Lower Reproductive Success Research Articles

Juvenile rank acquisition is associated with fitness independent of adult rank.

Social rank is a significant determinant of fitness in a variety of species. The importance of social rank suggests that the process by which juveniles come to establish their position in the social hierarchy is a critical component of development. Here, we use the highly predictable process of rank acquisition in spotted hyenas to study the consequences of variation in rank acquisition in early life. In spotted hyenas, rank is 'inherited' through a learning process called 'maternal rank inheritance.' This pattern is very consistent: approximately 80% of juveniles acquire the exact rank expected under the rules of maternal rank inheritance. The predictable nature of rank acquisition in these societies allows the process of rank acquisition to be studied independently from the ultimate rank that each juvenile attains. In this study, we use Elo-deviance scores, a novel application of the Elo-rating method, to calculate each juvenile's deviation from the expected pattern of maternal rank inheritance during development. Despite variability in rank acquisition among juveniles, most of these juveniles come to attain the exact rank expected of them according to the rules of maternal rank inheritance. Nevertheless, we find that transient variation in rank acquisition in early life is associated with long-term fitness consequences for these individuals: juveniles 'underperforming' their expected ranks show reduced survival and lower lifetime reproductive success than better-performing peers, and this relationship is independent of both maternal rank and rank achieved in adulthood. We also find that multiple sources of early life adversity have cumulative, but not compounding, effects on fitness. Future work is needed to determine if variation in rank acquisition directly affects fitness, or if some other variable, such as maternal investment or juvenile condition, causes variation in both of these outcomes.

More social female yellow-bellied marmots, Marmota flaviventer, have enhanced summer survival

For many animals, group living mitigates predation risk and ensures survival. However, in yellow-bellied marmots, increased sociality is associated with lower female reproductive success, decreased female longevity and increased overwinter mortality for both males and females, which raises questions about the adaptive value of sociality in this facultatively social mammal. Here we used social network analysis to examine the relationship between sociality and summer survival, which is almost always attributable to predation. Yearling females had enhanced survival when they had stronger social relationships and were more central in their network. Adult female survival was not associated with social network traits, but females were more likely to survive the summer if they lived in larger groups. Survival of yearling and adult males was not associated with either social network trait variation or variation in group size. These findings identify a potential benefit for marmot sociality and an explanation for marmot colony social structuring.

Prosociality and a Sociosexual Hypothesis for the Evolution of Same-Sex Attraction in Humans.

Human same-sex sexual attraction (SSSA) has long been considered to be an evolutionary puzzle. The trait is clearly biological: it is widespread and has a strong additive genetic basis, but how SSSA has evolved remains a subject of debate. Of itself, homosexual sexual behavior will not yield offspring, and consequently individuals expressing strong SSSA that are mostly or exclusively homosexual are presumed to have lower fitness and reproductive success. How then did the trait evolve, and how is it maintained in populations? Here we develop a novel argument for the evolution of SSSA that focuses on the likely adaptive social consequences of SSSA. We argue that same sex sexual attraction evolved as just one of a suite of traits responding to strong selection for ease of social integration or prosocial behavior. A strong driver of recent human behavioral evolution has been selection for reduced reactive aggression, increased social affiliation, social communication, and ease of social integration. In many prosocial mammals sex has adopted new social functions in contexts of social bonding, social reinforcement, appeasement, and play. We argue that for humans the social functions and benefits of sex apply to same-sex sexual behavior as well as heterosexual behavior. As a consequence we propose a degree of SSSA, was selected for in recent human evolution for its non-conceptive social benefits. We discuss how this hypothesis provides a better explanation for human sexual attractions and behavior than theories that invoke sexual inversion or single-locus genetic models.

Consequences of hatching deviations for breeding success: a long-term study on blue tits Cyanistes caeruleus

The causes and consequences of variation in the incubation regimes of oviparous animals remain unclear, despite having important fitness consequences. Avian incubation regimes can be shortened by parents initiating incubation prior to clutch completion or prolonged when there are gaps in the laying sequence. Here, we begin by quantifying variation in the incubation regimes of three populations of blue tits Cyanistes caeruleus from the UK and Poland before examining the consequences of such variation for their hatching and fledging success. We then investigate the mechanism causing such variation by exploring the impact of local weather conditions on incubation regimes. The difference between the expected and actual hatching dates of clutches was termed the “hatching deviation” and this showed considerable variation. Hatching deviation was negatively related to local temperature and clutch size. Hatching deviation affected hatching success and hatching deviation, temperature, wind speed and clutch size affected fledging success. Deviating from the expected laying and incubation regime caused lowered reproductive success. The most successful birds were those that were able to lay one egg per day and begin incubation upon clutch completion.

Elevated temperature, but not acidification, reduces fertilization success in the small giant clam, Tridacna maxima

Elevated temperature and decreased ocean pH (ocean acidification) are associated with anthropogenic climate change and can adversely affect fertilization and development in marine invertebrates. However, the potential synergistic impact of these stressors on fertilization success remains unresolved for many ecologically and economically important species including giant clams of the genus Tridacna. Individual and interactive effects of warming and acidification on fertilization (successful first cleavage) were investigated in the small giant clam, Tridacna maxima. Experiments were performed on gametes of T. maxima (collected in October 2015 from the island of Moorea, French Polynesia; 17.54° S, 149.83° W) fertilized under ambient conditions (27 °C, pH 8.1) and under conditions congruent with temperature and pH projections for the coming century (31 °C, pH 7.6). Fertilization success was low, but within previously reported levels, under ambient conditions (47.7 ± 3.4%) and was significantly reduced at elevated temperature per se and in combination with lowered pH (18.5 ± 4.4% and 21.2 ± 4.6%, respectively). However, acidification alone had no effect on fertilization success in T. maxima (48.2 ± 3.1%). These results indicate that although fertilization in T. maxima is resilient to lowered pH, it is strongly inhibited by elevated temperature. Populations of T. maxima may, therefore, be at risk of low reproductive success over the coming century as a result of rising ocean temperature.

Lifetime reproductive success of northern elephant seals (Mirounga angustirostris)

Lifetime reproductive success of individuals in a natural population provides an estimate of Darwinian fitness. We calculated lifetime reproductive success in a colony of female northern elephant seals (Mirounga angustirostris (Gill, 1866)) by monitoring annual breeding throughout life of 7735 female weanlings marked individually at Año Nuevo, California, USA, from 1963 to 2005. Great variation in lifetime reproductive success was evident in three aspects of life history: (1) 75% of the females died before reaching breeding age and produced no pups; (2) nearly half of the survivors bred for only a few years before dying, and young females had low weaning success; (3) less than 1% of the females in the sample were exceptionally successful producing up to 20 pups in life. Many females that bred early, while still growing, had decreased lifespan, low weaning success, and lower lifetime reproductive success than females that postponed first breeding. Exceptional reproductive success was associated with giving birth annually, living long (up to age 23), and weaning large pups that were more likely to survive and breed. We conclude that there is strong selection for increased lifespan and multiparous supermoms that contribute significantly to pup production in the next generation.

A literature review of the pollination strategies and breeding systems in Oncidiinae orchids

ABSTRACT Oncidiinae is an exclusively Neotropical orchid subtribe with about 1600 described species and an impressive array of vegetative and floral morphological adaptations. We present the results of a literature survey on the pollination strategies and breeding systems of this orchid subtribe. The flowers are pollinated by a wide range of insects (mostly bees) and, sometimes, hummingbirds. Several genera reward their pollinators with floral resources such as oils, nectar or perfumes. Whereas pollination by oil-gathering bees likely evolved several times within Oncidiinae, exclusive pollination by perfume-gathering male Euglossine bees is likely restricted to a set of closely-related genera. Pollination by food or sexual deception is also present within the subtribe. Up to date, the pollen-vectors of the 92 species of Oncidiinae studied so far are as follows: 84.7 % are pollinated by bees, 6.5 % by wasps, 4.3 % by hummingbirds, 3.2 % by butterflies and 3.2 % by flies. Oncidiinae orchids are preferentially self-incompatible (69.4 % of the species studied so far), some may also present protandry as a mechanism to promote cross-pollination. Fruiting success is generally low. The rate of visitation with subsequent pollination is low, in general, which contributes to the low reproductive success of this plant group.

Hybrids as potential mediators spreading non‐native genes: Comparison of survival, growth, and movement among native, introduced and their hybrid salmonids

AbstractComparing multiple fitness components and potential movement of wild hybrids with their parental species is necessary to fully understand the consequences of human‐mediated introgression, but studies tracking both parental species and their hybrids at the individual‐level are limited. Here, we compared growth, survival and movement of sympatric introduced brook trout (BT: Salvelinus fontinalis) and native white‐spotted charr (WSC: S. leucomaenis) with their hybrids (HYB) in a northern Japanese stream, using mark‐recapture data (1,087 marked individuals) collected over 4 years (2013–2016). The mark‐recapture data with a single cohort showed that HYB had a comparable or even higher growth rate to BT and WSC. In addition, there is no evidence that hybrid survival was lower than both parental species throughout the entire study period. Furthermore, HYB showed high mobility equivalent to WSC, while BT showed the lowest mobility. Although our previous studies have documented the reduction of BT distribution and lowered reproductive success of HYB, non‐native genes can pose a threat to native WSC via relatively high survival, growth and/or mobility of HYB.

Does prey availability affect the reproductive performance of Barn Swallows (Hirundo rustica) breeding in Ontario, Canada?

Animal populations are often limited by food availability, particularly during the breeding season. In birds, food limitation can impact several components of the reproductive cycle, including the timing of reproduction and reproductive output. Barn Swallows (Hirundo rustica Linnaeus, 1758) have experienced a population decline over the past 40 years in North America that is thought to be related to changes in prey availability. We monitored Barn Swallow reproductive behaviour and prey availability throughout two breeding seasons at 10 sites in Ontario, Canada, to test the hypothesis that limited prey availability during the breeding season affected reproductive behaviour. We found no relationship between food availability and number of eggs laid or number of young fledged. Neither did we observe higher rates of second brooding or more pairs nesting at breeding sites with higher food availability. Barn Swallows did not time their reproductive effort to maximize prey availability during the nesting period, but any mismatch in phenology of prey and bird reproduction at a breeding site was not associated with lower reproductive success. The results of this study did not support our hypothesis and suggest that Barn Swallow reproductive behaviour was not negatively affected by limited prey availability on the breeding grounds.

Rearing Success Does Not Improve With Apparent Pair Coordination in Offspring Provisioning

In species with biparental care, behavioural coordination in the provisioning of the progeny is hypothesized to increase the number of offspring that survive to independence. Coordination is often quantified by two metrics, alternation and synchrony. Turn-taking (leading to an alternation pattern) can result when one parent’s investment strategy is based on the investment of its partner (i.e. conditional cooperation). This should increase the overall provisioning rate and improve offspring body condition. Synchrony might equalise food delivery among offspring and therefore decrease the variance in offspring body condition within the brood. Overall, offspring survival could be increased by parental coordination. Finally, pairs with low coordination, and with potentially lower reproductive success, are expected to be more likely to divorce. In this study, we use a dataset on 473 pairs of house sparrows in a natural insular population to test these hypotheses. We found no effect of the pair’s apparent coordination on offspring condition, offspring survival, or divorce rate, questioning the adaptive significance of this behaviour. We argue that, in this species, the detection of a higher frequency of alternation and synchrony, when compared to chance expectation, might be induced by the environment, rather than result from an emergent pair behaviour selected for fitness benefits.

Correlates of maternal glucocorticoid levels in a socially flexible rodent

While it is generally accepted that social isolation has detrimental effects on social species, little is known about the importance of social interactions in less social species–particularly for wild reproductive females. We studied socially-flexible yellow-bellied marmots (Marmota flaviventer) and asked whether features of the social environment are associated with maternal fecal glucocorticoid metabolite (FGM) concentrations. Since changes in maternal baseline glucocorticoids may have positive or negative consequences for offspring fitness, we were also interested in estimating their relationship with measures of reproductive success. We fitted generalized linear mixed effects models to a dataset including maternal FGM measurements, social network metrics, maternal/alloparental care, and pup FGM and survival. Agonistic interactions were positively associated with maternal FGM levels, while mothers that engaged in relatively more affiliative interactions had reduced FGM levels when living in environments with low predator pressure. Pups associated with mothers exhibiting high FGM levels had low annual survival rates, received less maternal/alloparental care and had higher FGM levels. Interestingly, offspring from mothers with high FGM levels were more likely to survive the summer when born in small litters. In sum, social interactions likely influence and are influenced by glucocorticoid levels of facultatively social females. Potential benefits of social bonds may be context-specific, and agonistic interactions may be tightly correlated with fitness. Female marmots exhibiting high FGM levels had overall low reproductive success, which is predicted by the cort-fitness hypothesis. However, under adverse conditions, offspring summer survival can be maximized if pups are born in small litters.

Effect of age, haemosporidian infection and body condition on pair composition and reproductive success in Great Tits Parus major

Several factors shape lifetime reproductive success, including genetic background, body condition, environmental conditions and ecological interactions such as parasitism. Adults often show higher reproductive success than their young conspecifics, especially in long‐lived bird species, and this may be explained by the cumulative effects of an increase in reproductive experience and the selection of high‐quality individuals from one year to the next. To test whether this pattern also exists in short‐lived bird species, we used 13 years of monitoring data from two Great Tit Parus major populations. The effects of male and female age on several reproductive parameters were analysed in 419 pairs of Great Tits, while accounting for body condition and infection by haemosporidian parasites. Reproductive success was mainly affected by the age‐class of males. Pairs containing a sub‐adult male fledged one‐third fewer chicks than pairs containing an adult male. The difference was not caused by variation in male fertility but could have been caused by better parental care provided by adult birds. In addition to lower reproductive success, first‐year males also had reduced access to mating compared with adult males, suggesting an avoidance of sub‐adult males by females. Nestling body condition was positively correlated with parental body condition, and the body condition of male and female members of breeding pairs was positively correlated. Finally, the number of fledged chicks was mainly affected by the infection status of males. These results temper our previously published results showing an effect of infection on Great Tit reproduction regardless of their sex. In our previous study, and as in most cases, the status of the partner was not taken into account and we show here that this is essential because it can lead to a biased interpretation of the results.

Effects of Copper Oxide Nanoparticles (CuO-NPs) on Parturition Time, Survival Rate and Reproductive Success of Guppy Fish, Poecilia reticulata

The purpose of the present study was to evaluate acute and chronic effects of CuO-NPs on survival rate and reproductive success of mature guppy (Poecilia reticulata) and their larvae. During the acute toxicity test, mature fish and their larvae were exposed to series of different concentrations of (0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 mg L−1) CuO-NPs for 96 h and during the chronic phase we exposed mature individuals to 0, 5, 10 mg L−1 of CuO-NPs for 8 weeks. Results showed a significant correlation between mortality rate and CuO-NPs concentrations. Furthermore, the LC50 96 h of CuO-NP for mature and larvae of P. reticulata were 28.354 and 5.649 mg L−1, respectively. Finally, the fish exposed to series of CuO-NP concentrations exhibited various clinical signs such as darkening of skin, anxiety and death with open mouth. Chronic exposure affected reproductive traits of fish, with greatest effects reported in treatment with 10 mg L−1 of CuO-NPs. Those individuals had lowest reproductive success, prolonged parturition time and highest mortality rate. Results highlight toxic potential of CuO-NPs on mature and larvae fish, both increased mortality rate and lower reproductive success, by increasing parturition time and reducing number of larvae.

Essential dependence on wild pollination service: a medicinal plant under threat Minthostachys verticillata (Lamiaceae)

Fil: Glinos, Evangelina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto Multidisciplinario de Biologia Vegetal. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas y Naturales. Instituto Multidisciplinario de Biologia Vegetal; Argentina

Ambient temperature provides an adaptive explanation for seasonal reproduction in a tropical mammal

AbstractUnderstanding how reproductive timing has evolved to reflect climatic conditions is increasingly important as the climate changes, influencing species persistence and ecosystem dynamics. Among endotherms, seasonal reproduction is often linked to natural selection for reproducing when biotic conditions (e.g. food availability) are most favourable. In contrast, we present evidence that direct effects of an abiotic factor have selected for seasonal reproduction in a tropical mammal. We have shown previously that the African wild dog (Lycaon pictus), a diurnally active coursing predator, has lower reproductive success at high ambient temperatures, when its hunting activity is constrained. We therefore hypothesized that natural selection would favour reproduction during cool weather conditions, in locations where such conditions occur predictably. We show that, as predicted, wild dogs reproduce seasonally at latitudes from 7 to 25°S, such that their pup‐rearing periods coincide with the coolest (but not the driest) weeks of the year. Wild dog reproduction is aseasonal at latitudes ≤2°. As the climate warms, some temperate‐zone species have tracked optimal conditions through altered phenology. However, in seasonally breeding wild dog populations, any alteration in phenology would require breeding in hotter weather, probably reducing reproductive success. This endangered species may thus have a limited ability to adapt to climate change. Seasonal reproduction might be a trait indicating climate change vulnerability among tropical species.

Region-wide mass mortality of Japanese oak due to ambrosia beetle infestation: Mortality factors and change in oak abundance

Insect and pathogen disturbances can result in a decline in the abundance of host tree species, leading to changes in tree species composition at a regional scale. Quercus crispula and Q. serrata are dominant oak species in Japanese secondary forests, which are mostly composed of abandoned coppice. In recent decades, these two oak species have suffered mass mortality from Japanese oak wilt disease (JOW), which is caused by the ambrosia beetle Platypus quercivorus. This study analyzed factors affecting oak mortality during a JOW epidemic, and quantified the impact of the epidemic on forests at a regional scale in Toyama Prefecture, central Japan using data from 101 plots in the National Forest Inventory. Plot measurements before the epidemic (1999–2003) and re-measurements after the epidemic (2012–2014) were used for analysis. Before the epidemic, Q. crispula was the most dominant species in the natural forests and was distributed at a wider elevation range than Q. serrata (the third most dominant species). The mortality rate during the epidemic was 68% for Q. crispula and 21% for Q. serrata. The mortality of both species positively related with plot-level oak volume, suggesting that stand development after abandonment of coppice forests was an important factor in the epidemic. The mortality of Q. crispula related inversely with elevation and was especially low above 1000 m, probably because of the low reproductive success of P. quercivorus at high elevation, suggesting that global warming was a factor increasing the mortality from JOW. The total volume of Q. crispula in the study region decreased by 56% during the epidemic, while that of Q. serrata increased by 13%. After the epidemic, the dominance of Q. crispula in the natural forests decreased below that of Fagus crenata and Q. serrata. There were few regenerating Q. crispula and Q. serrata in the canopy gaps formed by dead oak because of their low numbers of saplings. Regenerating trees comprised various shade-tolerant canopy tree species and shrub species, and forests will change toward multispecies mixed, uneven-aged forests. This study comprehensively quantified forest change due to a JOW epidemic at a region-wide scale, and revealed that the epidemic was caused by multiple interactions among coppice abandonment, global warming, ambrosia beetles, and oak trees.

When more is not merrier: Using wild population dynamics to understand the effect of density on ex situ seahorse mating behaviors.

Seahorses are considered one of the most iconic examples of a monogamous species in the animal kingdom. This study investigates the relationship between stocking density and mating and competitive behavior from the context of the field biology of the dwarf seahorse, Hippocampus zosterae (Jordan & Gilbert). Animals were housed in 38 liter tanks at a range of densities and sex ratios (from 2–8 animals per tank), and their reproductive and other social behaviors were monitored from tank introduction through copulation. At low tank densities and even sex ratios but comparatively high field densities, frequency of both mating and competitive behaviors was low in trials. A higher level of males in tanks across all densities increased competition, activity levels, and aggression leading to egg transfer errors and brood expulsion, resulting in lower reproductive success. Across seahorse species, mean and maximum wild densities were consistently lower than those used in ex situ breeding, with adult sex ratios that were significantly female biased. However, significant variation exists in wild seahorse densities across species, with higher densities detected in focal/mark recapture studies and on artificial habitat structures than reported with belt transect sampling techniques. Interchange of knowledge gained in both aquarium and wild contexts will allow us to better understand the biology of this genus, and improve reproduction in captivity. Interpreting ex situ reproductive behaviors of seahorses within various densities reported from natural populations will help us predict the impact of conservation efforts and increase the likelihood of long-term persistence of populations for this threatened genus.

Pair-bonding influences affective state in a monogamous fish species.

In humans, affective states are a key component in pair-bonding, particularly in the early stage of a relationship. Pairing with a high-quality partner elicits positive affective states which, in turn, validate and reinforce the mate choice. Affective states thus strongly affect pair stability and future reproductive success. We propose generalizing the link between affective states and pair-bonding to encompass other monogamous species exhibiting biparental care, chiefly where the reproductive success of the pair critically depends on the coordination between partners. The convict cichlid Amatitlania siquia is a monogamous fish species that forms long-lasting pairs with strong cooperation between parents for parental care. In this species, we showed that females paired with their non-preferred male had lower reproductive success than those paired with their preferred male. We then transposed the judgement bias paradigm, previously used in other animal species, to assess objectively affective states in fishes. Females that were assigned their non-preferred partner exhibited pessimistic bias, which indicates a negative affective state. By contrast, females that were assigned their preferred partner did not exhibit changes in their affective state. Our results highlight that the influence of pair-bonding on affective states is not human-specific and can also be observed in non-human species.

Reproductive success of assisted reproductive technology in couples with chromosomal abnormalities.

Infertility is estimated to affect 15% of couples, having chromosome abnormalities an important role in its etiology. The main objective of this work was to access the reproductive success of ART in infertile couples with chromosomal abnormalities comparing to a control group with normal karyotype. A 7-year retrospective karyotype analysis of infertile couples was done. Data regarding type of infertility, couples' ages, ART performed, and their reproductive success were obtained. Adjusted odds ratio (OR) were used to estimate magnitude of association between the reproductive success and the different groups. We found a prevalence of 7.83% of chromosome abnormalities in our population (233 couples out of 2989). Chromosomal anomalies were found in 82 men (34.75%) and 154 women (65.25%), with low-grade mosaicism being the most prevalent (50.85%), followed by autosomal translocations (17.37%) and sex chromosomes abnormalities (13.56%). Only 2359 couples were treated with ART. There was a non-significant lower reproductive success rate in the cases (OR = 0.899, p = 0.530) with IVF providing the higher success rate. In general, female carriers of chromosome anomalies had a higher success rate, although not significant. Although the differences regarding success rate between groups were not found statistically significant, we still advocate that cytogenetic analysis should be performed routinely in all infertile couples namely before ART. This might help deciding the best treatment options including Preimplantation Genetic Testing for aneuploidies or structural rearrangements and minimize the risk of transmission of anomalies to the offspring.

A meta-analysis of herbivore effects on plant attractiveness to pollinators.

Herbivores may directly or indirectly affect plant attractiveness to pollinators. Although several studies have reported on these effects, there is yet no general consensus on the strength and sign of such interactions or their contingency on herbivory features such as the plant tissue attacked. We performed a meta-analysis of studies testing for effects of herbivores on floral traits, plant attractiveness to pollinators, and plant reproductive success. We also assessed whether herbivore effects depended on the plant tissue attacked by herbivores and if real or simulated herbivory was used. We found an overall significant negative effect of herbivores on floral traits, plant attractiveness to pollinators, and plant reproductive success. These effects were, however, contingent on the plant tissue attacked and on whether real or simulated damage was used. Real floral and leaf, but not root, herbivores showed detrimental effects on floral traits and plant attractiveness to pollinators. In addition, real leaf, but not floral or root herbivory, lowered plant reproductive success. Contrastingly, simulated leaf and floral herbivory showed no effect on any of the response variables. These findings help move forward our understanding of the strength and directionality of herbivore effects on plant attractiveness to pollinators and their underlying mechanisms.