High Female Fecundity Research Articles

Annual reproductive cycle of Chinese sleeper Perccottus glenii, Dybowski, 1877 (Teleostei: Gobiiformes: Odontobutidae) an invasive fish inhabiting Central Europe

Chinese sleeper is an invasive species from South Asia inhabiting Eastern and Central Europe. So far, no detailed analysis of the reproductive cycle of Chinese sleepers has been conducted. The aim of the study was to describe the reproductive cycle of Chinese sleepers in the Wilanówka River, Vistula tributary (Poland, Central Europe). Fish morphometric data, age, gonadal maturity, and absolute and relative fecundity of females were analysed. A standard paraffin technique and six-stage scales were used to assess the gonad development and maturation in both sexes. The age of the studied fish ranged from 0+ to 6+.The female-to-male ratio was 1:1. Females and males mature at age 1+.The smallest female and male reaching maturity were 3.8 and 3.7 cm long, respectively. An extended spawning season from the beginning of April to mid-September was determined based on gonadal maturity analysis. The mean absolute fecundity was 2,971 (180–19,656) oocytes. The male reproductive system comprises paired testis (spermatogenic region, blackish color) and paired testicular gland (secretory region, whitish color). In both regions, seasonal changes were observed. Male gonads during winter had completed spermatogenesis, and the lobules were filled with spermatozoa. Very fast spermatogenesis and overlapping of reproductive cycles have been observed in Chinese sleeper males. Almost all year round testis contains spermatozoa. In the new habitat examined, this species was characterized by earlier maturation and longer reproduction season, compared to the native habitat and other native species of the examined area. Moreover, high female fecundity, multiple spawning, and lower investment in the development of gonads in males allow maintaining vitality and protecting the nest, contribute to the species competitiveness and successful colonization of new areas.

Effects of polyploidization and their evolutionary implications are revealed by heritable polyploidy in the haplodiploid wasp Nasonia vitripennis.

Recurrent polyploidization occurred in the evolutionary history of most Eukaryota. However, how neopolyploid detriment (sterility, gigantism, gene dosage imbalances) has been overcome and even been bridged to evolutionary advantage (gene network diversification, mass radiation, range expansion) is largely unknown, particularly for animals. We used the parasitoid wasp Nasonia vitripennis, a rare insect system with heritable polyploidy, to begin addressing this knowledge gap. In Hymenoptera the sexes have different ploidies (haploid males, diploid females) and neopolyploids (diploid males, triploid females) occur for various species. Although such polyploids are usually sterile, those of N. vitripennis are reproductively capable and can even establish stable polyploid lines. To assess the effects of polyploidization, we compared a long-established polyploid line, the Whiting polyploid line (WPL) and a newly generated transformer knockdown line (tKDL) for fitness traits, absolute gene expression, and cell size and number. WPL polyploids have high male fitness and low female fecundity, while tKDL polyploids have poor male mate competition ability and high fertility. WPL has larger cells and cell number reduction, but the tKDL does not differ in this respect. Expression analyses of two housekeeping genes indicated that gene dosage is linked to sex irrespective of ploidy. Our study suggests that polyploid phenotypic variation may explain why some polyploid lineages thrive and others die out; a commonly proposed but difficult-to-test hypothesis. This documentation of diploid males (tKDL) with impaired competitive mating ability; triploid females with high fitness variation; and hymenopteran sexual dosage compensation (despite the lack of sex chromosomes) all challenges general assumptions on hymenopteran biology. We conclude that polyploidization is dependent on the duplicated genome characteristics and that genomes of different lines are unequally suited to survive diploidization. These results demonstrate the utility of N. vitripennis for delineating mechanisms of animal polyploid evolution, analogous to more advanced polyploid plant models.

A bioengineer in the city —the Darwinian fitness of fiddler crabs inhabiting plastic pollution hotspots

Mangrove forests have been widely recognized as effective traps for plastic litter, which tends to accumulate in landward areas. In mangrove forests surrounding cities, plastic litter may increase up to two orders of magnitude. Therefore, crabs that process sediments for feeding and burrowing in landward areas are likely to be impacted by marine litter and other disturbances. As counterintuitive as it may seem, crabs are developing dense populations in urban mangroves from different countries, suggesting parallel adaptive processes related to the availability of anthropogenic food sources. To better understand this, we compared the loads of macroplastics within and between mangroves along an urban-rural-wild forest gradient in the Urabá Gulf, Colombian Caribbean. We then assessed if there is directional selection on crab phenotypes likely associated with human-provided food sources in urbanized forests. Finally, we evaluated the hypothesis that crabs in urban areas exhibit increased fecundity and survival - components of the Darwinian fitness - of female crabs in urban (versus wild) populations through three spawning seasons. Crabs in urban areas were larger (males), showed a healthier body condition (both sexes), and females had a larger reproductive lifespan than crabs in wild areas, strongly suggesting responses to the availability of predictable anthropogenic food subsidies in urban forests. Despite this, higher female fecundity was observed only during a spawning season. However, this short-lived increase in fecundity was offset by reduced survival among female crabs in urban forests, likely due to increased predation by birds, which appear to be emerging as dominant consumers in urban mangroves.

Multigenerational experimental simulation of climate change on an economically important insect pest.

Long‐term multigenerational experimental simulations of climate change on insect pests of economically and socially important crops are crucial to anticipate challenges for feeding humanity in the not‐so‐far future. Mexican bean weevil Zabrotes subfasciatus, is a worldwide pest that attacks the common bean Phaseolus vulgaris seeds, in crops and storage. We designed a long term (i.e., over 10 generations), experimental simulation of climate change by increasing temperature and CO2 air concentration in controlled conditions according to model predictions for 2100. Higher temperature and CO2 concentrations favored pest's egg‐to‐adult development survival, even at high female fecundity. It also induced a reduction of fat storage and increase of protein content but did not alter body size. After 10 generations of simulation, genetic adaptation was detected for total lipid content only, however, other traits showed signs of such process. Future experimental designs and methods similar to ours, are key for studying long‐term effects of climate change through multigenerational experimental designs.

A comparative study of survival, recruitment and population growth in two translocated populations of the threatened greater bilby (Macrotis lagotis)

Abstract Context Translocations have been widely used to re-establish populations of threatened Australian mammalian species. However, they are limited by the availability of sites where key threats can be effectively minimised or eliminated. Outside of ‘safe havens’, threats such as exotic predators, introduced herbivores and habitat degradation are often unable to be completely eliminated. Understanding how different threats affect Australian mammal populations can assist in prioritising threat-management actions outside of safe havens. AimsWe sought to determine whether translocations of the greater bilby to two sites in the temperate zone of South Australia could be successful when human-induced threats, such as prior habitat clearance, historic grazing, the presence of feral cats and European rabbits, could not be completely eliminated. Methods Greater bilbies were regularly cage trapped at two translocation sites and a capture–mark–recapture study was used to determine survival, recruitment and population growth at both sites. Key results Our study showed that bilbies were successfully translocated to an offshore island with a previous history of grazing and habitat clearance, but which was free of exotic predators. At a second site, a mainland exclosure with feral cats and European rabbits present, the bilby population declined over time. Adult bilbies had similar survival rates in both populations; however, the mainland bilby population had low recruitment rates and low numbers of subadults despite high adult female fecundity. ConclusionsThe results indicated that past grazing and habitat clearance did not prevent the bilby population on the offshore island establishing and reaching a high population density. In the mainland exclosure, the low recruitment is probably due to feral cats predating on subadult bilbies following pouch emergence. Implications The results demonstrated that the bilby, an ecologically flexible Australian marsupial, can be successfully translocated to sites with a history of habitat degradation if exotic predators are absent. At the mainland exclosure site, threat mitigation for bilbies should focus on control or eradication of the feral cats. The control of European rabbits without control of feral cats could lead to prey-switching by feral cats, further increasing predation pressure on the small bilby population.

Enhanced fecundity and parasite release in the first amphipod invader on the Iberian Peninsula

Crangonyx pseudogracilis is a North American amphipod recently detected in Portugal and it is the first invasive freshwater amphipod detected in the Iberian Peninsula. The aim of this study was to assess the population structure and its invasion range in this area, but also to assess its pathogen profile and its origin through genetic analyses. Crangonyx pseudogracilis was only found in the lowlands of the Tagus River basin, a restricted area of the three sampled river basins (Tagus, Guadiana and Sado). Only one mitochondrial DNA (mtDNA) gene cytochrome oxidase subunit 1 (COI) haplotype, identical to the one already detected in Europe and in the Lake Charles, USA, was identified. The obtained data show that the studied populations are well-established, have a high female fecundity and a reproduction period extended throughout the year. No parasites were detected in the 236 dissected specimens. The dissimilarity of parasites prevalence to other European invasive populations opens the possibility of a direct introduction from North America but it also does not exclude the possibility of a secondary introduction from another European country.

An integrative mating system assessment of a nonmodel, economically important Pacific rockfish (Sebastes melanops) reveals nonterritorial polygamy and conservation implications for a large species flock.

Characterizing the mating systems of long‐lived, economically important Pacific rockfishes comprising the viviparous Sebastes species flock is crucial for their conservation. However, direct assignment of mating success to sires is precluded by open, offshore populations and high female fecundity. We addressed this challenge by integrating paternity‐assigned mating success of females with the adult sex ratio (ASR) of the population, male evolutionary responses to receptive females, and reproductive life history traits—in the framework of sexual selection theory—to assess the mating system of Sebastes melanops. Microsatellite parentage analysis of 17 pregnant females, 1,256 of their progeny, and 106 adults from the population yielded one to four sires per brood, a mean of two sires, and a female mate frequency distribution with a truncated normal (random) pattern. The 11 multiple paternity broods all contained higher median allele richness than the six single paternity broods (Wilcoxon test: W = 0, p < .001), despite similar levels of average heterozygosity. By sampling sperm and alleles from different males, polyandrous females gain opportunities to enhance their sperm supply and to lower the cost of mating with genetically incompatible males through reproductive compensation. A mean of two mates per mated female with a variance of one, an ASR = 1.2 females per male, and the expected population mean of 2.4 mates for mated males (and the estimated 35 unavailable sires), fits polygamous male mate frequency distributions that distinguish polygynandry and polyandrogyny mating systems, that is, variations of polygamy, but not polyandry. Inference for polygamy is consistent with weak premating sexual selection on males, expected in mid‐water, schooling S. melanops, owing to polyandrous mating, moderately aggregated receptive females, an even ASR, and no territories and nests used for reproduction. Each of these characteristics facilitates more mating males and erodes conspicuous sexual dimorphism. Evaluation of male evolutionary responses of demersal congeners that express reproductively territorial behavior revealed they have more potential mechanisms for producing premating sexual selection, greater variation in reproductive success, and a reduced breeding effective population size of adults and annual effective size of a cohort, compared to S. melanops modeled with two mates per adult. Such divergence in behavior and mating system by territorial species may differentially lower their per capita birth rates, subsequent population growth, and slow their recovery from exploitation.

The concordance between greenhouse gas emissions, livestock production and profitability of extensive beef farming systems

Here we examine the concordance among emissions, production and gross margins of extensive beef farming systems by modelling a range of scenarios for herd management, animal genotype and pasture nutritive quality. We based our simulations on a case-study farm in central Queensland, Australia, and studied the influence of interventions designed for emissions mitigation, increasing productivity, or increasing gross margin. Interventions included replacing urea supplementation with nitrate, finishing cattle on the perennial forage leucaena (L), herd structure optimisation (HO), higher female fecundity (HF), and a leucaena finishing enterprise that had net farm emissions equal to the baseline (leucaena equal emissions; LEE). The HO intervention reduced the ratio of breeding cows relative to steers and unmated heifers, and lowered the ratio of costs to net cattle sales. Gross margin of the baseline, nitrate, L, LEE, HO and HF scenarios were AU$146 000, AU$91 000, AU$153 000, AU$170 000, AU$204 000 and AU$216 000, respectively. Enterprises with early joining of maiden heifers as well as HO and HF further increased gross margin (AU$323 000), while systems incorporating all compatible interventions (HO, HF, early joining, LEE) had a gross margin of AU$315 000. We showed that interventions that increase liveweight turnoff while maintaining net farm emissions resulted in higher gross margins than did interventions that maintained liveweight production and reduced net emissions. A key insight of this work was that the relationship between emissions intensity (emissions per unit liveweight production) or liveweight turnoff with gross margin were negative and positive, respectively, but only when combinations of (compatible) interventions were included in the dataset. For example, herd optimisation by reducing the number of breeding cows and increasing the number of sale animals increased gross margin by 40%, but this intervention had little effect on liveweight turnoff and emissions intensity. However, when herd optimisation was combined with other interventions that increased production, gross margins increased and emissions intensity declined. This is a fortuitous outcome, since it implies that imposing more interventions with the potential to profitably enhance liveweight turnoff allows a greater reduction in emissions intensity, but only when each intervention works synergistically with those already in place.

Body Size, Fecundity, and Sexual Size Dimorphism in the Neotropical Cricket Macroanaxipha macilenta (Saussure) (Orthoptera: Gryllidae)

Body size is directly or indirectly correlated with fitness. Body size, which conveys maximal fitness, often differs between sexes. Sexual size dimorphism (SSD) evolves because body size tends to be related to reproductive success through different pathways in males and females. In general, female insects are larger than males, suggesting that natural selection for high female fecundity could be stronger than sexual selection in males. I assessed the role of body size and fecundity in SSD in the Neotropical cricket Macroanaxipha macilenta (Saussure). This species shows a SSD bias toward males. Females did not present a correlation between number of eggs and body size. Nonetheless, there were fluctuations in the number of eggs carried by females during the sampling period, and the size of females that were collected carrying eggs was larger than that of females collected with no eggs. Since mating induces vitellogenesis in some cricket species, differences in female body size might suggest male mate choice. Sexual selection in the body size of males of M. macilenta may possibly be stronger than the selection of female fecundity. Even so, no mating behavior was observed during the field observations, including audible male calling or courtship songs, yet males may produce ultrasonic calls due to their size. If female body size in M. macilenta is not directly related to fecundity, the lack of a correlated response to selection on female body size could represent an alternate evolutionary pathway in the evolution of body size and SSD in insects.

Bagworm, Thyridopteryx ephemeraeformis Haworth (Insecta: Lepidoptera: Psychidae)

North American bagworm can feed on over 50 families of deciduous and evergreen trees and shrubs. Severe infestations can damage the aesthetics and health of host plants, especially juniper and arborvitae species. Many of the preferred host plants do not grow well below the USDA hardiness zone 8A, but due to its wide host range, high female fecundity, and method of dispersal, bagworm can still be problematic in the Florida landscape. This 5-page fact sheet was written by Brooke L. Moffis and Steven P. Arthurs and published by the UF Department of Entomology and Nematology, March 2013.&#x0D; http://edis.ifas.ufl.edu/in981

Strategic mating effort in a simultaneous hermaphrodite

Sexual selection theory for simultaneously hermaphroditic animals predicts an overall preference for inseminating partners that have a relatively higher female fecundity. Previous work on the link between male mating decisions and female fecundity has primarily focused on the effect of the partners’ body size using existing variation in this trait within a study population. On the assumption that the body size is positively correlated with female fecundity, sperm donors should preferentially inseminate relatively larger individuals to obtain a higher fitness gain through their male sex function. However, empirical evidence for such size-dependent mate choice in simultaneous hermaphrodites is equivocal, possibly because of confounding variables. We studied the mating behavior of the simultaneously hermaphroditic flatworm Macrostomum lignano and tested for a strategic mating effort in response to the feeding status of the partner. We experimentally manipulated the feeding status of potential mating partners in order to generate variation in female fecundity among them and tested whether this affected the copulation number and the number of sperm that the focal worm managed to store in the partner’s sperm storage organ. We found that the manipulation of the feeding status had a strong effect on the body size of the potential mating partners and that focal worms copulated more frequently with, and stored more sperm in well-fed partners compared to unfed partners. Our results suggest that M. lignano adjusts its mating effort in response to the feeding status of the mating partner.

Population demography of Northern muriquis (Brachyteles hypoxanthus) at the Estação Biológica de Caratinga/Reserva particular do Patrimônio Natural‐Felìciano Miguel Abdala, Minas Gerais, Brazil

The 957-ha forest at the Estação Biológica de Caratinga/Reserva Particular do Patrimônio Natural-Felìciano Miguel Abdala, in Minas Gerais, Brazil, supports one of the largest known populations of the critically endangered northern muriqui (Brachyteles hypoxanthus). We combine long-term data on one group that has been monitored since 1982 with new data obtained on the other three groups since 2002 and 2003 to describe the demographic structure of this population, evaluate its potential for future growth, and predict how dispersal and competitive regimes may change in response to current demographic conditions. As of January 2005, the 226 individuals in the population were divided into four mixed-sex groups with 37-77 members, and an all-male unit whose eight males maintained transient associations with two of the mixed-sex groups. Although 51.77% of the population was female, the sex ratio among adults and subadults was female-biased (0.75), while that among immatures was male-biased (1.47). Consistent with expectations from mean interbirth intervals, 64.18% of adult females gave birth in 2003 and 2004. However, by January 2005, only 52.31% of adult females were still carrying infants <24 months of age due to unusually high infant mortality. First-year survivorship among the 25 infants born in the population in 2003 was only 76%, considerably lower than previously documented in the longest-studied group. High female fecundity is indicative of a healthy population, but the current male bias in births will result in a decline in the population growth rate within two decades, and may increase levels of male reproductive competition and alter dispersal patterns.

LEARNING AND COLONIZATION OF NEW NICHES: A FIRST STEP TOWARD SPECIATION

Learning processes potentially play a role in speciation but are often ignored in speciation models. Learning may, for instance, play a role when a new niche is being colonized, because the learning of niche features may cause niche-specific assortative mating and a tendency to produce young in this niche. Several animal species learn about their environmental features that may be important in finding or attracting mates. We use a gene-culture coevolutionary model to look into the effect of such learning on the colonization of new niches and on the genetic divergence between groups using different niches, which are steps necessary in achieving speciation. We assume that density is regulated separately in each of the two niches and that the viability of an individual depends on its genotype as well as on which niche it exploits. Our results show that genetic adaptation to the new niche is enhanced by a high female fecundity and a low viability selection against heterozygotes. Furthermore, when initial colonization (without genetic adaptation) fails, genetic divergence is more difficult when the mating preference is stronger. In contrast, when colonization without genetic adaptation is successful, a stronger mating preference makes genetic divergence easier. An increase in the number of egg-laying mistakes by females can have a positive or negative effect on the success of genetic adaptation depending on other parameters. We show that genetic divergence can be prevented by a niche shift, which can occur only if viabilities in the two niches are asymmetrical.

LEARNING AND COLONIZATION OF NEW NICHES: A FIRST STEP TOWARD SPECIATION

Learning processes potentially play a role in speciation but are often ignored in speciation models. Learning may, for instance, play a role when a new niche is being colonized, because the learning of niche features may cause niche-specific assortative mating and a tendency to produce young in this niche. Several animal species learn about their environmental features that may be important in finding or attracting mates. We use a gene-culture coevolutionary model to look into the effect of such learning on the colonization of new niches and on the genetic divergence between groups using different niches, which are steps necessary in achieving speciation. We assume that density is regulated separately in each of the two niches and that the viability of an individual depends on its genotype as well as on which niche it exploits. Our results show that genetic adaptation to the new niche is enhanced by a high female fecundity and a low viability selection against heterozygotes. Furthermore, when initial colonization (without genetic adaptation) fails, genetic divergence is more difficult when the mating preference is stronger. In contrast, when colonization without genetic adaptation is successful, a stronger mating preference makes genetic divergence easier. An increase in the number of egg-laying mistakes by females can have a positive or negative effect on the success of genetic adaptation depending on other parameters. We show that genetic divergence can be prevented by a niche shift, which can occur only if viabilities in the two niches are asymmetrical.

Evidence for unconditional sperm transfer and sperm‐dependent parthenogenesis in a hermaphroditic flatworm (Girardia tigrina) with fissipary

AbstractSperm‐dependent parthenogens are expected to promote higher female fecundity at the expense of the production of excessive numbers of sperm. They are also expected to trade sperm strictly, in order to compensate for the loss of nutrients invested in sperm, that otherwise could be allocated to the female function. In this paper, we present evidence that in a natural population of the freshwater planarian Girardia (= Dugesia) tigrina, sperm‐dependent parthenogenesis is alternated with fissipary, a combination not reported before for freshwater flatworms. More specifically, we found that most individuals that engage in a copulation have no or only few testes and sperm available, despite the presence of a fully developed penis, indicating that male allocation is fairly low in this (dense) population. Female fecundity on the contrary is rather high, with isolated individuals producing up to six fertilized cocoons over a 3‐week period, releasing five young per cocoon on average. An analysis of the mating behaviour further shows that matings in this species are simple and direct with no distinct courtship behaviour. Copulations last for about 36 min and occur at a rate of at least one copulation a day. Bilateral sperm transfer is the rule, but a considerable number of copulations are unidirectional or without sperm transfer. Non‐reciprocal inseminations mainly result from the fact that one or both partners has no sperm stored prior to copulation, indicating that strict sperm trading plays no role in this population of G. tigrina.

Morphological and Biological Studies on Typhlodromus Talbii Athias-Henriot (Gamasida: Phytoseiidae)

The immature stages of the predaceous mite Typhlodromus talbii Athias-Henriot are described. The mite was reared on different prey species and pollen in the laboratory, and its developmental parameters calculated. Tydeus californicus (Banks) was found to be the most suitable and nourishing diet, giving a shorter life cycle and higher female fecundity (8.8 days and 33.4 eggs respectively), than the scale insect Coccus acuminatum (Gennadius) (10.0 days and 24.8 eggs respectively) at 25 °C. Other associates of Typ. talbii, the eriophyid Cesaberoptus kenyae Keifer, the tetranychid Oligonychus mangiferus (R. &amp; S.) as well as date palm and castor oil pollen, were unsuitable diet. When reared on moving stages of Tyd. californicus (Banks) at 70 ± 5 % RH, 16:8 (L:D) h photoperiod and temperatures of 15,20,25,28,30,32 and 35 °C, the total developmental time of Typ. talbii averaged 21.3, 12.4, 8.8, 7.6, 7.1, 5.8 and 11.6 days respectively. The intrinsic rate of natural increase (rm) and the net reproduction (Ro) reached maximum values of 0.299 individuals per female per day and 28.06 times respectively, at 32 °C.

High Fecundity and Low Fertility in Parthenogenetic Planarians

High Fecundity and Low Fertility in Parthenogenetic Planarians

Larval performance of two leafroller species on known and potential hosts

AbstractTwo univoltine leafroller species, Archips argyrospila Walker and Archips rosana L., were reared from eclosion to adulthood on known or potential host plants. Both species were able to complete development on eight of the ten plants tested, the exceptions being apricot and peach. Rates of development differed among hosts, and indicated a range of host suitability. Differences in female pupal weights were apparent following the different rearing treatments, but these did not correlate with subsequent female fecundity. When development was compared between the two leafroller species, A. rosana had higher survivorship, more rapid development and higher female fecundity than did A. argyrospila, regardless of host. These findings indicate that A. rosana may successfully exploit a wider host range than does A. argyrospila. Comparisons of survivorship and developmental rates among hosts for each species of leafroller suggest that both species may have the potential for host‐range expansion.

Recent situation of the Colorado beetle (Leptinotarsa decemlineata) in Poland

During the last 20 years there have been two outbreaks (1972 and 1976) of the Colorado beetle and one decline (1980). The new outbreak in 1983 was unusually massive as the population density of the pest was 2–3 times higher than in previous years. Almost 100% of potato crops and more than 50% of plants were attacked by the pest. This was due to low mortality of hibernating beetles during winter of 1982/83 and very favourable weather conditions in 1983 which resulted in an early emergence of hibernating beetles in the spring, intensive migration and high female fecundity. In 1983 insecticide treatments were applied to an area of 3.49 million ha as compared to 1.8 million ha treated in an average year. In 1984 there was a serious decline of the Colorado beetle population.