scholarly journals Sex-specific predation risk and the evolution of sexual dimorphism in immunocompetence: a theoretical analysis

2014 ◽  
Author(s):  
Benjamin Fanson ◽  
Eirik Søvik
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sexual Dimorphism ◽  
Immune Function ◽  
Predation Risk ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Defense Strategies ◽  
Differential Predation ◽  
Predation Costs

Sexual dimorphism in immunocompetence, with males having lower immune function, is a prevalent pattern in nature. The main evolutionary explanation for this pattern is that males preferentially allocate resources away from immune function and towards reproductive effort to increase their competitiveness for limited females. However, the role of differential predation risk between the sexes has not been considered, despite predation risk being a major driver of life history strategies and male sexual traits often having associated predation costs. It is unclear whether increased predation risk should increase or decrease investment in immune function, as males have been shown to utilize both behavioural (e.g. decrease foraging activity) and/or life-history (e.g. decrease investment in sexual trait) defense strategies to manage predation risk. Here, we modelled optimal resource acquisition and allocation towards immune function under differential predation risk with multiple defense strategies. If males have limited defense strategies, increasing predation risk caused males to trade-off immune function for reproductive effort, leading to reduced immunocompetence. In contrast, if males can only decrease predation risk through reduction of reproductive effort (e.g. decrease colouration or calling rates), then increasing predation risk causes immune function to increase. If males can utilize multiple defense strategies and sexual selection is low, then males maintain a constant immune function as predation risk increases. Sexual selection robustly resulted in decreased immunocompetence. Overall, our results suggest that predation plays an important role in the evolution of sexual dimorphism in immunocompetence, but predicting its effect requires understanding the integrated defense strategies available.

scholarly journals Sex-specific predation risk and the evolution of sexual dimorphism in immunocompetence: a theoretical analysis

2014 ◽  
Author(s):  
Benjamin Fanson ◽  
Eirik Søvik
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sexual Dimorphism ◽  
Immune Function ◽  
Predation Risk ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Defense Strategies ◽  
Differential Predation ◽  
Predation Costs

Sexual dimorphism in immunocompetence, with males having lower immune function, is a prevalent pattern in nature. The main evolutionary explanation for this pattern is that males preferentially allocate resources away from immune function and towards reproductive effort to increase their competitiveness for limited females. However, the role of differential predation risk between the sexes has not been considered, despite predation risk being a major driver of life history strategies and male sexual traits often having associated predation costs. It is unclear whether increased predation risk should increase or decrease investment in immune function, as males have been shown to utilize both behavioural (e.g. decrease foraging activity) and/or life-history (e.g. decrease investment in sexual trait) defense strategies to manage predation risk. Here, we modelled optimal resource acquisition and allocation towards immune function under differential predation risk with multiple defense strategies. If males have limited defense strategies, increasing predation risk caused males to trade-off immune function for reproductive effort, leading to reduced immunocompetence. In contrast, if males can only decrease predation risk through reduction of reproductive effort (e.g. decrease colouration or calling rates), then increasing predation risk causes immune function to increase. If males can utilize multiple defense strategies and sexual selection is low, then males maintain a constant immune function as predation risk increases. Sexual selection robustly resulted in decreased immunocompetence. Overall, our results suggest that predation plays an important role in the evolution of sexual dimorphism in immunocompetence, but predicting its effect requires understanding the integrated defense strategies available.

scholarly journals Using life history trade-offs to understand core-transient structuring of a small mammal community

2014 ◽  
Author(s):  
Sarah R Supp ◽  
David N. Koons ◽  
S. K. Morgan Ernest
Keyword(s):  
Life History ◽  
Reproductive Effort ◽  
Survival Strategies ◽  
Life History Strategies ◽  
High Survival ◽  
Transient Species ◽  
Ecological Specialization ◽  
Core Species ◽  
Trade Offs ◽  
Source Sink

An emerging conceptual framework suggests that communities are comprised of two main groups of species: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local vs. regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local vs. regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also exhibit different life-history strategies. Specifically, core species should display relatively low dispersal rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and dispersal probabilities, and reproductive effort from transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating source-sink dynamics and nomadic transience in local communities. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study.

scholarly journals Morphometric differentiation and sexual dimorphism in Limnomedusa macroglossa (Duméril & Bibron, 1841) (Anura: Alsodidae) from Uruguay

2021 ◽  
Vol 16 (1) ◽  
pp. 11-25
Author(s):  
Valeria De Olivera-López ◽  
Arley Camargo ◽  
Raúl Maneyro
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Phenotypic Plasticity ◽  
Life History Strategies ◽  
Clinal Variation ◽  
Size And Shape ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Morphological Differences

Intersexual morphological differences within a species occur in many traits, including body size and shape. Many processes that cause geographic variability in morphology have been proposed: population structure, phenotypic plasticity (environmental effects on development), and natural and/or sexual selection. Several hypotheses can explain patterns of sexual dimorphism in anurans, including natural or intra/inter-sexual selection, and differences in life history strategies between sexes. Limnomedusa macroglossa is considered a habitat specialist restricted to rocky outcrops in Brazil, Argentina, Paraguay, and Uruguay. We evaluated the extent of sexual (size and shape) dimorphism in L. macroglossa from Uruguay based on morphometrics and secondary sexual characteristics, while taking into account geographic variation. Sexual dimorphism in body size of adults was found, but multivariate analyses did not demonstrate the existence of significant differences in shape. There were also significant differences in body size and hind leg measurements among six hydrographic basins as a result from the phenotypic plasticity correlated with local temperature, representing a clinal variation along the latitudinal gradient of Uruguay. The sexual dimorphism found in body size is probably the consequence of higher growth rates and/or late sexual maturity in females, which favors larger body size for accommodating larger ovaries, and thus, higher reproductive output. 

scholarly journals Breeding Biology of Passerines in a Subtropical Montane Forest in Northwestern Argentina

The Condor ◽  
2007 ◽  
Vol 109 (2) ◽  
pp. 321-333 ◽  
Author(s):  
Sonya K. Auer ◽  
Ronald D. Bassar ◽  
Joseph J. Fontaine ◽  
Thomas E. Martin
Keyword(s):  
Life History ◽  
Predation Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Life History Strategies ◽  
Temperate Species ◽  
Egg Mass ◽  
Breeding Ecology ◽  
Feeding Rates ◽  
Northwestern Argentina

Abstract The breeding ecology of south temperate bird species is less widely known than that of north temperate species, yet because they comprise a large portion of the world's avian diversity, knowledge of their breeding ecology can contribute to a more comprehensive understanding of the geographic diversity of avian reproductive traits and life history strategies. We provide the first detailed examination of the reproductive strategies of 18 forest passerines of subtropical, northwestern Argentina. Mean clutch sizes were smaller and egg mass was greater than for north temperate birds, but differed among species and nest types, with cavity-nesters having larger clutches than species with open-cup and enclosed nests. Across all species, the average breeding season duration was 50 days; thus, the common perception that southern species have smaller clutch sizes because of longer breeding seasons is not supported in this community. Daily nest predation rates were influenced by nest type, cavity nests suffering the least from predation, as found in north temperate systems. Only females incubated eggs in all but one species, whereas both parents fed and cared for nestlings in all species. Mean nest attentiveness was low compared to north temperate passerines. Mean hourly nestling feeding rates differed among species and were negatively related to nest predation risk. In short, coexisting species in this subtropical forest varied in their life history strategies, in part correlated with variation in nest predation risk, but also differing from north temperate species.

scholarly journals Predation risk alters life history strategies in an oceanic copepod

Ecology ◽  
2020 ◽  
Author(s):  
Kristina Øie Kvile ◽  
Dag Altin ◽  
Lotte Thommesen ◽  
Josefin Titelman
Keyword(s):  
Life History ◽  
Predation Risk ◽  
Life History Strategies

scholarly journals Between semelparity and iteroparity: empirical evidence for a continuum of modes of parity

2017 ◽  
Author(s):  
P. William Hughes
Keyword(s):  
Life History ◽  
Mathematical Models ◽  
Molecular Basis ◽  
Life Histories ◽  
Life History Theory ◽  
Reproductive Effort ◽  
Theoretical Biology ◽  
Relative Fitness ◽  
Life History Strategies ◽  
Molecular Evidence

ABSTRACTThe number of times an organism reproduces (i.e. its mode of parity) is a fundamental life-history character, and evolutionary and ecological models that compare the relative fitness of strategies are common in life history theory and theoretical biology. Despite the success of mathematical models designed to compare intrinsic rates of increase between annual-semelparous and perennial-iteroparous reproductive schedules, there is widespread evidence that variation in reproductive allocation among semelparous and iteroparous organisms alike is continuous. This paper reviews the ecological and molecular evidence for the continuity and plasticity of modes of parity––that is, the idea that annual-semelparous and perennial-iteroparous life histories are better understood as endpoints along a continuum of possible strategies. I conclude that parity should be understood as a continuum of different modes of parity, which differ by the degree to which they disperse or concentrate reproductive effort in time. I further argue that there are three main implications of this conclusion: (1) That seasonality should not be conflated with parity; (2) that mathematical models purporting to explain the evolution of semelparous life histories from iteroparous ones (or vice versa) should not assume that organisms can only display either an annual-semelparous life history or a perennial-iteroparous one; and (3) that evolutionary ecologists should examine the physiological or molecular basis of traits underlying different modes of parity, in order to obtain a general understanding of how different life history strategies can evolve from one another.

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