Reproductive Life History Research Articles

Regulation of Migration inMythimna separata(Walker) in China: A Review Integrating Environmental, Physiological, Hormonal, Genetic, and Molecular Factors

Each year the Mythimna separate (Walker), undertakes a seasonal, long-distance, multigeneration roundtrip migration between southern and northern China. Despite its regularity, the decision to migrate is facultative, and is controlled by environmental, physiological, hormonal, genetic, and molecular factors. Migrants take off on days 1 or 2 after eclosion, although the preoviposition period lasts ≈7 d. The trade-offs among the competing physiological demands of migration and reproduction are coordinated in M. separata by the "oogenesis-flight syndrome." Larvae that experience temperatures above or below certain thresholds accompanied by appropriate humidity, short photoperiod, poor nutrition, and moderate density tend to develop into migrants. However, there is a short window of sensitivity within 24 h after adult eclosion when migrants can be induced to switch to reproductive residents if they encounter extreme environmental factors including starvation, low temperature and long photoperiod. Juvenile hormone (JH) titer is low before migration but high titers are associated with termination of migratory behavior and the switch to reproduction. Early release of JH by the corpora allata in environmentally stressed 1-d old adults, otherwise destined by larval conditions to be migrants, switches them to residents. Offspring inherit parental additive genetic effects governing migratory behavior. However, they also retain flexibility in expression of both flight and reproductive life history traits. The insect neuropeptide, allatotropin, which activates corpora allata to synthesize JH, controls adult flight and reproduction. Future research directions to better understand regulation of migration in this species are discussed.

Phenotypic plasticity of life history traits in relation to reproductive strategies in Boa constrictor occidentalis

The close connection between reproductive ecology and life history in snakes leads to trade-offs between reproductive and other life-history traits. Optimal energy allocation to growth and reproduction is a key factor to determine life history structure. Therefore, elucidating the relationship between body size variations and reproductive characters is essential for a better understanding of life-history plasticity. The aim of this work was to determine to what extent life-history differs among populations of Boa constrictor occidentalis and to identify possible life-history trade-offs between morphological and reproductive traits. We compared two populations from areas that are separated latitudinally, with different climatic conditions and vegetation landscape structure. Reproductive and morphological data of specimens were recorded. Although populations had a similar mean length of mature snakes, the frequency of some size classes tended to be different. Size at sexual maturity differed between populations for females, generating variations in the proportion of mature individuals. Reproductive threshold and follicular size also varied, but female reproductive frequency was similar between populations. Reproductive frequency of males varied between populations although their body condition was similar. We discussed two major issues: (1) implications of size at sexual maturity for body size and fecundity; (2) trade-offs in reproductive characters.

Effects of climate change on fish reproduction and early life history stages

Seasonal change in temperature has a profound effect on reproduction in fish. Increasing temperatures cue reproductive development in spring-spawning species, and falling temperatures stimulate reproduction in autumn-spawners. Elevated temperatures truncate spring spawning, and delay autumn spawning. Temperature increases will affect reproduction, but the nature of these effects will depend on the period and amplitude of the increase and range from phase-shifting of spawning to complete inhibition of reproduction. This latter effect will be most marked in species that are constrained in their capacity to shift geographic range. Studies from a range of taxa, habitats and temperature ranges all show inhibitory effects of elevated temperature albeit about different environmental set points. The effects are generated through the endocrine system, particularly through the inhibition of ovarian oestrogen production. Larval fishes are usually more sensitive than adults to environmental fluctuations, and might be especially vulnerable to climate change. In addition to direct effects on embryonic duration and egg survival, temperature also influences size at hatching, developmental rate, pelagic larval duration and survival. A companion effect of marine climate change is ocean acidification, which may pose a significant threat through its capacity to alter larval behaviour and impair sensory capabilities. This in turn impacts on population replenishment and connectivity patterns of marine fishes.

Reviewing the Effects of Ocean Acidification on Sexual Reproduction and Early Life History Stages of Reef-Building Corals

Ocean acidification (OA) is a relatively young yet rapidly developing scientific field. Assessing the potential response(s) of marine organisms to projected near-future OA scenarios has been at the forefront of scientific research, with a focus on ecosystems (e.g., coral reefs) and processes (e.g., calcification) that are deemed particularly vulnerable. Recently, a heightened emphasis has been placed on evaluating early life history stages as these stages are generally perceived to be more sensitive to environmental change. The number of acidification-related studies focused on early life stages has risen dramatically over the last several years. While early life history stages of corals have been understudied compared to other marine invertebrate taxa (e.g., echinoderms, mollusks), numerous studies exist to contribute to our status of knowledge regarding the potential impacts of OA on coral recruitment dynamics. To synthesize this information, the present paper reviews the primary literature on the effects of acidification on sexual reproduction and early stages of corals, incorporating lessons learned from more thoroughly studied taxa to both assess our current understanding of the potential impacts of OA on coral recruitment and to inform and guide future research in this area.

Longevity cost of remaining unmated under dietary restriction

Summary 1. Increases in longevity from dietary restriction (DR) have been linked to the evolution of physiological strategies for maintaining lifetime reproductive output despite periods of nutritional deficiency. If this is the case, then reproductive life history and mating status should determine whether or not dietary restriction increases longevity. 2. We investigate the effects of DR and mating status (mated or unmated) on longevity and lifetime reproductive output and explore mechanisms underlying these patterns by measuring resting energetic rates and changes in mass over time. We study iteroparous female Australian redback spiders (Latrodectus hasselti), which are known to tolerate periods of starvation (ecologically relevant DR) in nature. 3. Mated DR females had the highest longevity of any experimental group, in strong contrast to results for semelparous males of this species [M.M. Kasumovic, M.C.B. Andrade & R.C. Brooks (2009), Biology Letters,5, 636]. Most strikingly, mated females (whether DR or not) had higher longevity than unmated females. 4. Mated females rapidly decreased their resting energetic rates and stopped egg production under DR. Once feeding returned to normal, resting energetic rates of mated females increased immediately, egg sac production continued and there was no net decrease in lifetime reproductive output relative to mated females without DR. 5. This shows DR increases longevity for mated females, but there is a longevity cost of remaining unmated, which may arise because unmated females (regardless of diet) maintained high energetic rates. This may be an evolved pattern of physiological support for reproductive readiness which exerts a fitness cost when mating is delayed. Taken together, these results suggest positive effects of DR on longevity critically depend on reproductive life history (iteroparity or semelparity) and individual mating status.

Correlation between Male Social Status, Testosterone Levels, and Parasitism in a Dimorphic Polygynous Mammal

Life history trade-offs have often been assumed to be the consequence of restrictions in the availability of critical resources such as energy and nutrients, which necessitate the differential allocation of resources to costly traits. Here, we examined endocrine (testosterone) and health (parasite burdens) parameters in territorial and non-territorial New Zealand fur seal males. We documented intra-sexual differences in sexual behaviours, testosterone levels, and parasitism that suggest a trade-off exists between reproductive success and physical health, particularly susceptibility to helminths and acanthocephalans, in males displaying different mating tactics (i.e., territorial and non-territorial tactics). Levels of testosterone were higher in territorial males and correlated positively with reproductive effort (i.e., intra- and inter-sexual interactions). However, these territorial males also exhibited high levels of parasitic infection, which may impair survival in the long-term. Our study, while limited in sample size, provides preliminary evidence for a link between male mating tactics, testosterone levels and parasite loads, and potential effects on reproductive success and life history that should be explored further.

Sex differences in dental caries experience: clinical evidence, complex etiology

A sex difference in oral health has been widely documented through time and across cultures. Women's oral health declines more rapidly than men's with the onset of agriculture and the associated rise in fertility. The magnitude of this disparity in oral health by sex increases during ontogeny: from childhood, to adolescence, and through the reproductive years. Representative studies of sex differences in caries, tooth loss, and periodontal disease are critically reviewed. Surveys conducted in Hungary, India, and in an isolated traditional Brazilian sample provide additional support for a significant sex bias in dental caries, especially in mature adults. Compounding hormonal and reproductive factors, the sex difference in oral health in India appears to involve social and religious causes such as son preference, ritual fasting, and dietary restrictions during pregnancy. Like the sex difference in caries, tooth loss in women is greater than in men and has been linked to caries and parity. Results of genome wide association studies have found caries susceptible and caries protective loci that influence variation in taste, saliva, and enamel proteins, affecting the oral environment and the micro-structure of enamel. Genetic variation, some of which is X-linked, may partly explain how sex differences in oral health originate. A primary, but neglected, factor in explaining the sex differential in oral health is the complex and synergistic changes associated with female sex hormones, pregnancy, and women's reproductive life history. Caries etiology is complex and impacts understanding of the sex difference in oral health. Both biological (genetics, hormones, and reproductive history) and anthropological (behavioral) factors such culture-based division of labor and gender-based dietary preferences play a role.

The evolution of mating systems in barnacles

Thoracican barnacles exhibit tremendous diversity among species in reproductive life histories, including hermaphroditism, dioecy and androdioecy. Androdioecy (where populations contain a mix of males and hermaphrodites) is rare among animals, but has been described in more than 30 species of barnacles and appears to have evolved independently at least four times in this clade. Several models have been suggested to explain the evolution and stability of different mating systems in barnacles, including the relatively high frequency of androdioecy. We review this body of theory and compare predictions to existing empirical data on interspecific patterns of sex allocation. Allocation to male and female reproduction may also vary within barnacle species, and these patterns may provide additional insight into the evolutionary forces that select for different mating systems. Theory predicts that for simultaneous hermaphrodites, the optimal allocation to male function should increase with the size of mating groups, due to sperm competition. This prediction is supported by the only previously published study to address this issue. We present new data from another intertidal barnacle ( Tetraclita rubescens) that do not support the predicted association between investment in male reproduction and local density of conspecifics. We suggest that this departure from the expected relationship may arise from a reduced importance of sperm competition in this species. Despite over 150 years of interest in barnacle mating systems, many questions remain unanswered. We argue that barnacles provide a superb opportunity to test predictions of sex allocation theory and we offer suggestions for promising areas of future research.

Reproductive life history of Thornicroft’s giraffe in Zambia

AbstractKnowledge of the reproductive life history of giraffe in the wild is sparse. Giraffe have two fairly unusual reproductive patterns among large mammals: they can become pregnant while lactating, and calf mortality is extremely high. Longitudinal records are largely absent, so tracking reproductive parameters tends to combine information from captive and field studies. In this study, we examine longitudinal data obtained over a 33‐year period in one population of Thornicroft’s giraffe in order to chart their reproductive careers. We found that age at first parturition was 6.4 years, or slightly later than in captivity. Giraffe bred throughout the year, with cows producing offspring on average every 677.7 days. About half of the calves died before one year of age, but death of a calf did not reduce interbirth interval. We conclude that the lifetime reproductive success of giraffe is more dependent on longevity and calf survivorship than on reproductive rate.

Silk gene transcripts in the developing tubuliform glands of the Western black widow, Latrodectus hesperus

Spiders spin a variety of task-specific silk fibers, each composed of one or more unique proteins synthesized within specialized glands in the spider's abdomen. Tubuliform glands are the source of the large diameter silk fibers used by many species in the construction of egg cases. Unlike other silk glands that synthesize protein throughout a spider's lifetime, the tubuliform glands synthesize silk in association with the maturation of oocytes, culminating in the production of an egg case. In the Western black widow, Lactrodectus hesperus Chamberlin & Ivie (1935), egg case fibers are composed of at least three proteins: tubuliform spidroin 1 (TuSp1), egg case protein-1 (ECP-1), and egg case protein-2 (ECP-2). Here, we present the first study to quantify the pattern of transcription for these three genes in a developmental series of tubuliform glands from L. hesperus. All three transcripts increase in abundance prior to the production of an egg case, but at different time points. After egg case production, silk transcripts are still detectable in the tubuliform glands. Relative abundance of TuSp1 mRNA is several orders of magnitude higher than that of ECP-1 and ECP-2 at almost every stage. The relative abundance of silk transcripts across the reproductive life history of black widows suggests differential regulation of silk gene transcription within tubuliform glands.

Tumor and reproductive traits are linked by RNA metabolism genes in the mouse ovary: a transcriptome-phenotype association analysis

BackgroundThe link between reproductive life history and incidence of ovarian tumors is well known. Periods of reduced ovulations may confer protection against ovarian cancer. Using phenotypic data available for mouse, a possible association between the ovarian transcriptome, reproductive records and spontaneous ovarian tumor rates was investigated in four mouse inbred strains. NIA15k-DNA microarrays were employed to obtain expression profiles of BalbC, C57BL6, FVB and SWR adult ovaries.ResultsLinear regression analysis with multiple-test control (adjusted p ≤ 0.05) resulted in ovarian tumor frequency (OTF) and number of litters (NL) as the top-correlated among five tested phenotypes. Moreover, nearly one-hundred genes were coincident between these two traits and were decomposed in 76 OTF(–) NL(+) and 20 OTF(+) NL(–) genes, where the plus/minus signs indicate the direction of correlation. Enriched functional categories were RNA-binding/mRNA-processing and protein folding in the OTF(–) NL(+) and the OTF(+) NL(–) subsets, respectively. In contrast, no associations were detected between OTF and litter size (LS), the latter a measure of ovulation events in a single estrous cycle.ConclusionLiterature text-mining pointed to post-transcriptional control of ovarian processes including oocyte maturation, folliculogenesis and angiogenesis as possible causal relationships of observed tumor and reproductive phenotypes. We speculate that repetitive cycling instead of repetitive ovulations represent the actual link between ovarian tumorigenesis and reproductive records.

Reproductive Characteristics and Mortality of Female Giant Grenadiers in the Northern Pacific Ocean

AbstractGiant grenadiersAlbatrossia pectoralisare caught as bycatch in deep‐sea commercial fisheries in relatively large numbers. The population appears to be stable, although there is no directed fishery, catch limits, or reporting requirements. The purpose of our study was to describe and quantify the reproductive life history characteristics and natural mortality of female giant grenadiers. During the summers of 2004 and 2006, a total of 338 specimens were collected from the Gulf of Alaska. Every phase of reproductive development was found, suggesting a protracted annual spawning season. An ovarian wall thickness technique was used to successfully place 31% (n= 24) of the fish with an unknown maturity status into a known category. Female age at 50% maturity was 22.9 years, and preanal fin length at 50% maturity was 26 cm. Total fecundity ranged from 35,000 to 231,000 oocytes (mean = 106,761), with a mean mature oocyte diameter of 1.26 mm. We developed a new technique for preparing otoliths for age determination by grinding off the distal surface to elucidate the growth zones; age ranged from 14 to 58 years. Estimates of natural female mortality ranged from 0.052 to 0.079 and estimates of total female mortality from 0.061 to 0.149. This life history information will be essential for future management of giant grenadier populations in the North Pacific Ocean.

Life history variation along a salinity gradient in coastal marshes

Coastal habitats are susceptible to changes in the environment associated with alter- ations in salinity. A field study was conducted on natural populations of the sailfin molly Poecilia latipinna, the western mosquitofish Gambusia affinis and the least killifish Heterandria formosa col- lected from coastal marsh sites along a salinity gradient, to investigate the influence of salinity on body condition and reproductive life history traits. In brackish marsh sites male P. latipinna had the best body conditions, while females had similar body conditions across all 3 marsh types. Female P. latipinna had greater reproductive allotment and fecundity in brackish marshes, where this fish was most abundant. Specimens of G. affinis collected from fresh marsh sites had less favorable body condition, and females had lower reproductive allotment and fecundity than those collected from higher salinities. While G. affinis was more abundant in freshwater marshes than in higher salinity marshes, this higher abundance did not correspond with a better body condition or higher reproduc- tive effort, suggesting that G. affinis may be stressed in freshwater. There was no difference in the conditions between (both male and female) H. formosa from fresh and intermediate marshes. Female H. formosa from fresh marshes had a similar reproductive allotment and lower fecundity than those from intermediate marshes. The 3 species exhibited different life history patterns along the salinity gradient, and some of these patterns conflicted with expectations based on species abundances. When assessing habitat quality along an environmental gradient, measures of abundance should be accompanied by more sensitive indicators of environmental stress.

Reproductive Biology of Agkistrodon piscivorus Lacépède (Squamata, Serpentes, Viperidae, Crotalinae)

Aspects of the reproductive biology of male and female Agkistrodon piscivorus are described using histological techniques, reviewed, and compared with historical data on A. piscivorus. These include anatomical description at the macro and microscopic levels, and correlation of the male and female urogenital cycles to the reproductive life history of A. piscivorus. New anatomical descriptions and discussion of the efferent ducts, including the ductuli efferentes, proximal and distal ductuli epididymides, ductus deferens, and ampulla ductus deferens, are also presented here at the light and electron microscopy levels. Morphology of all distinct regions of the male and female urogenital systems are discussed and compared with historical investigations on other squamates. In comparison to other snakes, A. piscivorus possesses some unique reproductive characters, whereas others are more conserved. In terms of the reproductive cycle, the ability of males and females to store sperm allows the dissociation of reproductive event timing between the sexes. Thus, the only event that must be coordinated between the sexes is copulation, which is proposed to occur in the fall and the spring in A. piscivorus. In females, the atrophy and activity of the reproductive organs (e.g., secretory activity) varies concurrently with vitellogenesis and the mating seasons. In males, spermatogenesis peaks in the summer, independent of the mating season, except in Louisiana where a spring and fall peak of spermatogenesis occur, and where the spring and fall mating seasons overlap. Renal sexual segment hypertrophy in males peaks in the fall and spring in more southern populations (Alabama and Louisiana) concurrent with fall and spring mating seasons. In Georgia, only a fall peak is observed. Secretory activity of the male excurrent ducts also peaks during times of mating activity in one population studied (Louisiana).

Differences in the trait compositions of non-indigenous and native plants across Germany

This paper explores the differences in the trait compositions of non-indigenous (neophytic) and native plant species for selected traits in Germany. Our set of functional traits addresses species’ reproductive biology, life history, morphology and ecophysiology. To take account of broad-scale heterogeneity across the country we compared the relative frequencies of neophytes and natives with particular trait attributes at the scale of grid cells (c. 130 km2 each). Subsequently, we compared the differences at the grid cell scale to the differences in the corresponding comparisons at the scale of the entire country. Finally, we explored how variation in the trait compositions of the non-indigenous species across the country relates to variation in the trait compositions of the natives. We found remarkable differences in the trait compositions of neophytes and natives at the grid cell scale. Neophytes were over-represented in insect- and self-pollinated species and in species with a later and longer flowering season. Furthermore, the proportions of species with mesomorphic or hygromorphic leaf anatomy, of annual herbs and of trees as well as of non-clonals and polyploids were significantly higher in neophytes than in natives. These differences at the grid cell scale could vary distinctly from the corresponding differences observed at the country scale. This result highlights the complexity of the invasion process and suggests an importance of spatial scale for the comparisons. Correlation analysis indicated, that for traits relating to plant morphology and ecophysiology, the relative frequencies of the non-indigenous species increased with those of the natives. This suggests that favourable environments for natives with particular attributes constitute an increased suitability for neophytes with these attributes as well. Our study provides a step forward towards an integrated understanding of traits in plant invasions across spatial scales and broad-scale heterogeneity and underlines the necessity to understand the role of functional traits in plant invasions with reference to spatial scale and in the context of the environment.

The role of experiments in understanding fishery-induced evolution.

Evidence of fishery-induced evolution has been accumulating rapidly from various avenues of investigation. Here we review the knowledge gained from experimental approaches. The strength of experiments is in their ability to disentangle genetic from environmental differences. Common garden experiments have provided direct evidence of adaptive divergence in the wild and therefore the evolvability of various traits that influence production in numerous species. Most of these cases involve countergradient variation in physiological, life history, and behavioral traits. Selection experiments have provided examples of rapid life history evolution and, more importantly, that fishery-induced selection pressures cause simultaneous divergence of not one but a cluster of genetically and phenotypically correlated traits that include physiology, behavior, reproduction, and other life history characters. The drawbacks of experiments are uncertainties in the scale-up from small, simple environments to larger and more complex systems; the concern that taxons with short life cycles used for experimental research are atypical of those of harvested species; and the difficulty of adequately simulating selection due to fishing. Despite these limitations, experiments have contributed greatly to our understanding of fishery-induced evolution on both empirical and theoretical levels. Future advances will depend on integrating knowledge from experiments with those from modeling, field studies, and molecular genetic approaches.

Population structure and reproductive biology of the stone crab Xantho poressa (Crustacea: Decapoda: Xanthidae) in the ‘Corrales de Rota’ (south-western Spain), a human-modified intertidal fishing area

The present study describes the reproductive biology, population structure and life history traits of the abundant intertidal crab Xantho poressa. Between March 2007 and April 2008, a total of 1918 individuals were collected in Corrales de Rota (south-western Spain), a human-modified intertidal habitat characterized by an artificial high complexity. Suitable refuges for crabs (cobbles and boulders) are very abundant in this area and density (maximum of 50 ind*m−2) was directly related with the area covered by these stones. In spring and summer, size–frequency distributions showed a polymodal pattern with seasonal variations related to the incorporation of juveniles to the adult population. Newly settled juveniles were not found in the Corrales suggesting an ontogenetic migration from a distant recruitment habitat. The annual reproductive cycle was seasonal and successive peaks in the abundance of ovigerous females were observed in late spring and summer. Females probably produced multiple broods during a long intermoult period. The gonadosomatic index had a cyclic pattern of variation with peaks two weeks prior to those of ovigerous females; it was lower during the non-reproductive season. The hepatosomatic index was high during spring, decreased during summer and increased gradually at the end of the reproductive season. There was a monthly cycle of larval release resulting from a combination of a cyclic and synchronic ovarian maturity, oviposition and incubation; hatching took place during neap tides when the moon was at last quarter. The adaptive significance of the rhythmic reproduction and hatching observed may not be explained by the predator avoidance hypotheses. The overall sex-ratio did not differ from 1:1 but one male and several females coexist under a stone, indicating a female biased operative sex-ratio. The combination of a complex habitat, its use, and a strong sexual dimorphism suggest a refuge–defence polygenic mating system. The survival and fitness of X. poressa in the Corrales de Rota are probably enhanced by the availability of shelter, a consequence of a highly complex habitat, and probably, of human activity.

Forest age correlates with fine-scale spatial structure of Matsutake mycorrhizas

Examining the fine-scale spatial structure of fungal populations can tell us much about how individual species reproduce and disperse throughout natural landscapes. Here we study the fine-scale genetic structure of Tricholoma matsutake, a prized edible and medicinal mushroom, by systematic sampling of mycorrhizas within fairy rings in 50-y-old and old-growth forests in two villages. Using single nucleotide polymorphism DNA markers we show that mycorrhizas in both forest age classes in both villages showed high levels of genotypic diversity, consistent with a reproductive life history predominated by outcrossing via basidiospore dispersal. Both the percentage of polymorphic loci within fairy rings, as well as genotype diversity were higher in old-growth compared to 50-y-old forests. Fifty-year-old forests showed significant spatial autocorrelation between pairs of mycorrhizas up to 42 m, and a pattern consistent isolation-by-distance structure. Spatial patterns in old-growth forests were random. Furthermore, AMOVA analysis indicates that 11 % of molecular variance in 50-y-old forests is partitioned between villages, whereas no significant variance is partitioned between villages in old-growth forests. We conclude that populations of T. matsutake in 50-y-old forests are the result of a founder effect maintained by local inoculation sources. This pattern attenuates as forests age and accumulate inocula from more distance sources. We speculate on how genetic mosaicism within T. matsutake fairy rings may structure populations within a chronosequence. Finally, we discuss how population spatial dynamics and dispersal strategy in T. matsutake contrast with other ectomycorrhizal species.

Geometric Morphological Differences Distinguish Populations of Scup in the Northwestern Atlantic Ocean

AbstractScup Stenotomus chrysops, a commercially important marine species, are distributed from Nova Scotia to south Florida, and may represent morphologically distinct populations across their range. It was determined whether there were morphological differences between a North Atlantic Bight (NAB) population (41°N) and two South Atlantic Bight (SAB) populations (30°N and 32°N) of this species from April 2005 to July 2005, when the populations had formed spawning groups. Morphology was compared among populations by means of a geometric, landmark‐based analysis of morphological and meristic traits for 180 individuals that were sexed and staged to maturity. A backward, stepwise discriminant functions analysis (DFA) produced a model that generated DFA scores that differed significantly between the NAB and SAB populations. Forehead and body depth dimensions differed among populations but not sexes. The DFA model predicted similar scores for 32 new NAB individuals and 31 new SAB individuals; however, scores were consistently underpredicted for the NAB individuals and overpredicted for the SAB individuals. We concluded that distinct northern and southern populations support a two‐stock or two‐species hypothesis; however, it is unclear whether this stock structure is related to reproductive or other life history traits. Either phenotypic plasticity or divergent selection may explain the morphological dissimilarities among these populations, but their influence on individual fitness remains unknown.

Breeding Biology of the Three-Striped Warbler in Venezuela: a Contrast between Tropical and Temperate Parulids

We document reproductive life history traits of the Three-striped Warbler (Basileuterus tristriatus) from 146 nests in Venezuela and compare our results to data from the literature for other tropical and temperate parulid species. Mean (± SE) clutch size was 1.96 ± 0.03 eggs (n = 96) and fresh egg mass was 2.09 ± 0.02 g. The incubation period was 15.8 ± 0.2 days (n = 23) and the nestling period was 10.5 ± 0.3 days (n = 12). Males did not incubate and rarely provided food for females during incubation. Females had 57 ± 2% (n = 49) nest attentiveness (% of time on the nest incubating), which caused egg temperature to commonly become cold relative to development. Both adults fed nestlings and feeding rates increased with nestling age. The growth rate constant for nestlings based on mass was K = 0.490, which is slower than for north temperate warblers. Predation was the primary source of nest failure and only 22% of nests were successful based on a Mayfield daily predation rate of 0.048 ± 0.006. Our literature review indicates parulids differ strongly in life histories between temperate and tropical/subtropical sites with species in the tropics having, on average, smaller clutches, longer incubation periods, lower nest attentiveness, longer off-bouts, and longer nestling periods.