Egg size and taxon: their influence on survival and development of chrysopid hatchlings after food and water deprivation

1991 ◽  
Vol 69 (10) ◽  
pp. 2644-2650 ◽  
Author(s):  
Catherine A. Tauber ◽  
Maurice J. Tauber ◽  
Michael J. Tauber
Keyword(s):  
Life History ◽  
Water Deprivation ◽  
Egg Size ◽  
Maternal Investment ◽  
Developmental Rate ◽  
Life History Variation ◽  
Larval Size ◽  
First Instar ◽  
Survival And Development ◽  
Phylogenetic Lineages

Genus- and species-level differences characterize the pattern of life-history variation in two distinct phylogenetic lineages of chrysopids, Chrysopa and Chrysoperla. Species in the genus Chrysopa exhibit significant variation in egg size, and this variation is positively correlated with the ability of hatchlings to withstand periods of food and water deprivation prior to their initial feeding. The variation is also significantly correlated with larval size, as measured by the tibial length of first-instar larvae. Although the six Chrysopa species differ in several other life-history traits (i.e, the incubation period and rate of first-instar larval development), the variation is unrelated to egg size. It appears that maternal allocation of resources to eggs largely serves to enhance embryonic growth and the survival of hatchlings during searching. That is, within the Chrysopa lineage egg size varies; larger eggs yield larger, more robust hatchlings. These hatchlings may or may not develop faster than congeners from small eggs. In comparison with Chrysopa, the genus Chrysoperla has less variability in egg size and developmental rate. Furthermore, although Chrysoperla eggs are relatively small, the ability of hatchlings to endure periods of food or water deprivation is at least as great as it is in the Chrysopa species with large eggs. We conclude that maternal investment in larval fitness has different ontogenetic pathways, ecological roles, and phylogenetic histories in the two genera.

Maternal investment mediates offspring life history variation with context-dependent fitness consequences

Ecology ◽  
2015 ◽  
Vol 96 (9) ◽  
pp. 2499-2509 ◽  
Author(s):  
Michael P. Moore ◽  
Tobias Landberg ◽  
Howard H. Whiteman
Keyword(s):  
Life History ◽  
Maternal Investment ◽  
Life History Variation ◽  
Fitness Consequences ◽  
Context Dependent

The unity of characters: ecological and morphological specialisation in larvae of Hawaiian platynine Carabidae (Coleoptera)

2000 ◽  
Vol 14 (6) ◽  
pp. 931 ◽  
Author(s):  
James K. Liebherr
Keyword(s):  
Life History ◽  
Egg Size ◽  
Life History Traits ◽  
Phylogenetic Inference ◽  
Larval Period ◽  
Larval Duration ◽  
Similar Treatment ◽  
First Instar ◽  
Functional Linkage ◽  
History Information

Life history information and first instar egg bursters are compared for larvae of 25 species across the monophyletic radiation of Hawaiian Platynini (Coleoptera : Carabidae). The plesiotypic larval duration is approximately five weeks, with derived extension of the larval period having evolved during phylogenetic diversification of the radiation. This extension in larval duration is associated with vestigialisation of the metathoracic flight wings. Egg size is larger in those brachypterous species with slower developing larvae, reflecting pervasive ecological specialisation of these taxa in the isolated, favourable, and temporally stable habitats of Hawaiian montane forests. First instar egg bursters are also compared across these taxa, with evolution of a keel-like egg burster congruently defining a clade also characterised by longer larval duration and larger egg size. A functional linkage between egg burster configuration and egg size is rejected by lack of any association between egg size and egg burster type in the related genus Calathus. Such rejection does not reduce the value of the egg burster for phylogenetic inference. The ability to assess taxa for both life history traits and egg burster configuration argues for similar treatment of all such characters, both ecological and morphological, when estimating phylogeny.

scholarly journals The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4028 ◽  
Author(s):  
Tanmay Dixit ◽  
Sinead English ◽  
Dieter Lukas
Keyword(s):  
Life History ◽  
Social Environment ◽  
Group Size ◽  
Egg Size ◽  
Reproductive Investment ◽  
Maternal Investment ◽  
Differential Allocation ◽  
The Social ◽  
Cooperatively Breeding ◽  
The Relationship

BackgroundLife history theory predicts that mothers should adjust reproductive investment depending on benefits of current reproduction and costs of reduced future reproductive success. These costs and benefits may in turn depend on the breeding female’s social environment. Cooperative breeders provide an ideal system to test whether changes in maternal investment are associated with the social conditions mothers experience. As alloparental helpers assist in offspring care, larger groups might reduce reproductive costs for mothers or alternatively indicate attractive conditions for reproduction. Thus, mothers may show reduced (load-lightening) or increased (differential allocation) reproductive investment in relation to group size. A growing number of studies have investigated how cooperatively breeding mothers adjust pre-natal investment depending on group size. Our aim was to survey these studies to assess, first, whether mothers consistently reduce or increase pre-natal investment when in larger groups and, second, whether these changes relate to variation in post-natal investment.MethodsWe extracted data on the relationship between helper number and maternal pre-natal investment (egg size) from 12 studies on 10 species of cooperatively breeding vertebrates. We performed meta-analyses to calculate the overall estimated relationship between egg size and helper number, and to quantify variation among species. We also tested whether these relationships are stronger in species in which the addition of helpers is associated with significant changes in maternal and helper post-natal investment.ResultsAcross studies, there is a significant negative relationship between helper number and egg size, suggesting that in most instances mothers show reduced reproductive investment in larger groups, in particular in species in which mothers also show a significant reduction in post-natal investment. However, even in this limited sample, substantial variation exists in the relationship between helper number and egg size, and the overall effect appears to be driven by a few well-studied species.DiscussionOur results, albeit based on a small sample of studies and species, indicate that cooperatively breeding females tend to produce smaller eggs in larger groups. These findings on prenatal investment accord with previous studies showing similar load-lightening reductions in postnatal parental effort (leading to concealed helper effects), but do not provide empirical support for differential allocation. However, the considerable variation in effect size across studies suggests that maternal investment is mitigated by additional factors. Our findings indicate that variation in the social environment may influence life-history strategies and suggest that future studies investigating within-individual changes in maternal investment in cooperative breeders offer a fruitful avenue to study the role of adaptive plasticity.

Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov.

1996 ◽  
Vol 74 (2) ◽  
pp. 357-379 ◽  
Author(s):  
Jessica A. Marks
Keyword(s):  
Life History ◽  
Sibling Species ◽  
Distinct Species ◽  
Morphological Characters ◽  
Reticulate Evolution ◽  
Life History Variation ◽  
Larval Size ◽  
Colonial Ascidian ◽  
Northern Norway ◽  
Didemnid Ascidians

Recent advances in taxonomy have disclosed the prevalence of cryptic sibling species in marine systems. In didemnid ascidians, morphological variation between species is often slight, and many species may have been overlooked. Species boundaries within this group are often equivocal, and patterns among taxa are reminiscent of those formed by reticulate evolution in plants. Specimens of the sessile colonial ascidian Didemnum albidum (Verrill, 1871) were examined for life-history and morphological characters and found to constitute at least three sympatric sibling species. One of these, Didemnum romssae, is described here as a new species. Colonies were collected from hard-bottom assemblages in Troms and Finnmark counties in northern Norway. Zooid morphology in D. romssae is similar to that of D. albidum, but varies within each species, even for traits usually considered specific. Didemnum romssae is proposed as a distinct species on the basis of consistent differences in (i) the shape and size of calcium carbonate spicules within the common test; (ii) larval size and the number of lateral ampullae; (iii) timing of reproduction; and (iv) the absence of a seasonal nonfeeding, overwintering stage, which occurs in D. albidum. Examination of specimens from museum collections considered synonymous with D. albidum confirmed the presence of a third species, Didemnum polare (Hartmeyer, 1903), which differed from the other two species in zooid and larval morphology as well as spicule shape. Complexes of sibling species such as these provide a tractable system for studying the consequences of life-history variation among closely related taxa.

scholarly journals Genomic variation underlying complex life-history traits revealed by genome sequencing in Chinook salmon

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180935 ◽  
Author(s):  
Shawn R. Narum ◽  
Alex Di Genova ◽  
Steven J. Micheletti ◽  
Alejandro Maass
Keyword(s):  
Life History ◽  
Association Mapping ◽  
Chinook Salmon ◽  
Phenotypic Variation ◽  
Life History Traits ◽  
Phenotypic Diversity ◽  
Genomic Variation ◽  
Phenotypic Traits ◽  
Life History Variation ◽  
Phylogenetic Lineages

A broad portfolio of phenotypic diversity in natural organisms can buffer against exploitation and increase species persistence in disturbed ecosystems. The study of genomic variation that accounts for ecological and evolutionary adaptation can represent a powerful approach to extend understanding of phenotypic variation in nature. Here we present a chromosome-level reference genome assembly for Chinook salmon ( Oncorhynchus tshawytscha ; 2.36 Gb) that enabled association mapping of life-history variation and phenotypic traits for this species. Whole-genome re-sequencing of populations with distinct life-history traits provided evidence that divergent selection was extensive throughout the genome within and among phylogenetic lineages, indicating that a broad portfolio of phenotypic diversity exists in this species that is related to local adaptation and life-history variation. Association mapping with millions of genome-wide SNPs revealed that a genomic region of major effect on chromosome 28 was associated with phenotypes for premature and mature arrival to spawning grounds and was consistent across three distinct phylogenetic lineages. Our results demonstrate how genomic resources can enlighten the genetic basis of known phenotypes in exploited species and assist in clarifying phenotypic variation that may be difficult to observe in naturally occurring organisms.

Comparison of egg size and related life-history characteristics for two predaceous tree-hole mosquitoes (Toxorhynchites)

1980 ◽  
Vol 58 (11) ◽  
pp. 2065-2070 ◽  
Author(s):  
R. J. Lamb ◽  
S. M. Smith
Keyword(s):  
Life History ◽  
Egg Size ◽  
Prey Size ◽  
Prey Availability ◽  
Fourth Instar ◽  
Natural Environments ◽  
First Instar ◽  
Life History Characteristics ◽  
Tree Hole ◽  
Toxorhynchites Rutilus

Certain life-history characteristics of Toxorhynchites brevipalpis and Tx. rutilus septentrionalis were compared in the laboratory with the aim of accounting for a more than twofold difference in the weight of their eggs. First- and second-instar larvae of Tx. rutilus were longer and third-instar larvae shorter than corresponding stages of Tx. brevipalpis. The sizes of the two species did not differ appreciably in the later stages. Toxorhynchites rutilus first-instar larvae consumed more prey but total prey consumption was much greater for Tx. brevipalpis due to differences in consumption during the fourth instar. Developmental times from egg to adult did not differ at 25 °C. Toxorhynchites brevipalpis produced twice as many eggs per day during the first 14 days of oviposition but, due to size differences, the weight of the eggs produced per day was equal for the two species. Female Tx. brevipalpis laid an average of 5.9 eggs per oviposition flight. A corresponding value for Tx. rutilus was not determined. Newly hatched Tx. brevipalpis larvae withstood starvation for a longer period of time than Tx. rutilus larvae. Larval Tx. rutilus captured and consumed larger prey.It is hypothesized that egg size and fecundity are adapted to prey size and heterogeneity in prey availability in the natural environments of the two species.

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