Reproductive Life History Research Articles

Reproductive life-history strategies in a species-rich assemblage of Amazonian electric fishes.

The reproductive biology of only a small fraction of Neotropical freshwater fishes has been described, and detailed comparative studies of reproductive life-history variation in the Neotropical ichthyofauna are lacking. Here we describe interspecific variation in reproductive life history for a multi-species assemblage of the electric knifefish genus Brachyhypopomus (Hypopomidae: Gymnotiformes: Ostariophysi) from Amazonian floodplain and terra firme stream systems. During a year-round quantitative sampling program, we collected and measured key life-history traits from 3,410 individuals. Based on oocyte size distributions, and on circannual variation in gonadosomatic indices, hepatosomatic indices, and capture-per-unit-effort abundance of reproductive adults, we concluded that all species exhibit a single protracted annual breeding season during which females spawn fractionally. We found small clusters of post-larval individuals in one floodplain species and one terra firme stream species, but no signs of parental care. From analyses of body size-frequency distributions and otolith growth increments, we concluded that five species in our study area have approximately one-year (annual) semelparous life history with a single reproductive period followed by death, while two species have a two-year iteroparous life history, with breeding in both year-groups. Despite predictions from life-history theory we found no salient correlations between life history strategy (semelparity or iteroparity) and habitat occupancy (floodplain or terra firme stream). In the iteroparous species B. beebei, we documented evidence for reproductive restraint in the first breeding season relative to the second breeding season and argue that this is consistent with age-regulated terminal investment.

Geographical and temporal variation of multiple paternity in invasive mosquitofish (Gambusia holbrooki, Gambusia affinis).

Multiple paternity (MP) increases offspring's genetic variability, which could be linked to invasive species' evolvability in novel distribution ranges. Shifts in MP can be adaptive, with greater MP in harsher/colder environments or towards the end of the reproductive season, but climate could also affect MP indirectly via its effect on reproductive life histories. We tested these hypotheses by genotyping N=2,903 offspring from N=306 broods of two closely related livebearing fishes, Gambusia holbrooki and Gambusia affinis. We sampled pregnant females across latitudinal gradients in their invasive ranges in Europe and China, and found more sires per brood and a greater reproductive skew towards northern sampling sites. Moreover, examining monthly sampling from two G. affinis populations, we found MP rates to vary across the reproductive season in a northern Chinese, but not in a southern Chinese population. While our results confirm an increase of MP in harsher/more unpredictable environments, path analysis indicated that, in both cases, the effects of climate are likely to be indirect, mediated by altered life histories. In both species, which rank amongst the 100 most invasive species worldwide, higher MP at the northern edge of their distribution probably increases their invasive potential and favours range expansions, especially in light of the predicted temperature increases due to global climate changes.

A temporal assessment of family composition and genetic diversity in a commercial cohort of Dusky Kob, Argyrosomus japonicus, across the production cycle

The reproductive modes and life history of aquaculture species, such as dusky kob (Argyrosomus japonicus), characterised by high fecundity, mass larval mortality and skewed broodstock spawning success, poses a challenge for the implementation of selective breeding programmes. This often results in inbreeding and the loss of genetic diversity and reduced overall population productivity. These effects might be further exacerbated by standard aquaculture production practices, such as size grading and culling, but this remains under-investigated. In the present study, 14 microsatellite markers were used to monitor changes in genetic diversity and family compositions throughout the production cycle of F1 dusky kob (weaning to marketable size). Overall, the F1 animals experienced a substantial reduction in allelic content and presented statistically significant differentiation from the wild, with a global FST of 0.03 (P < 0.01). Parentage analyses indicated an effective broodstock population size of only seven (out of 12) individuals, with only five full-sib families (from a potential of 16) and three half-sib offspring groups. Two families each had a starting contribution, at weaning, of less than 5%, though neither was eliminated following removal of the smallest animals by grading and culling. Culling, at the final stage, however, did contribute to a significant increase in genetic relatedness in the oldest (i.e. market-sized) group analysed and a single family represented 88% of the resulting stock, suggesting that these individuals were on average faster growing than others. The obtained results demonstrate that culling practices do have the potential to create bias in the representation of families, further complicating the selection of unrelated broodstock candidates in selective breeding programmes.

Life history alterations upon oral and hemocoelic bacterial exposure in the butterfly Melitaea cinxia.

Life history strategies often shape biological interactions by specifying the parameters for possible encounters, such as the timing, frequency, or way of exposure to parasites. Consequentially, alterations in life‐history strategies are closely intertwined with such interaction processes. Understanding the connection between life‐history alterations and host–parasite interactions can therefore be important to unveil potential links between adaptation to environmental change and changes in interaction processes. Here, we studied how two different host–parasite interaction processes, oral and hemocoelic exposure to bacteria, affect various life histories of the Glanville fritillary butterfly Melitaea cinxia. We either fed or injected adult butterflies with the bacterium Micrococcus luteus and observed for differences in immune defenses, reproductive life histories, and longevity, compared to control exposures. Our results indicate differences in how female butterflies adapt to the two exposure types. Orally infected females showed a reduction in clutch size and an earlier onset of reproduction, whereas a reduction in egg weight was observed for hemocoelically exposed females. Both exposure types also led to shorter intervals between clutches and a reduced life span. These results indicate a relationship between host–parasite interactions and changes in life‐history strategies. This relationship could cast restrictions on the ability to adapt to new environments and consequentially influence the population dynamics of a species in changing environmental conditions.

Fecundity of haddock (Melanogrammus aeglefinus) off southern Newfoundland

Reproductive life history parameters, such as size-specific fecundity, can contribute to our understanding of fish population dynamics. However, most of these parameters are difficult or time-consuming to obtain. Therefore, previously calculated parameters are often used in combination with more easily collected metrics of size. Significant temporal variation in fecundity is known to occur in many fish species, meaning that previous estimates may be unreliable when examining contemporary fish stocks. For southern Newfoundland haddock, the only published fecundity data were collected more than 50 years ago when this species supported a major fishery in the area. Here we present fecundity data collected during the 1960s immediately following stock collapse, as well as data from 2013 to 2014 (after 20 years of a fishing moratorium) and examine potential differences in egg production among the time periods. Contemporary estimates of haddock fecundity were more similar to estimates of fecundity immediately following stock collapse than estimates during the period of maximum exploitation. Additionally, comparison of haddock fecundity throughout the northwest Atlantic Ocean revealed contemporary estimates from southern Newfoundland to generally be higher than those from the Scotian Shelf for haddock at all lengths as well as greater than those from George’s Bank until about 60 cm in total length. The ability of various fish characteristics (length, weight, age, and condition) to serve as metrics of haddock fecundity were investigated and found that while length was the best predictor of fecundity, explanatory power was relatively low (maximum R2 = 0.37), and there was little to no effect of fish condition on fecundity. Inter-annual variability in fecundity estimates, coupled with the lack of a suitable proxy for fecundity for Newfoundland haddock suggests that ongoing monitoring is required to accurately estimate reproductive potential.

Fecundity and reproductive life history of anadromous rainbow smelt (Osmerus mordax) in coastal waters of Massachusetts

Fecundity and reproductive life history of anadromous rainbow smelt (Osmerus mordax) in coastal waters of Massachusetts

Reproductive biology of Grey-breasted Wood-Wren (Henicorhina leucophrys): A comparative study of tropical and temperate wrens

ABSTRACT We provide a detailed breeding biology account for the Grey-breasted Wood-Wren (Henicorhina leucophrys) and a comparison of the reproductive life history of tropical and temperate wrens us...

Reproductive differences among species, and between individuals and cohorts, in the leech genus Helobdella (Lophotrochozoa; Annelida; Clitellata; Hirudinida; Glossiphoniidae), with implications for reproductive resource allocation in hermaphrodites.

Leeches and oligochaetes comprise a monophyletic group of annelids, the Clitellata, whose reproduction is characterized by simultaneous hermaphroditism. While most clitellate species reproduce by cross-fertilization, self-fertilization has been described within the speciose genus Helobdella. Here we document the reproductive life histories and reproductive capacities for three other Helobdella species. Under laboratory conditions, both H. robusta and H. octatestisaca exhibit uniparental reproduction, apparently reflecting self-fertility, and suggesting that this trait is ancestral for the genus. However, the third species, H. austinensis, seems incapable of reproduction by self-fertilization, so we inferred its reproductive life history by analyzing reproduction in breeding cohorts. Comparing the reproductive parameters for H. robusta reproducing in isolation and in cohorts revealed that reproduction in cohorts is dramatically delayed with respect to that of isolated individuals, and that cohorts of leeches coordinate their cocoon deposition in a manner that is not predicted from the reproductive parameters of individuals reproducing in isolation. Finally, our comparisons of reproductive capacity for individuals versus cohorts for H. robusta, and between different sizes of cohorts for H. austinensis, reveal differences in resource allocation between male and female reproductive roles that are consistent with evolutionary theory.

Reproduction and embryonic development of the red stingray Hemitrygon akajei from Ariake Bay, Japan

The reproductive system of the red stingray Hemitrygon akajei was described from 1,418 specimens, 682 males and 736 females, sampled year-round (2003–2014) from Ariake Bay to provide reproductive life history information for conservation and management of the species. Females reach sexual maturity at a larger size than males with the size at 50% sexual maturity 522.2 mm disc width (DW) and 321.5 mm DW, respectively. Male stingrays had semen in the seminal vesicles year-round. Dental sexual dimorphism was aseasonal. The mating period is protracted, spanning 7 consecutive months October–April but ovulation occurred during May. This suggests female sperm storage, which has not been described for dasyatid stingrays. Females have a single functional ovary and uterus (left) and reproduce via aplacental viviparity with lipid histotrophy. Gestation required 3 months with parturition during late July and early August. Uterine eggs without macroscopic embryos were observed during the first half of gestation suggesting a short period of arrested development or diapause. Developmental cohorts based on morphological features were described for embryos and can be used to characterize embryo growth and development for other stingray species. Observations of foetal mortality (1.25%) and morphologically abnormal embryos (0.72%) were uncommon. Pregnancy rate was 90% and reproduction was annual and synchronous. Hemitrygon akajei fecundity ranged from 7 to 25 and increased with female size. Although H. akajei is a medium-sized dasyatid ray, it has the highest fecundity reported for any batoid species. Elasmobranchs life histories usually are associated with a low degree of productivity that results in rapid population decline with increased fishing pressure. Producing high numbers of small young is a successful reproductive strategy for H. akajei that may be partly responsible for their resilience to fishing pressure and continued abundance in Ariake Bay. This study is the first to describe reproduction of H. akajei, an economically important top predator inhabiting coastal ecosystems throughout Asia.

Male mating and female postmating performances in cotton mealybug (Hemiptera: Pseudococcidae): effects of female density.

For insects, female density is closely related to reproductive output. However, little is known about the effects of female density on male mating and female postmating performances. Here, we explored the effects of female density in cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive, rapidly spreading pest in Asia damaging multiple crops and horticultural plants. Using USB digital microscopes, we investigated the frequency, duration, and intervals of mating for males that were individually supplied with 1, 5, 10, and 15 females. We also evaluated the reproduction of mated females and the sex ratio of their offspring. As the female density increased, males mated with more females while substantially shortening mating intervals. Mating occurred actively at the densities of 10 and 15 females, where males mated four times on average, and some mated 6–9 times. However, mating duration and the observed reproductive parameters of females (preoviposition period, overall period from formation of ovisacs to female death, fecundity, and offspring sex ratio) did not differ significantly with female density. A weak trade-off existed between males’ mating frequency and longevity, but there was no relationship between females’ fecundity and longevity. In conclusion, despite their short lifespan, P. solenopsis males have a high mating capacity, and their mating frequency and intervals can be significantly affected by female density. In contrast, female density has little influence on females’ postmating performance. Our findings indicate the significance of the reproductive biology and life history strategies for rapid establishment and population development of mealybugs in newly invaded regions.

Reframing HIV Stigma and Fear

HIV stigma and fears surrounding the disease pose a challenge for public health interventions, particularly those that target pregnant women. In order to reduce stigma and improve the lives of vulnerable populations, researchers have recognized a need to integrate different types of support at various levels. To better inform HIV interventions, the current study draws on social-ecological and evolutionary theories of reproduction to predict stigma and fear of contracting HIV among pregnant women in South India. The aims of this study were twofold: compare the social-ecological model to a modified maternal-fetal protection model and test a combined model that included strong predictors from each model. The study took place in 2008-2011 in Mysore District, Karnataka, India. Using data from a cross-sectional survey and biological indicators of health, we statistically modeled social-ecological variables representing individual, interpersonal, and community/institutional levels. Participants were 645 pregnant women. The social-ecological and combined models were the best-fitting models for HIV-related stigma, and the combined model was the best fit for HIV-related fear. Our findings suggest that combining reproductive life history factors along with individual, interpersonal, and community/institutional factors are significant indicators of HIV-related stigma and fear. Results of this study support a multifaceted approach to intervention development for HIV-related stigma and fear. The combined model in this study can be used as a predictive model for future research focused on HIV stigma and fear, with the intent that dual consideration of social-ecological and evolutionary theories will improve public health communication efforts.

Predatory marine bivalves: A review.

Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typically of meiobenthic crustaceans: copepods, cumaceans and ostracods. Propeamusiid scallops are one such group of predators. The largest numbers of predators, however, belong to the bivalve subclass Anomalodesmata and constitute, as currently recognised, some 500 species belonging principally to the Verticordioidea (120), Poromyoidea (75) and Cuspidarioidea (304) with four, two and four constituent families, respectively. A further family, the Parilimyidae, is considered to be derived from the Pholadomyoidea-the anomalodesmatan ancestor. These, generally small (<60mm shell length), nacreous and thin-shelled predators share many anatomical features that formerly allowed them to be collectively classified as the Septibranchia. Although this name is now rarely used, it refers to their possession of a ctenidially-derived septum in the mantle cavity and functioning in prey capture. Generally, there is a trend, possibly evolutionary, from a typical bivalve ctenidium (Parilimyidae and some Verticordioidea) to a complete septum (other Verticordioidea, Poromyoidea and Cuspidarioidea). In addition, the inhalant siphon, foot, labial palps, mouth and its lips play a role in prey capture, and ingestion. Similarly, the stomach is modified to digest such, typically chitinous, ingested prey. Most septibranchs are either consecutive or simultaneous hermaphrodites with self-fertilisation possibly usual and with some evidence in a few of larval brooding. Notwithstanding, the deep sea septibranch species are poorly studied with virtually nothing being known about their wider distributions, ecology, detailed reproductive strategies and life history traits.

Reproductive life history of snakes in temperate regions: what are the differences between oviparous and viviparous species?

Abstract Studying life history (LH) allows a broader understanding of organisms and populations’ responses to their environments. Snakes display an immense diversity in terms of reproductive traits, which is reflected in LH traits. The aim of this study is to compare reproductive biology and morphological variables in viviparous and oviparous snakes of a temperate South American community. We studied nearly 1000 specimens of eight oviparous and seven viviparous species pertaining to the four taxonomic families that inhabit the Paraná basin floodplain. Dimorphic variables did not show a different tendency between oviparous and viviparous species. Our results showed that the reproductive mode determined some reproductive traits of a snake’s LH, such as reproductive frequency and reproductive potential. Oviparous snakes reproduce annually, while viviparous snakes reproduce biannually or multi-annually. All species showed seasonal reproductive cycles and no correlation between clutch size (fecundity) and maternal body size. The reproductive strategy of both oviparous and viviparous species of the Paraná River floodplain was to adjust their reproductive cycles to both hydrological cycle of the river and temperature regime. The reproductive traits under study are suggested to have been influenced by environmental factors as well as by genetic characteristics. The studied assemblage is the result of an admixture of evolutionarily distinct clades, each contributing a set of species with different reproductive traits. Although we do not ignore this fact, we emphasize the importance of studying reproductive LH as raw material for an integrative analysis.

Challenging Dogma Concerning Biogeographic Patterns of Antarctica and the Southern Ocean

Antarctica is enormous, cold, remote, and particularly sensitive to climate change. Most biological research below 60°S has focused on the isolated nature of the biota and how organisms have adapted to the cold and ice. However, biogeographic patterns in Antarctica and the Southern Ocean, and the processes explaining how those patterns came about, still await adequate explanation. Both terrestrial and marine organisms have been influenced by climatic change (e.g., glaciation), physical phenomena (e.g., oceanic currents), and/or potential barriers to gene flow (e.g., steep thermal gradients). Whereas the Antarctic region contains diverse and complex marine communities, terrestrial systems tend to be comparatively simple with limited diversity. Here, we challenge the current dogma used to explain the diversity and biogeographic patterns present in the Antarctic. We assert that relatively modern processes within the last few million years, rather than geo-logical events that occurred in the Eocene and Miocene, account for present patterns of biodiversity in the region. Additionally, reproductive life history stages appear to have little influence in structuring genetic patterns in the Antarctic, as currents and glacial patterns are noted to be more important drivers of organismal patterns of distribution. Finally, we highlight the need for additional sampling, high-throughput genomic approaches, and broad, multinational cooperation for addressing outstanding questions of Antarctic biogeography and biodiversity.

Population viability analyses for threeMacrhybopsisspp. of the Lower Missouri River

Recent declines in three species of chubs that inhabit the lower Missouri River (shoal chub M. hyostoma, sicklefin chub M. meeki and sturgeon chub M. gelida) have become a concern in the management of their own populations and the endangered pallid sturgeon (Scaphirhynchus albus) that feeds on them. These chub populations encounter threats from fish predation and habitat loss. With the recent advancements in the understanding of the reproductive life history of these species, their declines have prompted development of population models and population viability analyses. For each species, we developed an age-structured population matrix model with hierarchical stochasticity, which partitions parameter total variance into sampling and temporal components. Using these models, we found population growth rate of all three chub species decreased when stochasticity was added to the model. While examining sensitivity, we found individual fish growth, as measured by length-at-age, to impact population growth rate and depending on the species, could be up to four times more influential than overall survival, the next most sensitive parameter. Current survival rates have large temporal variance; more research into accuracy and factors that influence survival rates is needed.

The first draft genome of Lophophorus: A step forward for Phasianidae genomic diversity and conservation

The monal genus (Lophophorus) is a branch of Phasianidae and its species inhabit the high-altitude mountains of the Qinghai-Tibet Plateau. The Chinese monal, L. lhuysii, is a threatened endemic bird of China that possesses high-altitude adaptability, diversity of plumage color and potentially low reproductive life history. This is the first study to describe the monal genome using next generation sequencing technology. The Chinese monal genome size is 1.01 Gb, with 16,940 protein-coding genes. Gene annotation yielded 100.93 Mb (9.97%) repeat elements, 785 ncRNA, 5,465,549 bp (0.54%) SSR and 15,550 (92%) genes in public databases. Compared to other birds and mammals, the genome evolution analysis showed numerous expanded gene families and positive selected genes involved in high-altitude adaptation, especially related to the adaptation of low temperature and hypoxia. Consequently, this gene data can be used to investigate the molecular evolution of high-altitude adaptation in future bird research. Our first published genome of the genus Lophophorus will be integral for the study of monal population genetic diversity and conservation, genomic evolution and Galliformes species differentiation in the Qinghai-Tibetan Plateau.

Reproductive differences between three species of Brachyrhaphis livebearing fishes in Panamá

Both theory and the published literature support the importance of demographic selection for differences in life history traits between populations as well as between related species. Much attention in this area has been paid to species in the livebearing fish family Poeciliidae. I studied populations of three species of poeciliid fishes of the genus Brachyrhaphis (episcopi, roswithae, terrabensis) found from low to high elevation in western and central Panamá for reproductive life history phenotypes. To determine how reproductive life history phenotypic characters subject to both selection and environmental influence may vary between these species, field collections were made at the end of the wet and dry seasons over several years. Work with other poeciliid species suggested that these three stream species, found in different environments largely defined along an elevational gradient, may have evolved different responses in their reproductive timing and effort in response to differences in abiotic and biotic environmental factors. Differences were found between female wet and dry season reproductive output in all three species. Brachyrhaphis episcopi and B. roswithae showed similar responses to seasonal changes, with larger reproductive allotment (RA) and brood size but smaller embryo size in the wet season and a higher percentage of gravid females found in the wet season compared to the dry, 86% to 49% for B. episcopi and 71% to 45% for B. roswithae. Female B. terrabensis showed different responses to seasonal changes. RA, brood size and embryo size were all larger in the wet season than in the dry season. The percentage of gravid females among those of reproductive size was 37% in the wet season compared to 10% in the dry season. Patterns of male size varied between the three species, with more muted seasonal differences than was found with females of all three species. Brachyrhaphis terrabensis males showed a much wider size range, possibly indicative of two male reproductive strategies in the species. There is a gradient in several measures from lowland to highland species such as highland reproduction apparently stopping entirely in the dry season.

Sea-to-sea survival of late-run adult steelhead (Oncorhynchus mykiss) from the Columbia and Snake rivers

We used biotelemetry and genetic stock identification to assess sea-to-sea survival and run composition of 1212 late-migrating adult steelhead (anadromous Oncorhynchus mykiss) through the Columbia River and Snake River migratory corridors. The late run was predominated by steelhead from Idaho’s Clearwater and Salmon rivers that must pass eight large hydroelectric dams during both prespawn and postspawn migrations. In 2 years (2013 and 2014), prespawn survival to Snake River tributaries (&gt;500 km) was 0.48–0.67 for the most abundant populations and was higher for females and 1-sea fish (i.e., fish that spend one winter at sea). Annual survival from Snake River tributary entry to postspawn kelt status was 0.14–0.17, with higher survival for females and those without hatchery fin clips. Kelt outmigration survival was 0.31–0.39 past four Snake River dams and 0.13–0.20 past all eight dams and was highest for smaller kelts. Full-cycle adult freshwater survival (sea-to-sea) including 16 dam passage events was 0.01–0.02. Younger steelhead and those without fin clips survived at the highest rates. This study uniquely partitioned mortality across prespawn, reproductive, and kelt life history stages and informs management strategies for this conservation-priority metapopulation.

Phylogenetics of Datureae (Solanaceae), including description of the new genus Trompettia and re–circumscription of the tribe

AbstractDatureae is a tribe in the Solanaceae known for its charismatic large–flowered species (jimsonweeds and angel trumpets). The monophyly of the tribe is well established, but the recent finding that a species previously described in Iochroma (also Solanaceae) belongs in Datureae calls for a reassessment of the tribe's circumscription. Here we estimated the phylogeny of Datureae, including all of its 18 species, using three nuclear regions, and incorporated fossil information to estimate divergence times. Based on this phylogeny, we reconstructed the evolution of key aspects of reproductive morphology and life history to identify diagnostic features. Our molecular phylogenetic analyses suggest that the diversification of Datureae began roughly ca. 35 Ma, around the beginning of the Andean uplift. Within the tribe, Datura and Brugmansia are monophyletic sister taxa and the misplaced species of Iochroma is sister to the remaining species. Based on our morphological analysis, we describe the latter as a new monotypic genus Trompettia. Ancestral state reconstructions identify diagnostic features for each of the three genera and show a large suite of changes along the Datura branch, including the evolution of erect flowers, capsular fruit, and annual life history. Using these features, we formally re–circumscribe Datureae to include all genera and their species and provide a taxonomic key for the tribe.

Reproduction of two loricariid species in a confined river and implications for environmental impacts of dams

ABSTRACT Fish reproduction in floodplain rivers is often linked to flow regime and with the inundation of floodplain habitats. However, in confined rivers, where floodplains are absent, the relation between reproduction and flow can in comparison be expected to be distinct. In this study, we describe the reproductive life-history of Hemiancistrus fuliginosus and Hypostomus isbrueckeri in a confined river and discuss its differences relative to floodplain loricariids and also the implications for effects of dam construction and flow regulation. We found the reproductive peak of both species occurred during lowering waters, just after maximum river flow, in contrast to floodplain species that tend to spawn during rising waters. The studied species presented attributes of equilibrium life-history strategy, which are related to predictable river flow variation. Because both species spawned during low river flow, which is historically predictable in summer, we suggest that their reproduction may be severely disrupted, depending on how flow regime is affected by dam operation. These results have implications for assessing and mitigating the impacts of river damming on fish populations in confined rivers, and we point to ecologically driven flow management and conservation of free-flowing rivers as mitigation and conservation alternatives.