Reproductive Success of Two Eucalyptus Hybrid Populations. I. Generalized Seed Output Model and Comparison of Fruit Parameters

1981 ◽  
Vol 29 (1) ◽  
pp. 25 ◽  
Author(s):  
DW Drake
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Significant Loss ◽  
Hybrid Population ◽  
Subsequent Paper ◽  
Species Trees ◽  
Seed Output ◽  
Eucalyptus Hybrid ◽  
Canopy Size ◽  
Two Populations

The dynamics of the reproductive success of two interspecific Eucalyptus hybrid populations are examined here and in a subsequent paper in relation to a generalized model of seed output of a single plant. The model describes a structural system of seed output per plant under both physiological and physical regulation. It can readily be extended to a population model and to postdispersal reproductive stages. Fruit loss, output and damage in the two populations are presented. The E. melanophloia × E. crebra hybrids are considerably less fertile than their parent species. Significant loss of reproductive structures during maturation and low reproductive effort, together with variable canopy size and proportion of canopy bearing fruits, result in the fruit output per average hybrid tree being 10% of either of the average species trees. Biotic damage to surviving hybrid fruits by an insect and a fungus is individually significantly greater than levels suffered by the species and together account for an average of 56% of fruits compared with 16% for either species. Damage and loss levels to these hybrids are more or less constant in space and time and constitute a strong selective force against these hybrids. In contrast, fruit loss parameters are low and differences between the taxa are non-significant throughout the E.populnea × E. crebra hybrid system, resulting in hybrid fertility about equal to the fertilities of the parents. These contrasting results are discussed in relation to hybrid frequencies in the ecotone and levels of hybrid population development.

Reproductive Success of Two Eucalyptus Hybrid Populations. II. Comparison of Predispersal Seed Parameters

1981 ◽  
Vol 29 (1) ◽  
pp. 37 ◽  
Author(s):  
DW Drake
Keyword(s):  
Reproductive Success ◽  
Single Species ◽  
Hybrid Population ◽  
Total Output ◽  
Species Trees ◽  
Hybrid Seeds ◽  
Seed Output ◽  
Total Seed ◽  
Insect Predation ◽  
Very High

The reproductive success of E. melanophloia × E. crebra and E. populnea × E. crebra hybrid populations is examined in terms of seed output. Predispersal seed losses and outputs from fruits and trees of hybrids and species in mixed- and single-species stands are presented. The contribution of the hybrid population to the total eucalypt seed output is considered by including in the estimates the numbers of hybrid and species trees per unit area of ecotone. Losses of E. melanophloia × E. crebra hybrid seeds through abortion, insect predation and fungal infection are significantly greater than losses of parent seeds and seeds of the other hybrid, and average 70% overall compared with 22% for each parent. If losses through bud maturation failure are included, 93% of the hybrid potential is lost. Hybrid outputs of 7 × 103 whole seeds per tree and 22 × 104 per ha of ecotone are respectively 1.5%, and 0.3% of the total seed output of the three taxa. Overall losses in the E. populnea × E. crebra hybrid system are much lower and less important to survival. The effect on seed number is dependent upon seed potential per fruit. E. populnea is the least affected (9% loss, very high potential), E. crebra the worst (21%, very low) and the hybrids are intermediate and in a relatively strong competitive position (20%, intermediate). Hybrid outputs of 145 × 103 seeds per tree and 23 × 103 per ha are respectively 21% and 17% of the total output. The significance of these results is discussed in relation to the reliance of eucalypts upon a high seed output strategy for survival and to the hybridization success of the two systems.

Energy Expenditure in Reproductive Effort of Male and Female Killdeer (Charadrius vociferus)

The Auk ◽  
1988 ◽  
Vol 105 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Dianne H. Brunton
Keyword(s):  
Reproductive Success ◽  
Energy Expenditure ◽  
Parental Care ◽  
Breeding Season ◽  
Reproductive Effort ◽  
Mating Effort ◽  
Parental Effort ◽  
Nest Failure ◽  
Male And Female ◽  
Charadrius Vociferus

Abstract The reproductive investment strategies of the sexes during the breeding season are detailed for Killdeer (Charadrius vociferus), a monogamous plover. I measured the energy investments of the sexes in reproductive, mating, and parental effort. As predicted, males expend more mating effort than females; however, the sexes expend equal amounts of parental effort. Total energy expenditure in reproductive effort (mating and parental effort) during a successful nesting attempt was also equal for the sexes. However, early parental effort expenditures by females, early mating effort expenditures by males, and high rates of nest failure combine to result in female reproductive energy expenditures being significantly higher over the breeding season. This suggests that energy expenditure alone is not adequate for accurate comparisons of the relative investments of the sexes. Studies investigating male and female investments need to consider the degree and pattern of nest failures along with patterns of energy expenditure. The advantages to male and female Killdeer of sharing parental care is demonstrated using adult removal experiments. In general, a deserted parent expends more energy in parental effort than a bi-parental parent and has significantly lower reproductive success. However, males are able to hatch chicks, whereas females lose or abandon their nests within a few days of mate removal. Thus, monogamy in Killdeer appears to result from high nest failure rates, the necessity of two parents for any reproductive success, and the generalizable nature of Killdeer parental care.

Growth and its relationship to the initial annual cycle of the golden-mantled ground squirrel, Spermophilus lateralis

1981 ◽  
Vol 59 (6) ◽  
pp. 865-871 ◽  
Author(s):  
John A. Phillips
Keyword(s):  
Litter Size ◽  
Annual Cycle ◽  
Ground Squirrel ◽  
Growth And Development ◽  
Reproductive Effort ◽  
Ground Squirrels ◽  
Active Season ◽  
Spermophilus Lateralis ◽  
Significant Difference ◽  
Two Populations

Thirty-eight litters of golden-mantled ground squirrels (Spermophilus lateralis), from two populations that experienced different lengths of active season, were born and raised in the laboratory. Growth and development in young were inversely related to litter size. Offspring from smaller litters were both able to attain their prehibernation peak of body mass sooner and hibernate after fewer days of homeothermy than squirrels from larger litters. Young that remained homeothermic throughout the initial overwintering period were always from large litters and among the slowest growing littermates. Fecundity was lower in females from the temporally compressed environment. There was no significant difference between populations in the nutrition provided by mothers to their litters. The results suggest that reproductive effort is more conservative in populations of ground squirrels that experience short seasons of activity, yet this conservatism allows the offspring of those populations to reach independence and attain the prehibernation state of preparedness at an earlier age than their counterparts from populations of more moderate climates.

A hybrid zone defined by allozymes and ventral colour in Geocrinia rosea (Anura:Myobatrachidae)

2007 ◽  
Vol 55 (6) ◽  
pp. 371 ◽  
Author(s):  
Don A. Driscoll ◽  
J. Dale Roberts
Keyword(s):  
Hybrid Zone ◽  
Range Expansion ◽  
Taxonomic Revision ◽  
Hybrid Population ◽  
Genetic Groups ◽  
Colour Patterns ◽  
Allozyme Loci ◽  
Two Populations ◽  
Genetic Division

The frog Geocrinia rosea is highly genetically subdivided with a major genetic division between northern and southern populations. Previous research did not sample a region spanning 12 km between these two populations. We report the distribution of G. rosea in the unsampled area and identify a geographically restricted hybrid zone. Boundaries of genetic groups were defined using two allozyme loci in 13 populations and ventral colouration. G. rosea was not continuously distributed in the area of parapatry. At the only point where the northern and southern groups met, there was a single hybrid population with genotypes demonstrating substantial interbreeding. Colour patterns implied a slightly broader hybrid zone, with four populations showing ventral colour introgression. Northern populations tended to have pink bellies whereas southern populations generally had orange bellies. We conclude that the two groups have diverged in allopatry and have formed a very narrow hybrid zone after range expansion. The magnitude of allozyme divergence between the four currently recognised species in the G. rosea complex is similar to the divergence between northern and southern G. rosea and is much greater than the divergence between other intraspecific groups. Taxonomic revision may therefore be warranted.

Reproductive Effort and Costs

2021 ◽  
pp. 59-74
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Total Energy ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Costs ◽  
Positive Outcomes ◽  
Differential Allocation ◽  
Trade Offs ◽  
Potential Benefits

Predictions about life-history evolution are intellectually bereft without a consideration of trade-offs. Benefits derived from making one life-history ‘decision’ are made at a cost of not realizing potential benefits associated with alternative decisions. These trade-offs are the inevitable product of constraints, often driven by an individual’s differential allocation of fixed resources to reproduction versus survival or growth. These allocations prevent multiple positive outcomes from being simultaneously realized. Reproductive effort is the proportion of total energy or resources allocated to all elements of reproduction. Reproductive effort generates reproductive costs. Increases in current reproductive effort reduce future reproductive success by affecting survival, growth, and/or fecundity. The causal mechanisms of these costs can be energetic, ecological, behavioural, or genetic. Evidence for reproductive costs is widespread. Instances where the evidence of costs is equivocal are usually caused by using among-individual correlations to study what is a within-individual phenomenon.

Older conservatives: reproduction in female Alpine chamois (Rupicapra rupicapra) is increasingly risk-averse with age

2016 ◽  
Vol 94 (5) ◽  
pp. 311-321 ◽  
Author(s):  
A. Morin ◽  
M. Rughetti ◽  
S. Rioux-Paquette ◽  
M. Festa-Bianchet
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Risk Averse ◽  
Costs Of Reproduction ◽  
Rupicapra Rupicapra ◽  
Terminal Investment ◽  
Age Dependent ◽  
Alpine Chamois ◽  
Old Females ◽  
Investment Hypothesis

In long-lived mammals, costs of reproduction may vary with age. The terminal investment hypothesis predicts greater reproductive effort as females approach the end of their life expectancy. We monitored 97 individually marked female Alpine chamois (Rupicapra rupicapra (L., 1758)) between 2007 and 2013 to determine how age-specific reproduction affected body mass and subsequent reproductive success. We captured and weighed females between April and August and monitored reproductive success from April to October through mother–kid associations. Reproductive success was strongly age-dependent and peaked at 70% for prime-aged females (4–7 years). Reproductive senescence began at 8 years, earlier than reported by other studies of ungulates. There was no clear evidence of reproductive costs in any age class. Reproductive success was very heterogeneous for old females, suggesting variability in the onset of senescence. Old females were less likely to reproduce in poor years despite being heavier than prime-aged females, suggesting reproductive restraint in late life rather than terminal investment. Female mass remained stable from May to August with no effect of lactation. Our results suggest that chamois reproductive strategy becomes increasingly conservative with age, resulting in no detectable costs of reproduction.

Pollination and reproductive success in the gynodioecious endemic Thymus loscosii (Lamiaceae)

2005 ◽  
Vol 83 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Maria Renée Orellana ◽  
Anna Maria Rovira ◽  
Cèsar Blanché ◽  
Maria Bosch
Keyword(s):  
Reproductive Success ◽  
Seed Quality ◽  
Seed Set ◽  
Pollen Deposition ◽  
Pollinator Visitation ◽  
Heterospecific Pollen ◽  
Pollen Loads ◽  
Visual Attraction ◽  
Insect Exclusion ◽  
Two Populations

Sexual dimorphism can have implications in the reproductive biology of gynodioecious species, affecting sex fitness. We explored the effects of flower sex on pollination visitation rates and pollinator efficiency in terms of stigmatic pollen loads, as well as on quantitative and qualitative aspects of reproductive success in two populations of Thymus loscosii Willk. (Lamiaceae) endemic to the northeastern Iberian Peninsula. We also assessed the dependence of T. loscosii on insect pollination in both hermaphrodite and female plants by performing an insect exclusion test. Apis mellifera and different species of Bombylidae were the most frequent pollinators (68% of approaches to studied plots and 93% of total visited flowers). Hermaphrodite plants received more visits than female ones, possibly as a response to visual attraction, since flowers of the former are larger. Conspecific pollen deposition was higher on stigmas of hermaphrodite flowers than on those of females; in contrast, female stigmas received more heterospecific pollen loads, notably higher in one population. Despite these differences, seed set from open-pollinated flowers was similar in both sexes and in both populations, and relatively low (around 0.5–1 nutlet per fruiting calyx, on average). Thymus loscosii is self-compatible as it was able to produce seeds by spontaneous selfing, but at very low rates, indicating that it is insect-dependent for pollination. In addition, bagged female flowers also set seeds formed by apomitic mechanisms. In general, seeds from females were slightly heavier and began to germinate earlier and at higher rates than those from hermaphrodites, even those formed by apomixis. These results suggest that female plants enjoy a resource allocation advantage that allows increased seed quality and contributes to the maintenance of gynodioecy.Key words: gynodioecy, pollinator visitation, pollen loads, seed set, sex fitness, Thymus loscosii.

scholarly journals Senescent birds redouble reproductive effort when ill: confirmation of the terminal investment hypothesis

2006 ◽  
Vol 273 (1593) ◽  
pp. 1443-1448 ◽  
Author(s):  
Alberto Velando ◽  
Hugh Drummond ◽  
Roxana Torres
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Initial Increase ◽  
Male Reproductive Success ◽  
Age Classes ◽  
Theoretical Idea ◽  
Sula Nebouxii ◽  
Terminal Investment ◽  
Survival And Reproduction ◽  
Investment Hypothesis

This study reports an experimental confirmation of the terminal investment hypothesis, a longstanding theoretical idea that animals should increase their reproductive effort as they age and their prospects for survival and reproduction decline. Previous correlational and experimental attempts to test this hypothesis have yielded contradictory results. In the blue-footed booby, Sula nebouxii , a long-lived bird, after initial increase, male reproductive success declines progressively with age. Before laying, males of two age classes were challenged with lipopolysaccharide to elicit an immune response, which induced symptoms of declining survival prospects. Reproductive success of immune-challenged mature males fell, while that of immune-challenged old males showed a 98% increase. These results demonstrate that senescent males with poor reproductive prospects increase their effort when those prospects are threatened, whereas younger males with good reproductive prospects do not.

scholarly journals Detection and mapping of a lethal locus in a eucalyptus hybrid population

2011 ◽  
Vol 46 (9) ◽  
pp. 1021-1028
Author(s):  
Tatiana Barbosa Rosado ◽  
Rafael Simões Tomaz ◽  
Rodrigo Barros Rocha ◽  
Antônio Marcos Rosado ◽  
Alexandre Alonso Alves ◽  
...  
Keyword(s):  
Linkage Group ◽  
Segregation Distortion ◽  
Expectation Maximization ◽  
Rust Resistance ◽  
Expectation Maximization Algorithm ◽  
Hybrid Population ◽  
Male Side ◽  
Group 3 ◽  
Eucalyptus Hybrid ◽  
Gametic Selection

The objective of this work was to verify the existence of a lethal locus in a eucalyptus hybrid population, and to quantify the segregation distortion in the linkage group 3 of the Eucalyptus genome. A E. grandis x E. urophylla hybrid population, which segregates for rust resistance, was genotyped with 19 microsatellite markers belonging to linkage group 3 of the Eucalyptus genome. To quantify the segregation distortion, maximum likelihood (ML) models, specific to outbreeding populations, were used. These models consider the observed marker genotypes and the lethal locus viability as parameters. The ML solutions were obtained using the expectation‑maximization algorithm. A lethal locus in the linkage group 3 was verified and mapped, with high confidence, between the microssatellites EMBRA 189 e EMBRA 122. This lethal locus causes an intense gametic selection from the male side. Its map position is 25 cM from the locus which controls the rust resistance in this population.

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