Variation In Reproductive Traits Research Articles

Environmentally-driven variations in reproductive traits in a sandy beach bivalve throughout its geographic range

The yellow clam Amarilladesma mactroides (Reeve, 1854) inhabits the intertidal zone of sandy beaches along the temperate Atlantic coast from Brazil to Argentina (24°-41°S). Over the past decades, there has been a noticeable decline in its abundance, underscoring the importance of understanding their reproductive strategies and phenotypic plasticity for conservation efforts. This study explored large-scale variations in the size at first sexual maturity (SL50), the age at maturity (A50), the vitellogenic oocyte area (VOA), and a reproductive age index (RAI) that combines A50 and the lifespan of each clam population, in relation to local habitat characteristics (e.g., beach morphodynamics) and large-scale environmental variables, such as salinity, sea surface temperature (SST) and chlorophyll-a. Four sandy beach clam populations from Uruguay and Argentina (latitudinal range: 33°45′S - 38°56′S) were sampled monthly between June and August during the reproductive season. SL50 increased linearly with the mean and maximum SST (SSTmean, SSTmax), while VOA and RAI decreased with tidal range and width of intertidal zone, respectively. In beaches that had higher SSTmean and SSTmax, yellow clams reached maturity earlier and spent more than 70% of their lifespan in reproduction. The yellow clam population at the lowest latitude showed the largest oocyte sizes and a shorter lifespan of 3.5 years, while the population at the highest latitude had a longer lifespan (7 years) and the smallest VOA values. Populations at intermediate latitudes showed delayed sexual maturity, a 50–60% investment of their lifespan in reproduction, the longest lifespan (up to 9 years) and intermediate VOA values. The influence of the Rio de la Plata and Bahia Blanca estuaries modified the expected latitudinal gradient in reproductive traits, but local habitat conditions prevailed over large-scale environmental variables as explanatory factors of the reproductive strategy of the yellow clam. Therefore, the species displays phenotypic plasticity in its reproductive aspects to ensure population success.

Geographic variation in reproductive traits and germination-niche dynamics in conservation-dependent Banksia arborea populations restricted to banded ironstone formations

The temperature and moisture requirements for reproduction (i.e. seed production and germination) underpin the biogeographical relationships between climate, distribution and population dynamics of plants, particularly narrow range endemic species. We aimed to investigate reproductive outputs and the responses of seeds to temperature and moisture availability across three Banksia arborea populations that are distributed over a narrow range (< 200 km2) of semi-arid habitat on banded ironstone formations of Western Australia. We conducted reproductive trait assessments by quantifying follicles per cone, proportion of viable seed and associated seed mass followed by hydrothermal germination assessments for each population to characterise temperature and water stress tolerance. We found the southern-most population, that receives marginally higher rainfall, had heavier seeds (10 ± 0.02 mg), a cooler optimum temperature (16.1 °C) and wider germination capacity under water stress at 10 °C and 15 °C (Ψb50 = -0.66 to -0.87 MPa) compared to the two northern populations (Ψb50 = -0.60 to -0.65 MPa). By contrast, both northern populations had slightly warmer optimum temperatures for germination (16.9–17.5 °C) and a higher capacity to germinate under water stress at warmer temperatures of 22.5 °C (Ψb50 = -0.43 to -0.56 MPa, compared to -0.29 MPa). Our work highlights that, even within the specific requirements of a narrow range endemic, different populations adapt to marginally different temperature and water stress tolerances. Warming of the southern populations could impact on future recruitment, and conservation action to promote resilient ecosystems are suggested.

Variation in reproductive traits associated with different host plants in the subsocial bug Elasmucha putoni (Hemiptera: Acanthosomatidae)

ABSTRACTHost plants are an important selective factor for the evolution of reproductive traits in herbivorous insects. Among different host plants, offspring will be exposed to different environmental conditions, and parents are expected to allocate reproductive resources adaptively to their offspring according to such environmental heterogeneity. Elasmucha putoni Scott (Hemiptera: Acanthosomatidae) is a bivoltine shield bug showing maternal care. We examined the variation in reproductive traits, that is, egg size, clutch size and the trade‐off between them, between two generations of a population and two populations of the same (later) generation, which differ in their host plants. Controlling for female body size, a significant difference was detected in egg size, but not in clutch size between the earlier generation on Morus australis and the later one on Euptelea polyandra or Rosa multiflora. Moreover, there was no difference in the two traits between the populations (one using E. polyandra and another using R. multiflora) of the same generation. A significant trade‐off between egg size and clutch size was detected in the earlier generation on M. australis but not in the later generation on E. polyandra or R. multiflora. This is the first study indicating variable reproductive allocation according to different host plants in herbivorous insects with maternal care.

Impacts of reduced water availability on vegetative and reproductive traits of a Solanum species

AbstractWhile drought is known to affect crop yields negatively, there is limited knowledge of the strategies used by animal‐pollinated plants to cope with such conditions. In this study, we simulated low and moderate drought conditions in a greenhouse experiment and examined the vegetative and reproductive traits of a buzz‐pollinated species (Solanum lycopersicum). Our findings indicate that individuals exposed to both drought conditions decreased in height and bore fewer leaves but increased in the ratio of root length to dry mass. The number of flowers produced per day and the overall flower production were higher in plants under control conditions. We found no differences in the onset of flowering between the treatments, but the plants exposed to low drought showed peak flowering earlier. Among the morphometric traits, flower height, floral diameter, petal length, and petal width were significantly lower in both drought conditions. Individuals in the moderate‐drought treatment displayed greater variation in reproductive traits than those in the low‐drought treatment. Overall, drought stress negatively impacted the aboveground vegetative growth and the reproductive efforts of plants.

Deprivation of Sexual Reproduction during Garlic Domestication and Crop Evolution

Garlic, originating in the mountains of Central Asia, has undergone domestication and subsequent widespread introduction to diverse regions. Human selection for adaptation to various climates has resulted in the development of numerous garlic varieties, each characterized by specific morphological and physiological traits. However, this process has led to a loss of fertility and seed production in garlic crops. In this study, we conducted morpho-physiological and transcriptome analyses, along with whole-genome resequencing of 41 garlic accessions from different regions, in order to assess the variations in reproductive traits among garlic populations. Our findings indicate that the evolution of garlic crops was associated with mutations in genes related to vernalization and the circadian clock. The decline in sexual reproduction is not solely attributed to a few mutations in specific genes, but is correlated with extensive alterations in the genetic regulation of the annual cycle, stress adaptations, and environmental requirements. The regulation of flowering ability, stress response, and metabolism occurs at both the genetic and transcriptional levels. We conclude that the migration and evolution of garlic crops involve substantial and diverse changes across the entire genome landscape. The construction of a garlic pan-genome, encompassing genetic diversity from various garlic populations, will provide further insights for research into and the improvement of garlic crops.

Effects of geo-climate factors on phenotypic variation in cone and seed traits of Pinus yunnanensis.

Evaluating variations in reproductive traits and the response of the variations to geo-climate conditions are essential for understanding the persistence, evolution, and range dynamics of plant populations. However, there are insufficient studies to attempt to analyze the importance of geo-climate factors in explaining within- or among-population variation in reproductive traits. We examined 14 traits for 2671 cones of Pinus yunnanensis collected from nine populations in the mountains of Southwest China to characterize the patterns of phenotypic variation of traits and estimate environmental effects on these trait performances and trait variation. We found the contribution of intrapopulation variation to the overall variation was greater than the interpopulation variation and the larger coefficients of variation for the populations lying at the edge of northern and southern regions. Climatic variables are more important than geographical and tree size variables in their relationships to cone and seed traits. Populations in more humid and warmer climate expressed greater cone and seed weight and seed number but lower seed abortion rate, while the larger coefficients of variation in seed weight and number were detected in northern and southern marginal regions with drier or colder climate. Our study illustrates that intraspecific trait variation should be considered when examining plant species response to changing climate and suggests that the high variability rather than high quality of seed traits in the marginal regions with drier or colder climate might foster plant-population persistence in stressful conditions.

Causes and consequences of sex ratio variation in plants. A commentary on: 'Life history characteristics and historical factors are important to explain regional variation in reproductive traits and genetic diversity in perennial mosses'.

Causes and consequences of sex ratio variation in plants. A commentary on: 'Life history characteristics and historical factors are important to explain regional variation in reproductive traits and genetic diversity in perennial mosses'.

Intraspecific variation in reproductive traits and embryo elemental composition of the crab Hemigrapsus crenulatus (Milne Edwards, 1837) across fluctuating coastal environments along Chilean coasts

The estuarine crab Hemigrapsus crenulatus has a wide distribution range along the coast of the South Pacific Ocean (from 20 °S to 53 S°). This decapod is abundant in these coastal and estuarine habitats and plays a key ecological role as prey of the snook fish (Eleginops maclovinus) and kelp gull (Larus dominicanus). Its diet consists of detritus, dead fish, and crustaceans, and the macroalgae Ulva sp. In response to contrasting environmental conditions and anthropogenic impacts along the Chilean coast, H. crenulatus may present intraspecific variations in its reproductive traits and changes in the elemental composition of its embryos, directly affecting its biological fitness. Along the Chilean coast, female individuals were collected during late spring 2019 and early summer 2020 (from November 2019 to February 2020) in six areas of Chile (north: Tongoy (30°S); south-central: Lenga (36°S), Tubul (37°S); south austral: Calbuco (41°S), Castro (42°S), Quellón (43°S). The environmental conditions (i.e. sea surface temperature, precipitation and chlorophyll α) present during each sampling event were also recorded. We evaluated the reproductive parameters of females (fecundity, reproductive output (RO)) as well as their body size (carapace width and dry weight), volume, water content, dry weight, elemental composition (carbon, hydrogen, nitrogen: CHN), and finally the energy content of their embryos. Our results indicated that the environmental conditions of the sea water temperature, precipitation (proxy of water salinity) and chlorophyll α (proxy of food availability) have direct effects on the reproductive parameters of females and the characteristics of their embryos. We observed a low fecundity and high RO in Calbuco and Quellón, where precipitation was high (i.e. diluted salinity) and temperatures and productivity was low. For embryo traits, the highest values of volume and water content were observed in female crabs from the estuarine areas (i.e. Tongoy, Lenga, Tubul), values much higher than those found in the internal sea of Chile (i.e. Calbuco, Castro, Quellón). For the elemental composition, we observed high nitrogen levels and a low C:N proportion in embryos from female crabs from Lenga (a nitrogen enriched area). Fluctuating environmental variables among localities proved to modulate intraspecific variations in females and embryos of H. crenulatus, revealing different reproductive strategies, particularly in the quality and energy investment per embryo, which subsequently influenced successful embryogenesis and larval survival.

Life-history characteristics and historical factors are important to explain regional variation in reproductive traits and genetic diversity in perennial mosses.

Plants have evolved an unrivalled diversity of reproductive strategies, including variation in the degree of sexual vs. clonal reproduction. This variation has important effects on the dynamics and genetic structure of populations. We examined the association between large-scale variation in reproductive patterns and intraspecific genetic diversity in two moss species where sex is manifested in the dominant haploid generation and sex expression is irregular. We predicted that in regions with more frequent realized sexual reproduction, populations should display less skewed sex ratios, should more often express sex and should have higher genetic diversity than in regions with largely clonal reproduction. We assessed reproductive status and phenotypic sex in the dioicous long-lived Drepanocladus trifarius and D. turgescens, in 248 and 438 samples across two regions in Scandinavia with frequent or rare realized sexual reproduction, respectively. In subsets of the samples, we analysed genetic diversity using nuclear and plastid sequence information and identified sex with a sex-specific molecular marker in non-reproductive samples. Contrary to our predictions, sex ratios did not differ between regions; genetic diversity did not differ in D. trifarius and it was higher in the region with rare sexual reproduction in D. turgescens. Supporting our predictions, relatively more samples expressed sex in D. trifarius in the region with frequent sexual reproduction. Overall, samples were mostly female. The degree of sex expression and genetic diversity differed between sexes. Sex expression levels, regional sex ratios and genetic diversity were not directly associated with the regional frequency of realized sexual reproduction, and relationships and variation patterns differed between species. We conclude that a combination of species-specific life histories, such as longevity, overall degree of successful sexual reproduction and recruitment, and historical factors are important to explain this variation. Our data on haploid-dominated plants significantly complement plant reproductive biology.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Analysis of reproductive traits reveals complex population dynamics on a small geographical scale in Atlantic herring

Atlantic herring (Clupea harengus) has a complex population structure and displays a variety of reproductive strategies. Differences in reproductive strategies among herring populations are linked to their time of spawning, as well as to their reproductive investment which can be an indicator for migratory vs. stationary behavior. These differences are reflected in the number of oocytes (fecundity) and the size of the oocytes prior spawning. We studied potential mixing of herring with different reproductive strategies during the spring spawning season on a coastal spawning ground. It has been hypothesized that both spring and autumn spawning herring co-occur on this specific spawning ground. Therefore, we investigated the reproductive traits oocyte size, fecundity, fertilization success as well as length of the hatching larvae during the spring spawning season from February to April. We used a set of 11 single nucleotide polymorphism markers (SNPs), which are associated with spawning season, to genetically identify autumn and spring spawning herring. Reproductive traits were investigated separately within these genetically distinct spawning types. Furthermore, we used multivariate analyses to identify groups with potentially different reproductive strategies within the genetic spring spawners. Our results indicate that mixing between ripe spring and autumn spawners occurs on the spawning ground during spring, with ripe autumn spawners being generally smaller but having larger oocytes than spring spawners. Within spring spawners, we found large variability in reproductive traits. A following multivariate cluster analysis indicated two groups with different reproductive investment. Comparisons with other herring populations along the Norwegian coastline suggest that the high variability can be explained by the co-occurrence of groups with different reproductive investments potentially resulting from stationary or migratory behavior. Fertilization success and the length of the hatching larvae decreased with progression of the spawning season, with strong inter-individual variation, supporting our findings. Incorporating such complex population dynamics into management strategies of this species will be essential to build its future population resilience.

Morphological Variation of Strychnos spinosa Lam. Morphotypes: A Case Study at Bonamanzi Game Reserve, KwaZulu-Natal, South Africa

Strychnos spinosa Lam. of the Loganiaceae family is associated with versatility, poverty eradication, and rural economic development. However, the morphological diversity of S. spinosa is not well documented. This limits efforts toward its improvement and commercial exploitation. This study aimed to characterize the variability, vegetative and reproductive traits, and heritability of S. spinosa morphotypes at Bonamanzi Game Reserve. The majority of the morphotypes had green, rough, round immature fruits with dark green, elongated, open fully developed leaves. Fruits varied between roundish and pyriform shape as well as green and purple colour. Positive correlation was mainly seen between fruit and seed traits. Principal component analysis indicated fruit and seed traits as major discriminating factors for morphotypes, followed by leaf size and seed thickness. A dendrogram primarily grouped morphotypes according to fruit texture. Genotypic variance and genotypic coefficient of variation were higher than environmental variance and environmental coefficient variation in reproductive traits of S. spinosa. A rough pericarp texture and purple tinge on the immature leaves of some morphotypes was recorded for the first time. Differences in morphological features across S. spinosa morphotypes indicate a high level of diversity that could be utilized by breeders to generate new cultivars. This first report on variability and heritability among S. spinosa morphotypes forms the basis of available germplasm essential for future breeding programs.

Non-genetic factors affecting litter size, age at first lambing and lambing interval of Romanov sheep in Croatia

Reproductive traits are of paramountimportance in an efficient lamb production system. In Croatia, values of reproductive traits of Romanov sheep are below the average expected for this breed, indicating the need for improvement of these traits to exploit the breed’s full reproductive potential. This study was conducted on 260 Romanov ewes located at a commercial Romanov sheep farm in Croatia. All ewes were kept under similar conditions, and reproductive management was based on accelerated lambing with continuous mating. Linear models with fixed effects were used to estimate the influence of year of birth/lambing, season of birth/lambing, ram, parity and litter type on litter size (LS), age at first lambing (AFL) and lambing interval (LI). Average LS was 2.11 ± 0.71, while the year of lambing and parity were the most important factors affecting this trait. The smallest litters were recorded after 1st parity (1.77 ± 0.06), and the largest after 5th parity (2.21 ± 0.08). AFL averaged 388.5 ± 72.4 days. All investigated non-genetic factors had a significant (P&amp;lt;0.05) influence on AFL, with year of birth as most important. The average LI was 241.2 ± 70.8 days. A significant (P&amp;lt;0.05) influence of all factors on LI was observed. Ewes lambing in spring (200.2 ± 7.9 days) or summer (190.5 ±6.6 days) had a significantly (P&amp;lt;0.05) shorter LI than ewes lambing in autumn (227.7 ± 8.3 days) or winter (237.2 ± 6.7 days). The longest LI was observed after the first parity (284.0 ±5.5 days). Average values for reproductive traits in the examined population of Romanov sheep were higher than those reported in the official Croatian database for breeding sheep. Non-genetic factors have a significant influence on the variation of reproductive traits of Romanov sheep, and therefore should be considered when assessing ewes’ reproductive performance.

Current and historical factors drive variation of reproductive traits in unisexual mosses in Europe: A case study

AbstractUnisexual bryophytes provide excellent models to study the mechanisms that regulate the frequency of sexual versus asexual reproduction in plants, and their ecological and evolutionary implications. Here, we determined sex expression, phenotypic sex ratio, and individual shoot traits in 242 populations of the cosmopolitan moss Pseudoscleropodium purum spanning its whole distributional range. We tested whether niche differentiation, sex‐specific differences in shoot size, and biogeographical history explained the spatial variation of reproductive traits. We observed high levels of sex expression and predominantly female‐biased populations, although both traits showed high intraspecific variation among populations. Sex expression and sex ratio were partly explained by current macroscale environmental variation, with male shoots being less frequent at the higher end of the environmental gradients defined by the current distribution of the species. Female bias in population sex ratio was significantly lower in areas recolonized after the last glacial maximum (recent populations) than in glacial refugia (long‐term persistent populations). We demonstrated that reproductive trait variation in perennial unisexual mosses is partially driven by macroscale and historical environmental variation. Based on our results, we hypothesize that sexual dimorphism in environmental tolerance and vegetative growth contribute to sex ratio bias over time, constraining the chances of sexual reproduction, especially in long‐term persistent populations. Further studies combining genetic analyses and population monitoring should improve our understanding of the implications of the intraspecific variation in the frequency of sexual versus asexual reproduction in bryophyte population fitness and eco‐evolutionary dynamics.

Architectural effects regulate resource allocation within the inflorescences with nonlinear blooming patterns.

Spatial and temporal resource allocations within inflorescences have been well-studied in many plants based on flowering sequence or floral position. However, there had been few attempts to investigate architectural effects and resource competition in species where the blooming pattern does not follow a linear positional pattern within the inflorescence. Moreover, most flowering plants show female-biased sex allocation in early or basal flowers, but it is unclear in species with inherent and changeless ovule production. We investigated intra-inflorescence variation in reproductive traits of Salvia przewalskii, a perennial herb with 4-ouvle ovary flowers and flowering sequence-floral position decoupled inflorescences. To detect the effects of resource competition and architectural effects on reproductive success, we manipulated inflorescence (removed floral buds by position and flowering sequence) and pollination (opened and supplemented pollination). Pollen production and dry mass deceased from bottom to top flowers but did not significantly differ following flowering sequence, resulting in male-biased sex allocation in basal flowers. The seed production, fruit set, and bud development exhibited significant declining trends from proximal to distal positions regardless of the thinning and pollen treatments. Meanwhile, the seed production, fruit set, and bud development success did not significant differ when thinning was conducted according to flowering sequence. Architectural effects plays a crucial role in resource allocation within decoupled flowering inflorescences. Moreover, our results highlighted that inherent floral traits such as changeless ovule production, may modify architectural effects on sex allocation.

Gynoecium structure in Sapindales and a case study of Trichilia pallens (Meliaceae).

Sapindales is a monophyletic order within the malvid clade of rosids. It represents an interesting group to address questions on floral structure and evolution due to a wide variation in reproductive traits. This review covers a detailed overview of gynoecium features, as well as a new structural study based on Trichilia pallens (Meliaceae), to provide characters to support systematic relationships and to recognize patterns of variations in gynoecium features in Sapindales. Several unique and shared characteristics are identified. Anacrostylous and basistylous carpels may have evolved multiple times in Sapindales, while ventrally bulging carpels are found in pseudomonomerous Anacardiaceae. Different from previous studies, similar gynoecium features, including degree of syncarpy, ontogenetic patterns, and PTTT structure, favors a closer phylogenetic proximity between Rutaceae and Simaroubaceae, or Rutaceae and Meliaceae. An apomorphic tendency for the order is that the floral apex is integrated in the syncarpous or apocarpous gynoecium, but with different length and shape among families. Nitrariaceae shares similar stigmatic features and PTTT structure with many Sapindaceae. As the current position of both families in Sapindales is uncertain, floral features should be investigated more extensively in future studies. Two different types of gynophore were identified in the order: either derived from intercalary growth below the gynoecium as a floral internode, or by extension of the base of the ovary locules as part of the gynoecium. Sapindales share a combination of gynoecial characters but variation is mostly caused by different degrees of development of the synascidiate part relative to the symplicate part of carpels, or the latter part is absent. Postgenital fusion of the upper part of the styles leads to a common stigma, while stylar lobes may be separate. Due to a wide variation in these features, a new terminology regarding fusion is proposed to describe the gynoecium of the order.

Experimental evidence for population variability of reproductive traits in Japanese anchovy Engraulis japonicus

Small pelagic fishes show spatiotemporal variations in reproductive traits due probably to responses to varying environmental conditions, but potential genetic contributions to such variations have received little attention. This study compared several reproductive traits of Japanese anchovy between two geographically isolated populations, from the central Seto Inland Sea and Omura Bay, western Japan, under common environmental conditions over three generations. There were no significant differences in age and standard length at sexual maturation between populations. Temperature-mediated variation in egg size was found in the two populations with decrease in egg size as temperature increased. However, regression analysis showed that the relationship between egg size and temperature differed significantly between the two populations over three generations. There was also a significant difference in the relative batch fecundity of the F1 and F2 generations between populations. Hence, females from the central Seto Inland Sea could produce a larger number of smaller eggs than females from Omura Bay. Variation in egg size appears to reflect significant differences in larval size at hatch and the onset of feeding in waters of different temperatures. These findings suggest that the thermal reaction norms of egg size observed in the two populations could have genetic contributions and that their egg traits may mediate a possible difference in offspring viability during early life stages.

Correlated evolution of larval development, egg size and genome size across two genera of snapping shrimp

Across plants and animals, genome size is often correlated with life-history traits: large genomes are correlated with larger seeds, slower development, larger body size and slower cell division. Among decapod crustaceans, caridean shrimps are among the most variable both in terms of genome size variation and life-history characteristics such as larval development mode and egg size, but the extent to which these traits are associated in a phylogenetic context is largely unknown. In this study, we examine correlations among egg size, larval development and genome size in two different genera of snapping shrimp, Alpheus and Synalpheus, using phylogenetically informed analyses. In both Alpheus and Synalpheus, egg size is strongly linked to larval development mode: species with abbreviated development had significantly larger eggs than species with extended larval development. We produced the first comprehensive dataset of genome size in Alpheus (n=37species) and demonstrated that genome size was strongly and positively correlated with egg size in both Alpheus and Synalpheus. Correlated trait evolution analyses showed that in Alpheus, changes in genome size were clearly dependent on egg size. In Synalpheus, evolutionary path analyses suggest that changes in development mode (from extended to abbreviated) drove increases in egg volume; larger eggs, in turn, resulted in larger genomes. These data suggest that variation in reproductive traits may underpin the high degree of variation in genome size seen in a wide variety of caridean shrimp groups more generally.

Reproductive trait differences drive offspring production in urban cavity-nesting bees and wasps.

The contrasting and idiosyncratic changes in biodiversity that have been documented across urbanization gradients call for a more mechanistic understanding of urban community assembly. The reproductive success of organisms in cities should underpin their population persistence and the maintenance of biodiversity in urban landscapes. We propose that exploring individual‐level reproductive traits and environmental drivers of reproductive success could provide the necessary links between environmental conditions, offspring production, and biodiversity in urban areas. For 3 years, we studied cavity‐nesting solitary bees and wasps in four urban green space types across Toronto, Canada. We measured three reproductive traits of each nest: the total number of brood cells, the proportion of parasite‐free cells, and the proportion of non‐emerged brood cells that were parasite‐free. We determined (a) how reproductive traits, trait diversity and offspring production respond to multiple environmental variables and (b) how well reproductive trait variation explains the offspring production of single nests, by reflecting the different ways organisms navigate trade‐offs between gathering of resources and exposure to parasites. Our results showed that environmental variables were poor predictors of mean reproductive trait values, trait diversity, and offspring production. However, offspring production was highly positively correlated with reproductive trait evenness and negatively correlated with trait richness and divergence. This suggests that a narrow range of reproductive traits are optimal for reproduction, and the even distribution of individual reproductive traits across those optimal phenotypes is consistent with the idea that selection could favor diverse reproductive strategies to reduce competition. This study is novel in its exploration of individual‐level reproductive traits and its consideration of multiple axes of urbanization. Reproductive trait variation did not follow previously reported biodiversity‐urbanization patterns; the insensitivity to urbanization gradients raise questions about the role of the spatial mosaic of habitats in cities and the disconnections between different metrics of biodiversity.

Reproductive Characteristics Differ in Two Invasive Populations of Blue Catfish

AbstractThe management of invasive Blue Catfish Ictalurus furcatus in Chesapeake Bay tributaries is hindered by the lack of information on its reproductive biology, which is a key component of population models used to forecast abundance. We quantified and compared the reproductive traits of female Blue Catfish from two populations from the tidal reaches of the James and York River subestuaries during 2015–2017. In these systems, Blue Catfish matured between the ages of 6 and 10 years and spawned between May and July, with larger fish spawning earlier in the season. During spawning events, Blue Catfish produced 2,613–68,356 eggs, with larger and older fish producing more eggs. Fish in the more densely populated James River matured at a marginally older age but a significantly smaller size than fish in the York River, but James River fish allocated more energy to reproduction. Fish in the James River also had greater mean values of the gonadosomatic index, relative fecundity, egg organic content, and proportion of organic content in the eggs. Relative fecundity of Blue Catfish decreased with fish size, contrary to observations in most other fishes. Based on the observed variability in reproductive traits and the size dependence of relative fecundity, we recommend incorporation of population‐specific reproductive rates into stock assessment models for invasive Blue Catfish.