scholarly journals Reproductive trade-offs of the estuarine copepod Eurytemora affinis under different thermal and haline regimes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anissa Souissi ◽  
Jiang-Shiou Hwang ◽  
Sami Souissi
Keyword(s):  
Clutch Size ◽  
Egg Size ◽  
Abiotic Factors ◽  
Negative Relationship ◽  
Cold Temperature ◽  
Female Size ◽  
Eurytemora Affinis ◽  
Trade Off ◽  
Trade Offs ◽  
Higher Temperature

AbstractCopepod females invest a quantity of resources in their reproduction. Depending on several biotic and abiotic factors and their evolutionary history a trade-off can be commonly observed between producing a large number of smaller offspring or a small number of larger offspring. In this study, a multi-generational approach was applied to determine whether a trade-off between clutch size and egg size existed in the copepod Eurytemora affinis under different controlled conditions of temperature and salinity. This protocol was based on the follow-up of reproductive (Clutch Size ‘CS’, Egg Diameter ‘ED’) and morphological (Prosome Length ‘PL’) traits during several generations. Copepods were acclimated to cold (7 °C) and warm (20 °C) temperatures, and then their reproductive output was tested at the higher temperature of 24 °C. CS and ED were positively correlated to PL, so as a first step linear regressions between each reproductive trait and female PL were performed. The residuals from the regression lines of CS and ED with PL were calculated to remove the effect of female size. When the normalized data (residuals) of CS and ED plotted together a negative relationship between egg size and egg number revealed the existence of a trade-off. Copepod populations initially acclimated to cold temperature are commonly characterized by relatively smaller CS and larger ED. Conversely, warm temperature adapted females produced relatively larger CS and smaller ED. After transfer to a temperature of 24 °C, the ED did not change but the CS showed high variability indicating stressful conditions and no trade-off was observed. These observations suggest that E. affinis is able to modulate its reproduction depending on the encountered temperature. It seems that this copepod species can shift between a K- and an r-strategy in response to colder or warmer conditions. In a late winter-early spring like cold temperature, copepod females seem to invest more on offspring quality by producing relatively larger eggs. This ecological strategy ensures a high recruitment of the spring generation that is responsible for the strength of the maximum population size usually observed in late spring-early summer (May–June). To the contrary, at summer-like temperature, where the population density decreases significantly in the Seine estuary, copepod females seem to switch from K to r strategy by favoring offspring number compared to offspring size. Finally, the use of a higher temperature of 24 °C seems to disrupt the observed reproductive trade-off even after several generations. These results suggest that a switching between K- or r-strategy of E. affinis depends highly on temperature effects. The effect of salinity increase during a summer-like temperature of 20 °C as well as after transfer to 24 °C decreased PL and CS but the ED did not change significantly.

Environmental, ontogenetic, and genetic variation in egg size of Pied Flycatchers

1993 ◽  
Vol 71 (8) ◽  
pp. 1534-1542 ◽  
Author(s):  
Jaime Potti
Keyword(s):  
Clutch Size ◽  
Egg Size ◽  
Relative Volume ◽  
Laying Date ◽  
Territory Quality ◽  
Trade Off ◽  
Nest Boxes ◽  
Female Condition ◽  
Almost All ◽  
Breeding Seasons

Ontogenetic, genetic, and environmental variation in egg length, breadth, and volume were investigated in the Pied Flycatcher across four breeding seasons in central Spain. Egg length and breadth were poorly correlated and did not vary with laying date. There was an indication of decreasing egg breadth with increasing clutch size that may indicate a trade-off between both variables. Egg size increased with female condition and, independently, with territory quality. Mean egg size decreased with advancing female age, which is perhaps related to the increase of clutch size with age in this species. There were high, significant repeatabilities of almost all egg dimensions, including relative volumes of first and last eggs, among females, both within and between years. Also, nest boxes were repeatable in the relative volume of the last eggs of (different) females laying in them, suggesting an influence of territory quality on relative egg size. Territory quality also had positive influences on some egg measurements that were independent of female condition. Heritability, estimated by mother–daughter regression, was significant only for egg length. These results are discussed in relation to proximate constraints on egg formation, predictions from the brood-survival hypothesis, and a possible trade-off between clutch and egg sizes.

scholarly journals Determinants of life-history traits in a fish ectoparasite: a hierarchical analysis

Parasitology ◽  
2011 ◽  
Vol 138 (7) ◽  
pp. 848-857 ◽  
Author(s):  
G. LOOT ◽  
N. POULET ◽  
S. BROSSE ◽  
L. TUDESQUE ◽  
F. THOMAS ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Size ◽  
Life History Traits ◽  
Abiotic Factors ◽  
Individual Characteristics ◽  
Trade Off ◽  
Individual Fitness ◽  
Parasite Number ◽  
Egg Number

SUMMARYObjective. Unravelling the determinants of parasite life-history traits in natural settings is complex. Here, we deciphered the relationships between biotic, abiotic factors and the variation in 4 life-history traits (body size, egg presence, egg number and egg size) in the fish ectoparasite Tracheliastes polycolpus. We then determined the factors affecting the strength of the trade-off between egg number and egg size. Methods. To do so, we used 4-level (parasite, microhabitat, host and environment) hierarchical models coupled to a field database. Results. Variation in life-history traits was mostly due to individual characteristics measured at the parasite level. At the microhabitat level (fins of fish hosts), parasite number was positively related to body size, egg presence and egg number. Higher parasite number on fins was positively associated with individual parasite fitness. At the host level, host body size was positively related to the individual fitness of the parasite; parasites were bigger and more fecund on bigger hosts. In contrast, factors measured at the environmental level had a weak influence on life-history traits. Finally, a site-dependent trade-off between egg number and egg size existed in this population. Conclusion. Our study illustrates the importance of considering parasite life-history traits in a hierarchical framework to decipher complex links between biotic, abiotic factors and parasite life-history traits.

Benefits of fidelity: does host specialization impact nematode parasite life history and fecundity?

Parasitology ◽  
2013 ◽  
Vol 140 (5) ◽  
pp. 587-597 ◽  
Author(s):  
J. KOPRIVNIKAR ◽  
H. S. RANDHAWA
Keyword(s):  
Life History ◽  
Host Specificity ◽  
Egg Size ◽  
Host Specialization ◽  
Published Data ◽  
Female Size ◽  
Patent Period ◽  
Trade Offs ◽  
Evolutionary Level ◽  
Host Parasite

SUMMARYThe range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host–parasite co-evolution), as well as ‘encounter filters’ and ‘compatibility filters’ at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.

Female reproductive characteristics of the Balkan wall lizard (Podarcis taurica) in the northwestern periphery of its range

2010 ◽  
Vol 5 (3) ◽  
pp. 391-395 ◽  
Author(s):  
Katarina Ljubisavljević ◽  
Georg Džukić ◽  
Miloš Kalezić
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Breeding Season ◽  
Egg Size ◽  
Reproductive Traits ◽  
Species Range ◽  
Trade Off ◽  
Female Body Size ◽  
Female Reproductive Traits ◽  
Gravid Females

AbstractWe present data on the female reproductive traits of the Balkan wall lizard in the Deliblato Sand, a large continental sandland in the Pannonian area in the northwestern periphery of the species range. The clutch and egg characteristics of the population were investigated on the basis of clutches laid in laboratory conditions by gravid females captured in one locality. Balkan wall lizards produced at least two clutches in a breeding season. Individual females laid clutches of commonly two (range 1–4) eggs. The female body size had no effect on clutch and egg size. There was no trade-off between egg size and clutch size.

scholarly journals Beyond size–number trade-offs: clutch size as a maternal effect

2009 ◽  
Vol 364 (1520) ◽  
pp. 1097-1106 ◽  
Author(s):  
Gregory P Brown ◽  
Richard Shine
Keyword(s):  
Clutch Size ◽  
Experimental Studies ◽  
Reproductive Traits ◽  
Nest Site Selection ◽  
The Body ◽  
Offspring Size ◽  
Trade Off ◽  
Trade Offs ◽  
Size Number ◽  
Hatchling Size

Traditionally, research on life-history traits has viewed the link between clutch size and offspring size as a straightforward linear trade-off; the product of these two components is taken as a measure of maternal reproductive output. Investing more per egg results in fewer but larger eggs and, hence, offspring. This simple size–number trade-off has proved attractive to modellers, but our experimental studies on keelback snakes ( Tropidonophis mairii , Colubridae) reveal a more complex relationship between clutch size and offspring size. At constant water availability, the amount of water taken up by a snake egg depends upon the number of adjacent eggs. In turn, water uptake affects hatchling size, and therefore an increase in clutch size directly increases offspring size (and thus fitness under field conditions). This allometric advantage may influence the evolution of reproductive traits such as growth versus reproductive effort, optimal age at female maturation, the body-reserve threshold required to initiate reproduction and nest-site selection (e.g. communal oviposition). The published literature suggests that similar kinds of complex effects of clutch size on offspring viability are widespread in both vertebrates and invertebrates. Our results also challenge conventional experimental methodologies such as split-clutch designs for laboratory incubation studies: by separating an egg from its siblings, we may directly affect offspring size and thus viability.

scholarly journals Heat hardening in a pair of Anolis lizards: constraints, dynamics, and ecological consequences

2021 ◽  
pp. jeb.240994
Author(s):  
Sean W. Deery ◽  
Julie E. Rej ◽  
Daniel Haro ◽  
Alex. R. Gunderson
Keyword(s):  
Heat Shock ◽  
Heat Tolerance ◽  
Negative Relationship ◽  
Anolis Carolinensis ◽  
Biophysical Model ◽  
Published Data ◽  
Lizard Species ◽  
Trade Off ◽  
Trade Offs ◽  
Heat Hardening

Heat tolerance plasticity is predicted to be an important buffer against global warming. Nonetheless, basal heat tolerance often correlates negatively with tolerance plasticity (“Trade-off Hypothesis”), a constraint that could limit plasticity benefits. We tested the trade-off hypothesis at the individual level with respect to heat hardening in two lizard species, Anolis carolinensis and A. sagrei. Heat hardening is a rapid increase in heat tolerance after heat shock that is rarely measured in reptiles but is generally considered a first line of physiological defense against heat. We also employed a biophysical model of operative habitat temperatures to estimate the performance consequences of hardening under ecologically relevant conditions. Anolis carolinensis hardened by two hours post heat shock and maintained hardening for several hours. However, A. sagrei did not harden. Biophysical models showed that hardening in A. carolinensis reduces their overheating risk in the field. Therefore, while not all lizards heat harden, hardening has benefits for species that can. We initially found a negative relationship between basal tolerance and hardening within both species, consistent with the trade-off hypothesis. However, permutation analyses showed that the apparent trade-offs could not be differentiated from statistical artifact. We found the same result when we re-analyzed published data supporting the trade-off hypothesis in another lizard species. Our results show that false positives may be common when testing the trade-off hypothesis. Statistical approaches that account for this are critical to ensure that the hypothesis, which has broad implications for thermal adaptation and responses to warming, is assessed appropriately.

scholarly journals Variations in the reproductive strategies of three populations of Phrynocephalus helioscopus in China

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5705
Author(s):  
Tao Liang ◽  
Lu Zhou ◽  
Wenfeng He ◽  
Lirong Xiao ◽  
Lei Shi
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Reproductive Strategies ◽  
Female Body ◽  
Egg Size ◽  
Reproductive Traits ◽  
Breeding Period ◽  
Female Body Size ◽  
Trade Offs ◽  
Morphological Constraint

Background Egg size and clutch size are key life history traits. During the breeding period, it is possible for females to increase their reproductive output either by increasing the number of eggs if the optimal egg size (OES) is maintained, or by increasing the allocation of energy to each egg. However, the strategies adopted are often influenced by animals’ morphology and environment. Methods Here, we examined variation in female morphological and reproductive traits, tested for trade-offs between egg size and clutch size, and evaluated the relationship between egg size and female morphology in three populations of Phrynocephalus helioscopus. Results Female body size, egg size, and clutch size were larger in the Yi Ning (YN) and Fu Yun (FY) populations than in the Bei Tun (BT) population (the FY and YN populations laid more, and rounder eggs). Egg size was independent of female body size in two populations (BT and FY), even though both populations had an egg-size/clutch size trade-off. In the YN population, egg size and clutch size were independent, but egg size was correlated with female body size, consistent with the hypothesis of morphological constraint. Conclusions Our study found geographical variation in body size and reproductive strategies of P. helioscopus. Egg size was correlated with morphology in the larger-bodied females of the YN population, but not in the smaller-bodied females of the BT population, illustrating that constraints on female body size and egg size are not consistent between populations.

scholarly journals Heterotrophic eukaryotes show a slow-fast continuum, not a gleaner–exploiter trade-off

2020 ◽  
Vol 117 (40) ◽  
pp. 24893-24899
Author(s):  
Thomas Kiørboe ◽  
Mridul K. Thomas
Keyword(s):  
Positive Relationship ◽  
Ingestion Rate ◽  
Negative Relationship ◽  
Large Mammals ◽  
Ecological Processes ◽  
Trade Off ◽  
Trade Offs ◽  
Wide Range ◽  
Fast Gradient ◽  
Using Data

Gleaners and exploiters (opportunists) are organisms adapted to feeding in nutritionally poor and rich environments, respectively. A trade-off between these two strategies—a negative relationship between the rate at which organisms can acquire food and ingest it—is a critical assumption in many ecological models. Here, we evaluate evidence for this trade-off across a wide range of heterotrophic eukaryotes from unicellular nanoflagellates to large mammals belonging to both aquatic and terrestrial realms. Using data on the resource acquisition and ingestion rates in >500 species, we find no evidence of a trade-off across species. Instead, there is a positive relationship between maximum clearance rate and maximum ingestion rate. The positive relationship is not a result of lumping together diverse taxa; it holds within all subgroups of organisms we examined as well. Correcting for differences in body mass weakens but does not reverse the positive relationship, so this is not an artifact of size scaling either. Instead, this positive relationship represents a slow–fast gradient in the “pace of life” that overrides the expected gleaner–exploiter trade-off. Other trade-offs must therefore shape ecological processes, and investigating them may provide deeper insights into coexistence, competitive dynamics, and biodiversity patterns in nature. A plausible target for study is the well-documented trade-off between growth rate and predation avoidance, which can also drive the slow–fast gradient we observe here.

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