Differences In Reproductive Strategies Research Articles

Contrasting Phenological Patterns and Reproductive Strategies in Closely Related Monoecious Fig Tree Species.

Understanding the ecological and evolutionary aspects of mutualistic interactions is essential for predicting species responses to environmental changes. This study aimed to investigate the phenological patterns and reproductive strategies in two closely related fig tree species, Ficus citrifolia and Ficus eximia. We monitored 99 F. citrifolia and 21 F. eximia trees weekly from January 2006 to April 2011 in an area close to the southern edge of the tropical region in Brazil. Our results revealed contrasting phenological patterns between the two species, with F. citrifolia displaying an annual flowering pattern (1.4 episodes per tree per year) and F. eximia a supra-annual pattern (0.5 episodes per tree per year). We also found significant differences in reproductive strategies, with F. eximia producing more pistillate flowers and, consequently, more seeds and pollinating wasps per fig than F. citrifolia, likely as an adaptation to overcome limitations of low population density by maximizing the gene flow. As the shorter-lived organism, the fig wasp was found to influence critical processes associated with the success and stability of mutualism, such as fig development and ripening. Our findings emphasize the importance of understanding the intricate interactions between mutualistic partners and their adaptive responses to environmental conditions in shaping fig tree populations' reproductive strategies and genetic structure.

Contradistinctive floral attributes, pollination guilds and their consequence on the outcrossing rate in two elevational morphs of Rhododendron arboreum Sm.

Infraspecific floral trait variations may appear in response to elevational differences in alpine plant species. There is enormous information on the selection of such morphs mediated by biotic and/or abiotic variables. Whether such differences contribute to differences in reproductive strategy and mating outcomes is rarely investigated. We investigated these aspects in two distinct elevational floral morphs (Red and Pink) of Rhododendron arboreum Sm. in Western Himalaya. The red morphs occupy the lower elevations while pink morphs the higher elevations. The two morphs differ in floral traits like phenology, dimension, display, quality of floral rewards, and pollinators that happen to influence interaction with available pollinator pool at each elevation. The pink morph exhibits entomophily, while the red ones show ornithophily. Although experimental pollinations established that both the morphs are self-compatible, selfing results in significantly lower fruit-set than either cross- or open-pollinations. The outcrossing rate in the red morph, as determined by using simple sequence repeat (SSR) markers, was higher (tm=0.82) than that in the pink morph (tm=0.76), with a tendency of the latter to be shifting towards mixed-mating strategy. However, the extent of biparental inbreeding was comparable among the two morphs. It is inferred that the differences in the mating outcomes among the morphs in the tree species are linked to those emerging from floral traits and the pollination by different functional groups of floral visitors.

The cuckoldry conundrum.

Concerns about cuckoldry are a dominant theme in evolutionary studies of mating, frequently used to explain sex differences in reproductive strategies. However, studies in nonhuman species have shown that cuckoldry can be associated with important benefits. These insights have not been well integrated with the human literature, which continues to focus on anticuckoldry tactics and negative repercussions for men. I evaluate two key assumptions central to human models of cuckoldry: (1) men are being tricked into investing in nonbiological offspring and (2) investment in nonbiological offspring is wasted. The ethnographic data on fatherhood shows that the concepts of pater and genitor are complex and locally constructed ideas that often include explicit knowledge of extra-pair paternity, countering the idea that nonpaternity results from trickery. Furthermore, rather than being a "waste," paternity loss can be associated with important gains for men, helping to explain why men invest in nonbiological offspring.

Reproductive strategies and their consequences for divergence, gene flow, and genetic diversity in three taxa of Clarkia.

Differences in reproductive strategies can have important implications for macro- and micro-evolutionary processes. We used a comparative approach through a population genetics lens to evaluate how three distinct reproductive strategies shape patterns of divergence among as well as gene flow and genetic diversity within three closely related taxa in the genus Clarkia. One taxon is a predominantly autonomous self-fertilizer and the other two taxa are predominantly outcrossing but vary in the primary pollinator they attract. In genotyping populations using genotyping-by-sequencing and comparing loci shared across taxa, our results suggest that differences in reproductive strategies in part promote evolutionary divergence among these closely related taxa. Contrary to expectations, we found that the selfing taxon had the highest levels of heterozygosity but a low rate of polymorphism. The high levels of fixed heterozygosity for a subset of loci suggests this pattern is driven by the presence of structural rearrangements in chromosomes common in other Clarkia taxa. In evaluating patterns within taxa, we found a complex interplay between reproductive strategy and geographic distribution. Differences in the mobility of primary pollinators did not translate to a difference in rates of genetic diversity and gene flow within taxa - a pattern likely due to one taxon having a patchier distribution and a less temporally and spatially reliable pollinator. Taken together, this work advances our understanding of the factors that shape gene flow and the distribution of genetic diversity within and among closely related taxa.

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.

Experimental life history evolution results in sex-specific evolution of gene expression in seed beetles.

The patterns of reproductive timing and senescence vary within and across species owing to differences in reproductive strategies, but our understanding of the molecular underpinnings of such variation is incomplete. This is perhaps particularly true for sex differences. We investigated the evolution of sex specific gene expression associated with life history divergence in replicated populations of the seed beetle Acanthoscelides obtectus, experimentally evolving under (E)arly or (L)ate life reproduction for >200 generations which has resulted in strongly divergent life histories. We detected 1,646 genes that were differentially expressed in E and L lines, consistent with a highly polygenic basis of life history evolution. Only 30% of differentially expressed genes were similarly affected in males and females. The evolution of long life was associated with significantly reduced sex differences in expression, especially in non-reproductive tissues. The expression differences were overall more pronounced in females, in accordance with their greater phenotypic divergence in lifespan. Functional enrichment analysis revealed differences between E and L beetles in gene categories previously implicated in ageing, such as mitochondrial function and defense response. The results show that divergent life history evolution can be associated with profound changes in gene expression that alter the transcriptome in a sex-specific way, highlighting the importance of understanding the mechanisms of ageing in each sex.

Contrasting parental roles shape sex differences in poison frog space use but not navigational performance.

Sex differences in vertebrate spatial abilities are typically interpreted under the adaptive specialization hypothesis, which posits that male reproductive success is linked to larger home ranges and better navigational skills. The androgen spillover hypothesis counters that enhanced male spatial performance may be a byproduct of higher androgen levels. Animal groups that include species where females are expected to outperform males based on life-history traits are key for disentangling these hypotheses. We investigated the association between sex differences in reproductive strategies, spatial behavior, and androgen levels in three species of poison frogs. We tracked individuals in natural environments to show that contrasting parental sex roles shape sex differences in space use, where the sex performing parental duties shows wider-ranging movements. We then translocated frogs from their home areas to test their navigational performance and found that the caring sex outperformed the non-caring sex only in one out of three species. In addition, males across species displayed more explorative behavior than females and androgen levels correlated with explorative behavior and homing accuracy. Overall, we reveal that poison frog reproductive strategies shape movement patterns but not necessarily navigational performance. Together this work suggests that prevailing adaptive hypotheses provide an incomplete explanation of sex differences in spatial abilities.

Reproductive phenology of neotropical leptodactylid frogs (genera Physalaemus and Pseudopaludicola): Integrating gametogenic cycle, sexual maturity and age

Ontogeny, temporal strategies and the reproductive cycle are basic aspects of a species' life history and can provide us with information about the current status and future trends of a population. Here, we present data on reproductive biology, influence of environmental factors on male and female reproductive parameters and intra- and interspecific comparisons regarding these parameters, as well as unpublished data on age at sexual maturity and longevity of the syntopic and phylogenetically close frogs Physalaemus cuvieri – dog frog –, Physalaemus riograndensis – Rio Grande frog – and Pseudopaludicola falcipes – Hensel's swamp frog –, in southern Brazil. Accordingly, we used morphoanatomical and histological analyses, whose results were associated with climatological environmental variables (temperature, rainfall, relative humidity and photoperiod). Our results indicate that although they are phylogenetically close and that they co-occur in reproductive environments, the species differ in terms of reproductive cycle and in how environmental variables affect reproductive parameters between the sexes: photoperiod was the most important environmental factor for males and females of P. falcipes, while air humidity was more important for P. cuvieri. The age aspects also varied between the species, where sexual maturity was reached later in the Physalaemus species and the greatest longevity recorded for P. cuvieri. In addition, we found that there was intersexual and interspecific variation in the patterns measured, reflecting intrinsic differences in reproductive strategies and modes. Such studies are of paramount importance, as they serve as a basis for further research, in addition to allowing comparisons and/or possible generalizations about the evolutionary meaning of reproductive strategies.

Males mate with females even after sperm depletion in the two-spotted spider mite

Generally, males increase their reproductive success by mating with as many females as possible, whereas females increase their reproductive success by choosing males who provide more direct and indirect benefits. The difference in reproductive strategy between the sexes creates intense competition among males for access to females, therefore males spend much energy and time for competition with rival males for their reproduction. However, if they do not need to engage themselves into male competition and females are in no short supply, how many females can a male mate with and fertilize? We address this question in the two-spotted spider mite, Tetranychus urticae Koch. In this study, we investigated how many females a young, virgin male mated in 3h, and checked whether the mated females were fertilized. We found that on average males mated with 12-13 females (range: 5-25). As latency to next mating did not change with the number of matings, the males are predicted to engage in even more matings if the mating trial were continued beyond 3h. Copulation durations decreased with the number of matings and typically after 11 copulations with females any further copulations did not lead to fertilization, suggesting that males continued to mate with females even after sperm depletion. We discuss why spider mite males continue to display mating and copulation behaviour even after their sperm is depleted.

Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals.

Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade‐off between resource acquisition and risk, and that individuals differ in their position along this trade‐off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post‐molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among‐individual variation in space use essential in wildlife management and conservation.

The influence of divergent reproductive strategies in shaping modularity and morphological evolution in mammalian jaws.

Marsupial neonates are born at an earlier developmental stage than placental mammals, but the rapid development of their forelimbs and cranial skeleton allows them to climb to the pouch, begin suckling and complete their development ex utero. The mechanical environment in which marsupial neonates develop is vastly different from that of placental neonates, which exhibit a more protracted development of oral muscles and bones. This difference in reproductive strategy has been theorized to constrain morphological evolution in the oral region of marsupials. Here, we use 3D morphometrics to characterize one of these oral bones, the lower jaw (dentary), and assess modularity (pattern of covariation among traits), morphological disparity and rates of morphological evolution in two clades of carnivorous mammals: the marsupial Dasyuromorphia and placental fissiped Carnivora. We find that dasyuromorph dentaries have fewer modules than carnivorans and exhibit tight covariation between the angular and coronoid processes, the primary attachment sites for jaw-closing muscles. This pattern of modularity may result from the uniform action of muscles on the developing mandible during suckling. Carnivorans are free from this constraint and exhibit a pattern of modularity that more strongly reflects genetic and developmental signals of trait covariation. Alongside differences in modularity, carnivorans exhibit greater disparity and faster rates of morphological evolution compared with dasyuromorphs. Taken together, this suggests dasyuromorphs have retained a signal of trait covariation that reflects the outsized influence of muscular force during early development, a feature that may have impacted the ability of marsupial carnivores to explore specialized regions of morphospace.

Reproductive one health in primates.

One Health is a collaborative trans-disciplinary approach to health; integrating human, animal, and environmental health. The focus is often on infection disease transmission and disease risk mitigation. However, One Health also includes the multidisciplinary and comparative approach to disease investigation and health of humans, animals, and the environment. One key aspect of environmental/ecosystem health is conservation, the maintenance of healthy, actively reproducing wildlife populations. Reproduction and reproductive health are an integral part of the One Health approach: the comparative aspects of reproduction can inform conservation policies or breeding strategies (in situ and ex situ) in addition to physiology and disease. Differences in reproductive strategies affect the impact poaching and habitat disruption might have on a given population, as well as ex situ breeding programs and the management of zoo and sanctuary populations. Much is known about chimpanzees, macaques, and marmosets as these are common animal models, but there is much that remains unknown regarding reproduction in many other primates. Examining the similarities and differences between and within taxonomic groups allows reasonable extrapolation for decision-making when there are knowledge gaps. For example: (1) knowing that a species has very low reproductive rates adds urgency to conservation policy for that region or species; (2) identifying species with short or absent lactation anestrus allows ex situ institutions to better plan contraception options for specific individuals or prepare for the immediate next pregnancy; (3) recognizing that progestin contraceptives are effective contraceptives, but may be associated with endometrial hyperplasia in some species (in Lemuridae but not great apes) better guides empirical contraceptive choice; (4) recognizing the variable endometriosis prevalence across taxa improves preventive medicine programs. A summary of anatomical variation, endocrinology, contraception, pathology, and diagnostics is provided to illustrate these features and aid in routine physical and postmortem examinations as well as primate management.

In Pursuit of Pleasure: A Biopsychosocial Perspective on Sexual Pleasure and Gender

Objective: Various sources of evidence suggest that men and women differ in their experience of sexual pleasure. Such gender differences have been attributed to men’s higher innate sex drive, supported by evolutionary psychology perspectives and gender differences in reproductive strategies. Method: This paper presents biopsychosocial evidence for gender similarities in the capacity to experience pleasure, and for substantial gender differences in opportunities for sexual pleasure. Results: We conclude that sexual activity, in most cultures, is less pleasurable and associated with greater cost for heterosexual women than for heterosexual men, even though they do not differ in the capacity for sexual pleasure. Conclusion: Since gender differences in experienced sexual pleasure are not a biological given, a more critical discourse of sexual pleasure might create awareness of current inequalities, help lift restrictions for women’s opportunities for pleasure, and could reduce gender differences in the cost of sex. That would truly serve sexual justice around the globe.

Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

BackgroundSexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host–pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexual dimorphism in immunity in seed beetles, where mating causes internal injuries in females.ResultsWe demonstrate that female phenoloxidase (PO) activity, involved in wound healing and defence against parasitic infections, is elevated relative to males. This difference is accompanied by concomitant sex differences in the expression of genes in the prophenoloxidase activating cascade. We document substantial phenotypic plasticity in female PO activity in response to mating and show that experimental evolution under enforced monogamy (resulting in low remating rates and reduced sexual conflict relative to natural polygamy) rapidly decreases female (but not male) PO activity. Moreover, monogamous females had evolved increased tolerance to bacterial infection unrelated to mating, implying that female responses to costly mating may trade off with other aspects of immune defence, an hypothesis which broadly accords with the documented sex differences in gene expression. Finally, female (but not male) PO activity shows correlated evolution with the perceived harmfulness of male genitalia across 12 species of seed beetles, suggesting that sexual conflict has a significant influence on sexual dimorphisms in immunity in this group of insects.ConclusionsOur study provides insights into the links between sexual conflict and sexual dimorphism in immunity and suggests that selection pressures moulded by mating interactions can lead to a sex-specific mosaic of immune responses with important implications for host–pathogen dynamics in sexually reproducing organisms.

Tail autotomy is associated with boldness in male but not female water anoles

Sex differences in personality traits, such as boldness, are often driven by differences in life history strategies. Specifically, in a polygynous mating system where males defend territories to acquire mates, it may be beneficial for males to exhibit higher levels of boldness compared to females. However, males may also suffer a higher cost due to their bold behavior. Yet, few studies have documented evidence of the differential costs of boldness between the sexes. We examined these relationships in water anoles (Anolis aquaticus), using tail autotomy as a proxy for predation risk and/or injury from intraspecific competition. We measured boldness as latency to emerge from a refuge into a novel environment. We predicted that (1) males would exhibit bolder behavior than females, (2) boldness would be positively associated with tail autotomy (i.e., lizards with evidence of autotomized tails would be bolder than lizards without evidence of tail autotomy), and (3) a higher proportion of males would exhibit evidence of tail autotomy than females. We found that in our behavioral test, (1) boldness did not differ between the sexes, but that (2) there were sex differences in the costs of boldness, such that boldness was positively associated with tail autotomy in males but not in females, and (3) males tended to be more likely to exhibit evidence of tail autotomy. Together, these results suggest that males may suffer a higher cost of boldness due to sex differences in reproductive strategies. The sexes often differ in behavior because males and females use different tactics to fulfill reproductive success. Boldness is a personality trait that benefits both sexes in terms of acquiring resources. However, boldness should benefit males more when they defend territories and compete for mates. Though what is the cost of bold behavior and does this differ between the sexes? Here, we found that boldness is associated with risk-induced injuries (tail loss) in male water anoles, but not in females. The loss of the tail has been shown to have serious fitness consequences in lizards. Thus, male water anoles suffer a higher cost of bold behavior than females. Our results provide insight on the ecological relevance of boldness, and how selection may have led to differences in personality between the sexes.

Experimentally induced intrasexual mating competition and sex-specific evolution in female and male nematodes.

Sexual dimorphism in life history traits and their trade‐offs is widespread among sexually reproducing animals and is strongly influenced by the differences in reproductive strategies between the sexes. We investigated how intrasexual competition influenced specific life history traits, important to fitness and their trade‐offs in the outcrossing nematode Caenorhabditis remanei. Here, we altered the strength of sex‐specific selection through experimental evolution with increased potential for intrasexual competition by skewing the adult sex ratio towards either females or males (1:10 or 10:1) over 30 generations and subsequently measured the phenotypic response to selection in three traits related to fitness: body size, fecundity and tolerance to heat stress. We observed a greater evolutionary change in females than males for body size and peak fitness, suggesting that females may experience stronger net selection and potentially harbour higher amounts of standing genetic variance compared to males. Our study highlights the importance of investigating direct and indirect effects of intrasexual competition in both sexes in order to capture sex‐specific responses and understand the evolution of sexual dimorphism in traits expressed by both sexes.

Consistency of structural color across molts: The effects of environmental conditions and stress on feather ultraviolet reflectance

AbstractPlumage ornamentation is often considered a signal of fitness, condition, sex, or social status. This theory holds for species with structural UV color, which is influenced by a variety of factors such as environmental pressures during molt or heritability. However, little is known about the consistency of ornamentation and signaling across time in individuals with structural color. We compared juvenile and adult feathers in free-living Florida Scrub-Jays (Aphelocoma coerulescens) to measure UV color change within individuals across molts and to assess possible sources of change. We used multiple imputation to estimate missing data and a combination of pooled estimates and model averaging to infer which parameters explain observed variation in UV color. We also tested whether adult color or relative color change from juvenile to adult plumage predicted acquisition of breeding space. UV color was not consistent across annual molts, as adult feathers reflected significantly less light but greater proportions of UV light than juvenile feathers. Juvenile color was most affected by quality of natal environment and maternal effects whereas adult color was influenced by condition and juvenile color. Adults dosed with corticosterone produced feathers with less UV ornamentation compared to control adults. Feather color did not predict acquisition of breeding space in adults, but females that experienced reductions in UV color across molts were more likely to obtain breeding space, which may reflect sex-specific differences in reproductive strategies in Florida Scrub-Jays. Our evidence suggests that structural color acts as a signal of sex, age, and condition; but ornamentation is only weakly related to acquisition of breeding space and thus unlikely to be under strong sexual selection. Ornamentation may just be one factor among many, such as personality, social dominance, or position in social networks, that determine how jays interact and compete for breeding space.

Cellular metabolic rates and oxidative stress profiles in primary fibroblast cells isolated from virgin females, reproductively experienced females, and male Sprague-Dawley rats.

Life‐history theory posits that differences in reproductive strategies may dictate lifespans of organisms. Animals that have higher investments in reproduction in terms of litter size and frequency of litters tend to have shorter lifespans. The accumulation of oxidative stress damage has been proposed to be a cost of reproduction and a mediator of life‐histories among animals, however, the implications of reproduction on oxidative stress still remain unclear. We tested physiological consequences of reproduction on metabolism and oxidative stress of Sprague‐Dawley Rats (Rattus norvegicus) with various reproductive experiences at the cell level. We grew primary dermal fibroblasts from Sprague‐Dawley rats which have the potential of having large litters frequently. Cells were isolated from virgin females, primiparous females, multiparous females, and reproductively‐experienced males. We measured basal oxygen consumption (OCR), proton leak, ATP production, spare respiratory capacity, coupling efficiency and glycolysis using a Seahorse XF96 oxygen flux analyzer. Additionally, we measured rates of RS (reactive species) production, reduced glutathione (GSH), mitochondrial content, and lipid peroxidation (LPO) damage to quantify oxidative stress. There were no significant differences in any OCR or glycolytic parameters across any of our groups. However, reproductively‐experienced females had significantly lower rates of LPO damage as compared with virgin females and males, as well as nonsignificant decreases in GSH concentration. Decreases in LPO damage and GSH indicate that reproductively‐experienced females potentially use their endogenous antioxidant system to combat delirious effects of increased metabolism during reproduction. Our results suggest that reproduction may, in fact, have a protective effect in females.

Concordant community similarity patterns across functional groups in subarctic plant assemblages

AbstractIn light of increasing threats to global biodiversity, identifying the patterns in and drivers of variation in species composition along the environmental gradients in understudied regions is crucial for understanding ecosystem vulnerability and resilience. Terrestrial plant communities of interior Alaska are dominated by three major groups of primary producers—vascular plants, mosses, and macrolichens. Recent work has demonstrated broad‐scale positive correlations in species richness patterns among these three functional groups across scales in this region. However, the conspicuous and fundamental differences in reproductive strategies, dispersal ability, and physiological adaptations among these functional groups prompted us to investigate how community composition and species turnover vary across environmental gradients among these disparate groups. We hypothesized that species turnover would be greater in vascular plants than for spore‐producing cryptogam functional groups across gradients of elevation, vegetation type, and distance due to underlying differences in dispersal abilities and the temporal and spatial resolution of habitat preferences among these disparate groups. To address these issues, we compiled a uniquely comprehensive species composition dataset in interior Alaska utilizing a multi‐stage systematic design. We analyzed community similarity using Morisita‐Horn index of multi‐community similarity among all pairs of vegetation types and elevation bands for each functional group and used regression analysis to quantify the rate at which compositional similarity decayed with geographical distance among groups. Our study reveals consistently higher compositional variation (lower similarity) among vascular plants as compared to mosses and macrolichens across landscape gradients and spatial scales in interior Alaska. We also found that the decay of similarity with distance was less for both of the cryptogam groups than for vascular plants. Taken together, our results suggest that differences in functional group dispersal abilities, in combination with varying abilities to utilize fine‐scale temporal and spatial habitat variation, result in reduced turnover among mosses and macrolichens as compared to vascular plants both along landscape gradients and across distance in interior Alaska.

Weather, hydroregime, and breeding effort influence juvenile recruitment of anurans: implications for climate change

AbstractAmphibians that primarily breed in ephemeral wetlands are especially vulnerable to climate change because they rely on rainfall or temperature to initiate breeding and create suitable hydroregimes (water duration, timing, frequency, depth) for reproductive success. Hydroregime effects on reproductive success are likely to differ among species because of differences in reproductive strategies: the length and timing of breeding period, rate of larval development, and timing of metamorphosis. We applied an information‐theoretic approach to 22 consecutive years of continuous amphibian trapping data at eight ephemeral wetlands to test hypotheses regarding environmental (hydroregime, weather) and biological (adult breeding effort) factors affecting juvenile recruitment (JR) by six focal species representing four reproductive strategies. We hypothesized that (1) JR by species with similar reproductive strategies would be influenced by similar variables; (2) JR would be higher for all species when models encompassed the maximum time span of potential tadpole occurrence and development; and (3) JR rates within individual wetlands and breeding cycles would correlate most closely between species with similar breeding strategies. The best model for all focal species (except Scaphiopus holbrookii) encompassed the maximum time span and indicated that ≥1 hydroregime variable, total precipitation, or both were important drivers of reproductive success; average air temperature was not. Continuous hydroperiod through peak juvenile emigration was an important predictor of JR for species with prolonged breeding periods, slow larval development, and a “fixed” late spring start date for juvenile emigration (regardless of when oviposition occurred, or cohort age; Lithobates capito, Lithobates sphenocephalus), but not for species with rapid larval development and continual emigration as cohorts complete metamorphosis (Anaxyrus terrestris, Anaxyrus quercicus, Gastrophryne carolinensis, S. holbrookii). Total rainfall was positively associated with recruitment for most species; depth characteristics affected species differently. Annual JR was positively correlated among species with similar reproductive strategies. Our results indicate that weather and hydroregime characteristics interact with reproductive strategies that differ among amphibian species and influence reproductive plasticity, opportunity, and success. Effects of altered weather patterns associated with climate change on amphibian reproductive success may correspond more closely among species having similar reproductive strategies, with critical implications for population trends and assemblages.