size points to conflicting management and conservation objectives for these two iconic species.

scholarly journals Size structure and fertility in an Eriocnema fulva Naudin (Melastomataceae) population in Southeastern Brazil

2007 ◽  
Vol 67 (4) ◽  
pp. 685-693 ◽  
Author(s):  
PM. Andrade ◽  
FAM. Santos ◽  
FR. Martins
Keyword(s):  
Population Size ◽  
Survival Probability ◽  
Size Structure ◽  
Size Variation ◽  
Fruit Production ◽  
Stem Length ◽  
Southeastern Brazil ◽  
Herbaceous Plant ◽  
Leaf Lamina ◽  
Number Of Leaves

Eriocnema fulva Naudin is an endangered perennial herbaceous plant, endemic to Minas Gerais state, Brazil. This study was conducted in the Jambreiro Forest (19° 58' -59'S and 43° 52' -55' W, 800-1100 m altitude). In an attempt to describe the population size structure and its association with individual fertility, fifteen 1 x 1 m contiguous plots were set. We tagged, counted, and measured a total of 260 individuals in 1997, 1998 and 1999. Young individuals with leaf lamina lengths < 3.4 cm comprised 33% of the total sampled, indicating that the population was reproducing locally. The number of leaves varied significantly, growth differences being detected only after two years of measurements. Stem length was the variable that best showed population size variation. The length of the largest leaf lamina was the best indication of its development phase. Assessing the number of leaves helped to evaluate the alteration in plant size during the study. The probability that individuals with laminas > 10 cm in length did not reproduce was 2.69%. The highest survival probability of the large-sized individuals confirmed the strong correlation between size and survival. The data indicated that size is important for the fertility of E. fulva, and it may be one of the relevant aspects to be considered for analyses of survival probability. The intraspecific competition, which was indicated by negative correlation between fruit production per size unit and density, can affect fertility, as larger plants had higher fruit production.

Effect of Experimental Manipulation of Feeding Conditions on the Population Stucture of Larval Cod (Gadus morhua) and Herring (Clupea harengus).

1996 ◽  
Vol 47 (2) ◽  
pp. 291 ◽  
Author(s):  
AJ Geffen
Keyword(s):  
Standard Deviation ◽  
Population Size ◽  
Gadus Morhua ◽  
Size Structure ◽  
Size Variation ◽  
Experimental Manipulation ◽  
Rate Of Change ◽  
Clupea Harengus ◽  
Final Size ◽  
Population Size Structure

Cod and herring larvae were fed either rotifers or mixtures of rotifers, Artemia, and wild plankton to test the effects of feeding conditions on the development of population size structure. The population size structure at each sample date was characterized by the skewness, the standard deviation of mean length, the coefficient of variation of mean length and the Gini coefficient. The development of size structure through time was characterized by the spreading rate, which is the rate of change in the standard deviation of mean length over time. Larvae fed on a single, small-sized prey item (rotifers) grew slowly, and size variation increased slowly. Larvae fed on mixed prey species showed better growth; the population structure changed more rapidly, and often led to a skewed size distribution dominated by larger individuals. The presence of larger prey items resulted in disproportionate growth rates in the mixed-diet groups. The presence of these faster-growing individuals was the most important factor in determining the shape of the final size distributions and the development of the population size structure.

Interactive effects of body-size structure and adaptive foraging on food-web stability

2012 ◽  
Vol 15 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Lotta Heckmann ◽  
Barbara Drossel ◽  
Ulrich Brose ◽  
Christian Guill
Keyword(s):  
Body Size ◽  
Food Web ◽  
Size Structure ◽  
Interactive Effects ◽  
Adaptive Foraging

scholarly journals Partitioning colony size variation into growth and partial mortality

2020 ◽  
Vol 16 (1) ◽  
pp. 20190727 ◽  
Author(s):  
Joshua S. Madin ◽  
Andrew H. Baird ◽  
Marissa L. Baskett ◽  
Sean R. Connolly ◽  
Maria A. Dornelas
Keyword(s):  
Life History ◽  
Body Size ◽  
Life History Strategy ◽  
Size Variation ◽  
Partial Mortality ◽  
Physical Damage ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Size Dependent

Body size is a trait that broadly influences the demography and ecology of organisms. In unitary organisms, body size tends to increase with age. In modular organisms, body size can either increase or decrease with age, with size changes being the net difference between modules added through growth and modules lost through partial mortality. Rates of colony extension are independent of body size, but net growth is allometric, suggesting a significant role of size-dependent mortality. In this study, we develop a generalizable model of partitioned growth and partial mortality and apply it to data from 11 species of reef-building coral. We show that corals generally grow at constant radial increments that are size independent, and that partial mortality acts more strongly on small colonies. We also show a clear life-history trade-off between growth and partial mortality that is governed by growth form. This decomposition of net growth can provide mechanistic insights into the relative demographic effects of the intrinsic factors (e.g. acquisition of food and life-history strategy), which tend to affect growth, and extrinsic factors (e.g. physical damage, and predation), which tend to affect mortality.

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