scholarly journals Reproductive biology of Synallaxis albescens (Aves: Furnariidae) in the cerrado of central Brazil

2012 ◽  
Vol 12 (4) ◽  
pp. 266-269 ◽  
Author(s):  
Miguel Ângelo Marini ◽  
Sheila Silva Rodrigues ◽  
Mariana Batista Silveira ◽  
Harold Francis Greeney
Keyword(s):  
Life History ◽  
Reproductive Biology ◽  
Reproductive Strategies ◽  
Life History Evolution ◽  
Average Height ◽  
Central Theme ◽  
Central Brazil ◽  
Nestling Period ◽  
Nesting Substrate ◽  
Breeding Seasons

Understanding the causes and consequences of variation in reproductive strategies is a central theme in studies of avian life history evolution. This study describes the reproductive biology of Synallaxis albescens (Furnariidae) in the cerrado biome of central Brazil. We monitored 35 nests during the 2003 to 2011 breeding seasons, visiting them every 2-4 days. Synallaxis albescens breeds from mid-September to mid-January, builds a retort-shaped nest, and generally lays three immaculate white eggs. Eggs weighed 1.75 g and measured 19.7 by 14.4 mm. Most nests studied were in open cerrado or shrub grassland at an average height above the ground of 0.3 m, with a preference for Davilla elliptica (Dilleniaceae) shrubs as a nesting substrate. Incubation period averaged 18.1 days, while the nestling period averaged 13.6 days. Of 16 closely monitored nests, four were successful (25%), 11 were depredated (69%), and one was abandoned. Predation was similar during incubation (45%) and nestling (55%) phases. In general, the breeding biology of S. albescens was similar to that described previously for this species and for related Furnariidae.

scholarly journals Ecology and the diversification of reproductive strategies in viviparous fishes

2018 ◽  
Author(s):  
Michael Tobler ◽  
Zachary Culumber
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Reproductive Strategies ◽  
Life History Evolution ◽  
Evolutionary Transitions ◽  
Cascading Effects ◽  
High Resource ◽  
Correlated Patterns ◽  
Maternal Provisioning ◽  
Provisioning Strategies

AbstractShifts in life history evolution can potentiate sexual selection and speciation. However, we rarely understand the causative links between correlated patterns of diversification or the tipping points that initiate changes with cascading effects. We investigated livebearing fishes with repeated transitions from pre- (lecithotrophy) to post-fertilization maternal provisioning (matrotrophy) to identify the potential ecological drivers of evolutionary transitions in life history. Phylogenetic comparative analyses across 94 species revealed that bi-directional evolution along the lecithotrophy-matrotrophy continuum is correlated with ecology, supporting adaptive hypotheses of life history diversification. Consistent with theory, matrotrophy was associated with high resource availability and low competition. Our results suggest that ecological sources of selection contribute to the diversification of female provisioning strategies in livebearing fishes, which have been associated with macroevolutionary patterns of sexual selection and speciation.

Reproductive-Biology of Megascolides Australis Mccoy (Oligochaeta, Megascolecidae)

1995 ◽  
Vol 43 (5) ◽  
pp. 489 ◽  
Author(s):  
BD Vanpraagh
Keyword(s):  
Life History ◽  
Reproductive Biology ◽  
Reproductive Strategies ◽  
Egg Laying ◽  
Dispersal Ability ◽  
Low Density ◽  
Spermathecal Duct ◽  
Dispersal Abilities ◽  
Reproductive Processes

Observations of gametogenesis facilitated understanding life history and reproductive processes in Megascolides australis, whose reproductive strategies are correlated with longevity, low density and poor dispersal ability. Worms are biparental and have a discrete breeding (egg laying) season in spring and summer. This coincides with the greatest number of mature ova and the glandular epidermis of the clitellar region being thickest. Gametogenesis occurs throughout the year, with sperm present in the spermathecae and available on male funnels ail year. Non-seasonal copulation may occur when two worms meet and conditions are favourable; this trait is advantageous for species in low densities with poor dispersal abilities. The spermathecal structure of M. australis differs from that of other megascolecids recorded in that the structure of the diverticulum includes many multiloculate chambers that do not connect directly with the spermathecal duct. The sperm form orientated bundles (spermatozeugmata) not previously described for Megascolecidae and are stored in the ampulla rather than the diverticula.

scholarly journals GEOGRAPHIC VARIATION IN CLUTCH SIZE AMONG Lophura AND Syrmaticus PHEASANTS ON TAIWAN AND MAINLAND OF CHINA

2006 ◽  
Vol 28 (63) ◽  
Author(s):  
Zuhao Huang ◽  
Naifa Liu
Keyword(s):  
Life History ◽  
Environmental Factors ◽  
Clutch Size ◽  
Reproductive Strategies ◽  
Egg Size ◽  
Significant Positive Correlation ◽  
Weather Condition ◽  
Life History Evolution ◽  
Breeding Strategy ◽  
The Difference

Clutch size, the important parameters of bird reproduction, directly influences bird reproductive result. The difference of interspecific or/and intraspecific clutch size has been widely applied to explain life history evolution. In order to know the factors limiting clutch size of pheasants on island and examine Ashmole’s hypothesis and Cody’s hypothesis,clutch size and egg size of Lophura swinhoii and Syrmaticus mikado on Taiwan were compared with those of relative species on mainland of China. The average clutch size of L.swinhoii and S.mikado on Taiwan were significantly less than those of relative species on mainland. But the egg size of the two pheasants on Taiwan was notably bigger than those of relative species on mainland. They reduced clutch size and increased egg sizes, their reproductive strategies tended to k-selection. While the relative species on mainland laid more and smaller eggs, their reproductive strategies tended to rselection. The analysis on environmental factors showed the pheasants on Taiwan didn’t support Ashmole’s and Cody’s hypotheses. Unexpected weather condition on island might lead to the breeding strategy on island tend to k-selection. Among Gallinaceous birds, there was a highly significant positive correlation between clutch size and their distributed area, and the number of subspecies. The breeding strategy of pheasants on island was determined by the effects of area and heredity.

scholarly journals Gene Trees versus Species Trees: Reassessing Life-History Evolution in a Freshwater Fish Radiation

2010 ◽  
Vol 59 (5) ◽  
pp. 504-517 ◽  
Author(s):  
Jonathan M. Waters ◽  
Diane L. Rowe ◽  
Christopher P. Burridge ◽  
Graham P. Wallis
Keyword(s):  
Life History ◽  
Freshwater Fish ◽  
Life History Evolution ◽  
Gene Trees ◽  
Species Trees ◽  
History Evolution

scholarly journals The physiological costs of reproduction in small mammals

2007 ◽  
Vol 363 (1490) ◽  
pp. 375-398 ◽  
Author(s):  
John R Speakman
Keyword(s):  
Life History ◽  
Small Mammals ◽  
Morphological Changes ◽  
Life History Evolution ◽  
Indirect Costs ◽  
Direct Costs ◽  
Costs Of Reproduction ◽  
Dominant Component ◽  
Trade Offs ◽  
Almost All

Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional ‘compensatory costs’ whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.

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