scholarly journals Size-dependent movement explains why bigger is better in fragmented landscapes

2018 ◽  
Author(s):  
Jasmijn Hillaert ◽  
Thomas Hovestadt ◽  
Martijn L. Vandegehuchte ◽  
Dries Bonte
Keyword(s):  
Body Size ◽  
Size Variation ◽  
The Body ◽  
Individual Development ◽  
Size Distributions ◽  
Fragmented Landscapes ◽  
Strong Selection ◽  
Size Dependent ◽  
Two Factors ◽  
Tightly Coupled

AbstractBody size is a fundamental trait known to allometrically scale with metabolic rate, and therefore a key determinant of individual development, life history and consequently fitness. In spatially structured environments, movement is an equally important driver of fitness. Because movement is tightly coupled with body size, we expect habitat fragmentation to induce a strong selection pressure on size variation across and within species. Changes in body size distributions are then, in turn, expected to alter food web dynamics. However, no consensus has been reached on how spatial isolation and resource growth affect body size distributions.Our aim was to investigate how these two factors shape the body size distribution of consumers under scenarios of size-dependent and -independent consumer movement by applying a mechanistic, individual-based resource-consumer model. The outcome was then linked to important ecosystem traits such as resource abundance and stability. Finally, we determined those factors that explain most variation in size distributions.We demonstrate that decreasing connectivity and resource growth select for communities (or populations) consisting of larger species (or individuals) due to strong selection for the ability to move over longer distances. When including size-dependent movement, moderate levels of connectivity result in increases in local size diversity. Due to this elevated functional diversity, resource uptake is optimized at the metapopulation or metacommunity level. At these intermediate levels of connectivity, size-dependent movement explains most of the observed variation in size distributions. Interestingly, local and spatial stability of consumer biomass are lowest when isolation and resource productivity are high. Finally, we highlight that size-dependent movement is of vital importance for the survival of populations within highly fragmented landscapes. Our results demonstrate that considering size-dependent movement and resource growth is essential to understand patterns of size distributions at the population or community level and the resulting metapopulation or metacommunity dynamics.

scholarly journals Evolution of body size in anteaters and sloths (Xenarthra, Pilosa): phylogeny, metabolism, diet and substrate preferences

2015 ◽  
Vol 106 (4) ◽  
pp. 289-301 ◽  
Author(s):  
N. Toledo ◽  
M.S. Bargo ◽  
S.F. Vizcaíno ◽  
G. De Iuliis ◽  
F. Pujos
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Dietary Habits ◽  
Decomposition Analysis ◽  
Size Variation ◽  
The Body ◽  
Phylogenetic Pattern ◽  
Substrate Preferences ◽  
Size Evolution ◽  
Main Factor

ABSTRACTPilosa include anteaters (Vermilingua) and sloths (Folivora). Modern tree sloths are represented by two genera, Bradypus and Choloepus (both around 4–6 kg), whereas the fossil record is very diverse, with approximately 90 genera ranging in age from the Oligocene to the early Holocene. Fossil sloths include four main clades, Megalonychidae, Megatheriidae, Nothrotheriidae, and Mylodontidae, ranging in size from tens of kilograms to several tons. Modern Vermilingua are represented by three genera, Cyclopes, Tamandua and Myrmecophaga, with a size range from 0.25 kg to about 30 kg, and their fossil record is scarce and fragmentary. The dependence of the body size on phylogenetic pattern of Pilosa is analysed here, according to current cladistic hypotheses. Orthonormal decomposition analysis and Abouheif C-mean were performed. Statistics were significantly different from the null-hypothesis, supporting the hypothesis that body size variation correlates with the phylogenetic pattern. Most of the correlation is concentrated within Vermilingua, and less within Mylodontidae, Megatheriidae, Nothrotheriidae and Megalonychidae. Influence of basal metabolic rate (BMR), dietary habits and substrate preference is discussed. In anteaters, specialised insectivory is proposed as the primary constraint on body size evolution. In the case of sloths, mylodontids, megatheriids and nothrotheriids show increasing body size through time; whereas megalonychids retain a wider diversity of sizes. Interplay between BMR and dietary habits appears to be the main factor in shaping evolution of sloth body size.

scholarly journals Body Size Differences between Foraging and Intranidal Workers of the Monomorphic Ant Lasius niger

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 433
Author(s):  
Mateusz Okrutniak ◽  
Bartosz Rom ◽  
Filip Turza ◽  
Irena M. Grześ
Keyword(s):  
Body Size ◽  
Field Experiment ◽  
Important Determinant ◽  
Size Variation ◽  
Division Of Labour ◽  
The Body ◽  
Food Type ◽  
Lasius Niger ◽  
Worker Size ◽  
Body Sizes

The association between the division of labour and worker body size of ants is typical for species that maintain physical castes. Some studies showed that this phenomenon can be also observed in the absence of distinct morphological subcastes among workers. However, the general and consistent patterns in the size-based division of labour in monomorphic ants are largely unidentified. In this study, we performed a field experiment to investigate the link between worker body size and the division of labour of the ant Lasius niger (Linnaeus, 1758), which displays limited worker size variation. We demonstrated that the body size of workers exploring tuna baits is slightly but significantly smaller than the size of workers located in the upper parts of the nest. Comparing the present results with existing studies, large workers do not seem to be dedicated to work outside the nest. We suggest that monomorphic workers of certain body sizes are flexible in the choice of task they perform, and food type may be the important determinant of this choice.

scholarly journals The evolution of genetic and conditional alternative reproductive tactics

2016 ◽  
Vol 283 (1825) ◽  
pp. 20152945 ◽  
Author(s):  
Leif Engqvist ◽  
Michael Taborsky
Keyword(s):  
Body Size ◽  
Size Variation ◽  
Alternative Reproductive Tactics ◽  
Disruptive Selection ◽  
Relevant Parameter ◽  
Reproductive Tactics ◽  
Adaptive Diversification ◽  
Size Dependent ◽  
Mortality Causes ◽  
Genetically Determined

Frequency-dependent selection may drive adaptive diversification within species. It is yet unclear why the occurrence of alternative reproductive tactics (ARTs) is highly divergent between major animal taxa. Here we aim to clarify the environmental and social conditions favouring the evolution of intra-population variance of male reproductive phenotypes. Our results suggest that genetically determined ARTs that are fixed for life evolve when there is strong selection on body size due to size-dependent competitiveness, in combination with environmental factors reducing size benefits. The latter may result from growth costs or, more generally, from age-dependent but size-independent mortality causes. This generates disruptive selection on growth trajectories underlying tactic choice. In many parameter settings, the model also predicts ARTs to evolve that are flexible and responsive to current conditions. Interestingly, the conditions favouring the evolution of flexible tactics diverge considerably from those favouring genetic variability. Nevertheless, in a restricted but relevant parameter space, our model predicts the simultaneous emergence and maintenance of a mixture of multiple tactics, both genetically and conditionally determined. Important conditions for the emergence of ARTs include size variation of competitors, which is inherently greater in species with indeterminate growth than in taxa reproducing only after reaching their terminal body size. This is probably the reason why ARTs are more common in fishes than in other major taxa.

The effects of temperature change and domestication on the body size of Late Pleistocene to Holocene mammals of Israel

Paleobiology ◽  
1981 ◽  
Vol 7 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Simon J. M. Davis
Keyword(s):  
Body Size ◽  
Temperature Change ◽  
Late Pleistocene ◽  
Eastern Mediterranean ◽  
Large Body ◽  
Size Variation ◽  
The Body ◽  
Main Body ◽  
Fossil Species ◽  
Late Pleistocene To Holocene

Size variation among several species of large mammals is examined both throughout a wide geographical range today and within the Late Pleistocene-Holocene archaeo-faunal sequence of Israel. A regression of log dental size on environmental temperature produces similar negative slopes for recent Palaearctic foxes, wolves and boars as well as for Nearctic foxes. These species, and others which also exhibit an inverse correlation between size and temperature today, became dwarfed at the end of the Pleistocene in Israel. Abundant fossil gazelle and fox mensural data indicate that this diminution coincided with the temperature elevation 12,000 yr ago. Both the similarity of regression slopes for the recent material and the temporal coincidence of dwarfing among fossil species, representing different ecologies, strongly implicate temperature as the main body-size determining factor. Changes evidenced in the fossil record for boar, wolf and fox approximate a 15°C temperature change (Δt) based on their respective present-day size-temperature regressions. This Δt, if taken as an estimate for the eastern Mediterranean, is considerably higher than generally accepted values.An additional size reduction of aurochs, wolf and boar at the end of the Pleistocene or several millenia later is associated with their domestication. It may reflect man's preference for a large “head count” over individual large body size.

scholarly journals Testing Equid Body Mass Estimate Equations on Modern Zebras—With Implications to Understanding the Relationship of Body Size, Diet, and Habitats of Equus in the Pleistocene of Europe

2021 ◽  
Vol 9 ◽  
Author(s):  
Juha Saarinen ◽  
Omar Cirilli ◽  
Flavia Strani ◽  
Keiko Meshida ◽  
Raymond L. Bernor
Keyword(s):  
Body Size ◽  
North America ◽  
Body Mass ◽  
Size Variation ◽  
Mass Range ◽  
The Body ◽  
Mass Estimation ◽  
Body Size Variation ◽  
Estimation Equations ◽  
Body Mass Estimation

The monodactyl horses of the genus Equus originated in North America during the Pliocene, and from the beginning of the Pleistocene, they have been an essential part of the large ungulate communities of Europe, North America and Africa. Understanding how body size of Equus species evolved and varied in relation to changes in environments and diet thus forms an important part of understanding the dynamics of ungulate body size variation in relation to Pleistocene paleoenvironmental changes. Here we test previously published body mass estimation equations for the family Equidae by investigating how accurately different skeletal and dental measurements estimate the mean body mass (and body mass range) reported for extant Grevy's zebra (Equus grevyi) and Burchell's zebra (Equus quagga). Based on these tests and information on how frequently skeletal elements occur in the fossil record, we construct a hierarchy of best practices for the selection of body mass estimation equations in Equus. As a case study, we explore body size variation in Pleistocene European Equus paleopopulations in relation to diet and vegetation structure in their paleoenvironments. We show a relationship between diet and body size in Equus: very large-sized species tend to have more browse-dominated diets than small and medium-sized species, and paleovegetation proxies indicate on average more open and grass-rich paleoenvironments for small-sized, grazing species of Equus. When more than one species of Equus co-occur sympatrically, the larger species tend to be less abundant and have more browse-dominated diets than the smaller species. We suggest that body size variation in Pleistocene Equus was driven by a combined effect of resource quality and availability, partitioning of habitats and resources between species, and the effect of environmental openness and group size on the body size of individuals.

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.

Is body size variation in the platypus (Ornithorhynchus anatinus) associated with environmental variables?

2011 ◽  
Vol 59 (4) ◽  
pp. 201 ◽  
Author(s):  
Elise Furlan ◽  
J. Griffiths ◽  
N. Gust ◽  
R. Armistead ◽  
P. Mitrovski ◽  
...  
Keyword(s):  
Body Size ◽  
Environmental Variables ◽  
Size Variation ◽  
The Body ◽  
Body Size Variation ◽  
Temperature Regimes ◽  
Ornithorhynchus Anatinus ◽  
Eastern Australia ◽  
Lower Temperature ◽  
Latitudinal Range

The body size of the platypus (Ornithorhynchus anatinus) is known to vary across both its latitudinal range and relatively short geographic distances. Here we consider how variation in platypus length and weight associates with environmental variables throughout the species’ range. Based on data from over 800 individuals, a Bergmann’s cline (increased body size in regions of lower temperature) was detected across the species latitudinal range. The opposite association, however, was present at smaller scales when comparing platypus body size and temperature within southern mainland Australia, or within an individual river basin. Temperature regimes alone clearly did not dictate body size in platypuses, although disentangling the effects of different climatic variables on body size variation was difficult because of correlations amongst variables. Nevertheless, within suitable platypus habitat in south-eastern Australia, areas of relatively lower rainfall and higher temperatures were typically associated with larger-bodied platypuses. The potential benefits to larger-bodied animals living under these conditions are explored, including consideration of variation in energy expenditure and food availability. Assuming these associations with environmental variables are biologically significant, a shift in platypus body size is anticipated in the future with predicted changes in climate.

Body size and sex ratio in emergent stonefly nymphs (Isogenoides olivaceus: Perlodidae): variation between cohorts and populations

1994 ◽  
Vol 72 (8) ◽  
pp. 1371-1375 ◽  
Author(s):  
Roger J. Haro ◽  
Kay Edley ◽  
Michael J. Wiley
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Annual Variation ◽  
Sexual Size Dimorphism ◽  
Population Regulation ◽  
Size Variation ◽  
Size Distributions ◽  
Ecological Significance ◽  
Male Size ◽  
Animal Size

The ecological significance of pattern in animal-size distribution has been receiving increased scrutiny in studies of population regulation and individual energetics. However, few studies have assessed differences in size variation between sequential generations or adjacent populations. Annual variation in body size and sex ratio of emergent perlodid stonefly nymphs, Isogenoides olivaceus (Frison) (Plecoptera: Perlodidae), were examined in populations from two Michigan mesic groundwater rivers. Final nymphal body size was estimated from sex-specific length to mass regression relationships using exuviae collected from each site. Sexual size dimorphism accounted for much of the intraspecific size variation within both populations and cohorts: females were larger ([Formula: see text]) than males ([Formula: see text]). Males showed less size variation than females; unlike those for females, size distributions for males were significantly skewed. Secondary sex ratios were female biased in both populations and all cohorts and ranged between 59.1 and 72.8%. Female sex bias increased with relative male size in both populations.

scholarly journals Climate change in size-structured ecosystems

2012 ◽  
Vol 367 (1605) ◽  
pp. 2903-2912 ◽  
Author(s):  
Ulrich Brose ◽  
Jennifer A. Dunne ◽  
Jose M. Montoya ◽  
Owen L. Petchey ◽  
Florian D. Schneider ◽  
...  
Keyword(s):  
Climate Change ◽  
Body Size ◽  
Size Structure ◽  
The Body ◽  
Size Distributions ◽  
Ecological Communities ◽  
Average Temperature ◽  
Mechanistic Approach ◽  
Effects Of Temperature ◽  
Future Consequences

One important aspect of climate change is the increase in average temperature, which will not only have direct physiological effects on all species but also indirectly modifies abundances, interaction strengths, food-web topologies, community stability and functioning. In this theme issue, we highlight a novel pathway through which warming indirectly affects ecological communities: by changing their size structure (i.e. the body-size distributions). Warming can shift these distributions towards dominance of small- over large-bodied species. The conceptual, theoretical and empirical research described in this issue, in sum, suggests that effects of temperature may be dominated by changes in size structure, with relatively weak direct effects. For example, temperature effects via size structure have implications for top-down and bottom-up control in ecosystems and may ultimately yield novel communities. Moreover, scaling up effects of temperature and body size from physiology to the levels of populations, communities and ecosystems may provide a crucially important mechanistic approach for forecasting future consequences of global warming.

scholarly journals Geographic body size variation of a tropical anuran: effects of water deficit and precipitation seasonality on Asian common toad from southern Asia

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Cheng Guo ◽  
Shuai Gao ◽  
Ali Krzton ◽  
Long Zhang
Keyword(s):  
Body Size ◽  
Water Deficit ◽  
Size Variation ◽  
The Body ◽  
Environmental Data ◽  
Common Toad ◽  
Tropical Regions ◽  
Positive Correlation ◽  
Body Size Variation ◽  
The Relationship

Abstract Background Two previous studies on interspecific body size variation of anurans found that the key drivers of variation are the species’ lifestyles and the environments that they live in. To examine whether those findings apply at the intraspecific level, we conducted a study of the Asian common toad (Duttaphrynus melanostictus), a terrestrial anuran distributed in tropical regions. The body size of toads from 15 locations, covering the majority of their geographic range, and local environmental data were summarized from published literature. We used a model selection process based on an information-theoretic approach to examine the relationship between toad body size and those environmental parameters. Results We found a positive correlation between the body size of the Asian common toad and the water deficit gradient, but no linkage between body size and temperature-related parameters. Furthermore, there was a positive correlation between the seasonality of precipitation and body size of females from different sampled populations. Conclusions As a terrestrial anuran, the Asian common toad should experience greater pressure from environmental fluctuations than aquatic species. It is mainly distributed in tropical regions where temperatures are generally warm and stable, but water availability fluctuates. Therefore, while thermal gradients are not strong enough to generate selection pressure on body size, the moisture gradient is strong enough to select for larger size in both males and females in dryer regions. Larger body size supports more efficient water conservation, a pattern in accordance with the prediction that lifestyles of different species and their local habitats determine the relationship between body size and environment. In addition, larger females occur in regions with greater seasonality in precipitation, which may happen because larger females can afford greater reproductive output in a limited reproductive season.

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